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| author | Mauro Carvalho Chehab <mchehab@redhat.com> | 2009-09-17 11:17:44 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2009-09-17 11:17:44 -0300 |
| commit | ee117cb21fc99d6d1ef141b62ac07c2c99ed6558 (patch) | |
| tree | b3109826151f5b2cacd01a2a78fc51079381fec7 /linux/Documentation/DocBook/v4l | |
| parent | 3c34c6c8fa0c2f378cdad415e8f15c0938c28cb8 (diff) | |
| parent | 26642526dd562aa77049bb56d5bf9ad64158c767 (diff) | |
| download | mediapointer-dvb-s2-ee117cb21fc99d6d1ef141b62ac07c2c99ed6558.tar.gz mediapointer-dvb-s2-ee117cb21fc99d6d1ef141b62ac07c2c99ed6558.tar.bz2 | |
merge: http://kernellabs.com/hg/~mkrufky/saa7164
From: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'linux/Documentation/DocBook/v4l')
102 files changed, 24160 insertions, 0 deletions
diff --git a/linux/Documentation/DocBook/v4l/biblio.xml b/linux/Documentation/DocBook/v4l/biblio.xml new file mode 100644 index 000000000..afc8a0dd2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/biblio.xml @@ -0,0 +1,188 @@ + <bibliography> + <title>References</title> + + <biblioentry id="eia608"> + <abbrev>EIA 608-B</abbrev> + <authorgroup> + <corpauthor>Electronic Industries Alliance (<ulink +url="http://www.eia.org">http://www.eia.org</ulink>)</corpauthor> + </authorgroup> + <title>EIA 608-B "Recommended Practice for Line 21 Data +Service"</title> + </biblioentry> + + <biblioentry id="en300294"> + <abbrev>EN 300 294</abbrev> + <authorgroup> + <corpauthor>European Telecommunication Standards Institute +(<ulink url="http://www.etsi.org">http://www.etsi.org</ulink>)</corpauthor> + </authorgroup> + <title>EN 300 294 "625-line television Wide Screen Signalling +(WSS)"</title> + </biblioentry> + + <biblioentry id="ets300231"> + <abbrev>ETS 300 231</abbrev> + <authorgroup> + <corpauthor>European Telecommunication Standards Institute +(<ulink +url="http://www.etsi.org">http://www.etsi.org</ulink>)</corpauthor> + </authorgroup> + <title>ETS 300 231 "Specification of the domestic video +Programme Delivery Control system (PDC)"</title> + </biblioentry> + + <biblioentry id="ets300706"> + <abbrev>ETS 300 706</abbrev> + <authorgroup> + <corpauthor>European Telecommunication Standards Institute +(<ulink url="http://www.etsi.org">http://www.etsi.org</ulink>)</corpauthor> + </authorgroup> + <title>ETS 300 706 "Enhanced Teletext specification"</title> + </biblioentry> + + <biblioentry id="mpeg2part1"> + <abbrev>ISO 13818-1</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>), International +Organisation for Standardisation (<ulink +url="http://www.iso.ch">http://www.iso.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-T Rec. H.222.0 | ISO/IEC 13818-1 "Information +technology — Generic coding of moving pictures and associated +audio information: Systems"</title> + </biblioentry> + + <biblioentry id="mpeg2part2"> + <abbrev>ISO 13818-2</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>), International +Organisation for Standardisation (<ulink +url="http://www.iso.ch">http://www.iso.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-T Rec. H.262 | ISO/IEC 13818-2 "Information +technology — Generic coding of moving pictures and associated +audio information: Video"</title> + </biblioentry> + + <biblioentry id="itu470"> + <abbrev>ITU BT.470</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-R Recommendation BT.470-6 "Conventional Television +Systems"</title> + </biblioentry> + + <biblioentry id="itu601"> + <abbrev>ITU BT.601</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-R Recommendation BT.601-5 "Studio Encoding Parameters +of Digital Television for Standard 4:3 and Wide-Screen 16:9 Aspect +Ratios"</title> + </biblioentry> + + <biblioentry id="itu653"> + <abbrev>ITU BT.653</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-R Recommendation BT.653-3 "Teletext systems"</title> + </biblioentry> + + <biblioentry id="itu709"> + <abbrev>ITU BT.709</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-R Recommendation BT.709-5 "Parameter values for the +HDTV standards for production and international programme +exchange"</title> + </biblioentry> + + <biblioentry id="itu1119"> + <abbrev>ITU BT.1119</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union (<ulink +url="http://www.itu.ch">http://www.itu.ch</ulink>)</corpauthor> + </authorgroup> + <title>ITU-R Recommendation BT.1119 "625-line +television Wide Screen Signalling (WSS)"</title> + </biblioentry> + + <biblioentry id="jfif"> + <abbrev>JFIF</abbrev> + <authorgroup> + <corpauthor>Independent JPEG Group (<ulink +url="http://www.ijg.org">http://www.ijg.org</ulink>)</corpauthor> + </authorgroup> + <title>JPEG File Interchange Format</title> + <subtitle>Version 1.02</subtitle> + </biblioentry> + + <biblioentry id="smpte12m"> + <abbrev>SMPTE 12M</abbrev> + <authorgroup> + <corpauthor>Society of Motion Picture and Television Engineers +(<ulink url="http://www.smpte.org">http://www.smpte.org</ulink>)</corpauthor> + </authorgroup> + <title>SMPTE 12M-1999 "Television, Audio and Film - Time and +Control Code"</title> + </biblioentry> + + <biblioentry id="smpte170m"> + <abbrev>SMPTE 170M</abbrev> + <authorgroup> + <corpauthor>Society of Motion Picture and Television Engineers +(<ulink url="http://www.smpte.org">http://www.smpte.org</ulink>)</corpauthor> + </authorgroup> + <title>SMPTE 170M-1999 "Television - Composite Analog Video +Signal - NTSC for Studio Applications"</title> + </biblioentry> + + <biblioentry id="smpte240m"> + <abbrev>SMPTE 240M</abbrev> + <authorgroup> + <corpauthor>Society of Motion Picture and Television Engineers +(<ulink url="http://www.smpte.org">http://www.smpte.org</ulink>)</corpauthor> + </authorgroup> + <title>SMPTE 240M-1999 "Television - Signal Parameters - +1125-Line High-Definition Production"</title> + </biblioentry> + + <biblioentry id="en50067"> + <abbrev>EN 50067</abbrev> + <authorgroup> + <corpauthor>European Committee for Electrotechnical Standardization +(<ulink url="http://www.cenelec.eu">http://www.cenelec.eu</ulink>)</corpauthor> + </authorgroup> + <title>Specification of the radio data system (RDS) for VHF/FM sound broadcasting +in the frequency range from 87,5 to 108,0 MHz</title> + </biblioentry> + + <biblioentry id="nrsc4"> + <abbrev>NRSC-4</abbrev> + <authorgroup> + <corpauthor>National Radio Systems Committee +(<ulink url="http://www.nrscstandards.org">http://www.nrscstandards.org</ulink>)</corpauthor> + </authorgroup> + <title>NTSC-4: United States RBDS Standard</title> + </biblioentry> + + </bibliography> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/common.xml b/linux/Documentation/DocBook/v4l/common.xml new file mode 100644 index 000000000..b1a81d246 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/common.xml @@ -0,0 +1,1160 @@ + <title>Common API Elements</title> + + <para>Programming a V4L2 device consists of these +steps:</para> + + <itemizedlist> + <listitem> + <para>Opening the device</para> + </listitem> + <listitem> + <para>Changing device properties, selecting a video and audio +input, video standard, picture brightness a. o.</para> + </listitem> + <listitem> + <para>Negotiating a data format</para> + </listitem> + <listitem> + <para>Negotiating an input/output method</para> + </listitem> + <listitem> + <para>The actual input/output loop</para> + </listitem> + <listitem> + <para>Closing the device</para> + </listitem> + </itemizedlist> + + <para>In practice most steps are optional and can be executed out of +order. It depends on the V4L2 device type, you can read about the +details in <xref linkend="devices" />. In this chapter we will discuss +the basic concepts applicable to all devices.</para> + + <section id="open"> + <title>Opening and Closing Devices</title> + + <section> + <title>Device Naming</title> + + <para>V4L2 drivers are implemented as kernel modules, loaded +manually by the system administrator or automatically when a device is +first opened. The driver modules plug into the "videodev" kernel +module. It provides helper functions and a common application +interface specified in this document.</para> + + <para>Each driver thus loaded registers one or more device nodes +with major number 81 and a minor number between 0 and 255. Assigning +minor numbers to V4L2 devices is entirely up to the system administrator, +this is primarily intended to solve conflicts between devices.<footnote> + <para>Access permissions are associated with character +device special files, hence we must ensure device numbers cannot +change with the module load order. To this end minor numbers are no +longer automatically assigned by the "videodev" module as in V4L but +requested by the driver. The defaults will suffice for most people +unless two drivers compete for the same minor numbers.</para> + </footnote> The module options to select minor numbers are named +after the device special file with a "_nr" suffix. For example "video_nr" +for <filename>/dev/video</filename> video capture devices. The number is +an offset to the base minor number associated with the device type. +<footnote> + <para>In earlier versions of the V4L2 API the module options +where named after the device special file with a "unit_" prefix, expressing +the minor number itself, not an offset. Rationale for this change is unknown. +Lastly the naming and semantics are just a convention among driver writers, +the point to note is that minor numbers are not supposed to be hardcoded +into drivers.</para> + </footnote> When the driver supports multiple devices of the same +type more than one minor number can be assigned, separated by commas: +<informalexample> + <screen> +> insmod mydriver.o video_nr=0,1 radio_nr=0,1</screen> + </informalexample></para> + + <para>In <filename>/etc/modules.conf</filename> this may be +written as: <informalexample> + <screen> +alias char-major-81-0 mydriver +alias char-major-81-1 mydriver +alias char-major-81-64 mydriver <co id="alias" /> +options mydriver video_nr=0,1 radio_nr=0,1 <co id="options" /> + </screen> + <calloutlist> + <callout arearefs="alias"> + <para>When an application attempts to open a device +special file with major number 81 and minor number 0, 1, or 64, load +"mydriver" (and the "videodev" module it depends upon).</para> + </callout> + <callout arearefs="options"> + <para>Register the first two video capture devices with +minor number 0 and 1 (base number is 0), the first two radio device +with minor number 64 and 65 (base 64).</para> + </callout> + </calloutlist> + </informalexample> When no minor number is given as module +option the driver supplies a default. <xref linkend="devices" /> +recommends the base minor numbers to be used for the various device +types. Obviously minor numbers must be unique. When the number is +already in use the <emphasis>offending device</emphasis> will not be +registered. <!-- Blessed by Linus Torvalds on +linux-kernel@vger.kernel.org, 2002-11-20. --></para> + + <para>By convention system administrators create various +character device special files with these major and minor numbers in +the <filename>/dev</filename> directory. The names recomended for the +different V4L2 device types are listed in <xref linkend="devices" />. +</para> + + <para>The creation of character special files (with +<application>mknod</application>) is a privileged operation and +devices cannot be opened by major and minor number. That means +applications cannot <emphasis>reliable</emphasis> scan for loaded or +installed drivers. The user must enter a device name, or the +application can try the conventional device names.</para> + + <para>Under the device filesystem (devfs) the minor number +options are ignored. V4L2 drivers (or by proxy the "videodev" module) +automatically create the required device files in the +<filename>/dev/v4l</filename> directory using the conventional device +names above.</para> + </section> + + <section id="related"> + <title>Related Devices</title> + + <para>Devices can support several related functions. For example +video capturing, video overlay and VBI capturing are related because +these functions share, amongst other, the same video input and tuner +frequency. V4L and earlier versions of V4L2 used the same device name +and minor number for video capturing and overlay, but different ones +for VBI. Experience showed this approach has several problems<footnote> + <para>Given a device file name one cannot reliable find +related devices. For once names are arbitrary and in a system with +multiple devices, where only some support VBI capturing, a +<filename>/dev/video2</filename> is not necessarily related to +<filename>/dev/vbi2</filename>. The V4L +<constant>VIDIOCGUNIT</constant> ioctl would require a search for a +device file with a particular major and minor number.</para> + </footnote>, and to make things worse the V4L videodev module +used to prohibit multiple opens of a device.</para> + + <para>As a remedy the present version of the V4L2 API relaxed the +concept of device types with specific names and minor numbers. For +compatibility with old applications drivers must still register different +minor numbers to assign a default function to the device. But if related +functions are supported by the driver they must be available under all +registered minor numbers. The desired function can be selected after +opening the device as described in <xref linkend="devices" />.</para> + + <para>Imagine a driver supporting video capturing, video +overlay, raw VBI capturing, and FM radio reception. It registers three +devices with minor number 0, 64 and 224 (this numbering scheme is +inherited from the V4L API). Regardless if +<filename>/dev/video</filename> (81, 0) or +<filename>/dev/vbi</filename> (81, 224) is opened the application can +select any one of the video capturing, overlay or VBI capturing +functions. Without programming (e. g. reading from the device +with <application>dd</application> or <application>cat</application>) +<filename>/dev/video</filename> captures video images, while +<filename>/dev/vbi</filename> captures raw VBI data. +<filename>/dev/radio</filename> (81, 64) is invariable a radio device, +unrelated to the video functions. Being unrelated does not imply the +devices can be used at the same time, however. The &func-open; +function may very well return an &EBUSY;.</para> + + <para>Besides video input or output the hardware may also +support audio sampling or playback. If so, these functions are +implemented as OSS or ALSA PCM devices and eventually OSS or ALSA +audio mixer. The V4L2 API makes no provisions yet to find these +related devices. If you have an idea please write to the linux-media +mailing list: &v4l-ml;.</para> + </section> + + <section> + <title>Multiple Opens</title> + + <para>In general, V4L2 devices can be opened more than once. +When this is supported by the driver, users can for example start a +"panel" application to change controls like brightness or audio +volume, while another application captures video and audio. In other words, panel +applications are comparable to an OSS or ALSA audio mixer application. +When a device supports multiple functions like capturing and overlay +<emphasis>simultaneously</emphasis>, multiple opens allow concurrent +use of the device by forked processes or specialized applications.</para> + + <para>Multiple opens are optional, although drivers should +permit at least concurrent accesses without data exchange, &ie; panel +applications. This implies &func-open; can return an &EBUSY; when the +device is already in use, as well as &func-ioctl; functions initiating +data exchange (namely the &VIDIOC-S-FMT; ioctl), and the &func-read; +and &func-write; functions.</para> + + <para>Mere opening a V4L2 device does not grant exclusive +access.<footnote> + <para>Drivers could recognize the +<constant>O_EXCL</constant> open flag. Presently this is not required, +so applications cannot know if it really works.</para> + </footnote> Initiating data exchange however assigns the right +to read or write the requested type of data, and to change related +properties, to this file descriptor. Applications can request +additional access privileges using the priority mechanism described in +<xref linkend="app-pri" />.</para> + </section> + + <section> + <title>Shared Data Streams</title> + + <para>V4L2 drivers should not support multiple applications +reading or writing the same data stream on a device by copying +buffers, time multiplexing or similar means. This is better handled by +a proxy application in user space. When the driver supports stream +sharing anyway it must be implemented transparently. The V4L2 API does +not specify how conflicts are solved. <!-- For example O_EXCL when the +application does not want to be preempted, PROT_READ mmapped buffers +which can be mapped twice, what happens when image formats do not +match etc.--></para> + </section> + + <section> + <title>Functions</title> + + <para>To open and close V4L2 devices applications use the +&func-open; and &func-close; function, respectively. Devices are +programmed using the &func-ioctl; function as explained in the +following sections.</para> + </section> + </section> + + <section id="querycap"> + <title>Querying Capabilities</title> + + <para>Because V4L2 covers a wide variety of devices not all +aspects of the API are equally applicable to all types of devices. +Furthermore devices of the same type have different capabilities and +this specification permits the omission of a few complicated and less +important parts of the API.</para> + + <para>The &VIDIOC-QUERYCAP; ioctl is available to check if the kernel +device is compatible with this specification, and to query the <link +linkend="devices">functions</link> and <link linkend="io">I/O +methods</link> supported by the device. Other features can be queried +by calling the respective ioctl, for example &VIDIOC-ENUMINPUT; +to learn about the number, types and names of video connectors on the +device. Although abstraction is a major objective of this API, the +ioctl also allows driver specific applications to reliable identify +the driver.</para> + + <para>All V4L2 drivers must support +<constant>VIDIOC_QUERYCAP</constant>. Applications should always call +this ioctl after opening the device.</para> + </section> + + <section id="app-pri"> + <title>Application Priority</title> + + <para>When multiple applications share a device it may be +desirable to assign them different priorities. Contrary to the +traditional "rm -rf /" school of thought a video recording application +could for example block other applications from changing video +controls or switching the current TV channel. Another objective is to +permit low priority applications working in background, which can be +preempted by user controlled applications and automatically regain +control of the device at a later time.</para> + + <para>Since these features cannot be implemented entirely in user +space V4L2 defines the &VIDIOC-G-PRIORITY; and &VIDIOC-S-PRIORITY; +ioctls to request and query the access priority associate with a file +descriptor. Opening a device assigns a medium priority, compatible +with earlier versions of V4L2 and drivers not supporting these ioctls. +Applications requiring a different priority will usually call +<constant>VIDIOC_S_PRIORITY</constant> after verifying the device with +the &VIDIOC-QUERYCAP; ioctl.</para> + + <para>Ioctls changing driver properties, such as &VIDIOC-S-INPUT;, +return an &EBUSY; after another application obtained higher priority. +An event mechanism to notify applications about asynchronous property +changes has been proposed but not added yet.</para> + </section> + + <section id="video"> + <title>Video Inputs and Outputs</title> + + <para>Video inputs and outputs are physical connectors of a +device. These can be for example RF connectors (antenna/cable), CVBS +a.k.a. Composite Video, S-Video or RGB connectors. Only video and VBI +capture devices have inputs, output devices have outputs, at least one +each. Radio devices have no video inputs or outputs.</para> + + <para>To learn about the number and attributes of the +available inputs and outputs applications can enumerate them with the +&VIDIOC-ENUMINPUT; and &VIDIOC-ENUMOUTPUT; ioctl, respectively. The +&v4l2-input; returned by the <constant>VIDIOC_ENUMINPUT</constant> +ioctl also contains signal status information applicable when the +current video input is queried.</para> + + <para>The &VIDIOC-G-INPUT; and &VIDIOC-G-OUTPUT; ioctl return the +index of the current video input or output. To select a different +input or output applications call the &VIDIOC-S-INPUT; and +&VIDIOC-S-OUTPUT; ioctl. Drivers must implement all the input ioctls +when the device has one or more inputs, all the output ioctls when the +device has one or more outputs.</para> + + <!-- + <figure id=io-tree> + <title>Input and output enumeration is the root of most device properties.</title> + <mediaobject> + <imageobject> + <imagedata fileref="links.pdf" format="ps" /> + </imageobject> + <imageobject> + <imagedata fileref="links.gif" format="gif" /> + </imageobject> + <textobject> + <phrase>Links between various device property structures.</phrase> + </textobject> + </mediaobject> + </figure> + --> + + <example> + <title>Information about the current video input</title> + + <programlisting> +&v4l2-input; input; +int index; + +if (-1 == ioctl (fd, &VIDIOC-G-INPUT;, &index)) { + perror ("VIDIOC_G_INPUT"); + exit (EXIT_FAILURE); +} + +memset (&input, 0, sizeof (input)); +input.index = index; + +if (-1 == ioctl (fd, &VIDIOC-ENUMINPUT;, &input)) { + perror ("VIDIOC_ENUMINPUT"); + exit (EXIT_FAILURE); +} + +printf ("Current input: %s\n", input.name); + </programlisting> + </example> + + <example> + <title>Switching to the first video input</title> + + <programlisting> +int index; + +index = 0; + +if (-1 == ioctl (fd, &VIDIOC-S-INPUT;, &index)) { + perror ("VIDIOC_S_INPUT"); + exit (EXIT_FAILURE); +} + </programlisting> + </example> + </section> + + <section id="audio"> + <title>Audio Inputs and Outputs</title> + + <para>Audio inputs and outputs are physical connectors of a +device. Video capture devices have inputs, output devices have +outputs, zero or more each. Radio devices have no audio inputs or +outputs. They have exactly one tuner which in fact +<emphasis>is</emphasis> an audio source, but this API associates +tuners with video inputs or outputs only, and radio devices have +none of these.<footnote> + <para>Actually &v4l2-audio; ought to have a +<structfield>tuner</structfield> field like &v4l2-input;, not only +making the API more consistent but also permitting radio devices with +multiple tuners.</para> + </footnote> A connector on a TV card to loop back the received +audio signal to a sound card is not considered an audio output.</para> + + <para>Audio and video inputs and outputs are associated. Selecting +a video source also selects an audio source. This is most evident when +the video and audio source is a tuner. Further audio connectors can +combine with more than one video input or output. Assumed two +composite video inputs and two audio inputs exist, there may be up to +four valid combinations. The relation of video and audio connectors +is defined in the <structfield>audioset</structfield> field of the +respective &v4l2-input; or &v4l2-output;, where each bit represents +the index number, starting at zero, of one audio input or output.</para> + + <para>To learn about the number and attributes of the +available inputs and outputs applications can enumerate them with the +&VIDIOC-ENUMAUDIO; and &VIDIOC-ENUMAUDOUT; ioctl, respectively. The +&v4l2-audio; returned by the <constant>VIDIOC_ENUMAUDIO</constant> ioctl +also contains signal status information applicable when the current +audio input is queried.</para> + + <para>The &VIDIOC-G-AUDIO; and &VIDIOC-G-AUDOUT; ioctl report +the current audio input and output, respectively. Note that, unlike +&VIDIOC-G-INPUT; and &VIDIOC-G-OUTPUT; these ioctls return a structure +as <constant>VIDIOC_ENUMAUDIO</constant> and +<constant>VIDIOC_ENUMAUDOUT</constant> do, not just an index.</para> + + <para>To select an audio input and change its properties +applications call the &VIDIOC-S-AUDIO; ioctl. To select an audio +output (which presently has no changeable properties) applications +call the &VIDIOC-S-AUDOUT; ioctl.</para> + + <para>Drivers must implement all input ioctls when the device +has one or more inputs, all output ioctls when the device has one +or more outputs. When the device has any audio inputs or outputs the +driver must set the <constant>V4L2_CAP_AUDIO</constant> flag in the +&v4l2-capability; returned by the &VIDIOC-QUERYCAP; ioctl.</para> + + <example> + <title>Information about the current audio input</title> + + <programlisting> +&v4l2-audio; audio; + +memset (&audio, 0, sizeof (audio)); + +if (-1 == ioctl (fd, &VIDIOC-G-AUDIO;, &audio)) { + perror ("VIDIOC_G_AUDIO"); + exit (EXIT_FAILURE); +} + +printf ("Current input: %s\n", audio.name); + </programlisting> + </example> + + <example> + <title>Switching to the first audio input</title> + + <programlisting> +&v4l2-audio; audio; + +memset (&audio, 0, sizeof (audio)); /* clear audio.mode, audio.reserved */ + +audio.index = 0; + +if (-1 == ioctl (fd, &VIDIOC-S-AUDIO;, &audio)) { + perror ("VIDIOC_S_AUDIO"); + exit (EXIT_FAILURE); +} + </programlisting> + </example> + </section> + + <section id="tuner"> + <title>Tuners and Modulators</title> + + <section> + <title>Tuners</title> + + <para>Video input devices can have one or more tuners +demodulating a RF signal. Each tuner is associated with one or more +video inputs, depending on the number of RF connectors on the tuner. +The <structfield>type</structfield> field of the respective +&v4l2-input; returned by the &VIDIOC-ENUMINPUT; ioctl is set to +<constant>V4L2_INPUT_TYPE_TUNER</constant> and its +<structfield>tuner</structfield> field contains the index number of +the tuner.</para> + + <para>Radio devices have exactly one tuner with index zero, no +video inputs.</para> + + <para>To query and change tuner properties applications use the +&VIDIOC-G-TUNER; and &VIDIOC-S-TUNER; ioctl, respectively. The +&v4l2-tuner; returned by <constant>VIDIOC_G_TUNER</constant> also +contains signal status information applicable when the tuner of the +current video input, or a radio tuner is queried. Note that +<constant>VIDIOC_S_TUNER</constant> does not switch the current tuner, +when there is more than one at all. The tuner is solely determined by +the current video input. Drivers must support both ioctls and set the +<constant>V4L2_CAP_TUNER</constant> flag in the &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl when the device has one or +more tuners.</para> + </section> + + <section> + <title>Modulators</title> + + <para>Video output devices can have one or more modulators, uh, +modulating a video signal for radiation or connection to the antenna +input of a TV set or video recorder. Each modulator is associated with +one or more video outputs, depending on the number of RF connectors on +the modulator. The <structfield>type</structfield> field of the +respective &v4l2-output; returned by the &VIDIOC-ENUMOUTPUT; ioctl is +set to <constant>V4L2_OUTPUT_TYPE_MODULATOR</constant> and its +<structfield>modulator</structfield> field contains the index number +of the modulator. This specification does not define radio output +devices.</para> + + <para>To query and change modulator properties applications use +the &VIDIOC-G-MODULATOR; and &VIDIOC-S-MODULATOR; ioctl. Note that +<constant>VIDIOC_S_MODULATOR</constant> does not switch the current +modulator, when there is more than one at all. The modulator is solely +determined by the current video output. Drivers must support both +ioctls and set the <constant>V4L2_CAP_MODULATOR</constant> flag in +the &v4l2-capability; returned by the &VIDIOC-QUERYCAP; ioctl when the +device has one or more modulators.</para> + </section> + + <section> + <title>Radio Frequency</title> + + <para>To get and set the tuner or modulator radio frequency +applications use the &VIDIOC-G-FREQUENCY; and &VIDIOC-S-FREQUENCY; +ioctl which both take a pointer to a &v4l2-frequency;. These ioctls +are used for TV and radio devices alike. Drivers must support both +ioctls when the tuner or modulator ioctls are supported, or +when the device is a radio device.</para> + </section> + </section> + + <section id="standard"> + <title>Video Standards</title> + + <para>Video devices typically support one or more different video +standards or variations of standards. Each video input and output may +support another set of standards. This set is reported by the +<structfield>std</structfield> field of &v4l2-input; and +&v4l2-output; returned by the &VIDIOC-ENUMINPUT; and +&VIDIOC-ENUMOUTPUT; ioctl, respectively.</para> + + <para>V4L2 defines one bit for each analog video standard +currently in use worldwide, and sets aside bits for driver defined +standards, ⪚ hybrid standards to watch NTSC video tapes on PAL TVs +and vice versa. Applications can use the predefined bits to select a +particular standard, although presenting the user a menu of supported +standards is preferred. To enumerate and query the attributes of the +supported standards applications use the &VIDIOC-ENUMSTD; ioctl.</para> + + <para>Many of the defined standards are actually just variations +of a few major standards. The hardware may in fact not distinguish +between them, or do so internal and switch automatically. Therefore +enumerated standards also contain sets of one or more standard +bits.</para> + + <para>Assume a hypothetic tuner capable of demodulating B/PAL, +G/PAL and I/PAL signals. The first enumerated standard is a set of B +and G/PAL, switched automatically depending on the selected radio +frequency in UHF or VHF band. Enumeration gives a "PAL-B/G" or "PAL-I" +choice. Similar a Composite input may collapse standards, enumerating +"PAL-B/G/H/I", "NTSC-M" and "SECAM-D/K".<footnote> + <para>Some users are already confused by technical terms PAL, +NTSC and SECAM. There is no point asking them to distinguish between +B, G, D, or K when the software or hardware can do that +automatically.</para> + </footnote></para> + + <para>To query and select the standard used by the current video +input or output applications call the &VIDIOC-G-STD; and +&VIDIOC-S-STD; ioctl, respectively. The <emphasis>received</emphasis> +standard can be sensed with the &VIDIOC-QUERYSTD; ioctl. Note parameter of all these ioctls is a pointer to a &v4l2-std-id; type (a standard set), <emphasis>not</emphasis> an index into the standard enumeration.<footnote> + <para>An alternative to the current scheme is to use pointers +to indices as arguments of <constant>VIDIOC_G_STD</constant> and +<constant>VIDIOC_S_STD</constant>, the &v4l2-input; and +&v4l2-output; <structfield>std</structfield> field would be a set of +indices like <structfield>audioset</structfield>.</para> + <para>Indices are consistent with the rest of the API +and identify the standard unambiguously. In the present scheme of +things an enumerated standard is looked up by &v4l2-std-id;. Now the +standards supported by the inputs of a device can overlap. Just +assume the tuner and composite input in the example above both +exist on a device. An enumeration of "PAL-B/G", "PAL-H/I" suggests +a choice which does not exist. We cannot merge or omit sets, because +applications would be unable to find the standards reported by +<constant>VIDIOC_G_STD</constant>. That leaves separate enumerations +for each input. Also selecting a standard by &v4l2-std-id; can be +ambiguous. Advantage of this method is that applications need not +identify the standard indirectly, after enumerating.</para><para>So in +summary, the lookup itself is unavoidable. The difference is only +whether the lookup is necessary to find an enumerated standard or to +switch to a standard by &v4l2-std-id;.</para> + </footnote> Drivers must implement all video standard ioctls +when the device has one or more video inputs or outputs.</para> + + <para>Special rules apply to USB cameras where the notion of video +standards makes little sense. More generally any capture device, +output devices accordingly, which is <itemizedlist> + <listitem> + <para>incapable of capturing fields or frames at the nominal +rate of the video standard, or</para> + </listitem> + <listitem> + <para>where <link linkend="buffer">timestamps</link> refer +to the instant the field or frame was received by the driver, not the +capture time, or</para> + </listitem> + <listitem> + <para>where <link linkend="buffer">sequence numbers</link> +refer to the frames received by the driver, not the captured +frames.</para> + </listitem> + </itemizedlist> Here the driver shall set the +<structfield>std</structfield> field of &v4l2-input; and &v4l2-output; +to zero, the <constant>VIDIOC_G_STD</constant>, +<constant>VIDIOC_S_STD</constant>, +<constant>VIDIOC_QUERYSTD</constant> and +<constant>VIDIOC_ENUMSTD</constant> ioctls shall return the +&EINVAL;.<footnote> + <para>See <xref linkend="buffer" /> for a rationale. Probably +even USB cameras follow some well known video standard. It might have +been better to explicitly indicate elsewhere if a device cannot live +up to normal expectations, instead of this exception.</para> + </footnote></para> + + <example> + <title>Information about the current video standard</title> + + <programlisting> +&v4l2-std-id; std_id; +&v4l2-standard; standard; + +if (-1 == ioctl (fd, &VIDIOC-G-STD;, &std_id)) { + /* Note when VIDIOC_ENUMSTD always returns EINVAL this + is no video device or it falls under the USB exception, + and VIDIOC_G_STD returning EINVAL is no error. */ + + perror ("VIDIOC_G_STD"); + exit (EXIT_FAILURE); +} + +memset (&standard, 0, sizeof (standard)); +standard.index = 0; + +while (0 == ioctl (fd, &VIDIOC-ENUMSTD;, &standard)) { + if (standard.id & std_id) { + printf ("Current video standard: %s\n", standard.name); + exit (EXIT_SUCCESS); + } + + standard.index++; +} + +/* EINVAL indicates the end of the enumeration, which cannot be + empty unless this device falls under the USB exception. */ + +if (errno == EINVAL || standard.index == 0) { + perror ("VIDIOC_ENUMSTD"); + exit (EXIT_FAILURE); +} + </programlisting> + </example> + + <example> + <title>Listing the video standards supported by the current +input</title> + + <programlisting> +&v4l2-input; input; +&v4l2-standard; standard; + +memset (&input, 0, sizeof (input)); + +if (-1 == ioctl (fd, &VIDIOC-G-INPUT;, &input.index)) { + perror ("VIDIOC_G_INPUT"); + exit (EXIT_FAILURE); +} + +if (-1 == ioctl (fd, &VIDIOC-ENUMINPUT;, &input)) { + perror ("VIDIOC_ENUM_INPUT"); + exit (EXIT_FAILURE); +} + +printf ("Current input %s supports:\n", input.name); + +memset (&standard, 0, sizeof (standard)); +standard.index = 0; + +while (0 == ioctl (fd, &VIDIOC-ENUMSTD;, &standard)) { + if (standard.id & input.std) + printf ("%s\n", standard.name); + + standard.index++; +} + +/* EINVAL indicates the end of the enumeration, which cannot be + empty unless this device falls under the USB exception. */ + +if (errno != EINVAL || standard.index == 0) { + perror ("VIDIOC_ENUMSTD"); + exit (EXIT_FAILURE); +} + </programlisting> + </example> + + <example> + <title>Selecting a new video standard</title> + + <programlisting> +&v4l2-input; input; +&v4l2-std-id; std_id; + +memset (&input, 0, sizeof (input)); + +if (-1 == ioctl (fd, &VIDIOC-G-INPUT;, &input.index)) { + perror ("VIDIOC_G_INPUT"); + exit (EXIT_FAILURE); +} + +if (-1 == ioctl (fd, &VIDIOC-ENUMINPUT;, &input)) { + perror ("VIDIOC_ENUM_INPUT"); + exit (EXIT_FAILURE); +} + +if (0 == (input.std & V4L2_STD_PAL_BG)) { + fprintf (stderr, "Oops. B/G PAL is not supported.\n"); + exit (EXIT_FAILURE); +} + +/* Note this is also supposed to work when only B + <emphasis>or</emphasis> G/PAL is supported. */ + +std_id = V4L2_STD_PAL_BG; + +if (-1 == ioctl (fd, &VIDIOC-S-STD;, &std_id)) { + perror ("VIDIOC_S_STD"); + exit (EXIT_FAILURE); +} + </programlisting> + </example> + </section> + + &sub-controls; + + <section id="format"> + <title>Data Formats</title> + + <section> + <title>Data Format Negotiation</title> + + <para>Different devices exchange different kinds of data with +applications, for example video images, raw or sliced VBI data, RDS +datagrams. Even within one kind many different formats are possible, +in particular an abundance of image formats. Although drivers must +provide a default and the selection persists across closing and +reopening a device, applications should always negotiate a data format +before engaging in data exchange. Negotiation means the application +asks for a particular format and the driver selects and reports the +best the hardware can do to satisfy the request. Of course +applications can also just query the current selection.</para> + + <para>A single mechanism exists to negotiate all data formats +using the aggregate &v4l2-format; and the &VIDIOC-G-FMT; and +&VIDIOC-S-FMT; ioctls. Additionally the &VIDIOC-TRY-FMT; ioctl can be +used to examine what the hardware <emphasis>could</emphasis> do, +without actually selecting a new data format. The data formats +supported by the V4L2 API are covered in the respective device section +in <xref linkend="devices" />. For a closer look at image formats see +<xref linkend="pixfmt" />.</para> + + <para>The <constant>VIDIOC_S_FMT</constant> ioctl is a major +turning-point in the initialization sequence. Prior to this point +multiple panel applications can access the same device concurrently to +select the current input, change controls or modify other properties. +The first <constant>VIDIOC_S_FMT</constant> assigns a logical stream +(video data, VBI data etc.) exclusively to one file descriptor.</para> + + <para>Exclusive means no other application, more precisely no +other file descriptor, can grab this stream or change device +properties inconsistent with the negotiated parameters. A video +standard change for example, when the new standard uses a different +number of scan lines, can invalidate the selected image format. +Therefore only the file descriptor owning the stream can make +invalidating changes. Accordingly multiple file descriptors which +grabbed different logical streams prevent each other from interfering +with their settings. When for example video overlay is about to start +or already in progress, simultaneous video capturing may be restricted +to the same cropping and image size.</para> + + <para>When applications omit the +<constant>VIDIOC_S_FMT</constant> ioctl its locking side effects are +implied by the next step, the selection of an I/O method with the +&VIDIOC-REQBUFS; ioctl or implicit with the first &func-read; or +&func-write; call.</para> + + <para>Generally only one logical stream can be assigned to a +file descriptor, the exception being drivers permitting simultaneous +video capturing and overlay using the same file descriptor for +compatibility with V4L and earlier versions of V4L2. Switching the +logical stream or returning into "panel mode" is possible by closing +and reopening the device. Drivers <emphasis>may</emphasis> support a +switch using <constant>VIDIOC_S_FMT</constant>.</para> + + <para>All drivers exchanging data with +applications must support the <constant>VIDIOC_G_FMT</constant> and +<constant>VIDIOC_S_FMT</constant> ioctl. Implementation of the +<constant>VIDIOC_TRY_FMT</constant> is highly recommended but +optional.</para> + </section> + + <section> + <title>Image Format Enumeration</title> + + <para>Apart of the generic format negotiation functions +a special ioctl to enumerate all image formats supported by video +capture, overlay or output devices is available.<footnote> + <para>Enumerating formats an application has no a-priori +knowledge of (otherwise it could explicitly ask for them and need not +enumerate) seems useless, but there are applications serving as proxy +between drivers and the actual video applications for which this is +useful.</para> + </footnote></para> + + <para>The &VIDIOC-ENUM-FMT; ioctl must be supported +by all drivers exchanging image data with applications.</para> + + <important> + <para>Drivers are not supposed to convert image formats in +kernel space. They must enumerate only formats directly supported by +the hardware. If necessary driver writers should publish an example +conversion routine or library for integration into applications.</para> + </important> + </section> + </section> + + <section id="crop"> + <title>Image Cropping, Insertion and Scaling</title> + + <para>Some video capture devices can sample a subsection of the +picture and shrink or enlarge it to an image of arbitrary size. We +call these abilities cropping and scaling. Some video output devices +can scale an image up or down and insert it at an arbitrary scan line +and horizontal offset into a video signal.</para> + + <para>Applications can use the following API to select an area in +the video signal, query the default area and the hardware limits. +<emphasis>Despite their name, the &VIDIOC-CROPCAP;, &VIDIOC-G-CROP; +and &VIDIOC-S-CROP; ioctls apply to input as well as output +devices.</emphasis></para> + + <para>Scaling requires a source and a target. On a video capture +or overlay device the source is the video signal, and the cropping +ioctls determine the area actually sampled. The target are images +read by the application or overlaid onto the graphics screen. Their +size (and position for an overlay) is negotiated with the +&VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctls.</para> + + <para>On a video output device the source are the images passed in +by the application, and their size is again negotiated with the +<constant>VIDIOC_G/S_FMT</constant> ioctls, or may be encoded in a +compressed video stream. The target is the video signal, and the +cropping ioctls determine the area where the images are +inserted.</para> + + <para>Source and target rectangles are defined even if the device +does not support scaling or the <constant>VIDIOC_G/S_CROP</constant> +ioctls. Their size (and position where applicable) will be fixed in +this case. <emphasis>All capture and output device must support the +<constant>VIDIOC_CROPCAP</constant> ioctl such that applications can +determine if scaling takes place.</emphasis></para> + + <section> + <title>Cropping Structures</title> + + <figure id="crop-scale"> + <title>Image Cropping, Insertion and Scaling</title> + <mediaobject> + <imageobject> + <imagedata fileref="crop.pdf" format="PS" /> + </imageobject> + <imageobject> + <imagedata fileref="crop.gif" format="GIF" /> + </imageobject> + <textobject> + <phrase>The cropping, insertion and scaling process</phrase> + </textobject> + </mediaobject> + </figure> + + <para>For capture devices the coordinates of the top left +corner, width and height of the area which can be sampled is given by +the <structfield>bounds</structfield> substructure of the +&v4l2-cropcap; returned by the <constant>VIDIOC_CROPCAP</constant> +ioctl. To support a wide range of hardware this specification does not +define an origin or units. However by convention drivers should +horizontally count unscaled samples relative to 0H (the leading edge +of the horizontal sync pulse, see <xref linkend="vbi-hsync" />). +Vertically ITU-R line +numbers of the first field (<xref linkend="vbi-525" />, <xref +linkend="vbi-625" />), multiplied by two if the driver can capture both +fields.</para> + + <para>The top left corner, width and height of the source +rectangle, that is the area actually sampled, is given by &v4l2-crop; +using the same coordinate system as &v4l2-cropcap;. Applications can +use the <constant>VIDIOC_G_CROP</constant> and +<constant>VIDIOC_S_CROP</constant> ioctls to get and set this +rectangle. It must lie completely within the capture boundaries and +the driver may further adjust the requested size and/or position +according to hardware limitations.</para> + + <para>Each capture device has a default source rectangle, given +by the <structfield>defrect</structfield> substructure of +&v4l2-cropcap;. The center of this rectangle shall align with the +center of the active picture area of the video signal, and cover what +the driver writer considers the complete picture. Drivers shall reset +the source rectangle to the default when the driver is first loaded, +but not later.</para> + + <para>For output devices these structures and ioctls are used +accordingly, defining the <emphasis>target</emphasis> rectangle where +the images will be inserted into the video signal.</para> + + </section> + + <section> + <title>Scaling Adjustments</title> + + <para>Video hardware can have various cropping, insertion and +scaling limitations. It may only scale up or down, support only +discrete scaling factors, or have different scaling abilities in +horizontal and vertical direction. Also it may not support scaling at +all. At the same time the &v4l2-crop; rectangle may have to be +aligned, and both the source and target rectangles may have arbitrary +upper and lower size limits. In particular the maximum +<structfield>width</structfield> and <structfield>height</structfield> +in &v4l2-crop; may be smaller than the +&v4l2-cropcap;.<structfield>bounds</structfield> area. Therefore, as +usual, drivers are expected to adjust the requested parameters and +return the actual values selected.</para> + + <para>Applications can change the source or the target rectangle +first, as they may prefer a particular image size or a certain area in +the video signal. If the driver has to adjust both to satisfy hardware +limitations, the last requested rectangle shall take priority, and the +driver should preferably adjust the opposite one. The &VIDIOC-TRY-FMT; +ioctl however shall not change the driver state and therefore only +adjust the requested rectangle.</para> + + <para>Suppose scaling on a video capture device is restricted to +a factor 1:1 or 2:1 in either direction and the target image size must +be a multiple of 16 × 16 pixels. The source cropping +rectangle is set to defaults, which are also the upper limit in this +example, of 640 × 400 pixels at offset 0, 0. An +application requests an image size of 300 × 225 +pixels, assuming video will be scaled down from the "full picture" +accordingly. The driver sets the image size to the closest possible +values 304 × 224, then chooses the cropping rectangle +closest to the requested size, that is 608 × 224 +(224 × 2:1 would exceed the limit 400). The offset +0, 0 is still valid, thus unmodified. Given the default cropping +rectangle reported by <constant>VIDIOC_CROPCAP</constant> the +application can easily propose another offset to center the cropping +rectangle.</para> + + <para>Now the application may insist on covering an area using a +picture aspect ratio closer to the original request, so it asks for a +cropping rectangle of 608 × 456 pixels. The present +scaling factors limit cropping to 640 × 384, so the +driver returns the cropping size 608 × 384 and adjusts +the image size to closest possible 304 × 192.</para> + + </section> + + <section> + <title>Examples</title> + + <para>Source and target rectangles shall remain unchanged across +closing and reopening a device, such that piping data into or out of a +device will work without special preparations. More advanced +applications should ensure the parameters are suitable before starting +I/O.</para> + + <example> + <title>Resetting the cropping parameters</title> + + <para>(A video capture device is assumed; change +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant> for other +devices.)</para> + + <programlisting> +&v4l2-cropcap; cropcap; +&v4l2-crop; crop; + +memset (&cropcap, 0, sizeof (cropcap)); +cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + +if (-1 == ioctl (fd, &VIDIOC-CROPCAP;, &cropcap)) { + perror ("VIDIOC_CROPCAP"); + exit (EXIT_FAILURE); +} + +memset (&crop, 0, sizeof (crop)); +crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; +crop.c = cropcap.defrect; + +/* Ignore if cropping is not supported (EINVAL). */ + +if (-1 == ioctl (fd, &VIDIOC-S-CROP;, &crop) + && errno != EINVAL) { + perror ("VIDIOC_S_CROP"); + exit (EXIT_FAILURE); +} + </programlisting> + </example> + + <example> + <title>Simple downscaling</title> + + <para>(A video capture device is assumed.)</para> + + <programlisting> +&v4l2-cropcap; cropcap; +&v4l2-format; format; + +reset_cropping_parameters (); + +/* Scale down to 1/4 size of full picture. */ + +memset (&format, 0, sizeof (format)); /* defaults */ + +format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + +format.fmt.pix.width = cropcap.defrect.width >> 1; +format.fmt.pix.height = cropcap.defrect.height >> 1; +format.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV; + +if (-1 == ioctl (fd, &VIDIOC-S-FMT;, &format)) { + perror ("VIDIOC_S_FORMAT"); + exit (EXIT_FAILURE); +} + +/* We could check the actual image size now, the actual scaling factor + or if the driver can scale at all. */ + </programlisting> + </example> + + <example> + <title>Selecting an output area</title> + + <programlisting> +&v4l2-cropcap; cropcap; +&v4l2-crop; crop; + +memset (&cropcap, 0, sizeof (cropcap)); +cropcap.type = V4L2_BUF_TYPE_VIDEO_OUTPUT; + +if (-1 == ioctl (fd, VIDIOC_CROPCAP;, &cropcap)) { + perror ("VIDIOC_CROPCAP"); + exit (EXIT_FAILURE); +} + +memset (&crop, 0, sizeof (crop)); + +crop.type = V4L2_BUF_TYPE_VIDEO_OUTPUT; +crop.c = cropcap.defrect; + +/* Scale the width and height to 50 % of their original size + and center the output. */ + +crop.c.width /= 2; +crop.c.height /= 2; +crop.c.left += crop.c.width / 2; +crop.c.top += crop.c.height / 2; + +/* Ignore if cropping is not supported (EINVAL). */ + +if (-1 == ioctl (fd, VIDIOC_S_CROP, &crop) + && errno != EINVAL) { + perror ("VIDIOC_S_CROP"); + exit (EXIT_FAILURE); +} +</programlisting> + </example> + + <example> + <title>Current scaling factor and pixel aspect</title> + + <para>(A video capture device is assumed.)</para> + + <programlisting> +&v4l2-cropcap; cropcap; +&v4l2-crop; crop; +&v4l2-format; format; +double hscale, vscale; +double aspect; +int dwidth, dheight; + +memset (&cropcap, 0, sizeof (cropcap)); +cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + +if (-1 == ioctl (fd, &VIDIOC-CROPCAP;, &cropcap)) { + perror ("VIDIOC_CROPCAP"); + exit (EXIT_FAILURE); +} + +memset (&crop, 0, sizeof (crop)); +crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + +if (-1 == ioctl (fd, &VIDIOC-G-CROP;, &crop)) { + if (errno != EINVAL) { + perror ("VIDIOC_G_CROP"); + exit (EXIT_FAILURE); + } + + /* Cropping not supported. */ + crop.c = cropcap.defrect; +} + +memset (&format, 0, sizeof (format)); +format.fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + +if (-1 == ioctl (fd, &VIDIOC-G-FMT;, &format)) { + perror ("VIDIOC_G_FMT"); + exit (EXIT_FAILURE); +} + +/* The scaling applied by the driver. */ + +hscale = format.fmt.pix.width / (double) crop.c.width; +vscale = format.fmt.pix.height / (double) crop.c.height; + +aspect = cropcap.pixelaspect.numerator / + (double) cropcap.pixelaspect.denominator; +aspect = aspect * hscale / vscale; + +/* Devices following ITU-R BT.601 do not capture + square pixels. For playback on a computer monitor + we should scale the images to this size. */ + +dwidth = format.fmt.pix.width / aspect; +dheight = format.fmt.pix.height; + </programlisting> + </example> + </section> + </section> + + <section id="streaming-par"> + <title>Streaming Parameters</title> + + <para>Streaming parameters are intended to optimize the video +capture process as well as I/O. Presently applications can request a +high quality capture mode with the &VIDIOC-S-PARM; ioctl.</para> + + <para>The current video standard determines a nominal number of +frames per second. If less than this number of frames is to be +captured or output, applications can request frame skipping or +duplicating on the driver side. This is especially useful when using +the &func-read; or &func-write;, which are not augmented by timestamps +or sequence counters, and to avoid unneccessary data copying.</para> + + <para>Finally these ioctls can be used to determine the number of +buffers used internally by a driver in read/write mode. For +implications see the section discussing the &func-read; +function.</para> + + <para>To get and set the streaming parameters applications call +the &VIDIOC-G-PARM; and &VIDIOC-S-PARM; ioctl, respectively. They take +a pointer to a &v4l2-streamparm;, which contains a union holding +separate parameters for input and output devices.</para> + + <para>These ioctls are optional, drivers need not implement +them. If so, they return the &EINVAL;.</para> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/compat.xml b/linux/Documentation/DocBook/v4l/compat.xml new file mode 100644 index 000000000..4d1902a54 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/compat.xml @@ -0,0 +1,2457 @@ + <title>Changes</title> + + <para>The following chapters document the evolution of the V4L2 API, +errata or extensions. They are also intended to help application and +driver writers to port or update their code.</para> + + <section id="diff-v4l"> + <title>Differences between V4L and V4L2</title> + + <para>The Video For Linux API was first introduced in Linux 2.1 to +unify and replace various TV and radio device related interfaces, +developed independently by driver writers in prior years. Starting +with Linux 2.5 the much improved V4L2 API replaces the V4L API, +although existing drivers will continue to support V4L applications in +the future, either directly or through the V4L2 compatibility layer in +the <filename>videodev</filename> kernel module translating ioctls on +the fly. For a transition period not all drivers will support the V4L2 +API.</para> + + <section> + <title>Opening and Closing Devices</title> + + <para>For compatibility reasons the character device file names +recommended for V4L2 video capture, overlay, radio, teletext and raw +vbi capture devices did not change from those used by V4L. They are +listed in <xref linkend="devices" /> and below in <xref + linkend="v4l-dev" />.</para> + + <para>The V4L <filename>videodev</filename> module automatically +assigns minor numbers to drivers in load order, depending on the +registered device type. We recommend that V4L2 drivers by default +register devices with the same numbers, but the system administrator +can assign arbitrary minor numbers using driver module options. The +major device number remains 81.</para> + + <table id="v4l-dev"> + <title>V4L Device Types, Names and Numbers</title> + <tgroup cols="3"> + <thead> + <row> + <entry>Device Type</entry> + <entry>File Name</entry> + <entry>Minor Numbers</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry>Video capture and overlay</entry> + <entry><para><filename>/dev/video</filename> and +<filename>/dev/bttv0</filename><footnote> <para>According to +Documentation/devices.txt these should be symbolic links to +<filename>/dev/video0</filename>. Note the original bttv interface is +not compatible with V4L or V4L2.</para> </footnote>, +<filename>/dev/video0</filename> to +<filename>/dev/video63</filename></para></entry> + <entry>0-63</entry> + </row> + <row> + <entry>Radio receiver</entry> + <entry><para><filename>/dev/radio</filename><footnote> + <para>According to +<filename>Documentation/devices.txt</filename> a symbolic link to +<filename>/dev/radio0</filename>.</para> + </footnote>, <filename>/dev/radio0</filename> to +<filename>/dev/radio63</filename></para></entry> + <entry>64-127</entry> + </row> + <row> + <entry>Teletext decoder</entry> + <entry><para><filename>/dev/vtx</filename>, +<filename>/dev/vtx0</filename> to +<filename>/dev/vtx31</filename></para></entry> + <entry>192-223</entry> + </row> + <row> + <entry>Raw VBI capture</entry> + <entry><para><filename>/dev/vbi</filename>, +<filename>/dev/vbi0</filename> to +<filename>/dev/vbi31</filename></para></entry> + <entry>224-255</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>V4L prohibits (or used to prohibit) multiple opens of a +device file. V4L2 drivers <emphasis>may</emphasis> support multiple +opens, see <xref linkend="open" /> for details and consequences.</para> + + <para>V4L drivers respond to V4L2 ioctls with an &EINVAL;. The +compatibility layer in the V4L2 <filename>videodev</filename> module +can translate V4L ioctl requests to their V4L2 counterpart, however a +V4L2 driver usually needs more preparation to become fully V4L +compatible. This is covered in more detail in <xref + linkend="driver" />.</para> + </section> + + <section> + <title>Querying Capabilities</title> + + <para>The V4L <constant>VIDIOCGCAP</constant> ioctl is +equivalent to V4L2's &VIDIOC-QUERYCAP;.</para> + + <para>The <structfield>name</structfield> field in struct +<structname>video_capability</structname> became +<structfield>card</structfield> in &v4l2-capability;, +<structfield>type</structfield> was replaced by +<structfield>capabilities</structfield>. Note V4L2 does not +distinguish between device types like this, better think of basic +video input, video output and radio devices supporting a set of +related functions like video capturing, video overlay and VBI +capturing. See <xref linkend="open" /> for an +introduction.<informaltable> + <tgroup cols="3"> + <thead> + <row> + <entry>struct +<structname>video_capability</structname> +<structfield>type</structfield></entry> + <entry>&v4l2-capability; +<structfield>capabilities</structfield> flags</entry> + <entry>Purpose</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>VID_TYPE_CAPTURE</constant></entry> + <entry><constant>V4L2_CAP_VIDEO_CAPTURE</constant></entry> + <entry>The <link linkend="capture">video +capture</link> interface is supported.</entry> + </row> + <row> + <entry><constant>VID_TYPE_TUNER</constant></entry> + <entry><constant>V4L2_CAP_TUNER</constant></entry> + <entry>The device has a <link linkend="tuner">tuner or +modulator</link>.</entry> + </row> + <row> + <entry><constant>VID_TYPE_TELETEXT</constant></entry> + <entry><constant>V4L2_CAP_VBI_CAPTURE</constant></entry> + <entry>The <link linkend="raw-vbi">raw VBI +capture</link> interface is supported.</entry> + </row> + <row> + <entry><constant>VID_TYPE_OVERLAY</constant></entry> + <entry><constant>V4L2_CAP_VIDEO_OVERLAY</constant></entry> + <entry>The <link linkend="overlay">video +overlay</link> interface is supported.</entry> + </row> + <row> + <entry><constant>VID_TYPE_CHROMAKEY</constant></entry> + <entry><constant>V4L2_FBUF_CAP_CHROMAKEY</constant> in +field <structfield>capability</structfield> of +&v4l2-framebuffer;</entry> + <entry>Whether chromakey overlay is supported. For +more information on overlay see +<xref linkend="overlay" />.</entry> + </row> + <row> + <entry><constant>VID_TYPE_CLIPPING</constant></entry> + <entry><constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant> +and <constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant> in field +<structfield>capability</structfield> of &v4l2-framebuffer;</entry> + <entry>Whether clipping the overlaid image is +supported, see <xref linkend="overlay" />.</entry> + </row> + <row> + <entry><constant>VID_TYPE_FRAMERAM</constant></entry> + <entry><constant>V4L2_FBUF_CAP_EXTERNOVERLAY</constant> +<emphasis>not set</emphasis> in field +<structfield>capability</structfield> of &v4l2-framebuffer;</entry> + <entry>Whether overlay overwrites frame buffer memory, +see <xref linkend="overlay" />.</entry> + </row> + <row> + <entry><constant>VID_TYPE_SCALES</constant></entry> + <entry><constant>-</constant></entry> + <entry>This flag indicates if the hardware can scale +images. The V4L2 API implies the scale factor by setting the cropping +dimensions and image size with the &VIDIOC-S-CROP; and &VIDIOC-S-FMT; +ioctl, respectively. The driver returns the closest sizes possible. +For more information on cropping and scaling see <xref + linkend="crop" />.</entry> + </row> + <row> + <entry><constant>VID_TYPE_MONOCHROME</constant></entry> + <entry><constant>-</constant></entry> + <entry>Applications can enumerate the supported image +formats with the &VIDIOC-ENUM-FMT; ioctl to determine if the device +supports grey scale capturing only. For more information on image +formats see <xref linkend="pixfmt" />.</entry> + </row> + <row> + <entry><constant>VID_TYPE_SUBCAPTURE</constant></entry> + <entry><constant>-</constant></entry> + <entry>Applications can call the &VIDIOC-G-CROP; ioctl +to determine if the device supports capturing a subsection of the full +picture ("cropping" in V4L2). If not, the ioctl returns the &EINVAL;. +For more information on cropping and scaling see <xref + linkend="crop" />.</entry> + </row> + <row> + <entry><constant>VID_TYPE_MPEG_DECODER</constant></entry> + <entry><constant>-</constant></entry> + <entry>Applications can enumerate the supported image +formats with the &VIDIOC-ENUM-FMT; ioctl to determine if the device +supports MPEG streams.</entry> + </row> + <row> + <entry><constant>VID_TYPE_MPEG_ENCODER</constant></entry> + <entry><constant>-</constant></entry> + <entry>See above.</entry> + </row> + <row> + <entry><constant>VID_TYPE_MJPEG_DECODER</constant></entry> + <entry><constant>-</constant></entry> + <entry>See above.</entry> + </row> + <row> + <entry><constant>VID_TYPE_MJPEG_ENCODER</constant></entry> + <entry><constant>-</constant></entry> + <entry>See above.</entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>The <structfield>audios</structfield> field was replaced +by <structfield>capabilities</structfield> flag +<constant>V4L2_CAP_AUDIO</constant>, indicating +<emphasis>if</emphasis> the device has any audio inputs or outputs. To +determine their number applications can enumerate audio inputs with +the &VIDIOC-G-AUDIO; ioctl. The audio ioctls are described in <xref + linkend="audio" />.</para> + + <para>The <structfield>maxwidth</structfield>, +<structfield>maxheight</structfield>, +<structfield>minwidth</structfield> and +<structfield>minheight</structfield> fields were removed. Calling the +&VIDIOC-S-FMT; or &VIDIOC-TRY-FMT; ioctl with the desired dimensions +returns the closest size possible, taking into account the current +video standard, cropping and scaling limitations.</para> + </section> + + <section> + <title>Video Sources</title> + + <para>V4L provides the <constant>VIDIOCGCHAN</constant> and +<constant>VIDIOCSCHAN</constant> ioctl using struct +<structname>video_channel</structname> to enumerate +the video inputs of a V4L device. The equivalent V4L2 ioctls +are &VIDIOC-ENUMINPUT;, &VIDIOC-G-INPUT; and &VIDIOC-S-INPUT; +using &v4l2-input; as discussed in <xref linkend="video" />.</para> + + <para>The <structfield>channel</structfield> field counting +inputs was renamed to <structfield>index</structfield>, the video +input types were renamed as follows: <informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>struct <structname>video_channel</structname> +<structfield>type</structfield></entry> + <entry>&v4l2-input; +<structfield>type</structfield></entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>VIDEO_TYPE_TV</constant></entry> + <entry><constant>V4L2_INPUT_TYPE_TUNER</constant></entry> + </row> + <row> + <entry><constant>VIDEO_TYPE_CAMERA</constant></entry> + <entry><constant>V4L2_INPUT_TYPE_CAMERA</constant></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>Unlike the <structfield>tuners</structfield> field +expressing the number of tuners of this input, V4L2 assumes each video +input is connected to at most one tuner. However a tuner can have more +than one input, &ie; RF connectors, and a device can have multiple +tuners. The index number of the tuner associated with the input, if +any, is stored in field <structfield>tuner</structfield> of +&v4l2-input;. Enumeration of tuners is discussed in <xref + linkend="tuner" />.</para> + + <para>The redundant <constant>VIDEO_VC_TUNER</constant> flag was +dropped. Video inputs associated with a tuner are of type +<constant>V4L2_INPUT_TYPE_TUNER</constant>. The +<constant>VIDEO_VC_AUDIO</constant> flag was replaced by the +<structfield>audioset</structfield> field. V4L2 considers devices with +up to 32 audio inputs. Each set bit in the +<structfield>audioset</structfield> field represents one audio input +this video input combines with. For information about audio inputs and +how to switch between them see <xref linkend="audio" />.</para> + + <para>The <structfield>norm</structfield> field describing the +supported video standards was replaced by +<structfield>std</structfield>. The V4L specification mentions a flag +<constant>VIDEO_VC_NORM</constant> indicating whether the standard can +be changed. This flag was a later addition together with the +<structfield>norm</structfield> field and has been removed in the +meantime. V4L2 has a similar, albeit more comprehensive approach +to video standards, see <xref linkend="standard" /> for more +information.</para> + </section> + + <section> + <title>Tuning</title> + + <para>The V4L <constant>VIDIOCGTUNER</constant> and +<constant>VIDIOCSTUNER</constant> ioctl and struct +<structname>video_tuner</structname> can be used to enumerate the +tuners of a V4L TV or radio device. The equivalent V4L2 ioctls are +&VIDIOC-G-TUNER; and &VIDIOC-S-TUNER; using &v4l2-tuner;. Tuners are +covered in <xref linkend="tuner" />.</para> + + <para>The <structfield>tuner</structfield> field counting tuners +was renamed to <structfield>index</structfield>. The fields +<structfield>name</structfield>, <structfield>rangelow</structfield> +and <structfield>rangehigh</structfield> remained unchanged.</para> + + <para>The <constant>VIDEO_TUNER_PAL</constant>, +<constant>VIDEO_TUNER_NTSC</constant> and +<constant>VIDEO_TUNER_SECAM</constant> flags indicating the supported +video standards were dropped. This information is now contained in the +associated &v4l2-input;. No replacement exists for the +<constant>VIDEO_TUNER_NORM</constant> flag indicating whether the +video standard can be switched. The <structfield>mode</structfield> +field to select a different video standard was replaced by a whole new +set of ioctls and structures described in <xref linkend="standard" />. +Due to its ubiquity it should be mentioned the BTTV driver supports +several standards in addition to the regular +<constant>VIDEO_MODE_PAL</constant> (0), +<constant>VIDEO_MODE_NTSC</constant>, +<constant>VIDEO_MODE_SECAM</constant> and +<constant>VIDEO_MODE_AUTO</constant> (3). Namely N/PAL Argentina, +M/PAL, N/PAL, and NTSC Japan with numbers 3-6 (sic).</para> + + <para>The <constant>VIDEO_TUNER_STEREO_ON</constant> flag +indicating stereo reception became +<constant>V4L2_TUNER_SUB_STEREO</constant> in field +<structfield>rxsubchans</structfield>. This field also permits the +detection of monaural and bilingual audio, see the definition of +&v4l2-tuner; for details. Presently no replacement exists for the +<constant>VIDEO_TUNER_RDS_ON</constant> and +<constant>VIDEO_TUNER_MBS_ON</constant> flags.</para> + + <para> The <constant>VIDEO_TUNER_LOW</constant> flag was renamed +to <constant>V4L2_TUNER_CAP_LOW</constant> in the &v4l2-tuner; +<structfield>capability</structfield> field.</para> + + <para>The <constant>VIDIOCGFREQ</constant> and +<constant>VIDIOCSFREQ</constant> ioctl to change the tuner frequency +where renamed to &VIDIOC-G-FREQUENCY; and &VIDIOC-S-FREQUENCY;. They +take a pointer to a &v4l2-frequency; instead of an unsigned long +integer.</para> + </section> + + <section id="v4l-image-properties"> + <title>Image Properties</title> + + <para>V4L2 has no equivalent of the +<constant>VIDIOCGPICT</constant> and <constant>VIDIOCSPICT</constant> +ioctl and struct <structname>video_picture</structname>. The following +fields where replaced by V4L2 controls accessible with the +&VIDIOC-QUERYCTRL;, &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls:<informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>struct <structname>video_picture</structname></entry> + <entry>V4L2 Control ID</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><structfield>brightness</structfield></entry> + <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry> + </row> + <row> + <entry><structfield>hue</structfield></entry> + <entry><constant>V4L2_CID_HUE</constant></entry> + </row> + <row> + <entry><structfield>colour</structfield></entry> + <entry><constant>V4L2_CID_SATURATION</constant></entry> + </row> + <row> + <entry><structfield>contrast</structfield></entry> + <entry><constant>V4L2_CID_CONTRAST</constant></entry> + </row> + <row> + <entry><structfield>whiteness</structfield></entry> + <entry><constant>V4L2_CID_WHITENESS</constant></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>The V4L picture controls are assumed to range from 0 to +65535 with no particular reset value. The V4L2 API permits arbitrary +limits and defaults which can be queried with the &VIDIOC-QUERYCTRL; +ioctl. For general information about controls see <xref +linkend="control" />.</para> + + <para>The <structfield>depth</structfield> (average number of +bits per pixel) of a video image is implied by the selected image +format. V4L2 does not explicitely provide such information assuming +applications recognizing the format are aware of the image depth and +others need not know. The <structfield>palette</structfield> field +moved into the &v4l2-pix-format;:<informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>struct <structname>video_picture</structname> +<structfield>palette</structfield></entry> + <entry>&v4l2-pix-format; +<structfield>pixfmt</structfield></entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>VIDEO_PALETTE_GREY</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-GREY"><constant>V4L2_PIX_FMT_GREY</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_HI240</constant></entry> + <entry><para><link +linkend="pixfmt-reserved"><constant>V4L2_PIX_FMT_HI240</constant></link><footnote> + <para>This is a custom format used by the BTTV +driver, not one of the V4L2 standard formats.</para> + </footnote></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_RGB565</constant></entry> + <entry><para><link +linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_RGB565</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_RGB555</constant></entry> + <entry><para><link +linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_RGB555</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_RGB24</constant></entry> + <entry><para><link +linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_BGR24</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_RGB32</constant></entry> + <entry><para><link +linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_BGR32</constant></link><footnote> + <para>Presumably all V4L RGB formats are +little-endian, although some drivers might interpret them according to machine endianess. V4L2 defines little-endian, big-endian and red/blue +swapped variants. For details see <xref linkend="pixfmt-rgb" />.</para> + </footnote></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV422</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link></para></entry> + </row> + <row> + <entry><para><constant>VIDEO_PALETTE_YUYV</constant><footnote> + <para><constant>VIDEO_PALETTE_YUV422</constant> +and <constant>VIDEO_PALETTE_YUYV</constant> are the same formats. Some +V4L drivers respond to one, some to the other.</para> + </footnote></para></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_UYVY</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-UYVY"><constant>V4L2_PIX_FMT_UYVY</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV420</constant></entry> + <entry>None</entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV411</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-Y41P"><constant>V4L2_PIX_FMT_Y41P</constant></link><footnote> + <para>Not to be confused with +<constant>V4L2_PIX_FMT_YUV411P</constant>, which is a planar +format.</para> </footnote></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_RAW</constant></entry> + <entry><para>None<footnote> <para>V4L explains this +as: "RAW capture (BT848)"</para> </footnote></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV422P</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-YUV422P"><constant>V4L2_PIX_FMT_YUV422P</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV411P</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-YUV411P"><constant>V4L2_PIX_FMT_YUV411P</constant></link><footnote> + <para>Not to be confused with +<constant>V4L2_PIX_FMT_Y41P</constant>, which is a packed +format.</para> </footnote></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV420P</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link></para></entry> + </row> + <row> + <entry><constant>VIDEO_PALETTE_YUV410P</constant></entry> + <entry><para><link +linkend="V4L2-PIX-FMT-YVU410"><constant>V4L2_PIX_FMT_YVU410</constant></link></para></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>V4L2 image formats are defined in <xref +linkend="pixfmt" />. The image format can be selected with the +&VIDIOC-S-FMT; ioctl.</para> + </section> + + <section> + <title>Audio</title> + + <para>The <constant>VIDIOCGAUDIO</constant> and +<constant>VIDIOCSAUDIO</constant> ioctl and struct +<structname>video_audio</structname> are used to enumerate the +audio inputs of a V4L device. The equivalent V4L2 ioctls are +&VIDIOC-G-AUDIO; and &VIDIOC-S-AUDIO; using &v4l2-audio; as +discussed in <xref linkend="audio" />.</para> + + <para>The <structfield>audio</structfield> "channel number" +field counting audio inputs was renamed to +<structfield>index</structfield>.</para> + + <para>On <constant>VIDIOCSAUDIO</constant> the +<structfield>mode</structfield> field selects <emphasis>one</emphasis> +of the <constant>VIDEO_SOUND_MONO</constant>, +<constant>VIDEO_SOUND_STEREO</constant>, +<constant>VIDEO_SOUND_LANG1</constant> or +<constant>VIDEO_SOUND_LANG2</constant> audio demodulation modes. When +the current audio standard is BTSC +<constant>VIDEO_SOUND_LANG2</constant> refers to SAP and +<constant>VIDEO_SOUND_LANG1</constant> is meaningless. Also +undocumented in the V4L specification, there is no way to query the +selected mode. On <constant>VIDIOCGAUDIO</constant> the driver returns +the <emphasis>actually received</emphasis> audio programmes in this +field. In the V4L2 API this information is stored in the &v4l2-tuner; +<structfield>rxsubchans</structfield> and +<structfield>audmode</structfield> fields, respectively. See <xref +linkend="tuner" /> for more information on tuners. Related to audio +modes &v4l2-audio; also reports if this is a mono or stereo +input, regardless if the source is a tuner.</para> + + <para>The following fields where replaced by V4L2 controls +accessible with the &VIDIOC-QUERYCTRL;, &VIDIOC-G-CTRL; and +&VIDIOC-S-CTRL; ioctls:<informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>struct +<structname>video_audio</structname></entry> + <entry>V4L2 Control ID</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><structfield>volume</structfield></entry> + <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry> + </row> + <row> + <entry><structfield>bass</structfield></entry> + <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry> + </row> + <row> + <entry><structfield>treble</structfield></entry> + <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry> + </row> + <row> + <entry><structfield>balance</structfield></entry> + <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>To determine which of these controls are supported by a +driver V4L provides the <structfield>flags</structfield> +<constant>VIDEO_AUDIO_VOLUME</constant>, +<constant>VIDEO_AUDIO_BASS</constant>, +<constant>VIDEO_AUDIO_TREBLE</constant> and +<constant>VIDEO_AUDIO_BALANCE</constant>. In the V4L2 API the +&VIDIOC-QUERYCTRL; ioctl reports if the respective control is +supported. Accordingly the <constant>VIDEO_AUDIO_MUTABLE</constant> +and <constant>VIDEO_AUDIO_MUTE</constant> flags where replaced by the +boolean <constant>V4L2_CID_AUDIO_MUTE</constant> control.</para> + + <para>All V4L2 controls have a <structfield>step</structfield> +attribute replacing the struct <structname>video_audio</structname> +<structfield>step</structfield> field. The V4L audio controls are +assumed to range from 0 to 65535 with no particular reset value. The +V4L2 API permits arbitrary limits and defaults which can be queried +with the &VIDIOC-QUERYCTRL; ioctl. For general information about +controls see <xref linkend="control" />.</para> + </section> + + <section> + <title>Frame Buffer Overlay</title> + + <para>The V4L2 ioctls equivalent to +<constant>VIDIOCGFBUF</constant> and <constant>VIDIOCSFBUF</constant> +are &VIDIOC-G-FBUF; and &VIDIOC-S-FBUF;. The +<structfield>base</structfield> field of struct +<structname>video_buffer</structname> remained unchanged, except V4L2 +defines a flag to indicate non-destructive overlays instead of a +<constant>NULL</constant> pointer. All other fields moved into the +&v4l2-pix-format; <structfield>fmt</structfield> substructure of +&v4l2-framebuffer;. The <structfield>depth</structfield> field was +replaced by <structfield>pixelformat</structfield>. See <xref + linkend="pixfmt-rgb" /> for a list of RGB formats and their +respective color depths.</para> + + <para>Instead of the special ioctls +<constant>VIDIOCGWIN</constant> and <constant>VIDIOCSWIN</constant> +V4L2 uses the general-purpose data format negotiation ioctls +&VIDIOC-G-FMT; and &VIDIOC-S-FMT;. They take a pointer to a +&v4l2-format; as argument. Here the <structfield>win</structfield> +member of the <structfield>fmt</structfield> union is used, a +&v4l2-window;.</para> + + <para>The <structfield>x</structfield>, +<structfield>y</structfield>, <structfield>width</structfield> and +<structfield>height</structfield> fields of struct +<structname>video_window</structname> moved into &v4l2-rect; +substructure <structfield>w</structfield> of struct +<structname>v4l2_window</structname>. The +<structfield>chromakey</structfield>, +<structfield>clips</structfield>, and +<structfield>clipcount</structfield> fields remained unchanged. Struct +<structname>video_clip</structname> was renamed to &v4l2-clip;, also +containing a struct <structname>v4l2_rect</structname>, but the +semantics are still the same.</para> + + <para>The <constant>VIDEO_WINDOW_INTERLACE</constant> flag was +dropped. Instead applications must set the +<structfield>field</structfield> field to +<constant>V4L2_FIELD_ANY</constant> or +<constant>V4L2_FIELD_INTERLACED</constant>. The +<constant>VIDEO_WINDOW_CHROMAKEY</constant> flag moved into +&v4l2-framebuffer;, under the new name +<constant>V4L2_FBUF_FLAG_CHROMAKEY</constant>.</para> + + <para>In V4L, storing a bitmap pointer in +<structfield>clips</structfield> and setting +<structfield>clipcount</structfield> to +<constant>VIDEO_CLIP_BITMAP</constant> (-1) requests bitmap +clipping, using a fixed size bitmap of 1024 × 625 bits. Struct +<structname>v4l2_window</structname> has a separate +<structfield>bitmap</structfield> pointer field for this purpose and +the bitmap size is determined by <structfield>w.width</structfield> and +<structfield>w.height</structfield>.</para> + + <para>The <constant>VIDIOCCAPTURE</constant> ioctl to enable or +disable overlay was renamed to &VIDIOC-OVERLAY;.</para> + </section> + + <section> + <title>Cropping</title> + + <para>To capture only a subsection of the full picture V4L +defines the <constant>VIDIOCGCAPTURE</constant> and +<constant>VIDIOCSCAPTURE</constant> ioctls using struct +<structname>video_capture</structname>. The equivalent V4L2 ioctls are +&VIDIOC-G-CROP; and &VIDIOC-S-CROP; using &v4l2-crop;, and the related +&VIDIOC-CROPCAP; ioctl. This is a rather complex matter, see +<xref linkend="crop" /> for details.</para> + + <para>The <structfield>x</structfield>, +<structfield>y</structfield>, <structfield>width</structfield> and +<structfield>height</structfield> fields moved into &v4l2-rect; +substructure <structfield>c</structfield> of struct +<structname>v4l2_crop</structname>. The +<structfield>decimation</structfield> field was dropped. In the V4L2 +API the scaling factor is implied by the size of the cropping +rectangle and the size of the captured or overlaid image.</para> + + <para>The <constant>VIDEO_CAPTURE_ODD</constant> +and <constant>VIDEO_CAPTURE_EVEN</constant> flags to capture only the +odd or even field, respectively, were replaced by +<constant>V4L2_FIELD_TOP</constant> and +<constant>V4L2_FIELD_BOTTOM</constant> in the field named +<structfield>field</structfield> of &v4l2-pix-format; and +&v4l2-window;. These structures are used to select a capture or +overlay format with the &VIDIOC-S-FMT; ioctl.</para> + </section> + + <section> + <title>Reading Images, Memory Mapping</title> + + <section> + <title>Capturing using the read method</title> + + <para>There is no essential difference between reading images +from a V4L or V4L2 device using the &func-read; function, however V4L2 +drivers are not required to support this I/O method. Applications can +determine if the function is available with the &VIDIOC-QUERYCAP; +ioctl. All V4L2 devices exchanging data with applications must support +the &func-select; and &func-poll; functions.</para> + + <para>To select an image format and size, V4L provides the +<constant>VIDIOCSPICT</constant> and <constant>VIDIOCSWIN</constant> +ioctls. V4L2 uses the general-purpose data format negotiation ioctls +&VIDIOC-G-FMT; and &VIDIOC-S-FMT;. They take a pointer to a +&v4l2-format; as argument, here the &v4l2-pix-format; named +<structfield>pix</structfield> of its <structfield>fmt</structfield> +union is used.</para> + + <para>For more information about the V4L2 read interface see +<xref linkend="rw" />.</para> + </section> + <section> + <title>Capturing using memory mapping</title> + + <para>Applications can read from V4L devices by mapping +buffers in device memory, or more often just buffers allocated in +DMA-able system memory, into their address space. This avoids the data +copying overhead of the read method. V4L2 supports memory mapping as +well, with a few differences.</para> + + <informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>V4L</entry> + <entry>V4L2</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry></entry> + <entry>The image format must be selected before +buffers are allocated, with the &VIDIOC-S-FMT; ioctl. When no format +is selected the driver may use the last, possibly by another +application requested format.</entry> + </row> + <row> + <entry><para>Applications cannot change the number of +buffers. The it is built into the driver, unless it has a module +option to change the number when the driver module is +loaded.</para></entry> + <entry><para>The &VIDIOC-REQBUFS; ioctl allocates the +desired number of buffers, this is a required step in the initialization +sequence.</para></entry> + </row> + <row> + <entry><para>Drivers map all buffers as one contiguous +range of memory. The <constant>VIDIOCGMBUF</constant> ioctl is +available to query the number of buffers, the offset of each buffer +from the start of the virtual file, and the overall amount of memory +used, which can be used as arguments for the &func-mmap; +function.</para></entry> + <entry><para>Buffers are individually mapped. The +offset and size of each buffer can be determined with the +&VIDIOC-QUERYBUF; ioctl.</para></entry> + </row> + <row> + <entry><para>The <constant>VIDIOCMCAPTURE</constant> +ioctl prepares a buffer for capturing. It also determines the image +format for this buffer. The ioctl returns immediately, eventually with +an &EAGAIN; if no video signal had been detected. When the driver +supports more than one buffer applications can call the ioctl multiple +times and thus have multiple outstanding capture +requests.</para><para>The <constant>VIDIOCSYNC</constant> ioctl +suspends execution until a particular buffer has been +filled.</para></entry> + <entry><para>Drivers maintain an incoming and outgoing +queue. &VIDIOC-QBUF; enqueues any empty buffer into the incoming +queue. Filled buffers are dequeued from the outgoing queue with the +&VIDIOC-DQBUF; ioctl. To wait until filled buffers become available this +function, &func-select; or &func-poll; can be used. The +&VIDIOC-STREAMON; ioctl must be called once after enqueuing one or +more buffers to start capturing. Its counterpart +&VIDIOC-STREAMOFF; stops capturing and dequeues all buffers from both +queues. Applications can query the signal status, if known, with the +&VIDIOC-ENUMINPUT; ioctl.</para></entry> + </row> + </tbody> + </tgroup> + </informaltable> + + <para>For a more in-depth discussion of memory mapping and +examples, see <xref linkend="mmap" />.</para> + </section> + </section> + + <section> + <title>Reading Raw VBI Data</title> + + <para>Originally the V4L API did not specify a raw VBI capture +interface, only the device file <filename>/dev/vbi</filename> was +reserved for this purpose. The only driver supporting this interface +was the BTTV driver, de-facto defining the V4L VBI interface. Reading +from the device yields a raw VBI image with the following +parameters:<informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>&v4l2-vbi-format;</entry> + <entry>V4L, BTTV driver</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry>sampling_rate</entry> + <entry>28636363 Hz NTSC (or any other 525-line +standard); 35468950 Hz PAL and SECAM (625-line standards)</entry> + </row> + <row> + <entry>offset</entry> + <entry>?</entry> + </row> + <row> + <entry>samples_per_line</entry> + <entry>2048</entry> + </row> + <row> + <entry>sample_format</entry> + <entry>V4L2_PIX_FMT_GREY. The last four bytes (a +machine endianess integer) contain a frame counter.</entry> + </row> + <row> + <entry>start[]</entry> + <entry>10, 273 NTSC; 22, 335 PAL and SECAM</entry> + </row> + <row> + <entry>count[]</entry> + <entry><para>16, 16<footnote><para>Old driver +versions used different values, eventually the custom +<constant>BTTV_VBISIZE</constant> ioctl was added to query the +correct values.</para></footnote></para></entry> + </row> + <row> + <entry>flags</entry> + <entry>0</entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>Undocumented in the V4L specification, in Linux 2.3 the +<constant>VIDIOCGVBIFMT</constant> and +<constant>VIDIOCSVBIFMT</constant> ioctls using struct +<structname>vbi_format</structname> were added to determine the VBI +image parameters. These ioctls are only partially compatible with the +V4L2 VBI interface specified in <xref linkend="raw-vbi" />.</para> + + <para>An <structfield>offset</structfield> field does not +exist, <structfield>sample_format</structfield> is supposed to be +<constant>VIDEO_PALETTE_RAW</constant>, equivalent to +<constant>V4L2_PIX_FMT_GREY</constant>. The remaining fields are +probably equivalent to &v4l2-vbi-format;.</para> + + <para>Apparently only the Zoran (ZR 36120) driver implements +these ioctls. The semantics differ from those specified for V4L2 in two +ways. The parameters are reset on &func-open; and +<constant>VIDIOCSVBIFMT</constant> always returns an &EINVAL; if the +parameters are invalid.</para> + </section> + + <section> + <title>Miscellaneous</title> + + <para>V4L2 has no equivalent of the +<constant>VIDIOCGUNIT</constant> ioctl. Applications can find the VBI +device associated with a video capture device (or vice versa) by +reopening the device and requesting VBI data. For details see +<xref linkend="open" />.</para> + + <para>No replacement exists for <constant>VIDIOCKEY</constant>, +and the V4L functions for microcode programming. A new interface for +MPEG compression and playback devices is documented in <xref + linkend="extended-controls" />.</para> + </section> + + </section> + + <section id="hist-v4l2"> + <title>Changes of the V4L2 API</title> + + <para>Soon after the V4L API was added to the kernel it was +criticised as too inflexible. In August 1998 Bill Dirks proposed a +number of improvements and began to work on documentation, example +drivers and applications. With the help of other volunteers this +eventually became the V4L2 API, not just an extension but a +replacement for the V4L API. However it took another four years and +two stable kernel releases until the new API was finally accepted for +inclusion into the kernel in its present form.</para> + + <section> + <title>Early Versions</title> + <para>1998-08-20: First version.</para> + + <para>1998-08-27: The &func-select; function was introduced.</para> + + <para>1998-09-10: New video standard interface.</para> + + <para>1998-09-18: The <constant>VIDIOC_NONCAP</constant> ioctl +was replaced by the otherwise meaningless <constant>O_TRUNC</constant> +&func-open; flag, and the aliases <constant>O_NONCAP</constant> and +<constant>O_NOIO</constant> were defined. Applications can set this +flag if they intend to access controls only, as opposed to capture +applications which need exclusive access. The +<constant>VIDEO_STD_XXX</constant> identifiers are now ordinals +instead of flags, and the <function>video_std_construct()</function> +helper function takes id and transmission arguments.</para> + + <para>1998-09-28: Revamped video standard. Made video controls +individually enumerable.</para> + + <para>1998-10-02: The <structfield>id</structfield> field was +removed from struct <structname>video_standard</structname> and the +color subcarrier fields were renamed. The &VIDIOC-QUERYSTD; ioctl was +renamed to &VIDIOC-ENUMSTD;, &VIDIOC-G-INPUT; to &VIDIOC-ENUMINPUT;. A +first draft of the Codec API was released.</para> + + <para>1998-11-08: Many minor changes. Most symbols have been +renamed. Some material changes to &v4l2-capability;.</para> + + <para>1998-11-12: The read/write directon of some ioctls was misdefined.</para> + + <para>1998-11-14: <constant>V4L2_PIX_FMT_RGB24</constant> +changed to <constant>V4L2_PIX_FMT_BGR24</constant>, and +<constant>V4L2_PIX_FMT_RGB32</constant> changed to +<constant>V4L2_PIX_FMT_BGR32</constant>. Audio controls are now +accessible with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls under +names starting with <constant>V4L2_CID_AUDIO</constant>. The +<constant>V4L2_MAJOR</constant> define was removed from +<filename>videodev.h</filename> since it was only used once in the +<filename>videodev</filename> kernel module. The +<constant>YUV422</constant> and <constant>YUV411</constant> planar +image formats were added.</para> + + <para>1998-11-28: A few ioctl symbols changed. Interfaces for codecs and +video output devices were added.</para> + + <para>1999-01-14: A raw VBI capture interface was added.</para> + + <para>1999-01-19: The <constant>VIDIOC_NEXTBUF</constant> ioctl + was removed.</para> + </section> + + <section> + <title>V4L2 Version 0.16 1999-01-31</title> + <para>1999-01-27: There is now one QBUF ioctl, VIDIOC_QWBUF and VIDIOC_QRBUF +are gone. VIDIOC_QBUF takes a v4l2_buffer as a parameter. Added +digital zoom (cropping) controls.</para> + </section> + + <!-- Where's 0.17? mhs couldn't find that videodev.h, perhaps Bill + forgot to bump the version number or never released it. --> + + <section> + <title>V4L2 Version 0.18 1999-03-16</title> + <para>Added a v4l to V4L2 ioctl compatibility layer to +videodev.c. Driver writers, this changes how you implement your ioctl +handler. See the Driver Writer's Guide. Added some more control id +codes.</para> + </section> + + <section> + <title>V4L2 Version 0.19 1999-06-05</title> + <para>1999-03-18: Fill in the category and catname fields of +v4l2_queryctrl objects before passing them to the driver. Required a +minor change to the VIDIOC_QUERYCTRL handlers in the sample +drivers.</para> + <para>1999-03-31: Better compatibility for v4l memory capture +ioctls. Requires changes to drivers to fully support new compatibility +features, see Driver Writer's Guide and v4l2cap.c. Added new control +IDs: V4L2_CID_HFLIP, _VFLIP. Changed V4L2_PIX_FMT_YUV422P to _YUV422P, +and _YUV411P to _YUV411P.</para> + <para>1999-04-04: Added a few more control IDs.</para> + <para>1999-04-07: Added the button control type.</para> + <para>1999-05-02: Fixed a typo in videodev.h, and added the +V4L2_CTRL_FLAG_GRAYED (later V4L2_CTRL_FLAG_GRABBED) flag.</para> + <para>1999-05-20: Definition of VIDIOC_G_CTRL was wrong causing +a malfunction of this ioctl.</para> + <para>1999-06-05: Changed the value of +V4L2_CID_WHITENESS.</para> + </section> + + <section> + <title>V4L2 Version 0.20 (1999-09-10)</title> + + <para>Version 0.20 introduced a number of changes which were +<emphasis>not backward compatible</emphasis> with 0.19 and earlier +versions. Purpose of these changes was to simplify the API, while +making it more extensible and following common Linux driver API +conventions.</para> + + <orderedlist> + <listitem> + <para>Some typos in <constant>V4L2_FMT_FLAG</constant> +symbols were fixed. &v4l2-clip; was changed for compatibility with +v4l. (1999-08-30)</para> + </listitem> + + <listitem> + <para><constant>V4L2_TUNER_SUB_LANG1</constant> was added. +(1999-09-05)</para> + </listitem> + + <listitem> + <para>All ioctl() commands that used an integer argument now +take a pointer to an integer. Where it makes sense, ioctls will return +the actual new value in the integer pointed to by the argument, a +common convention in the V4L2 API. The affected ioctls are: +VIDIOC_PREVIEW, VIDIOC_STREAMON, VIDIOC_STREAMOFF, VIDIOC_S_FREQ, +VIDIOC_S_INPUT, VIDIOC_S_OUTPUT, VIDIOC_S_EFFECT. For example +<programlisting> +err = ioctl (fd, VIDIOC_XXX, V4L2_XXX); +</programlisting> becomes <programlisting> +int a = V4L2_XXX; err = ioctl(fd, VIDIOC_XXX, &a); +</programlisting> + </para> + </listitem> + + <listitem> + <para>All the different get- and set-format commands were +swept into one &VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctl taking a union +and a type field selecting the union member as parameter. Purpose is to +simplify the API by eliminating several ioctls and to allow new and +driver private data streams without adding new ioctls.</para> + + <para>This change obsoletes the following ioctls: +<constant>VIDIOC_S_INFMT</constant>, +<constant>VIDIOC_G_INFMT</constant>, +<constant>VIDIOC_S_OUTFMT</constant>, +<constant>VIDIOC_G_OUTFMT</constant>, +<constant>VIDIOC_S_VBIFMT</constant> and +<constant>VIDIOC_G_VBIFMT</constant>. The image format structure +<structname>v4l2_format</structname> was renamed to &v4l2-pix-format;, +while &v4l2-format; is now the envelopping structure for all format +negotiations.</para> + </listitem> + + <listitem> + <para>Similar to the changes above, the +<constant>VIDIOC_G_PARM</constant> and +<constant>VIDIOC_S_PARM</constant> ioctls were merged with +<constant>VIDIOC_G_OUTPARM</constant> and +<constant>VIDIOC_S_OUTPARM</constant>. A +<structfield>type</structfield> field in the new &v4l2-streamparm; +selects the respective union member.</para> + + <para>This change obsoletes the +<constant>VIDIOC_G_OUTPARM</constant> and +<constant>VIDIOC_S_OUTPARM</constant> ioctls.</para> + </listitem> + + <listitem> + <para>Control enumeration was simplified, and two new +control flags were introduced and one dropped. The +<structfield>catname</structfield> field was replaced by a +<structfield>group</structfield> field.</para> + + <para>Drivers can now flag unsupported and temporarily +unavailable controls with <constant>V4L2_CTRL_FLAG_DISABLED</constant> +and <constant>V4L2_CTRL_FLAG_GRABBED</constant> respectively. The +<structfield>group</structfield> name indicates a possibly narrower +classification than the <structfield>category</structfield>. In other +words, there may be multiple groups within a category. Controls within +a group would typically be drawn within a group box. Controls in +different categories might have a greater separation, or may even +appear in separate windows.</para> + </listitem> + + <listitem> + <para>The &v4l2-buffer; <structfield>timestamp</structfield> +was changed to a 64 bit integer, containing the sampling or output +time of the frame in nanoseconds. Additionally timestamps will be in +absolute system time, not starting from zero at the beginning of a +stream. The data type name for timestamps is stamp_t, defined as a +signed 64-bit integer. Output devices should not send a buffer out +until the time in the timestamp field has arrived. I would like to +follow SGI's lead, and adopt a multimedia timestamping system like +their UST (Unadjusted System Time). See +http://reality.sgi.com/cpirazzi_engr/lg/time/intro.html. [This link is +no longer valid.] UST uses timestamps that are 64-bit signed integers +(not struct timeval's) and given in nanosecond units. The UST clock +starts at zero when the system is booted and runs continuously and +uniformly. It takes a little over 292 years for UST to overflow. There +is no way to set the UST clock. The regular Linux time-of-day clock +can be changed periodically, which would cause errors if it were being +used for timestamping a multimedia stream. A real UST style clock will +require some support in the kernel that is not there yet. But in +anticipation, I will change the timestamp field to a 64-bit integer, +and I will change the v4l2_masterclock_gettime() function (used only +by drivers) to return a 64-bit integer.</para> + </listitem> + + <listitem> + <para>A <structfield>sequence</structfield> field was added +to &v4l2-buffer;. The <structfield>sequence</structfield> field counts +captured frames, it is ignored by output devices. When a capture +driver drops a frame, the sequence number of that frame is +skipped.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 Version 0.20 incremental changes</title> + <!-- Version number didn't change anymore, reason unknown. --> + + <para>1999-12-23: In &v4l2-vbi-format; the +<structfield>reserved1</structfield> field became +<structfield>offset</structfield>. Previously drivers were required to +clear the <structfield>reserved1</structfield> field.</para> + + <para>2000-01-13: The + <constant>V4L2_FMT_FLAG_NOT_INTERLACED</constant> flag was added.</para> + + <para>2000-07-31: The <filename>linux/poll.h</filename> header +is now included by <filename>videodev.h</filename> for compatibility +with the original <filename>videodev.h</filename> file.</para> + + <para>2000-11-20: <constant>V4L2_TYPE_VBI_OUTPUT</constant> and +<constant>V4L2_PIX_FMT_Y41P</constant> were added.</para> + + <para>2000-11-25: <constant>V4L2_TYPE_VBI_INPUT</constant> was +added.</para> + + <para>2000-12-04: A couple typos in symbol names were fixed.</para> + + <para>2001-01-18: To avoid namespace conflicts the +<constant>fourcc</constant> macro defined in the +<filename>videodev.h</filename> header file was renamed to +<constant>v4l2_fourcc</constant>.</para> + + <para>2001-01-25: A possible driver-level compatibility problem +between the <filename>videodev.h</filename> file in Linux 2.4.0 and +the <filename>videodev.h</filename> file included in the +<filename>videodevX</filename> patch was fixed. Users of an earlier +version of <filename>videodevX</filename> on Linux 2.4.0 should +recompile their V4L and V4L2 drivers.</para> + + <para>2001-01-26: A possible kernel-level incompatibility +between the <filename>videodev.h</filename> file in the +<filename>videodevX</filename> patch and the +<filename>videodev.h</filename> file in Linux 2.2.x with devfs patches +applied was fixed.</para> + + <para>2001-03-02: Certain V4L ioctls which pass data in both +direction although they are defined with read-only parameter, did not +work correctly through the backward compatibility layer. +[Solution?]</para> + + <para>2001-04-13: Big endian 16-bit RGB formats were added.</para> + + <para>2001-09-17: New YUV formats and the &VIDIOC-G-FREQUENCY; and +&VIDIOC-S-FREQUENCY; ioctls were added. (The old +<constant>VIDIOC_G_FREQ</constant> and +<constant>VIDIOC_S_FREQ</constant> ioctls did not take multiple tuners +into account.)</para> + + <para>2000-09-18: <constant>V4L2_BUF_TYPE_VBI</constant> was +added. This may <emphasis>break compatibility</emphasis> as the +&VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctls may fail now if the struct +<structname>v4l2_fmt</structname> <structfield>type</structfield> +field does not contain <constant>V4L2_BUF_TYPE_VBI</constant>. In the +documentation of the &v4l2-vbi-format; +<structfield>offset</structfield> field the ambiguous phrase "rising +edge" was changed to "leading edge".</para> + </section> + + <section> + <title>V4L2 Version 0.20 2000-11-23</title> + + <para>A number of changes were made to the raw VBI +interface.</para> + + <orderedlist> + <listitem> + <para>Figures clarifying the line numbering scheme were +added to the V4L2 API specification. The +<structfield>start</structfield>[0] and +<structfield>start</structfield>[1] fields no longer count line +numbers beginning at zero. Rationale: a) The previous definition was +unclear. b) The <structfield>start</structfield>[] values are ordinal +numbers. c) There is no point in inventing a new line numbering +scheme. We now use line number as defined by ITU-R, period. +Compatibility: Add one to the start values. Applications depending on +the previous semantics may not function correctly.</para> + </listitem> + + <listitem> + <para>The restriction "count[0] > 0 and count[1] > 0" +has been relaxed to "(count[0] + count[1]) > 0". Rationale: +Drivers may allocate resources at scan line granularity and some data +services are transmitted only on the first field. The comment that +both <structfield>count</structfield> values will usually be equal is +misleading and pointless and has been removed. This change +<emphasis>breaks compatibility</emphasis> with earlier versions: +Drivers may return EINVAL, applications may not function +correctly.</para> + </listitem> + + <listitem> + <para>Drivers are again permitted to return negative +(unknown) start values as proposed earlier. Why this feature was +dropped is unclear. This change may <emphasis>break +compatibility</emphasis> with applications depending on the start +values being positive. The use of <constant>EBUSY</constant> and +<constant>EINVAL</constant> error codes with the &VIDIOC-S-FMT; ioctl +was clarified. The &EBUSY; was finally documented, and the +<structfield>reserved2</structfield> field which was previously +mentioned only in the <filename>videodev.h</filename> header +file.</para> + </listitem> + + <listitem> + <para>New buffer types +<constant>V4L2_TYPE_VBI_INPUT</constant> and +<constant>V4L2_TYPE_VBI_OUTPUT</constant> were added. The former is an +alias for the old <constant>V4L2_TYPE_VBI</constant>, the latter was +missing in the <filename>videodev.h</filename> file.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 Version 0.20 2002-07-25</title> + <para>Added sliced VBI interface proposal.</para> + </section> + + <section> + <title>V4L2 in Linux 2.5.46, 2002-10</title> + + <para>Around October-November 2002, prior to an announced +feature freeze of Linux 2.5, the API was revised, drawing from +experience with V4L2 0.20. This unnamed version was finally merged +into Linux 2.5.46.</para> + + <orderedlist> + <listitem> + <para>As specified in <xref linkend="related" />, drivers +must make related device functions available under all minor device +numbers.</para> + </listitem> + + <listitem> + <para>The &func-open; function requires access mode +<constant>O_RDWR</constant> regardless of the device type. All V4L2 +drivers exchanging data with applications must support the +<constant>O_NONBLOCK</constant> flag. The <constant>O_NOIO</constant> +flag, a V4L2 symbol which aliased the meaningless +<constant>O_TRUNC</constant> to indicate accesses without data +exchange (panel applications) was dropped. Drivers must stay in "panel +mode" until the application attempts to initiate a data exchange, see +<xref linkend="open" />.</para> + </listitem> + + <listitem> + <para>The &v4l2-capability; changed dramatically. Note that +also the size of the structure changed, which is encoded in the ioctl +request code, thus older V4L2 devices will respond with an &EINVAL; to +the new &VIDIOC-QUERYCAP; ioctl.</para> + + <para>There are new fields to identify the driver, a new RDS +device function <constant>V4L2_CAP_RDS_CAPTURE</constant>, the +<constant>V4L2_CAP_AUDIO</constant> flag indicates if the device has +any audio connectors, another I/O capability +<constant>V4L2_CAP_ASYNCIO</constant> can be flagged. In response to +these changes the <structfield>type</structfield> field became a bit +set and was merged into the <structfield>flags</structfield> field. +<constant>V4L2_FLAG_TUNER</constant> was renamed to +<constant>V4L2_CAP_TUNER</constant>, +<constant>V4L2_CAP_VIDEO_OVERLAY</constant> replaced +<constant>V4L2_FLAG_PREVIEW</constant> and +<constant>V4L2_CAP_VBI_CAPTURE</constant> and +<constant>V4L2_CAP_VBI_OUTPUT</constant> replaced +<constant>V4L2_FLAG_DATA_SERVICE</constant>. +<constant>V4L2_FLAG_READ</constant> and +<constant>V4L2_FLAG_WRITE</constant> were merged into +<constant>V4L2_CAP_READWRITE</constant>.</para> + + <para>The redundant fields +<structfield>inputs</structfield>, <structfield>outputs</structfield> +and <structfield>audios</structfield> were removed. These properties +can be determined as described in <xref linkend="video" /> and <xref +linkend="audio" />.</para> + + <para>The somewhat volatile and therefore barely useful +fields <structfield>maxwidth</structfield>, +<structfield>maxheight</structfield>, +<structfield>minwidth</structfield>, +<structfield>minheight</structfield>, +<structfield>maxframerate</structfield> were removed. This information +is available as described in <xref linkend="format" /> and +<xref linkend="standard" />.</para> + + <para><constant>V4L2_FLAG_SELECT</constant> was removed. We +believe the select() function is important enough to require support +of it in all V4L2 drivers exchanging data with applications. The +redundant <constant>V4L2_FLAG_MONOCHROME</constant> flag was removed, +this information is available as described in <xref + linkend="format" />.</para> + </listitem> + + <listitem> + <para>In &v4l2-input; the +<structfield>assoc_audio</structfield> field and the +<structfield>capability</structfield> field and its only flag +<constant>V4L2_INPUT_CAP_AUDIO</constant> was replaced by the new +<structfield>audioset</structfield> field. Instead of linking one +video input to one audio input this field reports all audio inputs +this video input combines with.</para> + + <para>New fields are <structfield>tuner</structfield> +(reversing the former link from tuners to video inputs), +<structfield>std</structfield> and +<structfield>status</structfield>.</para> + + <para>Accordingly &v4l2-output; lost its +<structfield>capability</structfield> and +<structfield>assoc_audio</structfield> fields. +<structfield>audioset</structfield>, +<structfield>modulator</structfield> and +<structfield>std</structfield> where added instead.</para> + </listitem> + + <listitem> + <para>The &v4l2-audio; field +<structfield>audio</structfield> was renamed to +<structfield>index</structfield>, for consistency with other +structures. A new capability flag +<constant>V4L2_AUDCAP_STEREO</constant> was added to indicated if the +audio input in question supports stereo sound. +<constant>V4L2_AUDCAP_EFFECTS</constant> and the corresponding +<constant>V4L2_AUDMODE</constant> flags where removed. This can be +easily implemented using controls. (However the same applies to AVL +which is still there.)</para> + + <para>Again for consistency the &v4l2-audioout; field +<structfield>audio</structfield> was renamed to +<structfield>index</structfield>.</para> + </listitem> + + <listitem> + <para>The &v4l2-tuner; +<structfield>input</structfield> field was replaced by an +<structfield>index</structfield> field, permitting devices with +multiple tuners. The link between video inputs and tuners is now +reversed, inputs point to their tuner. The +<structfield>std</structfield> substructure became a +simple set (more about this below) and moved into &v4l2-input;. A +<structfield>type</structfield> field was added.</para> + + <para>Accordingly in &v4l2-modulator; the +<structfield>output</structfield> was replaced by an +<structfield>index</structfield> field.</para> + + <para>In &v4l2-frequency; the +<structfield>port</structfield> field was replaced by a +<structfield>tuner</structfield> field containing the respective tuner +or modulator index number. A tuner <structfield>type</structfield> +field was added and the <structfield>reserved</structfield> field +became larger for future extensions (satellite tuners in +particular).</para> + </listitem> + + <listitem> + <para>The idea of completely transparent video standards was +dropped. Experience showed that applications must be able to work with +video standards beyond presenting the user a menu. Instead of +enumerating supported standards with an ioctl applications can now +refer to standards by &v4l2-std-id; and symbols defined in the +<filename>videodev2.h</filename> header file. For details see <xref + linkend="standard" />. The &VIDIOC-G-STD; and +&VIDIOC-S-STD; now take a pointer to this type as argument. +&VIDIOC-QUERYSTD; was added to autodetect the received standard, if +the hardware has this capability. In &v4l2-standard; an +<structfield>index</structfield> field was added for &VIDIOC-ENUMSTD;. +A &v4l2-std-id; field named <structfield>id</structfield> was added as +machine readable identifier, also replacing the +<structfield>transmission</structfield> field. The misleading +<structfield>framerate</structfield> field was renamed +to <structfield>frameperiod</structfield>. The now obsolete +<structfield>colorstandard</structfield> information, originally +needed to distguish between variations of standards, were +removed.</para> + + <para>Struct <structname>v4l2_enumstd</structname> ceased to +be. &VIDIOC-ENUMSTD; now takes a pointer to a &v4l2-standard; +directly. The information which standards are supported by a +particular video input or output moved into &v4l2-input; and +&v4l2-output; fields named <structfield>std</structfield>, +respectively.</para> + </listitem> + + <listitem> + <para>The &v4l2-queryctrl; fields +<structfield>category</structfield> and +<structfield>group</structfield> did not catch on and/or were not +implemented as expected and therefore removed.</para> + </listitem> + + <listitem> + <para>The &VIDIOC-TRY-FMT; ioctl was added to negotiate data +formats as with &VIDIOC-S-FMT;, but without the overhead of +programming the hardware and regardless of I/O in progress.</para> + + <para>In &v4l2-format; the <structfield>fmt</structfield> +union was extended to contain &v4l2-window;. All image format +negotiations are now possible with <constant>VIDIOC_G_FMT</constant>, +<constant>VIDIOC_S_FMT</constant> and +<constant>VIDIOC_TRY_FMT</constant>; ioctl. The +<constant>VIDIOC_G_WIN</constant> and +<constant>VIDIOC_S_WIN</constant> ioctls to prepare for a video +overlay were removed. The <structfield>type</structfield> field +changed to type &v4l2-buf-type; and the buffer type names changed as +follows.<informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>Old defines</entry> + <entry>&v4l2-buf-type;</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_BUF_TYPE_CAPTURE</constant></entry> + <entry><constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant></entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_CODECIN</constant></entry> + <entry>Omitted for now</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_CODECOUT</constant></entry> + <entry>Omitted for now</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_EFFECTSIN</constant></entry> + <entry>Omitted for now</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_EFFECTSIN2</constant></entry> + <entry>Omitted for now</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_EFFECTSOUT</constant></entry> + <entry>Omitted for now</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_VIDEOOUT</constant></entry> + <entry><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_BUF_TYPE_VBI_CAPTURE</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant></entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_PRIVATE_BASE</constant></entry> + <entry><constant>V4L2_BUF_TYPE_PRIVATE</constant></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + </listitem> + + <listitem> + <para>In &v4l2-fmtdesc; a &v4l2-buf-type; field named +<structfield>type</structfield> was added as in &v4l2-format;. The +<constant>VIDIOC_ENUM_FBUFFMT</constant> ioctl is no longer needed and +was removed. These calls can be replaced by &VIDIOC-ENUM-FMT; with +type <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para> + </listitem> + + <listitem> + <para>In &v4l2-pix-format; the +<structfield>depth</structfield> field was removed, assuming +applications which recognize the format by its four-character-code +already know the color depth, and others do not care about it. The +same rationale lead to the removal of the +<constant>V4L2_FMT_FLAG_COMPRESSED</constant> flag. The +<constant>V4L2_FMT_FLAG_SWCONVECOMPRESSED</constant> flag was removed +because drivers are not supposed to convert images in kernel space. A +user library of conversion functions should be provided instead. The +<constant>V4L2_FMT_FLAG_BYTESPERLINE</constant> flag was redundant. +Applications can set the <structfield>bytesperline</structfield> field +to zero to get a reasonable default. Since the remaining flags were +replaced as well, the <structfield>flags</structfield> field itself +was removed.</para> + <para>The interlace flags were replaced by a &v4l2-field; +value in a newly added <structfield>field</structfield> +field.<informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>Old flag</entry> + <entry>&v4l2-field;</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_FMT_FLAG_NOT_INTERLACED</constant></entry> + <entry>?</entry> + </row> + <row> + <entry><constant>V4L2_FMT_FLAG_INTERLACED</constant> += <constant>V4L2_FMT_FLAG_COMBINED</constant></entry> + <entry><constant>V4L2_FIELD_INTERLACED</constant></entry> + </row> + <row> + <entry><constant>V4L2_FMT_FLAG_TOPFIELD</constant> += <constant>V4L2_FMT_FLAG_ODDFIELD</constant></entry> + <entry><constant>V4L2_FIELD_TOP</constant></entry> + </row> + <row> + <entry><constant>V4L2_FMT_FLAG_BOTFIELD</constant> += <constant>V4L2_FMT_FLAG_EVENFIELD</constant></entry> + <entry><constant>V4L2_FIELD_BOTTOM</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_FIELD_SEQ_TB</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_FIELD_SEQ_BT</constant></entry> + </row> + <row> + <entry><constant>-</constant></entry> + <entry><constant>V4L2_FIELD_ALTERNATE</constant></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + + <para>The color space flags were replaced by a +&v4l2-colorspace; value in a newly added +<structfield>colorspace</structfield> field, where one of +<constant>V4L2_COLORSPACE_SMPTE170M</constant>, +<constant>V4L2_COLORSPACE_BT878</constant>, +<constant>V4L2_COLORSPACE_470_SYSTEM_M</constant> or +<constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant> replaces +<constant>V4L2_FMT_CS_601YUV</constant>.</para> + </listitem> + + <listitem> + <para>In &v4l2-requestbuffers; the +<structfield>type</structfield> field was properly defined as +&v4l2-buf-type;. Buffer types changed as mentioned above. A new +<structfield>memory</structfield> field of type &v4l2-memory; was +added to distinguish between I/O methods using buffers allocated +by the driver or the application. See <xref linkend="io" /> for +details.</para> + </listitem> + + <listitem> + <para>In &v4l2-buffer; the <structfield>type</structfield> +field was properly defined as &v4l2-buf-type;. Buffer types changed as +mentioned above. A <structfield>field</structfield> field of type +&v4l2-field; was added to indicate if a buffer contains a top or +bottom field. The old field flags were removed. Since no unadjusted +system time clock was added to the kernel as planned, the +<structfield>timestamp</structfield> field changed back from type +stamp_t, an unsigned 64 bit integer expressing the sample time in +nanoseconds, to struct <structname>timeval</structname>. With the +addition of a second memory mapping method the +<structfield>offset</structfield> field moved into union +<structfield>m</structfield>, and a new +<structfield>memory</structfield> field of type &v4l2-memory; was +added to distinguish between I/O methods. See <xref linkend="io" /> +for details.</para> + + <para>The <constant>V4L2_BUF_REQ_CONTIG</constant> +flag was used by the V4L compatibility layer, after changes to this +code it was no longer needed. The +<constant>V4L2_BUF_ATTR_DEVICEMEM</constant> flag would indicate if +the buffer was indeed allocated in device memory rather than DMA-able +system memory. It was barely useful and so was removed.</para> + </listitem> + + <listitem> + <para>In &v4l2-framebuffer; the +<structfield>base[3]</structfield> array anticipating double- and +triple-buffering in off-screen video memory, however without defining +a synchronization mechanism, was replaced by a single pointer. The +<constant>V4L2_FBUF_CAP_SCALEUP</constant> and +<constant>V4L2_FBUF_CAP_SCALEDOWN</constant> flags were removed. +Applications can determine this capability more accurately using the +new cropping and scaling interface. The +<constant>V4L2_FBUF_CAP_CLIPPING</constant> flag was replaced by +<constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant> and +<constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant>.</para> + </listitem> + + <listitem> + <para>In &v4l2-clip; the <structfield>x</structfield>, +<structfield>y</structfield>, <structfield>width</structfield> and +<structfield>height</structfield> field moved into a +<structfield>c</structfield> substructure of type &v4l2-rect;. The +<structfield>x</structfield> and <structfield>y</structfield> fields +were renamed to <structfield>left</structfield> and +<structfield>top</structfield>, &ie; offsets to a context dependent +origin.</para> + </listitem> + + <listitem> + <para>In &v4l2-window; the <structfield>x</structfield>, +<structfield>y</structfield>, <structfield>width</structfield> and +<structfield>height</structfield> field moved into a +<structfield>w</structfield> substructure as above. A +<structfield>field</structfield> field of type %v4l2-field; was added +to distinguish between field and frame (interlaced) overlay.</para> + </listitem> + + <listitem> + <para>The digital zoom interface, including struct +<structname>v4l2_zoomcap</structname>, struct +<structname>v4l2_zoom</structname>, +<constant>V4L2_ZOOM_NONCAP</constant> and +<constant>V4L2_ZOOM_WHILESTREAMING</constant> was replaced by a new +cropping and scaling interface. The previously unused struct +<structname>v4l2_cropcap</structname> and +<structname>v4l2_crop</structname> where redefined for this purpose. +See <xref linkend="crop" /> for details.</para> + </listitem> + + <listitem> + <para>In &v4l2-vbi-format; the +<structfield>SAMPLE_FORMAT</structfield> field now contains a +four-character-code as used to identify video image formats and +<constant>V4L2_PIX_FMT_GREY</constant> replaces the +<constant>V4L2_VBI_SF_UBYTE</constant> define. The +<structfield>reserved</structfield> field was extended.</para> + </listitem> + + <listitem> + <para>In &v4l2-captureparm; the type of the +<structfield>timeperframe</structfield> field changed from unsigned +long to &v4l2-fract;. This allows the accurate expression of multiples +of the NTSC-M frame rate 30000 / 1001. A new field +<structfield>readbuffers</structfield> was added to control the driver +behaviour in read I/O mode.</para> + + <para>Similar changes were made to &v4l2-outputparm;.</para> + </listitem> + + <listitem> + <para>The struct <structname>v4l2_performance</structname> +and <constant>VIDIOC_G_PERF</constant> ioctl were dropped. Except when +using the <link linkend="rw">read/write I/O method</link>, which is +limited anyway, this information is already available to +applications.</para> + </listitem> + + <listitem> + <para>The example transformation from RGB to YCbCr color +space in the old V4L2 documentation was inaccurate, this has been +corrected in <xref linkend="pixfmt" />.<!-- 0.5670G should be +0.587, and 127/112 != 255/224 --></para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 2003-06-19</title> + + <orderedlist> + <listitem> + <para>A new capability flag +<constant>V4L2_CAP_RADIO</constant> was added for radio devices. Prior +to this change radio devices would identify solely by having exactly one +tuner whose type field reads <constant>V4L2_TUNER_RADIO</constant>.</para> + </listitem> + + <listitem> + <para>An optional driver access priority mechanism was +added, see <xref linkend="app-pri" /> for details.</para> + </listitem> + + <listitem> + <para>The audio input and output interface was found to be +incomplete.</para> + <para>Previously the &VIDIOC-G-AUDIO; +ioctl would enumerate the available audio inputs. An ioctl to +determine the current audio input, if more than one combines with the +current video input, did not exist. So +<constant>VIDIOC_G_AUDIO</constant> was renamed to +<constant>VIDIOC_G_AUDIO_OLD</constant>, this ioctl will be removed in +the future. The &VIDIOC-ENUMAUDIO; ioctl was added to enumerate +audio inputs, while &VIDIOC-G-AUDIO; now reports the current audio +input.</para> + <para>The same changes were made to &VIDIOC-G-AUDOUT; and +&VIDIOC-ENUMAUDOUT;.</para> + <para>Until further the "videodev" module will automatically +translate between the old and new ioctls, but drivers and applications +must be updated to successfully compile again.</para> + </listitem> + + <listitem> + <para>The &VIDIOC-OVERLAY; ioctl was incorrectly defined with +write-read parameter. It was changed to write-only, while the write-read +version was renamed to <constant>VIDIOC_OVERLAY_OLD</constant>. The old +ioctl will be removed in the future. Until further the "videodev" +kernel module will automatically translate to the new version, so drivers +must be recompiled, but not applications.</para> + </listitem> + + <listitem> + <para><xref linkend="overlay" /> incorrectly stated that +clipping rectangles define regions where the video can be seen. +Correct is that clipping rectangles define regions where +<emphasis>no</emphasis> video shall be displayed and so the graphics +surface can be seen.</para> + </listitem> + + <listitem> + <para>The &VIDIOC-S-PARM; and &VIDIOC-S-CTRL; ioctls were +defined with write-only parameter, inconsistent with other ioctls +modifying their argument. They were changed to write-read, while a +<constant>_OLD</constant> suffix was added to the write-only versions. +The old ioctls will be removed in the future. Drivers and +applications assuming a constant parameter need an update.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 2003-11-05</title> + <orderedlist> + <listitem> + <para>In <xref linkend="pixfmt-rgb" /> the following pixel +formats were incorrectly transferred from Bill Dirks' V4L2 +specification. Descriptions below refer to bytes in memory, in +ascending address order.<informaltable> + <tgroup cols="3"> + <thead> + <row> + <entry>Symbol</entry> + <entry>In this document prior to revision +0.5</entry> + <entry>Corrected</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_PIX_FMT_RGB24</constant></entry> + <entry>B, G, R</entry> + <entry>R, G, B</entry> + </row> + <row> + <entry><constant>V4L2_PIX_FMT_BGR24</constant></entry> + <entry>R, G, B</entry> + <entry>B, G, R</entry> + </row> + <row> + <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry> + <entry>B, G, R, X</entry> + <entry>R, G, B, X</entry> + </row> + <row> + <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry> + <entry>R, G, B, X</entry> + <entry>B, G, R, X</entry> + </row> + </tbody> + </tgroup> + </informaltable> The +<constant>V4L2_PIX_FMT_BGR24</constant> example was always +correct.</para> + <para>In <xref linkend="v4l-image-properties" /> the mapping +of the V4L <constant>VIDEO_PALETTE_RGB24</constant> and +<constant>VIDEO_PALETTE_RGB32</constant> formats to V4L2 pixel formats +was accordingly corrected.</para> + </listitem> + + <listitem> + <para>Unrelated to the fixes above, drivers may still +interpret some V4L2 RGB pixel formats differently. These issues have +yet to be addressed, for details see <xref + linkend="pixfmt-rgb" />.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.6, 2004-05-09</title> + <orderedlist> + <listitem> + <para>The &VIDIOC-CROPCAP; ioctl was incorrectly defined +with read-only parameter. It is now defined as write-read ioctl, while +the read-only version was renamed to +<constant>VIDIOC_CROPCAP_OLD</constant>. The old ioctl will be removed +in the future.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.8</title> + <orderedlist> + <listitem> + <para>A new field <structfield>input</structfield> (former +<structfield>reserved[0]</structfield>) was added to the &v4l2-buffer; +structure. Purpose of this field is to alternate between video inputs +(⪚ cameras) in step with the video capturing process. This function +must be enabled with the new <constant>V4L2_BUF_FLAG_INPUT</constant> +flag. The <structfield>flags</structfield> field is no longer +read-only.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 spec erratum 2004-08-01</title> + + <orderedlist> + <listitem> + <para>The return value of the +<xref linkend="func-open" /> function was incorrectly documented.</para> + </listitem> + + <listitem> + <para>Audio output ioctls end in -AUDOUT, not -AUDIOOUT.</para> + </listitem> + + <listitem> + <para>In the Current Audio Input example the +<constant>VIDIOC_G_AUDIO</constant> ioctl took the wrong +argument.</para> + </listitem> + + <listitem> + <para>The documentation of the &VIDIOC-QBUF; and +&VIDIOC-DQBUF; ioctls did not mention the &v4l2-buffer; +<structfield>memory</structfield> field. It was also missing from +examples. Also on the <constant>VIDIOC_DQBUF</constant> page the &EIO; +was not documented.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.14</title> + <orderedlist> + <listitem> + <para>A new sliced VBI interface was added. It is documented +in <xref linkend="sliced" /> and replaces the interface first +proposed in V4L2 specification 0.8.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.15</title> + <orderedlist> + <listitem> + <para>The &VIDIOC-LOG-STATUS; ioctl was added.</para> + </listitem> + + <listitem> + <para>New video standards +<constant>V4L2_STD_NTSC_443</constant>, +<constant>V4L2_STD_SECAM_LC</constant>, +<constant>V4L2_STD_SECAM_DK</constant> (a set of SECAM D, K and K1), +and <constant>V4L2_STD_ATSC</constant> (a set of +<constant>V4L2_STD_ATSC_8_VSB</constant> and +<constant>V4L2_STD_ATSC_16_VSB</constant>) were defined. Note the +<constant>V4L2_STD_525_60</constant> set now includes +<constant>V4L2_STD_NTSC_443</constant>. See also <xref + linkend="v4l2-std-id" />.</para> + </listitem> + + <listitem> + <para>The <constant>VIDIOC_G_COMP</constant> and +<constant>VIDIOC_S_COMP</constant> ioctl were renamed to +<constant>VIDIOC_G_MPEGCOMP</constant> and +<constant>VIDIOC_S_MPEGCOMP</constant> respectively. Their argument +was replaced by a struct +<structname>v4l2_mpeg_compression</structname> pointer. (The +<constant>VIDIOC_G_MPEGCOMP</constant> and +<constant>VIDIOC_S_MPEGCOMP</constant> ioctls where removed in Linux +2.6.25.)</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 spec erratum 2005-11-27</title> + <para>The capture example in <xref linkend="capture-example" /> +called the &VIDIOC-S-CROP; ioctl without checking if cropping is +supported. In the video standard selection example in +<xref linkend="standard" /> the &VIDIOC-S-STD; call used the wrong +argument type.</para> + </section> + + <section> + <title>V4L2 spec erratum 2006-01-10</title> + <orderedlist> + <listitem> + <para>The <constant>V4L2_IN_ST_COLOR_KILL</constant> flag in +&v4l2-input; not only indicates if the color killer is enabled, but +also if it is active. (The color killer disables color decoding when +it detects no color in the video signal to improve the image +quality.)</para> + </listitem> + + <listitem> + <para>&VIDIOC-S-PARM; is a write-read ioctl, not write-only as +stated on its reference page. The ioctl changed in 2003 as noted above.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 spec erratum 2006-02-03</title> + <orderedlist> + <listitem> + <para>In &v4l2-captureparm; and &v4l2-outputparm; the +<structfield>timeperframe</structfield> field gives the time in +seconds, not microseconds.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 spec erratum 2006-02-04</title> + <orderedlist> + <listitem> + <para>The <structfield>clips</structfield> field in +&v4l2-window; must point to an array of &v4l2-clip;, not a linked +list, because drivers ignore the struct +<structname>v4l2_clip</structname>.<structfield>next</structfield> +pointer.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.17</title> + <orderedlist> + <listitem> + <para>New video standard macros were added: +<constant>V4L2_STD_NTSC_M_KR</constant> (NTSC M South Korea), and the +sets <constant>V4L2_STD_MN</constant>, +<constant>V4L2_STD_B</constant>, <constant>V4L2_STD_GH</constant> and +<constant>V4L2_STD_DK</constant>. The +<constant>V4L2_STD_NTSC</constant> and +<constant>V4L2_STD_SECAM</constant> sets now include +<constant>V4L2_STD_NTSC_M_KR</constant> and +<constant>V4L2_STD_SECAM_LC</constant> respectively.</para> + </listitem> + + <listitem> + <para>A new <constant>V4L2_TUNER_MODE_LANG1_LANG2</constant> +was defined to record both languages of a bilingual program. The +use of <constant>V4L2_TUNER_MODE_STEREO</constant> for this purpose +is deprecated now. See the &VIDIOC-G-TUNER; section for +details.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 spec erratum 2006-09-23 (Draft 0.15)</title> + <orderedlist> + <listitem> + <para>In various places +<constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> and +<constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant> of the sliced VBI +interface were not mentioned along with other buffer types.</para> + </listitem> + + <listitem> + <para>In <xref linkend="vidioc-g-audio" /> it was clarified +that the &v4l2-audio; <structfield>mode</structfield> field is a flags +field.</para> + </listitem> + + <listitem> + <para><xref linkend="vidioc-querycap" /> did not mention the +sliced VBI and radio capability flags.</para> + </listitem> + + <listitem> + <para>In <xref linkend="vidioc-g-frequency" /> it was +clarified that applications must initialize the tuner +<structfield>type</structfield> field of &v4l2-frequency; before +calling &VIDIOC-S-FREQUENCY;.</para> + </listitem> + + <listitem> + <para>The <structfield>reserved</structfield> array +in &v4l2-requestbuffers; has 2 elements, not 32.</para> + </listitem> + + <listitem> + <para>In <xref linkend="output" /> and <xref + linkend="raw-vbi" /> the device file names +<filename>/dev/vout</filename> which never caught on were replaced +by <filename>/dev/video</filename>.</para> + </listitem> + + <listitem> + <para>With Linux 2.6.15 the possible range for VBI device minor +numbers was extended from 224-239 to 224-255. Accordingly device file names +<filename>/dev/vbi0</filename> to <filename>/dev/vbi31</filename> are +possible now.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.18</title> + <orderedlist> + <listitem> + <para>New ioctls &VIDIOC-G-EXT-CTRLS;, &VIDIOC-S-EXT-CTRLS; +and &VIDIOC-TRY-EXT-CTRLS; were added, a flag to skip unsupported +controls with &VIDIOC-QUERYCTRL;, new control types +<constant>V4L2_CTRL_TYPE_INTEGER64</constant> and +<constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant> (<xref + linkend="v4l2-ctrl-type" />), and new control flags +<constant>V4L2_CTRL_FLAG_READ_ONLY</constant>, +<constant>V4L2_CTRL_FLAG_UPDATE</constant>, +<constant>V4L2_CTRL_FLAG_INACTIVE</constant> and +<constant>V4L2_CTRL_FLAG_SLIDER</constant> (<xref + linkend="control-flags" />). See <xref + linkend="extended-controls" /> for details.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.19</title> + <orderedlist> + <listitem> + <para>In &v4l2-sliced-vbi-cap; a buffer type field was added +replacing a reserved field. Note on architectures where the size of +enum types differs from int types the size of the structure changed. +The &VIDIOC-G-SLICED-VBI-CAP; ioctl was redefined from being read-only +to write-read. Applications must initialize the type field and clear +the reserved fields now. These changes may <emphasis>break the +compatibility</emphasis> with older drivers and applications.</para> + </listitem> + + <listitem> + <para>The ioctls &VIDIOC-ENUM-FRAMESIZES; and +&VIDIOC-ENUM-FRAMEINTERVALS; were added.</para> + </listitem> + + <listitem> + <para>A new pixel format <constant>V4L2_PIX_FMT_RGB444</constant> (<xref +linkend="rgb-formats" />) was added.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 spec erratum 2006-10-12 (Draft 0.17)</title> + <orderedlist> + <listitem> + <para><constant>V4L2_PIX_FMT_HM12</constant> (<xref +linkend="reserved-formats" />) is a YUV 4:2:0, not 4:2:2 format.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.21</title> + <orderedlist> + <listitem> + <para>The <filename>videodev2.h</filename> header file is +now dual licensed under GNU General Public License version two or +later, and under a 3-clause BSD-style license.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.22</title> + <orderedlist> + <listitem> + <para>Two new field orders + <constant>V4L2_FIELD_INTERLACED_TB</constant> and + <constant>V4L2_FIELD_INTERLACED_BT</constant> were + added. See <xref linkend="v4l2-field" /> for details.</para> + </listitem> + + <listitem> + <para>Three new clipping/blending methods with a global or +straight or inverted local alpha value were added to the video overlay +interface. See the description of the &VIDIOC-G-FBUF; and +&VIDIOC-S-FBUF; ioctls for details.</para> + <para>A new <structfield>global_alpha</structfield> field +was added to <link +linkend="v4l2-window"><structname>v4l2_window</structname></link>, +extending the structure. This may <emphasis>break +compatibility</emphasis> with applications using a struct +<structname>v4l2_window</structname> directly. However the <link +linkend="vidioc-g-fmt">VIDIOC_G/S/TRY_FMT</link> ioctls, which take a +pointer to a <link linkend="v4l2-format">v4l2_format</link> parent +structure with padding bytes at the end, are not affected.</para> + </listitem> + + <listitem> + <para>The format of the <structfield>chromakey</structfield> +field in &v4l2-window; changed from "host order RGB32" to a pixel +value in the same format as the framebuffer. This may <emphasis>break +compatibility</emphasis> with existing applications. Drivers +supporting the "host order RGB32" format are not known.</para> + </listitem> + + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.24</title> + <orderedlist> + <listitem> + <para>The pixel formats +<constant>V4L2_PIX_FMT_PAL8</constant>, +<constant>V4L2_PIX_FMT_YUV444</constant>, +<constant>V4L2_PIX_FMT_YUV555</constant>, +<constant>V4L2_PIX_FMT_YUV565</constant> and +<constant>V4L2_PIX_FMT_YUV32</constant> were added.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.25</title> + <orderedlist> + <listitem> + <para>The pixel formats <link linkend="V4L2-PIX-FMT-Y16"> +<constant>V4L2_PIX_FMT_Y16</constant></link> and <link +linkend="V4L2-PIX-FMT-SBGGR16"> +<constant>V4L2_PIX_FMT_SBGGR16</constant></link> were added.</para> + </listitem> + <listitem> + <para>New <link linkend="control">controls</link> +<constant>V4L2_CID_POWER_LINE_FREQUENCY</constant>, +<constant>V4L2_CID_HUE_AUTO</constant>, +<constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant>, +<constant>V4L2_CID_SHARPNESS</constant> and +<constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant> were added. The +controls <constant>V4L2_CID_BLACK_LEVEL</constant>, +<constant>V4L2_CID_WHITENESS</constant>, +<constant>V4L2_CID_HCENTER</constant> and +<constant>V4L2_CID_VCENTER</constant> were deprecated. +</para> + </listitem> + <listitem> + <para>A <link linkend="camera-controls">Camera controls +class</link> was added, with the new controls +<constant>V4L2_CID_EXPOSURE_AUTO</constant>, +<constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant>, +<constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant>, +<constant>V4L2_CID_PAN_RELATIVE</constant>, +<constant>V4L2_CID_TILT_RELATIVE</constant>, +<constant>V4L2_CID_PAN_RESET</constant>, +<constant>V4L2_CID_TILT_RESET</constant>, +<constant>V4L2_CID_PAN_ABSOLUTE</constant>, +<constant>V4L2_CID_TILT_ABSOLUTE</constant>, +<constant>V4L2_CID_FOCUS_ABSOLUTE</constant>, +<constant>V4L2_CID_FOCUS_RELATIVE</constant> and +<constant>V4L2_CID_FOCUS_AUTO</constant>.</para> + </listitem> + <listitem> + <para>The <constant>VIDIOC_G_MPEGCOMP</constant> and +<constant>VIDIOC_S_MPEGCOMP</constant> ioctls, which were superseded +by the <link linkend="extended-controls">extended controls</link> +interface in Linux 2.6.18, where finally removed from the +<filename>videodev2.h</filename> header file.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.26</title> + <orderedlist> + <listitem> + <para>The pixel formats +<constant>V4L2_PIX_FMT_Y16</constant> and +<constant>V4L2_PIX_FMT_SBGGR16</constant> were added.</para> + </listitem> + <listitem> + <para>Added user controls +<constant>V4L2_CID_CHROMA_AGC</constant> and +<constant>V4L2_CID_COLOR_KILLER</constant>.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.27</title> + <orderedlist> + <listitem> + <para>The &VIDIOC-S-HW-FREQ-SEEK; ioctl and the +<constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability were added.</para> + </listitem> + <listitem> + <para>The pixel formats +<constant>V4L2_PIX_FMT_YVYU</constant>, +<constant>V4L2_PIX_FMT_PCA501</constant>, +<constant>V4L2_PIX_FMT_PCA505</constant>, +<constant>V4L2_PIX_FMT_PCA508</constant>, +<constant>V4L2_PIX_FMT_PCA561</constant>, +<constant>V4L2_PIX_FMT_SGBRG8</constant>, +<constant>V4L2_PIX_FMT_PAC207</constant> and +<constant>V4L2_PIX_FMT_PJPG</constant> were added.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.28</title> + <orderedlist> + <listitem> + <para>Added <constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant> and +<constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant> MPEG audio encodings.</para> + </listitem> + <listitem> + <para>Added <constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant> MPEG +video encoding.</para> + </listitem> + <listitem> + <para>The pixel formats +<constant>V4L2_PIX_FMT_SGRBG10</constant> and +<constant>V4L2_PIX_FMT_SGRBG10DPCM8</constant> were added.</para> + </listitem> + </orderedlist> + </section> + + <section> + <title>V4L2 in Linux 2.6.29</title> + <orderedlist> + <listitem> + <para>The <constant>VIDIOC_G_CHIP_IDENT</constant> ioctl was renamed +to <constant>VIDIOC_G_CHIP_IDENT_OLD</constant> and &VIDIOC-DBG-G-CHIP-IDENT; +was introduced in its place. The old struct <structname>v4l2_chip_ident</structname> +was renamed to <structname id="v4l2-chip-ident-old">v4l2_chip_ident_old</structname>.</para> + </listitem> + <listitem> + <para>The pixel formats +<constant>V4L2_PIX_FMT_VYUY</constant>, +<constant>V4L2_PIX_FMT_NV16</constant> and +<constant>V4L2_PIX_FMT_NV61</constant> were added.</para> + </listitem> + <listitem> + <para>Added camera controls +<constant>V4L2_CID_ZOOM_ABSOLUTE</constant>, +<constant>V4L2_CID_ZOOM_RELATIVE</constant>, +<constant>V4L2_CID_ZOOM_CONTINUOUS</constant> and +<constant>V4L2_CID_PRIVACY</constant>.</para> + </listitem> + </orderedlist> + </section> + <section> + <title>V4L2 in Linux 2.6.30</title> + <orderedlist> + <listitem> + <para>New control flag <constant>V4L2_CTRL_FLAG_WRITE_ONLY</constant> was added.</para> + </listitem> + <listitem> + <para>New control <constant>V4L2_CID_COLORFX</constant> was added.</para> + </listitem> + </orderedlist> + </section> + <section> + <title>V4L2 in Linux 2.6.32</title> + <orderedlist> + <listitem> + <para>In order to be easier to compare a V4L2 API and a kernel +version, now V4L2 API is numbered using the Linux Kernel version numeration.</para> + </listitem> + <listitem> + <para>Finalized the RDS capture API. See <xref linkend="rds" /> for +more information.</para> + </listitem> + <listitem> + <para>Added new capabilities for modulators and RDS encoders.</para> + </listitem> + <listitem> + <para>Add description for libv4l API.</para> + </listitem> + <listitem> + <para>Added support for string controls via new type <constant>V4L2_CTRL_TYPE_STRING</constant>.</para> + </listitem> + <listitem> + <para>Added <constant>V4L2_CID_BAND_STOP_FILTER</constant> documentation.</para> + </listitem> + <listitem> + <para>Added FM Modulator (FM TX) Extended Control Class: <constant>V4L2_CTRL_CLASS_FM_TX</constant> and their Control IDs.</para> + </listitem> + <listitem> + <para>Added Remote Controller chapter, describing the default Remote Controller mapping for media devices.</para> + </listitem> + </orderedlist> + </section> + </section> + + <section id="other"> + <title>Relation of V4L2 to other Linux multimedia APIs</title> + + <section id="xvideo"> + <title>X Video Extension</title> + + <para>The X Video Extension (abbreviated XVideo or just Xv) is +an extension of the X Window system, implemented for example by the +XFree86 project. Its scope is similar to V4L2, an API to video capture +and output devices for X clients. Xv allows applications to display +live video in a window, send window contents to a TV output, and +capture or output still images in XPixmaps<footnote> + <para>This is not implemented in XFree86.</para> + </footnote>. With their implementation XFree86 makes the +extension available across many operating systems and +architectures.</para> + + <para>Because the driver is embedded into the X server Xv has a +number of advantages over the V4L2 <link linkend="overlay">video +overlay interface</link>. The driver can easily determine the overlay +target, &ie; visible graphics memory or off-screen buffers for a +destructive overlay. It can program the RAMDAC for a non-destructive +overlay, scaling or color-keying, or the clipping functions of the +video capture hardware, always in sync with drawing operations or +windows moving or changing their stacking order.</para> + + <para>To combine the advantages of Xv and V4L a special Xv +driver exists in XFree86 and XOrg, just programming any overlay capable +Video4Linux device it finds. To enable it +<filename>/etc/X11/XF86Config</filename> must contain these lines:</para> + <para><screen> +Section "Module" + Load "v4l" +EndSection</screen></para> + + <para>As of XFree86 4.2 this driver still supports only V4L +ioctls, however it should work just fine with all V4L2 devices through +the V4L2 backward-compatibility layer. Since V4L2 permits multiple +opens it is possible (if supported by the V4L2 driver) to capture +video while an X client requested video overlay. Restrictions of +simultaneous capturing and overlay are discussed in <xref + linkend="overlay" /> apply.</para> + + <para>Only marginally related to V4L2, XFree86 extended Xv to +support hardware YUV to RGB conversion and scaling for faster video +playback, and added an interface to MPEG-2 decoding hardware. This API +is useful to display images captured with V4L2 devices.</para> + </section> + + <section> + <title>Digital Video</title> + + <para>V4L2 does not support digital terrestrial, cable or +satellite broadcast. A separate project aiming at digital receivers +exists. You can find its homepage at <ulink +url="http://linuxtv.org">http://linuxtv.org</ulink>. The Linux DVB API +has no connection to the V4L2 API except that drivers for hybrid +hardware may support both.</para> + </section> + + <section> + <title>Audio Interfaces</title> + + <para>[to do - OSS/ALSA]</para> + </section> + </section> + + <section id="experimental"> + <title>Experimental API Elements</title> + + <para>The following V4L2 API elements are currently experimental +and may change in the future.</para> + + <itemizedlist> + <listitem> + <para>Video Output Overlay (OSD) Interface, <xref + linkend="osd" />.</para> + </listitem> + <listitem> + <para><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant>, + &v4l2-buf-type;, <xref linkend="v4l2-buf-type" />.</para> + </listitem> + <listitem> + <para><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant>, +&VIDIOC-QUERYCAP; ioctl, <xref linkend="device-capabilities" />.</para> + </listitem> + <listitem> + <para>&VIDIOC-ENUM-FRAMESIZES; and +&VIDIOC-ENUM-FRAMEINTERVALS; ioctls.</para> + </listitem> + <listitem> + <para>&VIDIOC-G-ENC-INDEX; ioctl.</para> + </listitem> + <listitem> + <para>&VIDIOC-ENCODER-CMD; and &VIDIOC-TRY-ENCODER-CMD; +ioctls.</para> + </listitem> + <listitem> + <para>&VIDIOC-DBG-G-REGISTER; and &VIDIOC-DBG-S-REGISTER; +ioctls.</para> + </listitem> + <listitem> + <para>&VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para> + </listitem> + </itemizedlist> + </section> + + <section id="obsolete"> + <title>Obsolete API Elements</title> + + <para>The following V4L2 API elements were superseded by new +interfaces and should not be implemented in new drivers.</para> + + <itemizedlist> + <listitem> + <para><constant>VIDIOC_G_MPEGCOMP</constant> and +<constant>VIDIOC_S_MPEGCOMP</constant> ioctls. Use Extended Controls, +<xref linkend="extended-controls" />.</para> + </listitem> + </itemizedlist> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/controls.xml b/linux/Documentation/DocBook/v4l/controls.xml new file mode 100644 index 000000000..f492accb6 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/controls.xml @@ -0,0 +1,2049 @@ + <section id="control"> + <title>User Controls</title> + + <para>Devices typically have a number of user-settable controls +such as brightness, saturation and so on, which would be presented to +the user on a graphical user interface. But, different devices +will have different controls available, and furthermore, the range of +possible values, and the default value will vary from device to +device. The control ioctls provide the information and a mechanism to +create a nice user interface for these controls that will work +correctly with any device.</para> + + <para>All controls are accessed using an ID value. V4L2 defines +several IDs for specific purposes. Drivers can also implement their +own custom controls using <constant>V4L2_CID_PRIVATE_BASE</constant> +and higher values. The pre-defined control IDs have the prefix +<constant>V4L2_CID_</constant>, and are listed in <xref +linkend="control-id" />. The ID is used when querying the attributes of +a control, and when getting or setting the current value.</para> + + <para>Generally applications should present controls to the user +without assumptions about their purpose. Each control comes with a +name string the user is supposed to understand. When the purpose is +non-intuitive the driver writer should provide a user manual, a user +interface plug-in or a driver specific panel application. Predefined +IDs were introduced to change a few controls programmatically, for +example to mute a device during a channel switch.</para> + + <para>Drivers may enumerate different controls after switching +the current video input or output, tuner or modulator, or audio input +or output. Different in the sense of other bounds, another default and +current value, step size or other menu items. A control with a certain +<emphasis>custom</emphasis> ID can also change name and +type.<footnote> + <para>It will be more convenient for applications if drivers +make use of the <constant>V4L2_CTRL_FLAG_DISABLED</constant> flag, but +that was never required.</para> + </footnote> Control values are stored globally, they do not +change when switching except to stay within the reported bounds. They +also do not change ⪚ when the device is opened or closed, when the +tuner radio frequency is changed or generally never without +application request. Since V4L2 specifies no event mechanism, panel +applications intended to cooperate with other panel applications (be +they built into a larger application, as a TV viewer) may need to +regularly poll control values to update their user +interface.<footnote> + <para>Applications could call an ioctl to request events. +After another process called &VIDIOC-S-CTRL; or another ioctl changing +shared properties the &func-select; function would indicate +readability until any ioctl (querying the properties) is +called.</para> + </footnote></para> + + <table pgwide="1" frame="none" id="control-id"> + <title>Control IDs</title> + <tgroup cols="3"> + &cs-def; + <thead> + <row> + <entry>ID</entry> + <entry>Type</entry> + <entry>Description</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_CID_BASE</constant></entry> + <entry></entry> + <entry>First predefined ID, equal to +<constant>V4L2_CID_BRIGHTNESS</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_CID_USER_BASE</constant></entry> + <entry></entry> + <entry>Synonym of <constant>V4L2_CID_BASE</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry> + <entry>integer</entry> + <entry>Picture brightness, or more precisely, the black +level.</entry> + </row> + <row> + <entry><constant>V4L2_CID_CONTRAST</constant></entry> + <entry>integer</entry> + <entry>Picture contrast or luma gain.</entry> + </row> + <row> + <entry><constant>V4L2_CID_SATURATION</constant></entry> + <entry>integer</entry> + <entry>Picture color saturation or chroma gain.</entry> + </row> + <row> + <entry><constant>V4L2_CID_HUE</constant></entry> + <entry>integer</entry> + <entry>Hue or color balance.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry> + <entry>integer</entry> + <entry>Overall audio volume. Note some drivers also +provide an OSS or ALSA mixer interface.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry> + <entry>integer</entry> + <entry>Audio stereo balance. Minimum corresponds to all +the way left, maximum to right.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry> + <entry>integer</entry> + <entry>Audio bass adjustment.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry> + <entry>integer</entry> + <entry>Audio treble adjustment.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUDIO_MUTE</constant></entry> + <entry>boolean</entry> + <entry>Mute audio, &ie; set the volume to zero, however +without affecting <constant>V4L2_CID_AUDIO_VOLUME</constant>. Like +ALSA drivers, V4L2 drivers must mute at load time to avoid excessive +noise. Actually the entire device should be reset to a low power +consumption state.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUDIO_LOUDNESS</constant></entry> + <entry>boolean</entry> + <entry>Loudness mode (bass boost).</entry> + </row> + <row> + <entry><constant>V4L2_CID_BLACK_LEVEL</constant></entry> + <entry>integer</entry> + <entry>Another name for brightness (not a synonym of +<constant>V4L2_CID_BRIGHTNESS</constant>). This control is deprecated +and should not be used in new drivers and applications.</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUTO_WHITE_BALANCE</constant></entry> + <entry>boolean</entry> + <entry>Automatic white balance (cameras).</entry> + </row> + <row> + <entry><constant>V4L2_CID_DO_WHITE_BALANCE</constant></entry> + <entry>button</entry> + <entry>This is an action control. When set (the value is +ignored), the device will do a white balance and then hold the current +setting. Contrast this with the boolean +<constant>V4L2_CID_AUTO_WHITE_BALANCE</constant>, which, when +activated, keeps adjusting the white balance.</entry> + </row> + <row> + <entry><constant>V4L2_CID_RED_BALANCE</constant></entry> + <entry>integer</entry> + <entry>Red chroma balance.</entry> + </row> + <row> + <entry><constant>V4L2_CID_BLUE_BALANCE</constant></entry> + <entry>integer</entry> + <entry>Blue chroma balance.</entry> + </row> + <row> + <entry><constant>V4L2_CID_GAMMA</constant></entry> + <entry>integer</entry> + <entry>Gamma adjust.</entry> + </row> + <row> + <entry><constant>V4L2_CID_WHITENESS</constant></entry> + <entry>integer</entry> + <entry>Whiteness for grey-scale devices. This is a synonym +for <constant>V4L2_CID_GAMMA</constant>. This control is deprecated +and should not be used in new drivers and applications.</entry> + </row> + <row> + <entry><constant>V4L2_CID_EXPOSURE</constant></entry> + <entry>integer</entry> + <entry>Exposure (cameras). [Unit?]</entry> + </row> + <row> + <entry><constant>V4L2_CID_AUTOGAIN</constant></entry> + <entry>boolean</entry> + <entry>Automatic gain/exposure control.</entry> + </row> + <row> + <entry><constant>V4L2_CID_GAIN</constant></entry> + <entry>integer</entry> + <entry>Gain control.</entry> + </row> + <row> + <entry><constant>V4L2_CID_HFLIP</constant></entry> + <entry>boolean</entry> + <entry>Mirror the picture horizontally.</entry> + </row> + <row> + <entry><constant>V4L2_CID_VFLIP</constant></entry> + <entry>boolean</entry> + <entry>Mirror the picture vertically.</entry> + </row> + <row> + <entry><constant>V4L2_CID_HCENTER_DEPRECATED</constant> (formerly <constant>V4L2_CID_HCENTER</constant>)</entry> + <entry>integer</entry> + <entry>Horizontal image centering. This control is +deprecated. New drivers and applications should use the <link +linkend="camera-controls">Camera class controls</link> +<constant>V4L2_CID_PAN_ABSOLUTE</constant>, +<constant>V4L2_CID_PAN_RELATIVE</constant> and +<constant>V4L2_CID_PAN_RESET</constant> instead.</entry> + </row> + <row> + <entry><constant>V4L2_CID_VCENTER_DEPRECATED</constant> + (formerly <constant>V4L2_CID_VCENTER</constant>)</entry> + <entry>integer</entry> + <entry>Vertical image centering. Centering is intended to +<emphasis>physically</emphasis> adjust cameras. For image cropping see +<xref linkend="crop" />, for clipping <xref linkend="overlay" />. This +control is deprecated. New drivers and applications should use the +<link linkend="camera-controls">Camera class controls</link> +<constant>V4L2_CID_TILT_ABSOLUTE</constant>, +<constant>V4L2_CID_TILT_RELATIVE</constant> and +<constant>V4L2_CID_TILT_RESET</constant> instead.</entry> + </row> + <row id="v4l2-power-line-frequency"> + <entry><constant>V4L2_CID_POWER_LINE_FREQUENCY</constant></entry> + <entry>enum</entry> + <entry>Enables a power line frequency filter to avoid +flicker. Possible values for <constant>enum v4l2_power_line_frequency</constant> are: +<constant>V4L2_CID_POWER_LINE_FREQUENCY_DISABLED</constant> (0), +<constant>V4L2_CID_POWER_LINE_FREQUENCY_50HZ</constant> (1) and +<constant>V4L2_CID_POWER_LINE_FREQUENCY_60HZ</constant> (2).</entry> + </row> + <row> + <entry><constant>V4L2_CID_HUE_AUTO</constant></entry> + <entry>boolean</entry> + <entry>Enables automatic hue control by the device. The +effect of setting <constant>V4L2_CID_HUE</constant> while automatic +hue control is enabled is undefined, drivers should ignore such +request.</entry> + </row> + <row> + <entry><constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant></entry> + <entry>integer</entry> + <entry>This control specifies the white balance settings +as a color temperature in Kelvin. A driver should have a minimum of +2800 (incandescent) to 6500 (daylight). For more information about +color temperature see <ulink +url="http://en.wikipedia.org/wiki/Color_temperature">Wikipedia</ulink>.</entry> + </row> + <row> + <entry><constant>V4L2_CID_SHARPNESS</constant></entry> + <entry>integer</entry> + <entry>Adjusts the sharpness filters in a camera. The +minimum value disables the filters, higher values give a sharper +picture.</entry> + </row> + <row> + <entry><constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant></entry> + <entry>integer</entry> + <entry>Adjusts the backlight compensation in a camera. The +minimum value disables backlight compensation.</entry> + </row> + <row> + <entry><constant>V4L2_CID_CHROMA_AGC</constant></entry> + <entry>boolean</entry> + <entry>Chroma automatic gain control.</entry> + </row> + <row> + <entry><constant>V4L2_CID_COLOR_KILLER</constant></entry> + <entry>boolean</entry> + <entry>Enable the color killer (&ie; force a black & white image in case of a weak video signal).</entry> + </row> + <row id="v4l2-colorfx"> + <entry><constant>V4L2_CID_COLORFX</constant></entry> + <entry>enum</entry> + <entry>Selects a color effect. Possible values for +<constant>enum v4l2_colorfx</constant> are: +<constant>V4L2_COLORFX_NONE</constant> (0), +<constant>V4L2_COLORFX_BW</constant> (1) and +<constant>V4L2_COLORFX_SEPIA</constant> (2).</entry> + </row> + <row> + <entry><constant>V4L2_CID_LASTP1</constant></entry> + <entry></entry> + <entry>End of the predefined control IDs (currently +<constant>V4L2_CID_COLORFX</constant> + 1).</entry> + </row> + <row> + <entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry> + <entry></entry> + <entry>ID of the first custom (driver specific) control. +Applications depending on particular custom controls should check the +driver name and version, see <xref linkend="querycap" />.</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Applications can enumerate the available controls with the +&VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls, get and set a +control value with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls. +Drivers must implement <constant>VIDIOC_QUERYCTRL</constant>, +<constant>VIDIOC_G_CTRL</constant> and +<constant>VIDIOC_S_CTRL</constant> when the device has one or more +controls, <constant>VIDIOC_QUERYMENU</constant> when it has one or +more menu type controls.</para> + + <example> + <title>Enumerating all controls</title> + + <programlisting> +&v4l2-queryctrl; queryctrl; +&v4l2-querymenu; querymenu; + +static void +enumerate_menu (void) +{ + printf (" Menu items:\n"); + + memset (&querymenu, 0, sizeof (querymenu)); + querymenu.id = queryctrl.id; + + for (querymenu.index = queryctrl.minimum; + querymenu.index <= queryctrl.maximum; + querymenu.index++) { + if (0 == ioctl (fd, &VIDIOC-QUERYMENU;, &querymenu)) { + printf (" %s\n", querymenu.name); + } else { + perror ("VIDIOC_QUERYMENU"); + exit (EXIT_FAILURE); + } + } +} + +memset (&queryctrl, 0, sizeof (queryctrl)); + +for (queryctrl.id = V4L2_CID_BASE; + queryctrl.id < V4L2_CID_LASTP1; + queryctrl.id++) { + if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &queryctrl)) { + if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) + continue; + + printf ("Control %s\n", queryctrl.name); + + if (queryctrl.type == V4L2_CTRL_TYPE_MENU) + enumerate_menu (); + } else { + if (errno == EINVAL) + continue; + + perror ("VIDIOC_QUERYCTRL"); + exit (EXIT_FAILURE); + } +} + +for (queryctrl.id = V4L2_CID_PRIVATE_BASE;; + queryctrl.id++) { + if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &queryctrl)) { + if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) + continue; + + printf ("Control %s\n", queryctrl.name); + + if (queryctrl.type == V4L2_CTRL_TYPE_MENU) + enumerate_menu (); + } else { + if (errno == EINVAL) + break; + + perror ("VIDIOC_QUERYCTRL"); + exit (EXIT_FAILURE); + } +} +</programlisting> + </example> + + <example> + <title>Changing controls</title> + + <programlisting> +&v4l2-queryctrl; queryctrl; +&v4l2-control; control; + +memset (&queryctrl, 0, sizeof (queryctrl)); +queryctrl.id = V4L2_CID_BRIGHTNESS; + +if (-1 == ioctl (fd, &VIDIOC-QUERYCTRL;, &queryctrl)) { + if (errno != EINVAL) { + perror ("VIDIOC_QUERYCTRL"); + exit (EXIT_FAILURE); + } else { + printf ("V4L2_CID_BRIGHTNESS is not supported\n"); + } +} else if (queryctrl.flags & V4L2_CTRL_FLAG_DISABLED) { + printf ("V4L2_CID_BRIGHTNESS is not supported\n"); +} else { + memset (&control, 0, sizeof (control)); + control.id = V4L2_CID_BRIGHTNESS; + control.value = queryctrl.default_value; + + if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &control)) { + perror ("VIDIOC_S_CTRL"); + exit (EXIT_FAILURE); + } +} + +memset (&control, 0, sizeof (control)); +control.id = V4L2_CID_CONTRAST; + +if (0 == ioctl (fd, &VIDIOC-G-CTRL;, &control)) { + control.value += 1; + + /* The driver may clamp the value or return ERANGE, ignored here */ + + if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &control) + && errno != ERANGE) { + perror ("VIDIOC_S_CTRL"); + exit (EXIT_FAILURE); + } +/* Ignore if V4L2_CID_CONTRAST is unsupported */ +} else if (errno != EINVAL) { + perror ("VIDIOC_G_CTRL"); + exit (EXIT_FAILURE); +} + +control.id = V4L2_CID_AUDIO_MUTE; +control.value = TRUE; /* silence */ + +/* Errors ignored */ +ioctl (fd, VIDIOC_S_CTRL, &control); +</programlisting> + </example> + </section> + + <section id="extended-controls"> + <title>Extended Controls</title> + + <section> + <title>Introduction</title> + + <para>The control mechanism as originally designed was meant +to be used for user settings (brightness, saturation, etc). However, +it turned out to be a very useful model for implementing more +complicated driver APIs where each driver implements only a subset of +a larger API.</para> + + <para>The MPEG encoding API was the driving force behind +designing and implementing this extended control mechanism: the MPEG +standard is quite large and the currently supported hardware MPEG +encoders each only implement a subset of this standard. Further more, +many parameters relating to how the video is encoded into an MPEG +stream are specific to the MPEG encoding chip since the MPEG standard +only defines the format of the resulting MPEG stream, not how the +video is actually encoded into that format.</para> + + <para>Unfortunately, the original control API lacked some +features needed for these new uses and so it was extended into the +(not terribly originally named) extended control API.</para> + + <para>Even though the MPEG encoding API was the first effort +to use the Extended Control API, nowadays there are also other classes +of Extended Controls, such as Camera Controls and FM Transmitter Controls. +The Extended Controls API as well as all Extended Controls classes are +described in the following text.</para> + </section> + + <section> + <title>The Extended Control API</title> + + <para>Three new ioctls are available: &VIDIOC-G-EXT-CTRLS;, +&VIDIOC-S-EXT-CTRLS; and &VIDIOC-TRY-EXT-CTRLS;. These ioctls act on +arrays of controls (as opposed to the &VIDIOC-G-CTRL; and +&VIDIOC-S-CTRL; ioctls that act on a single control). This is needed +since it is often required to atomically change several controls at +once.</para> + + <para>Each of the new ioctls expects a pointer to a +&v4l2-ext-controls;. This structure contains a pointer to the control +array, a count of the number of controls in that array and a control +class. Control classes are used to group similar controls into a +single class. For example, control class +<constant>V4L2_CTRL_CLASS_USER</constant> contains all user controls +(&ie; all controls that can also be set using the old +<constant>VIDIOC_S_CTRL</constant> ioctl). Control class +<constant>V4L2_CTRL_CLASS_MPEG</constant> contains all controls +relating to MPEG encoding, etc.</para> + + <para>All controls in the control array must belong to the +specified control class. An error is returned if this is not the +case.</para> + + <para>It is also possible to use an empty control array (count +== 0) to check whether the specified control class is +supported.</para> + + <para>The control array is a &v4l2-ext-control; array. The +<structname>v4l2_ext_control</structname> structure is very similar to +&v4l2-control;, except for the fact that it also allows for 64-bit +values and pointers to be passed.</para> + + <para>It is important to realize that due to the flexibility of +controls it is necessary to check whether the control you want to set +actually is supported in the driver and what the valid range of values +is. So use the &VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls to +check this. Also note that it is possible that some of the menu +indices in a control of type <constant>V4L2_CTRL_TYPE_MENU</constant> +may not be supported (<constant>VIDIOC_QUERYMENU</constant> will +return an error). A good example is the list of supported MPEG audio +bitrates. Some drivers only support one or two bitrates, others +support a wider range.</para> + </section> + + <section> + <title>Enumerating Extended Controls</title> + + <para>The recommended way to enumerate over the extended +controls is by using &VIDIOC-QUERYCTRL; in combination with the +<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag:</para> + + <informalexample> + <programlisting> +&v4l2-queryctrl; qctrl; + +qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL; +while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &qctrl)) { + /* ... */ + qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; +} +</programlisting> + </informalexample> + + <para>The initial control ID is set to 0 ORed with the +<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag. The +<constant>VIDIOC_QUERYCTRL</constant> ioctl will return the first +control with a higher ID than the specified one. When no such controls +are found an error is returned.</para> + + <para>If you want to get all controls within a specific control +class, then you can set the initial +<structfield>qctrl.id</structfield> value to the control class and add +an extra check to break out of the loop when a control of another +control class is found:</para> + + <informalexample> + <programlisting> +qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL; +while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &qctrl)) { + if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG) + break; + /* ... */ + qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; + } +</programlisting> + </informalexample> + + <para>The 32-bit <structfield>qctrl.id</structfield> value is +subdivided into three bit ranges: the top 4 bits are reserved for +flags (⪚ <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>) and are not +actually part of the ID. The remaining 28 bits form the control ID, of +which the most significant 12 bits define the control class and the +least significant 16 bits identify the control within the control +class. It is guaranteed that these last 16 bits are always non-zero +for controls. The range of 0x1000 and up are reserved for +driver-specific controls. The macro +<constant>V4L2_CTRL_ID2CLASS(id)</constant> returns the control class +ID based on a control ID.</para> + + <para>If the driver does not support extended controls, then +<constant>VIDIOC_QUERYCTRL</constant> will fail when used in +combination with <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>. In +that case the old method of enumerating control should be used (see +1.8). But if it is supported, then it is guaranteed to enumerate over +all controls, including driver-private controls.</para> + </section> + + <section> + <title>Creating Control Panels</title> + + <para>It is possible to create control panels for a graphical +user interface where the user can select the various controls. +Basically you will have to iterate over all controls using the method +described above. Each control class starts with a control of type +<constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant>. +<constant>VIDIOC_QUERYCTRL</constant> will return the name of this +control class which can be used as the title of a tab page within a +control panel.</para> + + <para>The flags field of &v4l2-queryctrl; also contains hints on +the behavior of the control. See the &VIDIOC-QUERYCTRL; documentation +for more details.</para> + </section> + + <section id="mpeg-controls"> + <title>MPEG Control Reference</title> + + <para>Below all controls within the MPEG control class are +described. First the generic controls, then controls specific for +certain hardware.</para> + + <section> + <title>Generic MPEG Controls</title> + + <table pgwide="1" frame="none" id="mpeg-control-id"> + <title>MPEG Control IDs</title> + <tgroup cols="4"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="6*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="6*" /> + <spanspec namest="c1" nameend="c2" spanname="id" /> + <spanspec namest="c2" nameend="c4" spanname="descr" /> + <thead> + <row> + <entry spanname="id" align="left">ID</entry> + <entry align="left">Type</entry> + </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CLASS</constant> </entry> + <entry>class</entry> + </row><row><entry spanname="descr">The MPEG class +descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a +description of this control class. This description can be used as the +caption of a Tab page in a GUI, for example.</entry> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-stream-type"> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_TYPE</constant> </entry> + <entry>enum v4l2_mpeg_stream_type</entry> + </row><row><entry spanname="descr">The MPEG-1, -2 or -4 +output stream type. One cannot assume anything here. Each hardware +MPEG encoder tends to support different subsets of the available MPEG +stream types. The currently defined stream types are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_PS</constant> </entry> + <entry>MPEG-2 program stream</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_TS</constant> </entry> + <entry>MPEG-2 transport stream</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_SS</constant> </entry> + <entry>MPEG-1 system stream</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_DVD</constant> </entry> + <entry>MPEG-2 DVD-compatible stream</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_VCD</constant> </entry> + <entry>MPEG-1 VCD-compatible stream</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD</constant> </entry> + <entry>MPEG-2 SVCD-compatible stream</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PMT</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Program Map Table +Packet ID for the MPEG transport stream (default 16)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_AUDIO</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Audio Packet ID for +the MPEG transport stream (default 256)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_VIDEO</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Video Packet ID for +the MPEG transport stream (default 260)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PCR</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Packet ID for the +MPEG transport stream carrying PCR fields (default 259)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_AUDIO</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Audio ID for MPEG +PES</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_VIDEO</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Video ID for MPEG +PES</entry> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-stream-vbi-fmt"> + <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_VBI_FMT</constant> </entry> + <entry>enum v4l2_mpeg_stream_vbi_fmt</entry> + </row><row><entry spanname="descr">Some cards can embed +VBI data (⪚ Closed Caption, Teletext) into the MPEG stream. This +control selects whether VBI data should be embedded, and if so, what +embedding method should be used. The list of possible VBI formats +depends on the driver. The currently defined VBI format types +are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_NONE</constant> </entry> + <entry>No VBI in the MPEG stream</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant> </entry> + <entry>VBI in private packets, IVTV format (documented +in the kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>)</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-sampling-freq"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ</constant> </entry> + <entry>enum v4l2_mpeg_audio_sampling_freq</entry> + </row><row><entry spanname="descr">MPEG Audio sampling +frequency. Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100</constant> </entry> + <entry>44.1 kHz</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000</constant> </entry> + <entry>48 kHz</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000</constant> </entry> + <entry>32 kHz</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-encoding"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_ENCODING</constant> </entry> + <entry>enum v4l2_mpeg_audio_encoding</entry> + </row><row><entry spanname="descr">MPEG Audio encoding. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_1</constant> </entry> + <entry>MPEG-1/2 Layer I encoding</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_2</constant> </entry> + <entry>MPEG-1/2 Layer II encoding</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_3</constant> </entry> + <entry>MPEG-1/2 Layer III encoding</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant> </entry> + <entry>MPEG-2/4 AAC (Advanced Audio Coding)</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant> </entry> + <entry>AC-3 aka ATSC A/52 encoding</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-l1-bitrate"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L1_BITRATE</constant> </entry> + <entry>enum v4l2_mpeg_audio_l1_bitrate</entry> + </row><row><entry spanname="descr">MPEG-1/2 Layer I bitrate. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_32K</constant> </entry> + <entry>32 kbit/s</entry></row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_64K</constant> </entry> + <entry>64 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_96K</constant> </entry> + <entry>96 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_128K</constant> </entry> + <entry>128 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_160K</constant> </entry> + <entry>160 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_192K</constant> </entry> + <entry>192 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_224K</constant> </entry> + <entry>224 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_256K</constant> </entry> + <entry>256 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_288K</constant> </entry> + <entry>288 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_320K</constant> </entry> + <entry>320 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_352K</constant> </entry> + <entry>352 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_384K</constant> </entry> + <entry>384 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_416K</constant> </entry> + <entry>416 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_448K</constant> </entry> + <entry>448 kbit/s</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-l2-bitrate"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L2_BITRATE</constant> </entry> + <entry>enum v4l2_mpeg_audio_l2_bitrate</entry> + </row><row><entry spanname="descr">MPEG-1/2 Layer II bitrate. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_32K</constant> </entry> + <entry>32 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_48K</constant> </entry> + <entry>48 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_56K</constant> </entry> + <entry>56 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_64K</constant> </entry> + <entry>64 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_80K</constant> </entry> + <entry>80 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_96K</constant> </entry> + <entry>96 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_112K</constant> </entry> + <entry>112 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_128K</constant> </entry> + <entry>128 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_160K</constant> </entry> + <entry>160 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_192K</constant> </entry> + <entry>192 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_224K</constant> </entry> + <entry>224 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_256K</constant> </entry> + <entry>256 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_320K</constant> </entry> + <entry>320 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_384K</constant> </entry> + <entry>384 kbit/s</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-l3-bitrate"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L3_BITRATE</constant> </entry> + <entry>enum v4l2_mpeg_audio_l3_bitrate</entry> + </row><row><entry spanname="descr">MPEG-1/2 Layer III bitrate. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_32K</constant> </entry> + <entry>32 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_40K</constant> </entry> + <entry>40 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_48K</constant> </entry> + <entry>48 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_56K</constant> </entry> + <entry>56 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_64K</constant> </entry> + <entry>64 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_80K</constant> </entry> + <entry>80 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_96K</constant> </entry> + <entry>96 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_112K</constant> </entry> + <entry>112 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_128K</constant> </entry> + <entry>128 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_160K</constant> </entry> + <entry>160 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_192K</constant> </entry> + <entry>192 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_224K</constant> </entry> + <entry>224 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_256K</constant> </entry> + <entry>256 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_320K</constant> </entry> + <entry>320 kbit/s</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AAC_BITRATE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">AAC bitrate in bits per second.</entry> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-ac3-bitrate"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AC3_BITRATE</constant> </entry> + <entry>enum v4l2_mpeg_audio_ac3_bitrate</entry> + </row><row><entry spanname="descr">AC-3 bitrate. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_32K</constant> </entry> + <entry>32 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_40K</constant> </entry> + <entry>40 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_48K</constant> </entry> + <entry>48 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_56K</constant> </entry> + <entry>56 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_64K</constant> </entry> + <entry>64 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_80K</constant> </entry> + <entry>80 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_96K</constant> </entry> + <entry>96 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_112K</constant> </entry> + <entry>112 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_128K</constant> </entry> + <entry>128 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_160K</constant> </entry> + <entry>160 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_192K</constant> </entry> + <entry>192 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_224K</constant> </entry> + <entry>224 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_256K</constant> </entry> + <entry>256 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_320K</constant> </entry> + <entry>320 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_384K</constant> </entry> + <entry>384 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_448K</constant> </entry> + <entry>448 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_512K</constant> </entry> + <entry>512 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_576K</constant> </entry> + <entry>576 kbit/s</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_640K</constant> </entry> + <entry>640 kbit/s</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-mode"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE</constant> </entry> + <entry>enum v4l2_mpeg_audio_mode</entry> + </row><row><entry spanname="descr">MPEG Audio mode. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_STEREO</constant> </entry> + <entry>Stereo</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_JOINT_STEREO</constant> </entry> + <entry>Joint Stereo</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_DUAL</constant> </entry> + <entry>Bilingual</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_MONO</constant> </entry> + <entry>Mono</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-mode-extension"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE_EXTENSION</constant> </entry> + <entry>enum v4l2_mpeg_audio_mode_extension</entry> + </row><row><entry spanname="descr">Joint Stereo +audio mode extension. In Layer I and II they indicate which subbands +are in intensity stereo. All other subbands are coded in stereo. Layer +III is not (yet) supported. Possible values +are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4</constant> </entry> + <entry>Subbands 4-31 in intensity stereo</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8</constant> </entry> + <entry>Subbands 8-31 in intensity stereo</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12</constant> </entry> + <entry>Subbands 12-31 in intensity stereo</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16</constant> </entry> + <entry>Subbands 16-31 in intensity stereo</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-emphasis"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_EMPHASIS</constant> </entry> + <entry>enum v4l2_mpeg_audio_emphasis</entry> + </row><row><entry spanname="descr">Audio Emphasis. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_NONE</constant> </entry> + <entry>None</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS</constant> </entry> + <entry>50/15 microsecond emphasis</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17</constant> </entry> + <entry>CCITT J.17</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-audio-crc"> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_CRC</constant> </entry> + <entry>enum v4l2_mpeg_audio_crc</entry> + </row><row><entry spanname="descr">CRC method. Possible +values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_AUDIO_CRC_NONE</constant> </entry> + <entry>None</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_CRC_CRC16</constant> </entry> + <entry>16 bit parity check</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MUTE</constant> </entry> + <entry>boolean</entry> + </row><row><entry spanname="descr">Mutes the audio when +capturing. This is not done by muting audio hardware, which can still +produce a slight hiss, but in the encoder itself, guaranteeing a fixed +and reproducable audio bitstream. 0 = unmuted, 1 = muted.</entry> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-video-encoding"> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ENCODING</constant> </entry> + <entry>enum v4l2_mpeg_video_encoding</entry> + </row><row><entry spanname="descr">MPEG Video encoding +method. Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_1</constant> </entry> + <entry>MPEG-1 Video encoding</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_2</constant> </entry> + <entry>MPEG-2 Video encoding</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant> </entry> + <entry>MPEG-4 AVC (H.264) Video encoding</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-video-aspect"> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ASPECT</constant> </entry> + <entry>enum v4l2_mpeg_video_aspect</entry> + </row><row><entry spanname="descr">Video aspect. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ASPECT_1x1</constant> </entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ASPECT_4x3</constant> </entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ASPECT_16x9</constant> </entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VIDEO_ASPECT_221x100</constant> </entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_B_FRAMES</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Number of B-Frames +(default 2)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_SIZE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">GOP size (default +12)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_CLOSURE</constant> </entry> + <entry>boolean</entry> + </row><row><entry spanname="descr">GOP closure (default +1)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_PULLDOWN</constant> </entry> + <entry>boolean</entry> + </row><row><entry spanname="descr">Enable 3:2 pulldown +(default 0)</entry> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-video-bitrate-mode"> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_MODE</constant> </entry> + <entry>enum v4l2_mpeg_video_bitrate_mode</entry> + </row><row><entry spanname="descr">Video bitrate mode. +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_VBR</constant> </entry> + <entry>Variable bitrate</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_CBR</constant> </entry> + <entry>Constant bitrate</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Video bitrate in bits +per second.</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_PEAK</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Peak video bitrate in +bits per second. Must be larger or equal to the average video bitrate. +It is ignored if the video bitrate mode is set to constant +bitrate.</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">For every captured +frame, skip this many subsequent frames (default 0).</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE</constant> </entry> + <entry>boolean</entry> + </row> + <row><entry spanname="descr">"Mutes" the video to a +fixed color when capturing. This is useful for testing, to produce a +fixed video bitstream. 0 = unmuted, 1 = muted.</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE_YUV</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Sets the "mute" color +of the video. The supplied 32-bit integer is interpreted as follows (bit +0 = least significant bit):</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry>Bit 0:7</entry> + <entry>V chrominance information</entry> + </row> + <row> + <entry>Bit 8:15</entry> + <entry>U chrominance information</entry> + </row> + <row> + <entry>Bit 16:23</entry> + <entry>Y luminance information</entry> + </row> + <row> + <entry>Bit 24:31</entry> + <entry>Must be zero.</entry> + </row> + </tbody> + </entrytbl> + </row> + </tbody> + </tgroup> + </table> + </section> + + <section> + <title>CX2341x MPEG Controls</title> + + <para>The following MPEG class controls deal with MPEG +encoding settings that are specific to the Conexant CX23415 and +CX23416 MPEG encoding chips.</para> + + <table pgwide="1" frame="none" id="cx2341x-control-id"> + <title>CX2341x Control IDs</title> + <tgroup cols="4"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="6*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="6*" /> + <spanspec namest="c1" nameend="c2" spanname="id" /> + <spanspec namest="c2" nameend="c4" spanname="descr" /> + <thead> + <row> + <entry spanname="id" align="left">ID</entry> + <entry align="left">Type</entry> + </row><row><entry spanname="descr" align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row><entry></entry></row> + <row id="v4l2-mpeg-cx2341x-video-spatial-filter-mode"> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE</constant> </entry> + <entry>enum v4l2_mpeg_cx2341x_video_spatial_filter_mode</entry> + </row><row><entry spanname="descr">Sets the Spatial +Filter mode (default <constant>MANUAL</constant>). Possible values +are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL</constant> </entry> + <entry>Choose the filter manually</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO</constant> </entry> + <entry>Choose the filter automatically</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER</constant> </entry> + <entry>integer (0-15)</entry> + </row><row><entry spanname="descr">The setting for the +Spatial Filter. 0 = off, 15 = maximum. (Default is 0.)</entry> + </row> + <row><entry></entry></row> + <row id="luma-spatial-filter-type"> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE</constant> </entry> + <entry>enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type</entry> + </row><row><entry spanname="descr">Select the algorithm +to use for the Luma Spatial Filter (default +<constant>1D_HOR</constant>). Possible values:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF</constant> </entry> + <entry>No filter</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR</constant> </entry> + <entry>One-dimensional horizontal</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT</constant> </entry> + <entry>One-dimensional vertical</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE</constant> </entry> + <entry>Two-dimensional separable</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE</constant> </entry> + <entry>Two-dimensional symmetrical +non-separable</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="chroma-spatial-filter-type"> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE</constant> </entry> + <entry>enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type</entry> + </row><row><entry spanname="descr">Select the algorithm +for the Chroma Spatial Filter (default <constant>1D_HOR</constant>). +Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF</constant> </entry> + <entry>No filter</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR</constant> </entry> + <entry>One-dimensional horizontal</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-cx2341x-video-temporal-filter-mode"> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE</constant> </entry> + <entry>enum v4l2_mpeg_cx2341x_video_temporal_filter_mode</entry> + </row><row><entry spanname="descr">Sets the Temporal +Filter mode (default <constant>MANUAL</constant>). Possible values +are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL</constant> </entry> + <entry>Choose the filter manually</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO</constant> </entry> + <entry>Choose the filter automatically</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER</constant> </entry> + <entry>integer (0-31)</entry> + </row><row><entry spanname="descr">The setting for the +Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale +capturing and 0 for scaled capturing.)</entry> + </row> + <row><entry></entry></row> + <row id="v4l2-mpeg-cx2341x-video-median-filter-type"> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE</constant> </entry> + <entry>enum v4l2_mpeg_cx2341x_video_median_filter_type</entry> + </row><row><entry spanname="descr">Median Filter Type +(default <constant>OFF</constant>). Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF</constant> </entry> + <entry>No filter</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR</constant> </entry> + <entry>Horizontal filter</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT</constant> </entry> + <entry>Vertical filter</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT</constant> </entry> + <entry>Horizontal and vertical filter</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG</constant> </entry> + <entry>Diagonal filter</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM</constant> </entry> + <entry>integer (0-255)</entry> + </row><row><entry spanname="descr">Threshold above which +the luminance median filter is enabled (default 0)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP</constant> </entry> + <entry>integer (0-255)</entry> + </row><row><entry spanname="descr">Threshold below which +the luminance median filter is enabled (default 255)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM</constant> </entry> + <entry>integer (0-255)</entry> + </row><row><entry spanname="descr">Threshold above which +the chroma median filter is enabled (default 0)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP</constant> </entry> + <entry>integer (0-255)</entry> + </row><row><entry spanname="descr">Threshold below which +the chroma median filter is enabled (default 255)</entry> + </row> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS</constant> </entry> + <entry>boolean</entry> + </row> + <row><entry spanname="descr">The CX2341X MPEG encoder +can insert one empty MPEG-2 PES packet into the stream between every +four video frames. The packet size is 2048 bytes, including the +packet_start_code_prefix and stream_id fields. The stream_id is 0xBF +(private stream 2). The payload consists of 0x00 bytes, to be filled +in by the application. 0 = do not insert, 1 = insert packets.</entry> + </row> + </tbody> + </tgroup> + </table> + </section> + </section> + + <section id="camera-controls"> + <title>Camera Control Reference</title> + + <para>The Camera class includes controls for mechanical (or +equivalent digital) features of a device such as controllable lenses +or sensors.</para> + + <table pgwide="1" frame="none" id="camera-control-id"> + <title>Camera Control IDs</title> + <tgroup cols="4"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="6*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="6*" /> + <spanspec namest="c1" nameend="c2" spanname="id" /> + <spanspec namest="c2" nameend="c4" spanname="descr" /> + <thead> + <row> + <entry spanname="id" align="left">ID</entry> + <entry align="left">Type</entry> + </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_CAMERA_CLASS</constant> </entry> + <entry>class</entry> + </row><row><entry spanname="descr">The Camera class +descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a +description of this control class.</entry> + </row> + <row><entry></entry></row> + + <row id="v4l2-exposure-auto-type"> + <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO</constant> </entry> + <entry>enum v4l2_exposure_auto_type</entry> + </row><row><entry spanname="descr">Enables automatic +adjustments of the exposure time and/or iris aperture. The effect of +manual changes of the exposure time or iris aperture while these +features are enabled is undefined, drivers should ignore such +requests. Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_EXPOSURE_AUTO</constant> </entry> + <entry>Automatic exposure time, automatic iris +aperture.</entry> + </row> + <row> + <entry><constant>V4L2_EXPOSURE_MANUAL</constant> </entry> + <entry>Manual exposure time, manual iris.</entry> + </row> + <row> + <entry><constant>V4L2_EXPOSURE_SHUTTER_PRIORITY</constant> </entry> + <entry>Manual exposure time, auto iris.</entry> + </row> + <row> + <entry><constant>V4L2_EXPOSURE_APERTURE_PRIORITY</constant> </entry> + <entry>Auto exposure time, manual iris.</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Determines the exposure +time of the camera sensor. The exposure time is limited by the frame +interval. Drivers should interpret the values as 100 µs units, +where the value 1 stands for 1/10000th of a second, 10000 for 1 second +and 100000 for 10 seconds.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant> </entry> + <entry>boolean</entry> + </row><row><entry spanname="descr">When +<constant>V4L2_CID_EXPOSURE_AUTO</constant> is set to +<constant>AUTO</constant> or <constant>APERTURE_PRIORITY</constant>, +this control determines if the device may dynamically vary the frame +rate. By default this feature is disabled (0) and the frame rate must +remain constant.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">This control turns the +camera horizontally by the specified amount. The unit is undefined. A +positive value moves the camera to the right (clockwise when viewed +from above), a negative value to the left. A value of zero does not +cause motion. This is a write-only control.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_TILT_RELATIVE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">This control turns the +camera vertically by the specified amount. The unit is undefined. A +positive value moves the camera up, a negative value down. A value of +zero does not cause motion. This is a write-only control.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_PAN_RESET</constant> </entry> + <entry>button</entry> + </row><row><entry spanname="descr">When this control is set, +the camera moves horizontally to the default position.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_TILT_RESET</constant> </entry> + <entry>button</entry> + </row><row><entry spanname="descr">When this control is set, +the camera moves vertically to the default position.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_PAN_ABSOLUTE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">This control +turns the camera horizontally to the specified position. Positive +values move the camera to the right (clockwise when viewed from above), +negative values to the left. Drivers should interpret the values as arc +seconds, with valid values between -180 * 3600 and +180 * 3600 +inclusive.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_TILT_ABSOLUTE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">This control +turns the camera vertically to the specified position. Positive values +move the camera up, negative values down. Drivers should interpret the +values as arc seconds, with valid values between -180 * 3600 and +180 +* 3600 inclusive.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_FOCUS_ABSOLUTE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">This control sets the +focal point of the camera to the specified position. The unit is +undefined. Positive values set the focus closer to the camera, +negative values towards infinity.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_FOCUS_RELATIVE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">This control moves the +focal point of the camera by the specified amount. The unit is +undefined. Positive values move the focus closer to the camera, +negative values towards infinity. This is a write-only control.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_FOCUS_AUTO</constant> </entry> + <entry>boolean</entry> + </row><row><entry spanname="descr">Enables automatic focus +adjustments. The effect of manual focus adjustments while this feature +is enabled is undefined, drivers should ignore such requests.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_ZOOM_ABSOLUTE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Specify the objective lens +focal length as an absolute value. The zoom unit is driver-specific and its +value should be a positive integer.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_ZOOM_RELATIVE</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Specify the objective lens +focal length relatively to the current value. Positive values move the zoom +lens group towards the telephoto direction, negative values towards the +wide-angle direction. The zoom unit is driver-specific. This is a write-only control.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_ZOOM_CONTINUOUS</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Move the objective lens group +at the specified speed until it reaches physical device limits or until an +explicit request to stop the movement. A positive value moves the zoom lens +group towards the telephoto direction. A value of zero stops the zoom lens +group movement. A negative value moves the zoom lens group towards the +wide-angle direction. The zoom speed unit is driver-specific.</entry> + </row> + <row><entry></entry></row> + + <row> + <entry spanname="id"><constant>V4L2_CID_PRIVACY</constant> </entry> + <entry>boolean</entry> + </row><row><entry spanname="descr">Prevent video from being acquired +by the camera. When this control is set to <constant>TRUE</constant> (1), no +image can be captured by the camera. Common means to enforce privacy are +mechanical obturation of the sensor and firmware image processing, but the +device is not restricted to these methods. Devices that implement the privacy +control must support read access and may support write access.</entry> + </row> + + <row> + <entry spanname="id"><constant>V4L2_CID_BAND_STOP_FILTER</constant> </entry> + <entry>integer</entry> + </row><row><entry spanname="descr">Switch the band-stop filter of a +camera sensor on or off, or specify its strength. Such band-stop filters can +be used, for example, to filter out the fluorescent light component.</entry> + </row> + <row><entry></entry></row> + </tbody> + </tgroup> + </table> + </section> + + <section id="fm-tx-controls"> + <title>FM Transmitter Control Reference</title> + + <para>The FM Transmitter (FM_TX) class includes controls for common features of +FM transmissions capable devices. Currently this class includes parameters for audio +compression, pilot tone generation, audio deviation limiter, RDS transmission and +tuning power features.</para> + + <table pgwide="1" frame="none" id="fm-tx-control-id"> + <title>FM_TX Control IDs</title> + + <tgroup cols="4"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="6*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="6*" /> + <spanspec namest="c1" nameend="c2" spanname="id" /> + <spanspec namest="c2" nameend="c4" spanname="descr" /> + <thead> + <row> + <entry spanname="id" align="left">ID</entry> + <entry align="left">Type</entry> + </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_FM_TX_CLASS</constant> </entry> + <entry>class</entry> + </row><row><entry spanname="descr">The FM_TX class +descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a +description of this control class.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_RDS_TX_DEVIATION</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Configures RDS signal frequency deviation level in Hz. +The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_RDS_TX_PI</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the RDS Programme Identification field +for transmission.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_RDS_TX_PTY</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the RDS Programme Type field for transmission. +This encodes up to 31 pre-defined programme types.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_RDS_TX_PS_NAME</constant> </entry> + <entry>string</entry> + </row> + <row><entry spanname="descr">Sets the Programme Service name (PS_NAME) for transmission. +It is intended for static display on a receiver. It is the primary aid to listeners in programme service +identification and selection. In Annex E of <xref linkend="en50067" />, the RDS specification, +there is a full description of the correct character encoding for Programme Service name strings. +Also from RDS specification, PS is usually a single eight character text. However, it is also possible +to find receivers which can scroll strings sized as 8 x N characters. So, this control must be configured +with steps of 8 characters. The result is it must always contain a string with size multiple of 8.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_RDS_TX_RADIO_TEXT</constant> </entry> + <entry>string</entry> + </row> + <row><entry spanname="descr">Sets the Radio Text info for transmission. It is a textual description of +what is being broadcasted. RDS Radio Text can be applied when broadcaster wishes to transmit longer PS names, +programme-related information or any other text. In these cases, RadioText should be used in addition to +<constant>V4L2_CID_RDS_TX_PS_NAME</constant>. The encoding for Radio Text strings is also fully described +in Annex E of <xref linkend="en50067" />. The length of Radio Text strings depends on which RDS Block is being +used to transmit it, either 32 (2A block) or 64 (2B block). However, it is also possible +to find receivers which can scroll strings sized as 32 x N or 64 x N characters. So, this control must be configured +with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_ENABLED</constant> </entry> + <entry>boolean</entry> + </row> + <row><entry spanname="descr">Enables or disables the audio deviation limiter feature. +The limiter is useful when trying to maximize the audio volume, minimize receiver-generated +distortion and prevent overmodulation. +</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_RELEASE_TIME</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the audio deviation limiter feature release time. +Unit is in useconds. Step and range are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_DEVIATION</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Configures audio frequency deviation level in Hz. +The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ENABLED</constant> </entry> + <entry>boolean</entry> + </row> + <row><entry spanname="descr">Enables or disables the audio compression feature. +This feature amplifies signals below the threshold by a fixed gain and compresses audio +signals above the threshold by the ratio of Threshold/(Gain + Threshold).</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_GAIN</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the gain for audio compression feature. It is +a dB value. The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_THRESHOLD</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the threshold level for audio compression freature. +It is a dB value. The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the attack time for audio compression feature. +It is a useconds value. The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the release time for audio compression feature. +It is a useconds value. The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_ENABLED</constant> </entry> + <entry>boolean</entry> + </row> + <row><entry spanname="descr">Enables or disables the pilot tone generation feature.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_DEVIATION</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Configures pilot tone frequency deviation level. Unit is +in Hz. The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_FREQUENCY</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Configures pilot tone frequency value. Unit is +in Hz. The range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_TUNE_PREEMPHASIS</constant> </entry> + <entry>integer</entry> + </row> + <row id="v4l2-preemphasis"><entry spanname="descr">Configures the pre-emphasis value for broadcasting. +A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies. +Depending on the region, a time constant of either 50 or 75 useconds is used. The enum v4l2_preemphasis +defines possible values for pre-emphasis. Here they are:</entry> + </row><row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_PREEMPHASIS_DISABLED</constant> </entry> + <entry>No pre-emphasis is applied.</entry> + </row> + <row> + <entry><constant>V4L2_PREEMPHASIS_50_uS</constant> </entry> + <entry>A pre-emphasis of 50 uS is used.</entry> + </row> + <row> + <entry><constant>V4L2_PREEMPHASIS_75_uS</constant> </entry> + <entry>A pre-emphasis of 75 uS is used.</entry> + </row> + </tbody> + </entrytbl> + + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_TUNE_POWER_LEVEL</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">Sets the output power level for signal transmission. +Unit is in dBuV. Range and step are driver-specific.</entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_TUNE_ANTENNA_CAPACITOR</constant> </entry> + <entry>integer</entry> + </row> + <row><entry spanname="descr">This selects the value of antenna tuning capacitor +manually or automatically if set to zero. Unit, range and step are driver-specific.</entry> + </row> + <row><entry></entry></row> + </tbody> + </tgroup> + </table> + +<para>For more details about RDS specification, refer to +<xref linkend="en50067" /> document, from CENELEC.</para> + </section> +</section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "common.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/crop.gif b/linux/Documentation/DocBook/v4l/crop.gif Binary files differnew file mode 100644 index 000000000..3b9e7d836 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/crop.gif diff --git a/linux/Documentation/DocBook/v4l/crop.pdf b/linux/Documentation/DocBook/v4l/crop.pdf Binary files differnew file mode 100644 index 000000000..c9fb81cd3 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/crop.pdf diff --git a/linux/Documentation/DocBook/v4l/dev-capture.xml b/linux/Documentation/DocBook/v4l/dev-capture.xml new file mode 100644 index 000000000..32807e43f --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-capture.xml @@ -0,0 +1,115 @@ + <title>Video Capture Interface</title> + + <para>Video capture devices sample an analog video signal and store +the digitized images in memory. Today nearly all devices can capture +at full 25 or 30 frames/second. With this interface applications can +control the capture process and move images from the driver into user +space.</para> + + <para>Conventionally V4L2 video capture devices are accessed through +character device special files named <filename>/dev/video</filename> +and <filename>/dev/video0</filename> to +<filename>/dev/video63</filename> with major number 81 and minor +numbers 0 to 63. <filename>/dev/video</filename> is typically a +symbolic link to the preferred video device. Note the same device +files are used for video output devices.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the video capture interface set the +<constant>V4L2_CAP_VIDEO_CAPTURE</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. As secondary device functions +they may also support the <link linkend="overlay">video overlay</link> +(<constant>V4L2_CAP_VIDEO_OVERLAY</constant>) and the <link +linkend="raw-vbi">raw VBI capture</link> +(<constant>V4L2_CAP_VBI_CAPTURE</constant>) interface. At least one of +the read/write or streaming I/O methods must be supported. Tuners and +audio inputs are optional.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>Video capture devices shall support <link +linkend="audio">audio input</link>, <link +linkend="tuner">tuner</link>, <link linkend="control">controls</link>, +<link linkend="crop">cropping and scaling</link> and <link +linkend="streaming-par">streaming parameter</link> ioctls as needed. +The <link linkend="video">video input</link> and <link +linkend="standard">video standard</link> ioctls must be supported by +all video capture devices.</para> + </section> + + <section> + <title>Image Format Negotiation</title> + + <para>The result of a capture operation is determined by +cropping and image format parameters. The former select an area of the +video picture to capture, the latter how images are stored in memory, +&ie; in RGB or YUV format, the number of bits per pixel or width and +height. Together they also define how images are scaled in the +process.</para> + + <para>As usual these parameters are <emphasis>not</emphasis> reset +at &func-open; time to permit Unix tool chains, programming a device +and then reading from it as if it was a plain file. Well written V4L2 +applications ensure they really get what they want, including cropping +and scaling.</para> + + <para>Cropping initialization at minimum requires to reset the +parameters to defaults. An example is given in <xref +linkend="crop" />.</para> + + <para>To query the current image format applications set the +<structfield>type</structfield> field of a &v4l2-format; to +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant> and call the +&VIDIOC-G-FMT; ioctl with a pointer to this structure. Drivers fill +the &v4l2-pix-format; <structfield>pix</structfield> member of the +<structfield>fmt</structfield> union.</para> + + <para>To request different parameters applications set the +<structfield>type</structfield> field of a &v4l2-format; as above and +initialize all fields of the &v4l2-pix-format; +<structfield>vbi</structfield> member of the +<structfield>fmt</structfield> union, or better just modify the +results of <constant>VIDIOC_G_FMT</constant>, and call the +&VIDIOC-S-FMT; ioctl with a pointer to this structure. Drivers may +adjust the parameters and finally return the actual parameters as +<constant>VIDIOC_G_FMT</constant> does.</para> + + <para>Like <constant>VIDIOC_S_FMT</constant> the +&VIDIOC-TRY-FMT; ioctl can be used to learn about hardware limitations +without disabling I/O or possibly time consuming hardware +preparations.</para> + + <para>The contents of &v4l2-pix-format; are discussed in <xref +linkend="pixfmt" />. See also the specification of the +<constant>VIDIOC_G_FMT</constant>, <constant>VIDIOC_S_FMT</constant> +and <constant>VIDIOC_TRY_FMT</constant> ioctls for details. Video +capture devices must implement both the +<constant>VIDIOC_G_FMT</constant> and +<constant>VIDIOC_S_FMT</constant> ioctl, even if +<constant>VIDIOC_S_FMT</constant> ignores all requests and always +returns default parameters as <constant>VIDIOC_G_FMT</constant> does. +<constant>VIDIOC_TRY_FMT</constant> is optional.</para> + </section> + + <section> + <title>Reading Images</title> + + <para>A video capture device may support the <link +linkend="rw">read() function</link> and/or streaming (<link +linkend="mmap">memory mapping</link> or <link +linkend="userp">user pointer</link>) I/O. See <xref +linkend="io" /> for details.</para> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-codec.xml b/linux/Documentation/DocBook/v4l/dev-codec.xml new file mode 100644 index 000000000..6e156dc45 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-codec.xml @@ -0,0 +1,26 @@ + <title>Codec Interface</title> + + <note> + <title>Suspended</title> + + <para>This interface has been be suspended from the V4L2 API +implemented in Linux 2.6 until we have more experience with codec +device interfaces.</para> + </note> + + <para>A V4L2 codec can compress, decompress, transform, or otherwise +convert video data from one format into another format, in memory. +Applications send data to be converted to the driver through a +&func-write; call, and receive the converted data through a +&func-read; call. For efficiency a driver may also support streaming +I/O.</para> + + <para>[to do]</para> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-effect.xml b/linux/Documentation/DocBook/v4l/dev-effect.xml new file mode 100644 index 000000000..9c243beba --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-effect.xml @@ -0,0 +1,25 @@ + <title>Effect Devices Interface</title> + + <note> + <title>Suspended</title> + + <para>This interface has been be suspended from the V4L2 API +implemented in Linux 2.6 until we have more experience with effect +device interfaces.</para> + </note> + + <para>A V4L2 video effect device can do image effects, filtering, or +combine two or more images or image streams. For example video +transitions or wipes. Applications send data to be processed and +receive the result data either with &func-read; and &func-write; +functions, or through the streaming I/O mechanism.</para> + + <para>[to do]</para> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-osd.xml b/linux/Documentation/DocBook/v4l/dev-osd.xml new file mode 100644 index 000000000..c9a68a2cc --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-osd.xml @@ -0,0 +1,164 @@ + <title>Video Output Overlay Interface</title> + <subtitle>Also known as On-Screen Display (OSD)</subtitle> + + <note> + <title>Experimental</title> + + <para>This is an <link linkend="experimental">experimental</link> +interface and may change in the future.</para> + </note> + + <para>Some video output devices can overlay a framebuffer image onto +the outgoing video signal. Applications can set up such an overlay +using this interface, which borrows structures and ioctls of the <link +linkend="overlay">Video Overlay</link> interface.</para> + + <para>The OSD function is accessible through the same character +special file as the <link linkend="capture">Video Output</link> function. +Note the default function of such a <filename>/dev/video</filename> device +is video capturing or output. The OSD function is only available after +calling the &VIDIOC-S-FMT; ioctl.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the <wordasword>Video Output +Overlay</wordasword> interface set the +<constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl.</para> + </section> + + <section> + <title>Framebuffer</title> + + <para>Contrary to the <wordasword>Video Overlay</wordasword> +interface the framebuffer is normally implemented on the TV card and +not the graphics card. On Linux it is accessible as a framebuffer +device (<filename>/dev/fbN</filename>). Given a V4L2 device, +applications can find the corresponding framebuffer device by calling +the &VIDIOC-G-FBUF; ioctl. It returns, amongst other information, the +physical address of the framebuffer in the +<structfield>base</structfield> field of &v4l2-framebuffer;. The +framebuffer device ioctl <constant>FBIOGET_FSCREENINFO</constant> +returns the same address in the <structfield>smem_start</structfield> +field of struct <structname>fb_fix_screeninfo</structname>. The +<constant>FBIOGET_FSCREENINFO</constant> ioctl and struct +<structname>fb_fix_screeninfo</structname> are defined in the +<filename>linux/fb.h</filename> header file.</para> + + <para>The width and height of the framebuffer depends on the +current video standard. A V4L2 driver may reject attempts to change +the video standard (or any other ioctl which would imply a framebuffer +size change) with an &EBUSY; until all applications closed the +framebuffer device.</para> + + <example> + <title>Finding a framebuffer device for OSD</title> + + <programlisting> +#include <linux/fb.h> + +&v4l2-framebuffer; fbuf; +unsigned int i; +int fb_fd; + +if (-1 == ioctl (fd, VIDIOC_G_FBUF, &fbuf)) { + perror ("VIDIOC_G_FBUF"); + exit (EXIT_FAILURE); +} + +for (i = 0; i > 30; ++i) { + char dev_name[16]; + struct fb_fix_screeninfo si; + + snprintf (dev_name, sizeof (dev_name), "/dev/fb%u", i); + + fb_fd = open (dev_name, O_RDWR); + if (-1 == fb_fd) { + switch (errno) { + case ENOENT: /* no such file */ + case ENXIO: /* no driver */ + continue; + + default: + perror ("open"); + exit (EXIT_FAILURE); + } + } + + if (0 == ioctl (fb_fd, FBIOGET_FSCREENINFO, &si)) { + if (si.smem_start == (unsigned long) fbuf.base) + break; + } else { + /* Apparently not a framebuffer device. */ + } + + close (fb_fd); + fb_fd = -1; +} + +/* fb_fd is the file descriptor of the framebuffer device + for the video output overlay, or -1 if no device was found. */ +</programlisting> + </example> + </section> + + <section> + <title>Overlay Window and Scaling</title> + + <para>The overlay is controlled by source and target rectangles. +The source rectangle selects a subsection of the framebuffer image to +be overlaid, the target rectangle an area in the outgoing video signal +where the image will appear. Drivers may or may not support scaling, +and arbitrary sizes and positions of these rectangles. Further drivers +may support any (or none) of the clipping/blending methods defined for +the <link linkend="overlay">Video Overlay</link> interface.</para> + + <para>A &v4l2-window; defines the size of the source rectangle, +its position in the framebuffer and the clipping/blending method to be +used for the overlay. To get the current parameters applications set +the <structfield>type</structfield> field of a &v4l2-format; to +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant> and call the +&VIDIOC-G-FMT; ioctl. The driver fills the +<structname>v4l2_window</structname> substructure named +<structfield>win</structfield>. It is not possible to retrieve a +previously programmed clipping list or bitmap.</para> + + <para>To program the source rectangle applications set the +<structfield>type</structfield> field of a &v4l2-format; to +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant>, initialize +the <structfield>win</structfield> substructure and call the +&VIDIOC-S-FMT; ioctl. The driver adjusts the parameters against +hardware limits and returns the actual parameters as +<constant>VIDIOC_G_FMT</constant> does. Like +<constant>VIDIOC_S_FMT</constant>, the &VIDIOC-TRY-FMT; ioctl can be +used to learn about driver capabilities without actually changing +driver state. Unlike <constant>VIDIOC_S_FMT</constant> this also works +after the overlay has been enabled.</para> + + <para>A &v4l2-crop; defines the size and position of the target +rectangle. The scaling factor of the overlay is implied by the width +and height given in &v4l2-window; and &v4l2-crop;. The cropping API +applies to <wordasword>Video Output</wordasword> and <wordasword>Video +Output Overlay</wordasword> devices in the same way as to +<wordasword>Video Capture</wordasword> and <wordasword>Video +Overlay</wordasword> devices, merely reversing the direction of the +data flow. For more information see <xref linkend="crop" />.</para> + </section> + + <section> + <title>Enabling Overlay</title> + + <para>There is no V4L2 ioctl to enable or disable the overlay, +however the framebuffer interface of the driver may support the +<constant>FBIOBLANK</constant> ioctl.</para> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-output.xml b/linux/Documentation/DocBook/v4l/dev-output.xml new file mode 100644 index 000000000..63c3c20e5 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-output.xml @@ -0,0 +1,111 @@ + <title>Video Output Interface</title> + + <para>Video output devices encode stills or image sequences as +analog video signal. With this interface applications can +control the encoding process and move images from user space to +the driver.</para> + + <para>Conventionally V4L2 video output devices are accessed through +character device special files named <filename>/dev/video</filename> +and <filename>/dev/video0</filename> to +<filename>/dev/video63</filename> with major number 81 and minor +numbers 0 to 63. <filename>/dev/video</filename> is typically a +symbolic link to the preferred video device. Note the same device +files are used for video capture devices.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the video output interface set the +<constant>V4L2_CAP_VIDEO_OUTPUT</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. As secondary device functions +they may also support the <link linkend="raw-vbi">raw VBI +output</link> (<constant>V4L2_CAP_VBI_OUTPUT</constant>) interface. At +least one of the read/write or streaming I/O methods must be +supported. Modulators and audio outputs are optional.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>Video output devices shall support <link +linkend="audio">audio output</link>, <link +linkend="tuner">modulator</link>, <link linkend="control">controls</link>, +<link linkend="crop">cropping and scaling</link> and <link +linkend="streaming-par">streaming parameter</link> ioctls as needed. +The <link linkend="video">video output</link> and <link +linkend="standard">video standard</link> ioctls must be supported by +all video output devices.</para> + </section> + + <section> + <title>Image Format Negotiation</title> + + <para>The output is determined by cropping and image format +parameters. The former select an area of the video picture where the +image will appear, the latter how images are stored in memory, &ie; in +RGB or YUV format, the number of bits per pixel or width and height. +Together they also define how images are scaled in the process.</para> + + <para>As usual these parameters are <emphasis>not</emphasis> reset +at &func-open; time to permit Unix tool chains, programming a device +and then writing to it as if it was a plain file. Well written V4L2 +applications ensure they really get what they want, including cropping +and scaling.</para> + + <para>Cropping initialization at minimum requires to reset the +parameters to defaults. An example is given in <xref +linkend="crop" />.</para> + + <para>To query the current image format applications set the +<structfield>type</structfield> field of a &v4l2-format; to +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant> and call the +&VIDIOC-G-FMT; ioctl with a pointer to this structure. Drivers fill +the &v4l2-pix-format; <structfield>pix</structfield> member of the +<structfield>fmt</structfield> union.</para> + + <para>To request different parameters applications set the +<structfield>type</structfield> field of a &v4l2-format; as above and +initialize all fields of the &v4l2-pix-format; +<structfield>vbi</structfield> member of the +<structfield>fmt</structfield> union, or better just modify the +results of <constant>VIDIOC_G_FMT</constant>, and call the +&VIDIOC-S-FMT; ioctl with a pointer to this structure. Drivers may +adjust the parameters and finally return the actual parameters as +<constant>VIDIOC_G_FMT</constant> does.</para> + + <para>Like <constant>VIDIOC_S_FMT</constant> the +&VIDIOC-TRY-FMT; ioctl can be used to learn about hardware limitations +without disabling I/O or possibly time consuming hardware +preparations.</para> + + <para>The contents of &v4l2-pix-format; are discussed in <xref +linkend="pixfmt" />. See also the specification of the +<constant>VIDIOC_G_FMT</constant>, <constant>VIDIOC_S_FMT</constant> +and <constant>VIDIOC_TRY_FMT</constant> ioctls for details. Video +output devices must implement both the +<constant>VIDIOC_G_FMT</constant> and +<constant>VIDIOC_S_FMT</constant> ioctl, even if +<constant>VIDIOC_S_FMT</constant> ignores all requests and always +returns default parameters as <constant>VIDIOC_G_FMT</constant> does. +<constant>VIDIOC_TRY_FMT</constant> is optional.</para> + </section> + + <section> + <title>Writing Images</title> + + <para>A video output device may support the <link +linkend="rw">write() function</link> and/or streaming (<link +linkend="mmap">memory mapping</link> or <link +linkend="userp">user pointer</link>) I/O. See <xref +linkend="io" /> for details.</para> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-overlay.xml b/linux/Documentation/DocBook/v4l/dev-overlay.xml new file mode 100644 index 000000000..92513cf79 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-overlay.xml @@ -0,0 +1,379 @@ + <title>Video Overlay Interface</title> + <subtitle>Also known as Framebuffer Overlay or Previewing</subtitle> + + <para>Video overlay devices have the ability to genlock (TV-)video +into the (VGA-)video signal of a graphics card, or to store captured +images directly in video memory of a graphics card, typically with +clipping. This can be considerable more efficient than capturing +images and displaying them by other means. In the old days when only +nuclear power plants needed cooling towers this used to be the only +way to put live video into a window.</para> + + <para>Video overlay devices are accessed through the same character +special files as <link linkend="capture">video capture</link> devices. +Note the default function of a <filename>/dev/video</filename> device +is video capturing. The overlay function is only available after +calling the &VIDIOC-S-FMT; ioctl.</para> + + <para>The driver may support simultaneous overlay and capturing +using the read/write and streaming I/O methods. If so, operation at +the nominal frame rate of the video standard is not guaranteed. Frames +may be directed away from overlay to capture, or one field may be used +for overlay and the other for capture if the capture parameters permit +this.</para> + + <para>Applications should use different file descriptors for +capturing and overlay. This must be supported by all drivers capable +of simultaneous capturing and overlay. Optionally these drivers may +also permit capturing and overlay with a single file descriptor for +compatibility with V4L and earlier versions of V4L2.<footnote> + <para>A common application of two file descriptors is the +XFree86 <link linkend="xvideo">Xv/V4L</link> interface driver and +a V4L2 application. While the X server controls video overlay, the +application can take advantage of memory mapping and DMA.</para> + <para>In the opinion of the designers of this API, no driver +writer taking the efforts to support simultaneous capturing and +overlay will restrict this ability by requiring a single file +descriptor, as in V4L and earlier versions of V4L2. Making this +optional means applications depending on two file descriptors need +backup routines to be compatible with all drivers, which is +considerable more work than using two fds in applications which do +not. Also two fd's fit the general concept of one file descriptor for +each logical stream. Hence as a complexity trade-off drivers +<emphasis>must</emphasis> support two file descriptors and +<emphasis>may</emphasis> support single fd operation.</para> + </footnote></para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the video overlay interface set the +<constant>V4L2_CAP_VIDEO_OVERLAY</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. The overlay I/O method specified +below must be supported. Tuners and audio inputs are optional.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>Video overlay devices shall support <link +linkend="audio">audio input</link>, <link +linkend="tuner">tuner</link>, <link linkend="control">controls</link>, +<link linkend="crop">cropping and scaling</link> and <link +linkend="streaming-par">streaming parameter</link> ioctls as needed. +The <link linkend="video">video input</link> and <link +linkend="standard">video standard</link> ioctls must be supported by +all video overlay devices.</para> + </section> + + <section> + <title>Setup</title> + + <para>Before overlay can commence applications must program the +driver with frame buffer parameters, namely the address and size of +the frame buffer and the image format, for example RGB 5:6:5. The +&VIDIOC-G-FBUF; and &VIDIOC-S-FBUF; ioctls are available to get +and set these parameters, respectively. The +<constant>VIDIOC_S_FBUF</constant> ioctl is privileged because it +allows to set up DMA into physical memory, bypassing the memory +protection mechanisms of the kernel. Only the superuser can change the +frame buffer address and size. Users are not supposed to run TV +applications as root or with SUID bit set. A small helper application +with suitable privileges should query the graphics system and program +the V4L2 driver at the appropriate time.</para> + + <para>Some devices add the video overlay to the output signal +of the graphics card. In this case the frame buffer is not modified by +the video device, and the frame buffer address and pixel format are +not needed by the driver. The <constant>VIDIOC_S_FBUF</constant> ioctl +is not privileged. An application can check for this type of device by +calling the <constant>VIDIOC_G_FBUF</constant> ioctl.</para> + + <para>A driver may support any (or none) of five clipping/blending +methods:<orderedlist> + <listitem> + <para>Chroma-keying displays the overlaid image only where +pixels in the primary graphics surface assume a certain color.</para> + </listitem> + <listitem> + <para>A bitmap can be specified where each bit corresponds +to a pixel in the overlaid image. When the bit is set, the +corresponding video pixel is displayed, otherwise a pixel of the +graphics surface.</para> + </listitem> + <listitem> + <para>A list of clipping rectangles can be specified. In +these regions <emphasis>no</emphasis> video is displayed, so the +graphics surface can be seen here.</para> + </listitem> + <listitem> + <para>The framebuffer has an alpha channel that can be used +to clip or blend the framebuffer with the video.</para> + </listitem> + <listitem> + <para>A global alpha value can be specified to blend the +framebuffer contents with video images.</para> + </listitem> + </orderedlist></para> + + <para>When simultaneous capturing and overlay is supported and +the hardware prohibits different image and frame buffer formats, the +format requested first takes precedence. The attempt to capture +(&VIDIOC-S-FMT;) or overlay (&VIDIOC-S-FBUF;) may fail with an +&EBUSY; or return accordingly modified parameters..</para> + </section> + + <section> + <title>Overlay Window</title> + + <para>The overlaid image is determined by cropping and overlay +window parameters. The former select an area of the video picture to +capture, the latter how images are overlaid and clipped. Cropping +initialization at minimum requires to reset the parameters to +defaults. An example is given in <xref linkend="crop" />.</para> + + <para>The overlay window is described by a &v4l2-window;. It +defines the size of the image, its position over the graphics surface +and the clipping to be applied. To get the current parameters +applications set the <structfield>type</structfield> field of a +&v4l2-format; to <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant> and +call the &VIDIOC-G-FMT; ioctl. The driver fills the +<structname>v4l2_window</structname> substructure named +<structfield>win</structfield>. It is not possible to retrieve a +previously programmed clipping list or bitmap.</para> + + <para>To program the overlay window applications set the +<structfield>type</structfield> field of a &v4l2-format; to +<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, initialize the +<structfield>win</structfield> substructure and call the +&VIDIOC-S-FMT; ioctl. The driver adjusts the parameters against +hardware limits and returns the actual parameters as +<constant>VIDIOC_G_FMT</constant> does. Like +<constant>VIDIOC_S_FMT</constant>, the &VIDIOC-TRY-FMT; ioctl can be +used to learn about driver capabilities without actually changing +driver state. Unlike <constant>VIDIOC_S_FMT</constant> this also works +after the overlay has been enabled.</para> + + <para>The scaling factor of the overlaid image is implied by the +width and height given in &v4l2-window; and the size of the cropping +rectangle. For more information see <xref linkend="crop" />.</para> + + <para>When simultaneous capturing and overlay is supported and +the hardware prohibits different image and window sizes, the size +requested first takes precedence. The attempt to capture or overlay as +well (&VIDIOC-S-FMT;) may fail with an &EBUSY; or return accordingly +modified parameters.</para> + + <table pgwide="1" frame="none" id="v4l2-window"> + <title>struct <structname>v4l2_window</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>&v4l2-rect;</entry> + <entry><structfield>w</structfield></entry> + <entry>Size and position of the window relative to the +top, left corner of the frame buffer defined with &VIDIOC-S-FBUF;. The +window can extend the frame buffer width and height, the +<structfield>x</structfield> and <structfield>y</structfield> +coordinates can be negative, and it can lie completely outside the +frame buffer. The driver clips the window accordingly, or if that is +not possible, modifies its size and/or position.</entry> + </row> + <row> + <entry>&v4l2-field;</entry> + <entry><structfield>field</structfield></entry> + <entry>Applications set this field to determine which +video field shall be overlaid, typically one of +<constant>V4L2_FIELD_ANY</constant> (0), +<constant>V4L2_FIELD_TOP</constant>, +<constant>V4L2_FIELD_BOTTOM</constant> or +<constant>V4L2_FIELD_INTERLACED</constant>. Drivers may have to choose +a different field order and return the actual setting here.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>chromakey</structfield></entry> + <entry>When chroma-keying has been negotiated with +&VIDIOC-S-FBUF; applications set this field to the desired pixel value +for the chroma key. The format is the same as the pixel format of the +framebuffer (&v4l2-framebuffer; +<structfield>fmt.pixelformat</structfield> field), with bytes in host +order. E. g. for <link +linkend="V4L2-PIX-FMT-BGR32"><constant>V4L2_PIX_FMT_BGR24</constant></link> +the value should be 0xRRGGBB on a little endian, 0xBBGGRR on a big +endian host.</entry> + </row> + <row> + <entry>&v4l2-clip; *</entry> + <entry><structfield>clips</structfield></entry> + <entry>When chroma-keying has <emphasis>not</emphasis> +been negotiated and &VIDIOC-G-FBUF; indicated this capability, +applications can set this field to point to an array of +clipping rectangles.</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry>Like the window coordinates +<structfield>w</structfield>, clipping rectangles are defined relative +to the top, left corner of the frame buffer. However clipping +rectangles must not extend the frame buffer width and height, and they +must not overlap. If possible applications should merge adjacent +rectangles. Whether this must create x-y or y-x bands, or the order of +rectangles, is not defined. When clip lists are not supported the +driver ignores this field. Its contents after calling &VIDIOC-S-FMT; +are undefined.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>clipcount</structfield></entry> + <entry>When the application set the +<structfield>clips</structfield> field, this field must contain the +number of clipping rectangles in the list. When clip lists are not +supported the driver ignores this field, its contents after calling +<constant>VIDIOC_S_FMT</constant> are undefined. When clip lists are +supported but no clipping is desired this field must be set to +zero.</entry> + </row> + <row> + <entry>void *</entry> + <entry><structfield>bitmap</structfield></entry> + <entry>When chroma-keying has +<emphasis>not</emphasis> been negotiated and &VIDIOC-G-FBUF; indicated +this capability, applications can set this field to point to a +clipping bit mask.</entry> + </row> + <row> + <entry spanname="hspan"><para>It must be of the same size +as the window, <structfield>w.width</structfield> and +<structfield>w.height</structfield>. Each bit corresponds to a pixel +in the overlaid image, which is displayed only when the bit is +<emphasis>set</emphasis>. Pixel coordinates translate to bits like: +<programlisting> +((__u8 *) <structfield>bitmap</structfield>)[<structfield>w.width</structfield> * y + x / 8] & (1 << (x & 7))</programlisting></para><para>where <structfield>0</structfield> ≤ x < +<structfield>w.width</structfield> and <structfield>0</structfield> ≤ +y <<structfield>w.height</structfield>.<footnote> + <para>Should we require + <structfield>w.width</structfield> to be a multiple of + eight?</para> + </footnote></para><para>When a clipping +bit mask is not supported the driver ignores this field, its contents +after calling &VIDIOC-S-FMT; are undefined. When a bit mask is supported +but no clipping is desired this field must be set to +<constant>NULL</constant>.</para><para>Applications need not create a +clip list or bit mask. When they pass both, or despite negotiating +chroma-keying, the results are undefined. Regardless of the chosen +method, the clipping abilities of the hardware may be limited in +quantity or quality. The results when these limits are exceeded are +undefined.<footnote> + <para>When the image is written into frame buffer +memory it will be undesirable if the driver clips out less pixels +than expected, because the application and graphics system are not +aware these regions need to be refreshed. The driver should clip out +more pixels or not write the image at all.</para> + </footnote></para></entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>global_alpha</structfield></entry> + <entry>The global alpha value used to blend the +framebuffer with video images, if global alpha blending has been +negotiated (<constant>V4L2_FBUF_FLAG_GLOBAL_ALPHA</constant>, see +&VIDIOC-S-FBUF;, <xref linkend="framebuffer-flags" />).</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry>Note this field was added in Linux 2.6.23, extending the structure. However +the <link linkend="vidioc-g-fmt">VIDIOC_G/S/TRY_FMT</link> ioctls, +which take a pointer to a <link +linkend="v4l2-format">v4l2_format</link> parent structure with padding +bytes at the end, are not affected.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-clip"> + <title>struct <structname>v4l2_clip</structname><footnote> + <para>The X Window system defines "regions" which are +vectors of struct BoxRec { short x1, y1, x2, y2; } with width = x2 - +x1 and height = y2 - y1, so one cannot pass X11 clip lists +directly.</para> + </footnote></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>&v4l2-rect;</entry> + <entry><structfield>c</structfield></entry> + <entry>Coordinates of the clipping rectangle, relative to +the top, left corner of the frame buffer. Only window pixels +<emphasis>outside</emphasis> all clipping rectangles are +displayed.</entry> + </row> + <row> + <entry>&v4l2-clip; *</entry> + <entry><structfield>next</structfield></entry> + <entry>Pointer to the next clipping rectangle, NULL when +this is the last rectangle. Drivers ignore this field, it cannot be +used to pass a linked list of clipping rectangles.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- NB for easier reading this table is duplicated + in the vidioc-cropcap chapter.--> + + <table pgwide="1" frame="none" id="v4l2-rect"> + <title>struct <structname>v4l2_rect</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__s32</entry> + <entry><structfield>left</structfield></entry> + <entry>Horizontal offset of the top, left corner of the +rectangle, in pixels.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>top</structfield></entry> + <entry>Vertical offset of the top, left corner of the +rectangle, in pixels. Offsets increase to the right and down.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>width</structfield></entry> + <entry>Width of the rectangle, in pixels.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>height</structfield></entry> + <entry>Height of the rectangle, in pixels. Width and +height cannot be negative, the fields are signed for hysterical +reasons. <!-- video4linux-list@redhat.com on 22 Oct 2002 subject +"Re:[V4L][patches!] Re:v4l2/kernel-2.5" --></entry> + </row> + </tbody> + </tgroup> + </table> + </section> + + <section> + <title>Enabling Overlay</title> + + <para>To start or stop the frame buffer overlay applications call +the &VIDIOC-OVERLAY; ioctl.</para> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-radio.xml b/linux/Documentation/DocBook/v4l/dev-radio.xml new file mode 100644 index 000000000..73aa90b45 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-radio.xml @@ -0,0 +1,57 @@ + <title>Radio Interface</title> + + <para>This interface is intended for AM and FM (analog) radio +receivers and transmitters.</para> + + <para>Conventionally V4L2 radio devices are accessed through +character device special files named <filename>/dev/radio</filename> +and <filename>/dev/radio0</filename> to +<filename>/dev/radio63</filename> with major number 81 and minor +numbers 64 to 127.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the radio interface set the +<constant>V4L2_CAP_RADIO</constant> and +<constant>V4L2_CAP_TUNER</constant> or +<constant>V4L2_CAP_MODULATOR</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. Other combinations of +capability flags are reserved for future extensions.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>Radio devices can support <link +linkend="control">controls</link>, and must support the <link +linkend="tuner">tuner or modulator</link> ioctls.</para> + + <para>They do not support the video input or output, audio input +or output, video standard, cropping and scaling, compression and +streaming parameter, or overlay ioctls. All other ioctls and I/O +methods are reserved for future extensions.</para> + </section> + + <section> + <title>Programming</title> + + <para>Radio devices may have a couple audio controls (as discussed +in <xref linkend="control" />) such as a volume control, possibly custom +controls. Further all radio devices have one tuner or modulator (these are +discussed in <xref linkend="tuner" />) with index number zero to select +the radio frequency and to determine if a monaural or FM stereo +program is received/emitted. Drivers switch automatically between AM and FM +depending on the selected frequency. The &VIDIOC-G-TUNER; or +&VIDIOC-G-MODULATOR; ioctl +reports the supported frequency range.</para> + </section> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-raw-vbi.xml b/linux/Documentation/DocBook/v4l/dev-raw-vbi.xml new file mode 100644 index 000000000..c5a70bdfa --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-raw-vbi.xml @@ -0,0 +1,347 @@ + <title>Raw VBI Data Interface</title> + + <para>VBI is an abbreviation of Vertical Blanking Interval, a gap +in the sequence of lines of an analog video signal. During VBI +no picture information is transmitted, allowing some time while the +electron beam of a cathode ray tube TV returns to the top of the +screen. Using an oscilloscope you will find here the vertical +synchronization pulses and short data packages ASK +modulated<footnote><para>ASK: Amplitude-Shift Keying. A high signal +level represents a '1' bit, a low level a '0' bit.</para></footnote> +onto the video signal. These are transmissions of services such as +Teletext or Closed Caption.</para> + + <para>Subject of this interface type is raw VBI data, as sampled off +a video signal, or to be added to a signal for output. +The data format is similar to uncompressed video images, a number of +lines times a number of samples per line, we call this a VBI image.</para> + + <para>Conventionally V4L2 VBI devices are accessed through character +device special files named <filename>/dev/vbi</filename> and +<filename>/dev/vbi0</filename> to <filename>/dev/vbi31</filename> with +major number 81 and minor numbers 224 to 255. +<filename>/dev/vbi</filename> is typically a symbolic link to the +preferred VBI device. This convention applies to both input and output +devices.</para> + + <para>To address the problems of finding related video and VBI +devices VBI capturing and output is also available as device function +under <filename>/dev/video</filename>. To capture or output raw VBI +data with these devices applications must call the &VIDIOC-S-FMT; +ioctl. Accessed as <filename>/dev/vbi</filename>, raw VBI capturing +or output is the default device function.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the raw VBI capturing or output API set +the <constant>V4L2_CAP_VBI_CAPTURE</constant> or +<constant>V4L2_CAP_VBI_OUTPUT</constant> flags, respectively, in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. At least one of the +read/write, streaming or asynchronous I/O methods must be +supported. VBI devices may or may not have a tuner or modulator.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>VBI devices shall support <link linkend="video">video +input or output</link>, <link linkend="tuner">tuner or +modulator</link>, and <link linkend="control">controls</link> ioctls +as needed. The <link linkend="standard">video standard</link> ioctls provide +information vital to program a VBI device, therefore must be +supported.</para> + </section> + + <section> + <title>Raw VBI Format Negotiation</title> + + <para>Raw VBI sampling abilities can vary, in particular the +sampling frequency. To properly interpret the data V4L2 specifies an +ioctl to query the sampling parameters. Moreover, to allow for some +flexibility applications can also suggest different parameters.</para> + + <para>As usual these parameters are <emphasis>not</emphasis> +reset at &func-open; time to permit Unix tool chains, programming a +device and then reading from it as if it was a plain file. Well +written V4L2 applications should always ensure they really get what +they want, requesting reasonable parameters and then checking if the +actual parameters are suitable.</para> + + <para>To query the current raw VBI capture parameters +applications set the <structfield>type</structfield> field of a +&v4l2-format; to <constant>V4L2_BUF_TYPE_VBI_CAPTURE</constant> or +<constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant>, and call the +&VIDIOC-G-FMT; ioctl with a pointer to this structure. Drivers fill +the &v4l2-vbi-format; <structfield>vbi</structfield> member of the +<structfield>fmt</structfield> union.</para> + + <para>To request different parameters applications set the +<structfield>type</structfield> field of a &v4l2-format; as above and +initialize all fields of the &v4l2-vbi-format; +<structfield>vbi</structfield> member of the +<structfield>fmt</structfield> union, or better just modify the +results of <constant>VIDIOC_G_FMT</constant>, and call the +&VIDIOC-S-FMT; ioctl with a pointer to this structure. Drivers return +an &EINVAL; only when the given parameters are ambiguous, otherwise +they modify the parameters according to the hardware capabilites and +return the actual parameters. When the driver allocates resources at +this point, it may return an &EBUSY; to indicate the returned +parameters are valid but the required resources are currently not +available. That may happen for instance when the video and VBI areas +to capture would overlap, or when the driver supports multiple opens +and another process already requested VBI capturing or output. Anyway, +applications must expect other resource allocation points which may +return <errorcode>EBUSY</errorcode>, at the &VIDIOC-STREAMON; ioctl +and the first read(), write() and select() call.</para> + + <para>VBI devices must implement both the +<constant>VIDIOC_G_FMT</constant> and +<constant>VIDIOC_S_FMT</constant> ioctl, even if +<constant>VIDIOC_S_FMT</constant> ignores all requests and always +returns default parameters as <constant>VIDIOC_G_FMT</constant> does. +<constant>VIDIOC_TRY_FMT</constant> is optional.</para> + + <table pgwide="1" frame="none" id="v4l2-vbi-format"> + <title>struct <structname>v4l2_vbi_format</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>sampling_rate</structfield></entry> + <entry>Samples per second, i. e. unit 1 Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>offset</structfield></entry> + <entry><para>Horizontal offset of the VBI image, +relative to the leading edge of the line synchronization pulse and +counted in samples: The first sample in the VBI image will be located +<structfield>offset</structfield> / +<structfield>sampling_rate</structfield> seconds following the leading +edge. See also <xref linkend="vbi-hsync" />.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>samples_per_line</structfield></entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>sample_format</structfield></entry> + <entry><para>Defines the sample format as in <xref +linkend="pixfmt" />, a four-character-code.<footnote> + <para>A few devices may be unable to +sample VBI data at all but can extend the video capture window to the +VBI region.</para> + </footnote> Usually this is +<constant>V4L2_PIX_FMT_GREY</constant>, i. e. each sample +consists of 8 bits with lower values oriented towards the black level. +Do not assume any other correlation of values with the signal level. +For example, the MSB does not necessarily indicate if the signal is +'high' or 'low' because 128 may not be the mean value of the +signal. Drivers shall not convert the sample format by software.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>start</structfield>[2]</entry> + <entry>This is the scanning system line number +associated with the first line of the VBI image, of the first and the +second field respectively. See <xref linkend="vbi-525" /> and +<xref linkend="vbi-625" /> for valid values. VBI input drivers can +return start values 0 if the hardware cannot reliable identify +scanning lines, VBI acquisition may not require this +information.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>count</structfield>[2]</entry> + <entry>The number of lines in the first and second +field image, respectively.</entry> + </row> + <row> + <entry spanname="hspan"><para>Drivers should be as +flexibility as possible. For example, it may be possible to extend or +move the VBI capture window down to the picture area, implementing a +'full field mode' to capture data service transmissions embedded in +the picture.</para><para>An application can set the first or second +<structfield>count</structfield> value to zero if no data is required +from the respective field; <structfield>count</structfield>[1] if the +scanning system is progressive, &ie; not interlaced. The +corresponding start value shall be ignored by the application and +driver. Anyway, drivers may not support single field capturing and +return both count values non-zero.</para><para>Both +<structfield>count</structfield> values set to zero, or line numbers +outside the bounds depicted in <xref linkend="vbi-525" /> and <xref + linkend="vbi-625" />, or a field image covering +lines of two fields, are invalid and shall not be returned by the +driver.</para><para>To initialize the <structfield>start</structfield> +and <structfield>count</structfield> fields, applications must first +determine the current video standard selection. The &v4l2-std-id; or +the <structfield>framelines</structfield> field of &v4l2-standard; can +be evaluated for this purpose.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>See <xref linkend="vbifmt-flags" /> below. Currently +only drivers set flags, applications must set this field to +zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>This array is reserved for future extensions. +Drivers and applications must set it to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="vbifmt-flags"> + <title>Raw VBI Format Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_VBI_UNSYNC</constant></entry> + <entry>0x0001</entry> + <entry><para>This flag indicates hardware which does not +properly distinguish between fields. Normally the VBI image stores the +first field (lower scanning line numbers) first in memory. This may be +a top or bottom field depending on the video standard. When this flag +is set the first or second field may be stored first, however the +fields are still in correct temporal order with the older field first +in memory.<footnote> + <para>Most VBI services transmit on both fields, but +some have different semantics depending on the field number. These +cannot be reliable decoded or encoded when +<constant>V4L2_VBI_UNSYNC</constant> is set.</para> + </footnote></para></entry> + </row> + <row> + <entry><constant>V4L2_VBI_INTERLACED</constant></entry> + <entry>0x0002</entry> + <entry>By default the two field images will be passed +sequentially; all lines of the first field followed by all lines of +the second field (compare <xref linkend="field-order" /> +<constant>V4L2_FIELD_SEQ_TB</constant> and +<constant>V4L2_FIELD_SEQ_BT</constant>, whether the top or bottom +field is first in memory depends on the video standard). When this +flag is set, the two fields are interlaced (cf. +<constant>V4L2_FIELD_INTERLACED</constant>). The first line of the +first field followed by the first line of the second field, then the +two second lines, and so on. Such a layout may be necessary when the +hardware has been programmed to capture or output interlaced video +images and is unable to separate the fields for VBI capturing at +the same time. For simplicity setting this flag implies that both +<structfield>count</structfield> values are equal and non-zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <figure id="vbi-hsync"> + <title>Line synchronization</title> + <mediaobject> + <imageobject> + <imagedata fileref="vbi_hsync.pdf" format="PS" /> + </imageobject> + <imageobject> + <imagedata fileref="vbi_hsync.gif" format="GIF" /> + </imageobject> + <textobject> + <phrase>Line synchronization diagram</phrase> + </textobject> + </mediaobject> + </figure> + + <figure id="vbi-525"> + <title>ITU-R 525 line numbering (M/NTSC and M/PAL)</title> + <mediaobject> + <imageobject> + <imagedata fileref="vbi_525.pdf" format="PS" /> + </imageobject> + <imageobject> + <imagedata fileref="vbi_525.gif" format="GIF" /> + </imageobject> + <textobject> + <phrase>NTSC field synchronization diagram</phrase> + </textobject> + <caption> + <para>(1) For the purpose of this specification field 2 +starts in line 264 and not 263.5 because half line capturing is not +supported.</para> + </caption> + </mediaobject> + </figure> + + <figure id="vbi-625"> + <title>ITU-R 625 line numbering</title> + <mediaobject> + <imageobject> + <imagedata fileref="vbi_625.pdf" format="PS" /> + </imageobject> + <imageobject> + <imagedata fileref="vbi_625.gif" format="GIF" /> + </imageobject> + <textobject> + <phrase>PAL/SECAM field synchronization diagram</phrase> + </textobject> + <caption> + <para>(1) For the purpose of this specification field 2 +starts in line 314 and not 313.5 because half line capturing is not +supported.</para> + </caption> + </mediaobject> + </figure> + + <para>Remember the VBI image format depends on the selected +video standard, therefore the application must choose a new standard or +query the current standard first. Attempts to read or write data ahead +of format negotiation, or after switching the video standard which may +invalidate the negotiated VBI parameters, should be refused by the +driver. A format change during active I/O is not permitted.</para> + </section> + + <section> + <title>Reading and writing VBI images</title> + + <para>To assure synchronization with the field number and easier +implementation, the smallest unit of data passed at a time is one +frame, consisting of two fields of VBI images immediately following in +memory.</para> + + <para>The total size of a frame computes as follows:</para> + + <programlisting> +(<structfield>count</structfield>[0] + <structfield>count</structfield>[1]) * +<structfield>samples_per_line</structfield> * sample size in bytes</programlisting> + + <para>The sample size is most likely always one byte, +applications must check the <structfield>sample_format</structfield> +field though, to function properly with other drivers.</para> + + <para>A VBI device may support <link + linkend="rw">read/write</link> and/or streaming (<link + linkend="mmap">memory mapping</link> or <link + linkend="userp">user pointer</link>) I/O. The latter bears the +possibility of synchronizing video and +VBI data by using buffer timestamps.</para> + + <para>Remember the &VIDIOC-STREAMON; ioctl and the first read(), +write() and select() call can be resource allocation points returning +an &EBUSY; if the required hardware resources are temporarily +unavailable, for example the device is already in use by another +process.</para> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-rds.xml b/linux/Documentation/DocBook/v4l/dev-rds.xml new file mode 100644 index 000000000..0869d701b --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-rds.xml @@ -0,0 +1,168 @@ + <title>RDS Interface</title> + + <para>The Radio Data System transmits supplementary +information in binary format, for example the station name or travel +information, on an inaudible audio subcarrier of a radio program. This +interface is aimed at devices capable of receiving and decoding RDS +information.</para> + + <para>For more information see the core RDS standard <xref linkend="en50067" /> +and the RBDS standard <xref linkend="nrsc4" />.</para> + + <para>Note that the RBDS standard as is used in the USA is almost identical +to the RDS standard. Any RDS decoder can also handle RBDS. Only some of the fields +have slightly different meanings. See the RBDS standard for more information.</para> + + <para>The RBDS standard also specifies support for MMBS (Modified Mobile Search). +This is a proprietary format which seems to be discontinued. The RDS interface does not +support this format. Should support for MMBS (or the so-called 'E blocks' in general) +be needed, then please contact the linux-media mailing list: &v4l-ml;.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the RDS capturing API +set the <constant>V4L2_CAP_RDS_CAPTURE</constant> flag in +the <structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. +Any tuner that supports RDS will set the +<constant>V4L2_TUNER_CAP_RDS</constant> flag in the <structfield>capability</structfield> +field of &v4l2-tuner;. +Whether an RDS signal is present can be detected by looking at +the <structfield>rxsubchans</structfield> field of &v4l2-tuner;: the +<constant>V4L2_TUNER_SUB_RDS</constant> will be set if RDS data was detected.</para> + + <para>Devices supporting the RDS output API +set the <constant>V4L2_CAP_RDS_OUTPUT</constant> flag in +the <structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. +Any modulator that supports RDS will set the +<constant>V4L2_TUNER_CAP_RDS</constant> flag in the <structfield>capability</structfield> +field of &v4l2-modulator;. +In order to enable the RDS transmission one must set the <constant>V4L2_TUNER_SUB_RDS</constant> +bit in the <structfield>txsubchans</structfield> field of &v4l2-modulator;.</para> + + </section> + + <section> + <title>Reading RDS data</title> + + <para>RDS data can be read from the radio device +with the &func-read; function. The data is packed in groups of three bytes, +as follows:</para> + <table frame="none" pgwide="1" id="v4l2-rds-data"> + <title>struct +<structname>v4l2_rds_data</structname></title> + <tgroup cols="3"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colname="c3" colwidth="5*" /> + <tbody valign="top"> + <row> + <entry>__u8</entry> + <entry><structfield>lsb</structfield></entry> + <entry>Least Significant Byte of RDS Block</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>msb</structfield></entry> + <entry>Most Significant Byte of RDS Block</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>block</structfield></entry> + <entry>Block description</entry> + </row> + </tbody> + </tgroup> + </table> + <table frame="none" pgwide="1" id="v4l2-rds-block"> + <title>Block description</title> + <tgroup cols="2"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="5*" /> + <tbody valign="top"> + <row> + <entry>Bits 0-2</entry> + <entry>Block (aka offset) of the received data.</entry> + </row> + <row> + <entry>Bits 3-5</entry> + <entry>Deprecated. Currently identical to bits 0-2. Do not use these bits.</entry> + </row> + <row> + <entry>Bit 6</entry> + <entry>Corrected bit. Indicates that an error was corrected for this data block.</entry> + </row> + <row> + <entry>Bit 7</entry> + <entry>Error bit. Indicates that an uncorrectable error occurred during reception of this block.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-rds-block-codes"> + <title>Block defines</title> + <tgroup cols="3"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colname="c3" colwidth="5*" /> + <tbody valign="top"> + <row> + <entry>V4L2_RDS_BLOCK_MSK</entry> + <entry>7</entry> + <entry>Mask for bits 0-2 to get the block ID.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_A</entry> + <entry>0</entry> + <entry>Block A.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_B</entry> + <entry>1</entry> + <entry>Block B.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_C</entry> + <entry>2</entry> + <entry>Block C.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_D</entry> + <entry>3</entry> + <entry>Block D.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_C_ALT</entry> + <entry>4</entry> + <entry>Block C'.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_INVALID</entry> + <entry>7</entry> + <entry>An invalid block.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_CORRECTED</entry> + <entry>0x40</entry> + <entry>A bit error was detected but corrected.</entry> + </row> + <row> + <entry>V4L2_RDS_BLOCK_ERROR</entry> + <entry>0x80</entry> + <entry>An incorrectable error occurred.</entry> + </row> + </tbody> + </tgroup> + </table> + </section> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-sliced-vbi.xml b/linux/Documentation/DocBook/v4l/dev-sliced-vbi.xml new file mode 100644 index 000000000..69e789fa7 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-sliced-vbi.xml @@ -0,0 +1,708 @@ + <title>Sliced VBI Data Interface</title> + + <para>VBI stands for Vertical Blanking Interval, a gap in the +sequence of lines of an analog video signal. During VBI no picture +information is transmitted, allowing some time while the electron beam +of a cathode ray tube TV returns to the top of the screen.</para> + + <para>Sliced VBI devices use hardware to demodulate data transmitted +in the VBI. V4L2 drivers shall <emphasis>not</emphasis> do this by +software, see also the <link linkend="raw-vbi">raw VBI +interface</link>. The data is passed as short packets of fixed size, +covering one scan line each. The number of packets per video frame is +variable.</para> + + <para>Sliced VBI capture and output devices are accessed through the +same character special files as raw VBI devices. When a driver +supports both interfaces, the default function of a +<filename>/dev/vbi</filename> device is <emphasis>raw</emphasis> VBI +capturing or output, and the sliced VBI function is only available +after calling the &VIDIOC-S-FMT; ioctl as defined below. Likewise a +<filename>/dev/video</filename> device may support the sliced VBI API, +however the default function here is video capturing or output. +Different file descriptors must be used to pass raw and sliced VBI +data simultaneously, if this is supported by the driver.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the sliced VBI capturing or output API +set the <constant>V4L2_CAP_SLICED_VBI_CAPTURE</constant> or +<constant>V4L2_CAP_SLICED_VBI_OUTPUT</constant> flag respectively, in +the <structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. At least one of the +read/write, streaming or asynchronous <link linkend="io">I/O +methods</link> must be supported. Sliced VBI devices may have a tuner +or modulator.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>Sliced VBI devices shall support <link linkend="video">video +input or output</link> and <link linkend="tuner">tuner or +modulator</link> ioctls if they have these capabilities, and they may +support <link linkend="control">control</link> ioctls. The <link +linkend="standard">video standard</link> ioctls provide information +vital to program a sliced VBI device, therefore must be +supported.</para> + </section> + + <section id="sliced-vbi-format-negotitation"> + <title>Sliced VBI Format Negotiation</title> + + <para>To find out which data services are supported by the +hardware applications can call the &VIDIOC-G-SLICED-VBI-CAP; ioctl. +All drivers implementing the sliced VBI interface must support this +ioctl. The results may differ from those of the &VIDIOC-S-FMT; ioctl +when the number of VBI lines the hardware can capture or output per +frame, or the number of services it can identify on a given line are +limited. For example on PAL line 16 the hardware may be able to look +for a VPS or Teletext signal, but not both at the same time.</para> + + <para>To determine the currently selected services applications +set the <structfield>type </structfield> field of &v4l2-format; to +<constant> V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> or <constant> +V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant>, and the &VIDIOC-G-FMT; +ioctl fills the <structfield>fmt.sliced</structfield> member, a +&v4l2-sliced-vbi-format;.</para> + + <para>Applications can request different parameters by +initializing or modifying the <structfield>fmt.sliced</structfield> +member and calling the &VIDIOC-S-FMT; ioctl with a pointer to the +<structname>v4l2_format</structname> structure.</para> + + <para>The sliced VBI API is more complicated than the raw VBI API +because the hardware must be told which VBI service to expect on each +scan line. Not all services may be supported by the hardware on all +lines (this is especially true for VBI output where Teletext is often +unsupported and other services can only be inserted in one specific +line). In many cases, however, it is sufficient to just set the +<structfield>service_set</structfield> field to the required services +and let the driver fill the <structfield>service_lines</structfield> +array according to hardware capabilities. Only if more precise control +is needed should the programmer set the +<structfield>service_lines</structfield> array explicitly.</para> + + <para>The &VIDIOC-S-FMT; ioctl modifies the parameters +according to hardware capabilities. When the driver allocates +resources at this point, it may return an &EBUSY; if the required +resources are temporarily unavailable. Other resource allocation +points which may return <errorcode>EBUSY</errorcode> can be the +&VIDIOC-STREAMON; ioctl and the first &func-read;, &func-write; and +&func-select; call.</para> + + <table frame="none" pgwide="1" id="v4l2-sliced-vbi-format"> + <title>struct +<structname>v4l2_sliced_vbi_format</structname></title> + <tgroup cols="5"> + <colspec colname="c1" colwidth="3*" /> + <colspec colname="c2" colwidth="3*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="2*" /> + <colspec colname="c5" colwidth="2*" /> + <spanspec namest="c3" nameend="c5" spanname="hspan" /> + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>service_set</structfield></entry> + <entry spanname="hspan"><para>If +<structfield>service_set</structfield> is non-zero when passed with +&VIDIOC-S-FMT; or &VIDIOC-TRY-FMT;, the +<structfield>service_lines</structfield> array will be filled by the +driver according to the services specified in this field. For example, +if <structfield>service_set</structfield> is initialized with +<constant>V4L2_SLICED_TELETEXT_B | V4L2_SLICED_WSS_625</constant>, a +driver for the cx25840 video decoder sets lines 7-22 of both +fields<footnote><para>According to <link +linkend="ets300706">ETS 300 706</link> lines 6-22 of the +first field and lines 5-22 of the second field may carry Teletext +data.</para></footnote> to <constant>V4L2_SLICED_TELETEXT_B</constant> +and line 23 of the first field to +<constant>V4L2_SLICED_WSS_625</constant>. If +<structfield>service_set</structfield> is set to zero, then the values +of <structfield>service_lines</structfield> will be used instead. +</para><para>On return the driver sets this field to the union of all +elements of the returned <structfield>service_lines</structfield> +array. It may contain less services than requested, perhaps just one, +if the hardware cannot handle more services simultaneously. It may be +empty (zero) if none of the requested services are supported by the +hardware.</para></entry> + </row> + <row> + <entry>__u16</entry> + <entry><structfield>service_lines</structfield>[2][24]</entry> + <entry spanname="hspan"><para>Applications initialize this +array with sets of data services the driver shall look for or insert +on the respective scan line. Subject to hardware capabilities drivers +return the requested set, a subset, which may be just a single +service, or an empty set. When the hardware cannot handle multiple +services on the same line the driver shall choose one. No assumptions +can be made on which service the driver chooses.</para><para>Data +services are defined in <xref linkend="vbi-services2" />. Array indices +map to ITU-R line numbers (see also <xref linkend="vbi-525" /> and <xref + linkend="vbi-625" />) as follows: <!-- No nested +tables, sigh. --></para></entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry>Element</entry> + <entry>525 line systems</entry> + <entry>625 line systems</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[0][1]</entry> + <entry align="center">1</entry> + <entry align="center">1</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[0][23]</entry> + <entry align="center">23</entry> + <entry align="center">23</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[1][1]</entry> + <entry align="center">264</entry> + <entry align="center">314</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[1][23]</entry> + <entry align="center">286</entry> + <entry align="center">336</entry> + </row> + <!-- End of line numbers table. --> + <row> + <entry></entry> + <entry></entry> + <entry spanname="hspan">Drivers must set +<structfield>service_lines</structfield>[0][0] and +<structfield>service_lines</structfield>[1][0] to zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>io_size</structfield></entry> + <entry spanname="hspan">Maximum number of bytes passed by +one &func-read; or &func-write; call, and the buffer size in bytes for +the &VIDIOC-QBUF; and &VIDIOC-DQBUF; ioctl. Drivers set this field to +the size of &v4l2-sliced-vbi-data; times the number of non-zero +elements in the returned <structfield>service_lines</structfield> +array (that is the number of lines potentially carrying data).</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry spanname="hspan">This array is reserved for future +extensions. Applications and drivers must set it to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- See also vidioc-g-sliced-vbi-cap.sgml --> + <table frame="none" pgwide="1" id="vbi-services2"> + <title>Sliced VBI services</title> + <tgroup cols="5"> + <colspec colname="c1" colwidth="2*" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colname="c3" colwidth="1*" /> + <colspec colname="c4" colwidth="2*" /> + <colspec colname="c5" colwidth="2*" /> + <spanspec namest="c3" nameend="c5" spanname="rlp" /> + <thead> + <row> + <entry>Symbol</entry> + <entry>Value</entry> + <entry>Reference</entry> + <entry>Lines, usually</entry> + <entry>Payload</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_SLICED_TELETEXT_B</constant> +(Teletext System B)</entry> + <entry>0x0001</entry> + <entry><xref linkend="ets300706" />, <xref linkend="itu653" /></entry> + <entry>PAL/SECAM line 7-22, 320-335 (second field 7-22)</entry> + <entry>Last 42 of the 45 byte Teletext packet, that is +without clock run-in and framing code, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VPS</constant></entry> + <entry>0x0400</entry> + <entry><xref linkend="ets300231" /></entry> + <entry>PAL line 16</entry> + <entry>Byte number 3 to 15 according to Figure 9 of +ETS 300 231, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_CAPTION_525</constant></entry> + <entry>0x1000</entry> + <entry><xref linkend="eia608" /></entry> + <entry>NTSC line 21, 284 (second field 21)</entry> + <entry>Two bytes in transmission order, including parity +bit, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_WSS_625</constant></entry> + <entry>0x4000</entry> + <entry><xref linkend="itu1119" />, <xref linkend="en300294" /></entry> + <entry>PAL/SECAM line 23</entry> + <entry><screen> +Byte 0 1 + msb lsb msb lsb + Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9 +</screen></entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VBI_525</constant></entry> + <entry>0x1000</entry> + <entry spanname="rlp">Set of services applicable to 525 +line systems.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VBI_625</constant></entry> + <entry>0x4401</entry> + <entry spanname="rlp">Set of services applicable to 625 +line systems.</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Drivers may return an &EINVAL; when applications attempt to +read or write data without prior format negotiation, after switching +the video standard (which may invalidate the negotiated VBI +parameters) and after switching the video input (which may change the +video standard as a side effect). The &VIDIOC-S-FMT; ioctl may return +an &EBUSY; when applications attempt to change the format while i/o is +in progress (between a &VIDIOC-STREAMON; and &VIDIOC-STREAMOFF; call, +and after the first &func-read; or &func-write; call).</para> + </section> + + <section> + <title>Reading and writing sliced VBI data</title> + + <para>A single &func-read; or &func-write; call must pass all data +belonging to one video frame. That is an array of +<structname>v4l2_sliced_vbi_data</structname> structures with one or +more elements and a total size not exceeding +<structfield>io_size</structfield> bytes. Likewise in streaming I/O +mode one buffer of <structfield>io_size</structfield> bytes must +contain data of one video frame. The <structfield>id</structfield> of +unused <structname>v4l2_sliced_vbi_data</structname> elements must be +zero.</para> + + <table frame="none" pgwide="1" id="v4l2-sliced-vbi-data"> + <title>struct +<structname>v4l2_sliced_vbi_data</structname></title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry>A flag from <xref linkend="vbi-services" /> +identifying the type of data in this packet. Only a single bit must be +set. When the <structfield>id</structfield> of a captured packet is +zero, the packet is empty and the contents of other fields are +undefined. Applications shall ignore empty packets. When the +<structfield>id</structfield> of a packet for output is zero the +contents of the <structfield>data</structfield> field are undefined +and the driver must no longer insert data on the requested +<structfield>field</structfield> and +<structfield>line</structfield>.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>field</structfield></entry> + <entry>The video field number this data has been captured +from, or shall be inserted at. <constant>0</constant> for the first +field, <constant>1</constant> for the second field.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>line</structfield></entry> + <entry>The field (as opposed to frame) line number this +data has been captured from, or shall be inserted at. See <xref + linkend="vbi-525" /> and <xref linkend="vbi-625" /> for valid +values. Sliced VBI capture devices can set the line number of all +packets to <constant>0</constant> if the hardware cannot reliably +identify scan lines. The field number must always be valid.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield></entry> + <entry>This field is reserved for future extensions. +Applications and drivers must set it to zero.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>data</structfield>[48]</entry> + <entry>The packet payload. See <xref + linkend="vbi-services" /> for the contents and number of +bytes passed for each data type. The contents of padding bytes at the +end of this array are undefined, drivers and applications shall ignore +them.</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Packets are always passed in ascending line number order, +without duplicate line numbers. The &func-write; function and the +&VIDIOC-QBUF; ioctl must return an &EINVAL; when applications violate +this rule. They must also return an &EINVAL; when applications pass an +incorrect field or line number, or a combination of +<structfield>field</structfield>, <structfield>line</structfield> and +<structfield>id</structfield> which has not been negotiated with the +&VIDIOC-G-FMT; or &VIDIOC-S-FMT; ioctl. When the line numbers are +unknown the driver must pass the packets in transmitted order. The +driver can insert empty packets with <structfield>id</structfield> set +to zero anywhere in the packet array.</para> + + <para>To assure synchronization and to distinguish from frame +dropping, when a captured frame does not carry any of the requested +data services drivers must pass one or more empty packets. When an +application fails to pass VBI data in time for output, the driver +must output the last VPS and WSS packet again, and disable the output +of Closed Caption and Teletext data, or output data which is ignored +by Closed Caption and Teletext decoders.</para> + + <para>A sliced VBI device may support <link +linkend="rw">read/write</link> and/or streaming (<link +linkend="mmap">memory mapping</link> and/or <link linkend="userp">user +pointer</link>) I/O. The latter bears the possibility of synchronizing +video and VBI data by using buffer timestamps.</para> + + </section> + + <section> + <title>Sliced VBI Data in MPEG Streams</title> + + <para>If a device can produce an MPEG output stream, it may be +capable of providing <link +linkend="sliced-vbi-format-negotitation">negotiated sliced VBI +services</link> as data embedded in the MPEG stream. Users or +applications control this sliced VBI data insertion with the <link +linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link> +control.</para> + + <para>If the driver does not provide the <link +linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link> +control, or only allows that control to be set to <link +linkend="v4l2-mpeg-stream-vbi-fmt"><constant> +V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link>, then the device +cannot embed sliced VBI data in the MPEG stream.</para> + + <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"> +V4L2_CID_MPEG_STREAM_VBI_FMT</link> control does not implicitly set +the device driver to capture nor cease capturing sliced VBI data. The +control only indicates to embed sliced VBI data in the MPEG stream, if +an application has negotiated sliced VBI service be captured.</para> + + <para>It may also be the case that a device can embed sliced VBI +data in only certain types of MPEG streams: for example in an MPEG-2 +PS but not an MPEG-2 TS. In this situation, if sliced VBI data +insertion is requested, the sliced VBI data will be embedded in MPEG +stream types when supported, and silently omitted from MPEG stream +types where sliced VBI data insertion is not supported by the device. +</para> + + <para>The following subsections specify the format of the +embedded sliced VBI data.</para> + + <section> + <title>MPEG Stream Embedded, Sliced VBI Data Format: NONE</title> + <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant> +V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link> embedded sliced VBI +format shall be interpreted by drivers as a control to cease +embedding sliced VBI data in MPEG streams. Neither the device nor +driver shall insert "empty" embedded sliced VBI data packets in the +MPEG stream when this format is set. No MPEG stream data structures +are specified for this format.</para> + </section> + + <section> + <title>MPEG Stream Embedded, Sliced VBI Data Format: IVTV</title> + <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant> +V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> embedded sliced VBI +format, when supported, indicates to the driver to embed up to 36 +lines of sliced VBI data per frame in an MPEG-2 <emphasis>Private +Stream 1 PES</emphasis> packet encapsulated in an MPEG-2 <emphasis> +Program Pack</emphasis> in the MPEG stream.</para> + + <para><emphasis>Historical context</emphasis>: This format +specification originates from a custom, embedded, sliced VBI data +format used by the <filename>ivtv</filename> driver. This format +has already been informally specified in the kernel sources in the +file <filename>Documentation/video4linux/cx2341x/README.vbi</filename> +. The maximum size of the payload and other aspects of this format +are driven by the CX23415 MPEG decoder's capabilities and limitations +with respect to extracting, decoding, and displaying sliced VBI data +embedded within an MPEG stream.</para> + + <para>This format's use is <emphasis>not</emphasis> exclusive to +the <filename>ivtv</filename> driver <emphasis>nor</emphasis> +exclusive to CX2341x devices, as the sliced VBI data packet insertion +into the MPEG stream is implemented in driver software. At least the +<filename>cx18</filename> driver provides sliced VBI data insertion +into an MPEG-2 PS in this format as well.</para> + + <para>The following definitions specify the payload of the +MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packets that contain +sliced VBI data when <link linkend="v4l2-mpeg-stream-vbi-fmt"> +<constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> is set. +(The MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packet header +and encapsulating MPEG-2 <emphasis>Program Pack</emphasis> header are +not detailed here. Please refer to the MPEG-2 specifications for +details on those packet headers.)</para> + + <para>The payload of the MPEG-2 <emphasis>Private Stream 1 PES +</emphasis> packets that contain sliced VBI data is specified by +&v4l2-mpeg-vbi-fmt-ivtv;. The payload is variable +length, depending on the actual number of lines of sliced VBI data +present in a video frame. The payload may be padded at the end with +unspecified fill bytes to align the end of the payload to a 4-byte +boundary. The payload shall never exceed 1552 bytes (2 fields with +18 lines/field with 43 bytes of data/line and a 4 byte magic number). +</para> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv"> + <title>struct <structname>v4l2_mpeg_vbi_fmt_ivtv</structname> + </title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u8</entry> + <entry><structfield>magic</structfield>[4]</entry> + <entry></entry> + <entry>A "magic" constant from <xref + linkend="v4l2-mpeg-vbi-fmt-ivtv-magic" /> that indicates +this is a valid sliced VBI data payload and also indicates which +member of the anonymous union, <structfield>itv0</structfield> or +<structfield>ITV0</structfield>, to use for the payload data.</entry> + </row> + <row> + <entry>union</entry> + <entry>(anonymous)</entry> + </row> + <row> + <entry></entry> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0"> + <structname>v4l2_mpeg_vbi_itv0</structname></link> + </entry> + <entry><structfield>itv0</structfield></entry> + <entry>The primary form of the sliced VBI data payload +that contains anywhere from 1 to 35 lines of sliced VBI data. +Line masks are provided in this form of the payload indicating +which VBI lines are provided.</entry> + </row> + <row> + <entry></entry> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-1"> + <structname>v4l2_mpeg_vbi_ITV0</structname></link> + </entry> + <entry><structfield>ITV0</structfield></entry> + <entry>An alternate form of the sliced VBI data payload +used when 36 lines of sliced VBI data are present. No line masks are +provided in this form of the payload; all valid line mask bits are +implcitly set.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv-magic"> + <title>Magic Constants for &v4l2-mpeg-vbi-fmt-ivtv; + <structfield>magic</structfield> field</title> + <tgroup cols="3"> + &cs-def; + <thead> + <row> + <entry align="left">Defined Symbol</entry> + <entry align="left">Value</entry> + <entry align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC0</constant> + </entry> + <entry>"itv0"</entry> + <entry>Indicates the <structfield>itv0</structfield> +member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC1</constant> + </entry> + <entry>"ITV0"</entry> + <entry>Indicates the <structfield>ITV0</structfield> +member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid and +that 36 lines of sliced VBI data are present.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0"> + <title>struct <structname>v4l2_mpeg_vbi_itv0</structname> + </title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__le32</entry> + <entry><structfield>linemask</structfield>[2]</entry> + <entry><para>Bitmasks indicating the VBI service lines +present. These <structfield>linemask</structfield> values are stored +in little endian byte order in the MPEG stream. Some reference +<structfield>linemask</structfield> bit positions with their +corresponding VBI line number and video field are given below. +b<subscript>0</subscript> indicates the least significant bit of a +<structfield>linemask</structfield> value:<screen> +<structfield>linemask</structfield>[0] b<subscript>0</subscript>: line 6 first field +<structfield>linemask</structfield>[0] b<subscript>17</subscript>: line 23 first field +<structfield>linemask</structfield>[0] b<subscript>18</subscript>: line 6 second field +<structfield>linemask</structfield>[0] b<subscript>31</subscript>: line 19 second field +<structfield>linemask</structfield>[1] b<subscript>0</subscript>: line 20 second field +<structfield>linemask</structfield>[1] b<subscript>3</subscript>: line 23 second field +<structfield>linemask</structfield>[1] b<subscript>4</subscript>-b<subscript>31</subscript>: unused and set to 0</screen></para></entry> + </row> + <row> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line"> + <structname>v4l2_mpeg_vbi_itv0_line</structname></link> + </entry> + <entry><structfield>line</structfield>[35]</entry> + <entry>This is a variable length array that holds from 1 +to 35 lines of sliced VBI data. The sliced VBI data lines present +correspond to the bits set in the <structfield>linemask</structfield> +array, starting from b<subscript>0</subscript> of <structfield> +linemask</structfield>[0] up through b<subscript>31</subscript> of +<structfield>linemask</structfield>[0], and from b<subscript>0 +</subscript> of <structfield>linemask</structfield>[1] up through b +<subscript>3</subscript> of <structfield>linemask</structfield>[1]. +<structfield>line</structfield>[0] corresponds to the first bit +found set in the <structfield>linemask</structfield> array, +<structfield>line</structfield>[1] corresponds to the second bit +found set in the <structfield>linemask</structfield> array, etc. +If no <structfield>linemask</structfield> array bits are set, then +<structfield>line</structfield>[0] may contain one line of +unspecified data that should be ignored by applications.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-1"> + <title>struct <structname>v4l2_mpeg_vbi_ITV0</structname> + </title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line"> + <structname>v4l2_mpeg_vbi_itv0_line</structname></link> + </entry> + <entry><structfield>line</structfield>[36]</entry> + <entry>A fixed length array of 36 lines of sliced VBI +data. <structfield>line</structfield>[0] through <structfield>line +</structfield>[17] correspond to lines 6 through 23 of the +first field. <structfield>line</structfield>[18] through +<structfield>line</structfield>[35] corresponds to lines 6 +through 23 of the second field.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-line"> + <title>struct <structname>v4l2_mpeg_vbi_itv0_line</structname> + </title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u8</entry> + <entry><structfield>id</structfield></entry> + <entry>A line identifier value from +<xref linkend="ITV0-Line-Identifier-Constants" /> that indicates +the type of sliced VBI data stored on this line.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>data</structfield>[42]</entry> + <entry>The sliced VBI data for the line.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="ITV0-Line-Identifier-Constants"> + <title>Line Identifiers for struct <link + linkend="v4l2-mpeg-vbi-itv0-line"><structname> +v4l2_mpeg_vbi_itv0_line</structname></link> <structfield>id +</structfield> field</title> + <tgroup cols="3"> + &cs-def; + <thead> + <row> + <entry align="left">Defined Symbol</entry> + <entry align="left">Value</entry> + <entry align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_TELETEXT_B</constant> + </entry> + <entry>1</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_CAPTION_525</constant> + </entry> + <entry>4</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_WSS_625</constant> + </entry> + <entry>5</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_VPS</constant> + </entry> + <entry>7</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + </tbody> + </tgroup> + </table> + + </section> + </section> + + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/dev-teletext.xml b/linux/Documentation/DocBook/v4l/dev-teletext.xml new file mode 100644 index 000000000..76184e8ed --- /dev/null +++ b/linux/Documentation/DocBook/v4l/dev-teletext.xml @@ -0,0 +1,40 @@ + <title>Teletext Interface</title> + + <para>This interface aims at devices receiving and demodulating +Teletext data [<xref linkend="ets300706" />, <xref linkend="itu653" />], evaluating the +Teletext packages and storing formatted pages in cache memory. Such +devices are usually implemented as microcontrollers with serial +interface (I<superscript>2</superscript>C) and can be found on older +TV cards, dedicated Teletext decoding cards and home-brew devices +connected to the PC parallel port.</para> + + <para>The Teletext API was designed by Martin Buck. It is defined in +the kernel header file <filename>linux/videotext.h</filename>, the +specification is available from <ulink url="ftp://ftp.gwdg.de/pub/linux/misc/videotext/"> +ftp://ftp.gwdg.de/pub/linux/misc/videotext/</ulink>. (Videotext is the name of +the German public television Teletext service.) Conventional character +device file names are <filename>/dev/vtx</filename> and +<filename>/dev/vttuner</filename>, with device number 83, 0 and 83, 16 +respectively. A similar interface exists for the Philips SAA5249 +Teletext decoder [specification?] with character device file names +<filename>/dev/tlkN</filename>, device number 102, N.</para> + + <para>Eventually the Teletext API was integrated into the V4L API +with character device file names <filename>/dev/vtx0</filename> to +<filename>/dev/vtx31</filename>, device major number 81, minor numbers +192 to 223. For reference the V4L Teletext API specification is +reproduced here in full: "Teletext interfaces talk the existing VTX +API." Teletext devices with major number 83 and 102 will be removed in +Linux 2.6.</para> + + <para>There are no plans to replace the Teletext API or to integrate +it into V4L2. Please write to the linux-media mailing list: &v4l-ml; +when the need arises.</para> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/driver.xml b/linux/Documentation/DocBook/v4l/driver.xml new file mode 100644 index 000000000..1f7eea5c4 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/driver.xml @@ -0,0 +1,208 @@ + <title>V4L2 Driver Programming</title> + + <!-- This part defines the interface between the "videodev" + module and individual drivers. --> + + <para>to do</para> +<!-- + <para>V4L2 is a two-layer driver system. The top layer is the "videodev" +kernel module. When videodev initializes it registers as character device +with major number 81, and it registers a set of file operations. All V4L2 +drivers are really clients of videodev, which calls V4L2 drivers through +driver method functions. V4L2 drivers are also written as kernel modules. +After probing the hardware they register one or more devices with +videodev.</para> + + <section id="driver-modules"> + <title>Driver Modules</title> + + <para>V4L2 driver modules must have an initialization function which is +called after the module was loaded into kernel, an exit function whis is +called before the module is removed. When the driver is compiled into the +kernel these functions called at system boot and shutdown time.</para> + + <informalexample> + <programlisting> +#include <linux/module.h> + +/* Export information about this module. For details and other useful + macros see <filename>linux/module.h</filename>. */ +MODULE_DESCRIPTION("my - driver for my hardware"); +MODULE_AUTHOR("Your name here"); +MODULE_LICENSE("GPL"); + +static void +my_module_exit (void) +{ + /* Free all resources allocated by my_module_init(). */ +} + +static int +my_module_init (void) +{ + /* Bind the driver to the supported hardware, see + <link linkend="driver-pci"> and + <link linkend="driver-usb"> for examples. */ + + return 0; /* a negative value on error, 0 on success. */ +} + +/* Export module functions. */ +module_init (my_module_init); +module_exit (my_module_exit); +</programlisting> + </informalexample> + + <para>Users can add parameters when kernel modules are inserted:</para> + + <informalexample> + <programlisting> +include <linux/moduleparam.h> + +static int my_option = 123; +static int my_option_array[47]; + +/* Export the symbol, an int, with access permissions 0664. + See <filename>linux/moduleparam.h</filename> for other types. */ +module_param (my_option, int, 0644); +module_param_array (my_option_array, int, NULL, 0644); + +MODULE_PARM_DESC (my_option, "Does magic things, default 123"); +</programlisting> + </informalexample> + + <para>One parameter should be supported by all V4L2 drivers, the minor +number of the device it will register. Purpose is to predictably link V4L2 +drivers to device nodes if more than one video device is installed. Use the +name of the device node followed by a "_nr" suffix, for example "video_nr" +for <filename>/dev/video</filename>.</para> + + <informalexample> + <programlisting> +/* Minor number of the device, -1 to allocate the first unused. */ +static int video_nr = -1; + +module_param (video_nr, int, 0444); +</programlisting> + </informalexample> + </section> + + <section id="driver-pci"> + <title>PCI Devices</title> + + <para>PCI devices are initialized like this:</para> + + <informalexample> + <programlisting> +typedef struct { + /* State of one physical device. */ +} my_device; + +static int +my_resume (struct pci_dev * pci_dev) +{ + /* Restore the suspended device to working state. */ +} + +static int +my_suspend (struct pci_dev * pci_dev, + pm_message_t state) +{ + /* This function is called before the system goes to sleep. + Stop all DMAs and disable interrupts, then put the device + into a low power state. For details see the kernel + sources under <filename>Documentation/power</filename>. */ + + return 0; /* a negative value on error, 0 on success. */ +} + +static void __devexit +my_remove (struct pci_dev * pci_dev) +{ + my_device *my = pci_get_drvdata (pci_dev); + + /* Describe me. */ +} + +static int __devinit +my_probe (struct pci_dev * pci_dev, + const struct pci_device_id * pci_id) +{ + my_device *my; + + /* Describe me. */ + + /* You can allocate per-device data here and store a pointer + to it in the pci_dev structure. */ + my = ...; + pci_set_drvdata (pci_dev, my); + + return 0; /* a negative value on error, 0 on success. */ +} + +/* A list of supported PCI devices. */ +static struct pci_device_id +my_pci_device_ids [] = { + { PCI_VENDOR_ID_FOO, PCI_DEVICE_ID_BAR, + PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, + { 0 } /* end of list */ +}; + +/* Load our module if supported PCI devices are installed. */ +MODULE_DEVICE_TABLE (pci, my_pci_device_ids); + +static struct pci_driver +my_pci_driver = { + .name = "my", + .id_table = my_pci_device_ids, + + .probe = my_probe, + .remove = __devexit_p (my_remove), + + /* Power management functions. */ + .suspend = my_suspend, + .resume = my_resume, +}; + +static void +my_module_exit (void) +{ + pci_unregister_driver (&my_pci_driver); +} + +static int +my_module_init (void) +{ + return pci_register_driver (&my_pci_driver); +} +</programlisting> + </informalexample> + </section> + + <section id="driver-usb"> + <title>USB Devices</title> + <para>to do</para> + </section> + <section id="driver-registering"> + <title>Registering V4L2 Drivers</title> + + <para>After a V4L2 driver probed the hardware it registers one or more +devices with the videodev module.</para> + </section> + <section id="driver-file-ops"> + <title>File Operations</title> + <para>to do</para> + </section> + <section id="driver-internal-api"> + <title>Internal API</title> + <para>to do</para> + </section> +--> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/fdl-appendix.xml b/linux/Documentation/DocBook/v4l/fdl-appendix.xml new file mode 100644 index 000000000..b6ce50dbe --- /dev/null +++ b/linux/Documentation/DocBook/v4l/fdl-appendix.xml @@ -0,0 +1,671 @@ +<!-- + The GNU Free Documentation License 1.1 in DocBook + Markup by Eric Baudais <baudais@okstate.edu> + Maintained by the GNOME Documentation Project + http://developer.gnome.org/projects/gdp + Version: 1.0.1 + Last Modified: Nov 16, 2000 +--> + +<appendix id="fdl"> + <appendixinfo> + <releaseinfo> + Version 1.1, March 2000 + </releaseinfo> + <copyright> + <year>2000</year><holder>Free Software Foundation, Inc.</holder> + </copyright> + <legalnotice id="fdl-legalnotice"> + <para> + <address>Free Software Foundation, Inc. <street>59 Temple Place, + Suite 330</street>, <city>Boston</city>, <state>MA</state> + <postcode>02111-1307</postcode> <country>USA</country></address> + Everyone is permitted to copy and distribute verbatim copies of this + license document, but changing it is not allowed. + </para> + </legalnotice> + </appendixinfo> + <title>GNU Free Documentation License</title> + + <sect1 id="fdl-preamble"> + <title>0. PREAMBLE</title> + <para> + The purpose of this License is to make a manual, textbook, or + other written document <quote>free</quote> in the sense of + freedom: to assure everyone the effective freedom to copy and + redistribute it, with or without modifying it, either + commercially or noncommercially. Secondarily, this License + preserves for the author and publisher a way to get credit for + their work, while not being considered responsible for + modifications made by others. + </para> + + <para> + This License is a kind of <quote>copyleft</quote>, which means + that derivative works of the document must themselves be free in + the same sense. It complements the GNU General Public License, + which is a copyleft license designed for free software. + </para> + + <para> + We have designed this License in order to use it for manuals for + free software, because free software needs free documentation: a + free program should come with manuals providing the same + freedoms that the software does. But this License is not limited + to software manuals; it can be used for any textual work, + regardless of subject matter or whether it is published as a + printed book. We recommend this License principally for works + whose purpose is instruction or reference. + </para> + </sect1> + <sect1 id="fdl-section1"> + <title>1. APPLICABILITY AND DEFINITIONS</title> + <para id="fdl-document"> + This License applies to any manual or other work that contains a + notice placed by the copyright holder saying it can be + distributed under the terms of this License. The + <quote>Document</quote>, below, refers to any such manual or + work. Any member of the public is a licensee, and is addressed + as <quote>you</quote>. + </para> + + <para id="fdl-modified"> + A <quote>Modified Version</quote> of the Document means any work + containing the Document or a portion of it, either copied + verbatim, or with modifications and/or translated into another + language. + </para> + + <para id="fdl-secondary"> + A <quote>Secondary Section</quote> is a named appendix or a + front-matter section of the <link + linkend="fdl-document">Document</link> that deals exclusively + with the relationship of the publishers or authors of the + Document to the Document's overall subject (or to related + matters) and contains nothing that could fall directly within + that overall subject. (For example, if the Document is in part a + textbook of mathematics, a Secondary Section may not explain any + mathematics.) The relationship could be a matter of historical + connection with the subject or with related matters, or of + legal, commercial, philosophical, ethical or political position + regarding them. + </para> + + <para id="fdl-invariant"> + The <quote>Invariant Sections</quote> are certain <link + linkend="fdl-secondary"> Secondary Sections</link> whose titles + are designated, as being those of Invariant Sections, in the + notice that says that the <link + linkend="fdl-document">Document</link> is released under this + License. + </para> + + <para id="fdl-cover-texts"> + The <quote>Cover Texts</quote> are certain short passages of + text that are listed, as Front-Cover Texts or Back-Cover Texts, + in the notice that says that the <link + linkend="fdl-document">Document</link> is released under this + License. + </para> + + <para id="fdl-transparent"> + A <quote>Transparent</quote> copy of the <link + linkend="fdl-document"> Document</link> means a machine-readable + copy, represented in a format whose specification is available + to the general public, whose contents can be viewed and edited + directly and straightforwardly with generic text editors or (for + images composed of pixels) generic paint programs or (for + drawings) some widely available drawing editor, and that is + suitable for input to text formatters or for automatic + translation to a variety of formats suitable for input to text + formatters. A copy made in an otherwise Transparent file format + whose markup has been designed to thwart or discourage + subsequent modification by readers is not Transparent. A copy + that is not <quote>Transparent</quote> is called + <quote>Opaque</quote>. + </para> + + <para> + Examples of suitable formats for Transparent copies include + plain ASCII without markup, Texinfo input format, LaTeX input + format, SGML or XML using a publicly available DTD, and + standard-conforming simple HTML designed for human + modification. Opaque formats include PostScript, PDF, + proprietary formats that can be read and edited only by + proprietary word processors, SGML or XML for which the DTD + and/or processing tools are not generally available, and the + machine-generated HTML produced by some word processors for + output purposes only. + </para> + + <para id="fdl-title-page"> + The <quote>Title Page</quote> means, for a printed book, the + title page itself, plus such following pages as are needed to + hold, legibly, the material this License requires to appear in + the title page. For works in formats which do not have any title + page as such, <quote>Title Page</quote> means the text near the + most prominent appearance of the work's title, preceding the + beginning of the body of the text. + </para> + </sect1> + + <sect1 id="fdl-section2"> + <title>2. VERBATIM COPYING</title> + <para> + You may copy and distribute the <link + linkend="fdl-document">Document</link> in any medium, either + commercially or noncommercially, provided that this License, the + copyright notices, and the license notice saying this License + applies to the Document are reproduced in all copies, and that + you add no other conditions whatsoever to those of this + License. You may not use technical measures to obstruct or + control the reading or further copying of the copies you make or + distribute. However, you may accept compensation in exchange for + copies. If you distribute a large enough number of copies you + must also follow the conditions in <link + linkend="fdl-section3">section 3</link>. + </para> + + <para> + You may also lend copies, under the same conditions stated + above, and you may publicly display copies. + </para> + </sect1> + + <sect1 id="fdl-section3"> + <title>3. COPYING IN QUANTITY</title> + <para> + If you publish printed copies of the <link + linkend="fdl-document">Document</link> numbering more than 100, + and the Document's license notice requires <link + linkend="fdl-cover-texts">Cover Texts</link>, you must enclose + the copies in covers that carry, clearly and legibly, all these + Cover Texts: Front-Cover Texts on the front cover, and + Back-Cover Texts on the back cover. Both covers must also + clearly and legibly identify you as the publisher of these + copies. The front cover must present the full title with all + words of the title equally prominent and visible. You may add + other material on the covers in addition. Copying with changes + limited to the covers, as long as they preserve the title of the + <link linkend="fdl-document">Document</link> and satisfy these + conditions, can be treated as verbatim copying in other + respects. + </para> + + <para> + If the required texts for either cover are too voluminous to fit + legibly, you should put the first ones listed (as many as fit + reasonably) on the actual cover, and continue the rest onto + adjacent pages. + </para> + + <para> + If you publish or distribute <link + linkend="fdl-transparent">Opaque</link> copies of the <link + linkend="fdl-document">Document</link> numbering more than 100, + you must either include a machine-readable <link + linkend="fdl-transparent">Transparent</link> copy along with + each Opaque copy, or state in or with each Opaque copy a + publicly-accessible computer-network location containing a + complete Transparent copy of the Document, free of added + material, which the general network-using public has access to + download anonymously at no charge using public-standard network + protocols. If you use the latter option, you must take + reasonably prudent steps, when you begin distribution of Opaque + copies in quantity, to ensure that this Transparent copy will + remain thus accessible at the stated location until at least one + year after the last time you distribute an Opaque copy (directly + or through your agents or retailers) of that edition to the + public. + </para> + + <para> + It is requested, but not required, that you contact the authors + of the <link linkend="fdl-document">Document</link> well before + redistributing any large number of copies, to give them a chance + to provide you with an updated version of the Document. + </para> + </sect1> + + <sect1 id="fdl-section4"> + <title>4. MODIFICATIONS</title> + <para> + You may copy and distribute a <link + linkend="fdl-modified">Modified Version</link> of the <link + linkend="fdl-document">Document</link> under the conditions of + sections <link linkend="fdl-section2">2</link> and <link + linkend="fdl-section3">3</link> above, provided that you release + the Modified Version under precisely this License, with the + Modified Version filling the role of the Document, thus + licensing distribution and modification of the Modified Version + to whoever possesses a copy of it. In addition, you must do + these things in the Modified Version: + </para> + + <itemizedlist mark="opencircle"> + <listitem> + <formalpara> + <title>A</title> + <para> + Use in the <link linkend="fdl-title-page">Title + Page</link> (and on the covers, if any) a title distinct + from that of the <link + linkend="fdl-document">Document</link>, and from those of + previous versions (which should, if there were any, be + listed in the History section of the Document). You may + use the same title as a previous version if the original + publisher of that version gives permission. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>B</title> + <para> + List on the <link linkend="fdl-title-page">Title + Page</link>, as authors, one or more persons or entities + responsible for authorship of the modifications in the + <link linkend="fdl-modified">Modified Version</link>, + together with at least five of the principal authors of + the <link linkend="fdl-document">Document</link> (all of + its principal authors, if it has less than five). + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>C</title> + <para> + State on the <link linkend="fdl-title-page">Title + Page</link> the name of the publisher of the <link + linkend="fdl-modified">Modified Version</link>, as the + publisher. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>D</title> + <para> + Preserve all the copyright notices of the <link + linkend="fdl-document">Document</link>. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>E</title> + <para> + Add an appropriate copyright notice for your modifications + adjacent to the other copyright notices. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>F</title> + <para> + Include, immediately after the copyright notices, a + license notice giving the public permission to use the + <link linkend="fdl-modified">Modified Version</link> under + the terms of this License, in the form shown in the + Addendum below. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>G</title> + <para> + Preserve in that license notice the full lists of <link + linkend="fdl-invariant"> Invariant Sections</link> and + required <link linkend="fdl-cover-texts">Cover + Texts</link> given in the <link + linkend="fdl-document">Document's</link> license notice. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>H</title> + <para> + Include an unaltered copy of this License. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>I</title> + <para> + Preserve the section entitled <quote>History</quote>, and + its title, and add to it an item stating at least the + title, year, new authors, and publisher of the <link + linkend="fdl-modified">Modified Version </link>as given on + the <link linkend="fdl-title-page">Title Page</link>. If + there is no section entitled <quote>History</quote> in the + <link linkend="fdl-document">Document</link>, create one + stating the title, year, authors, and publisher of the + Document as given on its Title Page, then add an item + describing the Modified Version as stated in the previous + sentence. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>J</title> + <para> + Preserve the network location, if any, given in the <link + linkend="fdl-document">Document</link> for public access + to a <link linkend="fdl-transparent">Transparent</link> + copy of the Document, and likewise the network locations + given in the Document for previous versions it was based + on. These may be placed in the <quote>History</quote> + section. You may omit a network location for a work that + was published at least four years before the Document + itself, or if the original publisher of the version it + refers to gives permission. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>K</title> + <para> + In any section entitled <quote>Acknowledgements</quote> or + <quote>Dedications</quote>, preserve the section's title, + and preserve in the section all the substance and tone of + each of the contributor acknowledgements and/or + dedications given therein. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>L</title> + <para> + Preserve all the <link linkend="fdl-invariant">Invariant + Sections</link> of the <link + linkend="fdl-document">Document</link>, unaltered in their + text and in their titles. Section numbers or the + equivalent are not considered part of the section titles. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>M</title> + <para> + Delete any section entitled + <quote>Endorsements</quote>. Such a section may not be + included in the <link linkend="fdl-modified">Modified + Version</link>. + </para> + </formalpara> + </listitem> + + <listitem> + <formalpara> + <title>N</title> + <para> + Do not retitle any existing section as + <quote>Endorsements</quote> or to conflict in title with + any <link linkend="fdl-invariant">Invariant + Section</link>. + </para> + </formalpara> + </listitem> + </itemizedlist> + + <para> + If the <link linkend="fdl-modified">Modified Version</link> + includes new front-matter sections or appendices that qualify as + <link linkend="fdl-secondary">Secondary Sections</link> and + contain no material copied from the Document, you may at your + option designate some or all of these sections as invariant. To + do this, add their titles to the list of <link + linkend="fdl-invariant">Invariant Sections</link> in the + Modified Version's license notice. These titles must be + distinct from any other section titles. + </para> + + <para> + You may add a section entitled <quote>Endorsements</quote>, + provided it contains nothing but endorsements of your <link + linkend="fdl-modified">Modified Version</link> by various + parties--for example, statements of peer review or that the text + has been approved by an organization as the authoritative + definition of a standard. + </para> + + <para> + You may add a passage of up to five words as a <link + linkend="fdl-cover-texts">Front-Cover Text</link>, and a passage + of up to 25 words as a <link + linkend="fdl-cover-texts">Back-Cover Text</link>, to the end of + the list of <link linkend="fdl-cover-texts">Cover Texts</link> + in the <link linkend="fdl-modified">Modified Version</link>. + Only one passage of Front-Cover Text and one of Back-Cover Text + may be added by (or through arrangements made by) any one + entity. If the <link linkend="fdl-document">Document</link> + already includes a cover text for the same cover, previously + added by you or by arrangement made by the same entity you are + acting on behalf of, you may not add another; but you may + replace the old one, on explicit permission from the previous + publisher that added the old one. + </para> + + <para> + The author(s) and publisher(s) of the <link + linkend="fdl-document">Document</link> do not by this License + give permission to use their names for publicity for or to + assert or imply endorsement of any <link + linkend="fdl-modified">Modified Version </link>. + </para> + </sect1> + + <sect1 id="fdl-section5"> + <title>5. COMBINING DOCUMENTS</title> + <para> + You may combine the <link linkend="fdl-document">Document</link> + with other documents released under this License, under the + terms defined in <link linkend="fdl-section4">section 4</link> + above for modified versions, provided that you include in the + combination all of the <link linkend="fdl-invariant">Invariant + Sections</link> of all of the original documents, unmodified, + and list them all as Invariant Sections of your combined work in + its license notice. + </para> + + <para> + The combined work need only contain one copy of this License, + and multiple identical <link linkend="fdl-invariant">Invariant + Sections</link> may be replaced with a single copy. If there are + multiple Invariant Sections with the same name but different + contents, make the title of each such section unique by adding + at the end of it, in parentheses, the name of the original + author or publisher of that section if known, or else a unique + number. Make the same adjustment to the section titles in the + list of Invariant Sections in the license notice of the combined + work. + </para> + + <para> + In the combination, you must combine any sections entitled + <quote>History</quote> in the various original documents, + forming one section entitled <quote>History</quote>; likewise + combine any sections entitled <quote>Acknowledgements</quote>, + and any sections entitled <quote>Dedications</quote>. You must + delete all sections entitled <quote>Endorsements.</quote> + </para> + </sect1> + + <sect1 id="fdl-section6"> + <title>6. COLLECTIONS OF DOCUMENTS</title> + <para> + You may make a collection consisting of the <link + linkend="fdl-document">Document</link> and other documents + released under this License, and replace the individual copies + of this License in the various documents with a single copy that + is included in the collection, provided that you follow the + rules of this License for verbatim copying of each of the + documents in all other respects. + </para> + + <para> + You may extract a single document from such a collection, and + dispbibute it individually under this License, provided you + insert a copy of this License into the extracted document, and + follow this License in all other respects regarding verbatim + copying of that document. + </para> + </sect1> + + <sect1 id="fdl-section7"> + <title>7. AGGREGATION WITH INDEPENDENT WORKS</title> + <para> + A compilation of the <link + linkend="fdl-document">Document</link> or its derivatives with + other separate and independent documents or works, in or on a + volume of a storage or distribution medium, does not as a whole + count as a <link linkend="fdl-modified">Modified Version</link> + of the Document, provided no compilation copyright is claimed + for the compilation. Such a compilation is called an + <quote>aggregate</quote>, and this License does not apply to the + other self-contained works thus compiled with the Document , on + account of their being thus compiled, if they are not themselves + derivative works of the Document. If the <link + linkend="fdl-cover-texts">Cover Text</link> requirement of <link + linkend="fdl-section3">section 3</link> is applicable to these + copies of the Document, then if the Document is less than one + quarter of the entire aggregate, the Document's Cover Texts may + be placed on covers that surround only the Document within the + aggregate. Otherwise they must appear on covers around the whole + aggregate. + </para> + </sect1> + + <sect1 id="fdl-section8"> + <title>8. TRANSLATION</title> + <para> + Translation is considered a kind of modification, so you may + distribute translations of the <link + linkend="fdl-document">Document</link> under the terms of <link + linkend="fdl-section4">section 4</link>. Replacing <link + linkend="fdl-invariant"> Invariant Sections</link> with + translations requires special permission from their copyright + holders, but you may include translations of some or all + Invariant Sections in addition to the original versions of these + Invariant Sections. You may include a translation of this + License provided that you also include the original English + version of this License. In case of a disagreement between the + translation and the original English version of this License, + the original English version will prevail. + </para> + </sect1> + + <sect1 id="fdl-section9"> + <title>9. TERMINATION</title> + <para> + You may not copy, modify, sublicense, or distribute the <link + linkend="fdl-document">Document</link> except as expressly + provided for under this License. Any other attempt to copy, + modify, sublicense or distribute the Document is void, and will + automatically terminate your rights under this License. However, + parties who have received copies, or rights, from you under this + License will not have their licenses terminated so long as such + parties remain in full compliance. + </para> + </sect1> + + <sect1 id="fdl-section10"> + <title>10. FUTURE REVISIONS OF THIS LICENSE</title> + <para> + The <ulink type="http" + url="http://www.gnu.org/fsf/fsf.html">Free Software + Foundation</ulink> may publish new, revised versions of the GNU + Free Documentation License from time to time. Such new versions + will be similar in spirit to the present version, but may differ + in detail to address new problems or concerns. See <ulink + type="http" + url="http://www.gnu.org/copyleft">http://www.gnu.org/copyleft/</ulink>. + </para> + + <para> + Each version of the License is given a distinguishing version + number. If the <link linkend="fdl-document">Document</link> + specifies that a particular numbered version of this License + <quote>or any later version</quote> applies to it, you have the + option of following the terms and conditions either of that + specified version or of any later version that has been + published (not as a draft) by the Free Software Foundation. If + the Document does not specify a version number of this License, + you may choose any version ever published (not as a draft) by + the Free Software Foundation. + </para> + </sect1> + + <sect1 id="fdl-using"> + <title>Addendum</title> + <para> + To use this License in a document you have written, include a copy of + the License in the document and put the following copyright and + license notices just after the title page: + </para> + + <blockquote> + <para> + Copyright © YEAR YOUR NAME. + </para> + <para> + Permission is granted to copy, distribute and/or modify this + document under the terms of the GNU Free Documentation + License, Version 1.1 or any later version published by the + Free Software Foundation; with the <link + linkend="fdl-invariant">Invariant Sections</link> being LIST + THEIR TITLES, with the <link + linkend="fdl-cover-texts">Front-Cover Texts</link> being LIST, + and with the <link linkend="fdl-cover-texts">Back-Cover + Texts</link> being LIST. A copy of the license is included in + the section entitled <quote>GNU Free Documentation + License</quote>. + </para> + </blockquote> + + <para> + If you have no <link linkend="fdl-invariant">Invariant + Sections</link>, write <quote>with no Invariant Sections</quote> + instead of saying which ones are invariant. If you have no + <link linkend="fdl-cover-texts">Front-Cover Texts</link>, write + <quote>no Front-Cover Texts</quote> instead of + <quote>Front-Cover Texts being LIST</quote>; likewise for <link + linkend="fdl-cover-texts">Back-Cover Texts</link>. + </para> + + <para> + If your document contains nontrivial examples of program code, + we recommend releasing these examples in parallel under your + choice of free software license, such as the <ulink type="http" + url="http://www.gnu.org/copyleft/gpl.html"> GNU General Public + License</ulink>, to permit their use in free software. + </para> + </sect1> +</appendix> + + + + + + diff --git a/linux/Documentation/DocBook/v4l/fieldseq_bt.gif b/linux/Documentation/DocBook/v4l/fieldseq_bt.gif Binary files differnew file mode 100644 index 000000000..60e8569a7 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/fieldseq_bt.gif diff --git a/linux/Documentation/DocBook/v4l/fieldseq_bt.pdf b/linux/Documentation/DocBook/v4l/fieldseq_bt.pdf Binary files differnew file mode 100644 index 000000000..26598b23f --- /dev/null +++ b/linux/Documentation/DocBook/v4l/fieldseq_bt.pdf diff --git a/linux/Documentation/DocBook/v4l/fieldseq_tb.gif b/linux/Documentation/DocBook/v4l/fieldseq_tb.gif Binary files differnew file mode 100644 index 000000000..718492f1c --- /dev/null +++ b/linux/Documentation/DocBook/v4l/fieldseq_tb.gif diff --git a/linux/Documentation/DocBook/v4l/fieldseq_tb.pdf b/linux/Documentation/DocBook/v4l/fieldseq_tb.pdf Binary files differnew file mode 100644 index 000000000..4965b22dd --- /dev/null +++ b/linux/Documentation/DocBook/v4l/fieldseq_tb.pdf diff --git a/linux/Documentation/DocBook/v4l/func-close.xml b/linux/Documentation/DocBook/v4l/func-close.xml new file mode 100644 index 000000000..dfb41cbbb --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-close.xml @@ -0,0 +1,70 @@ +<refentry id="func-close"> + <refmeta> + <refentrytitle>V4L2 close()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-close</refname> + <refpurpose>Close a V4L2 device</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <unistd.h></funcsynopsisinfo> + <funcprototype> + <funcdef>int <function>close</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Closes the device. Any I/O in progress is terminated and +resources associated with the file descriptor are freed. However data +format parameters, current input or output, control values or other +properties remain unchanged.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>The function returns <returnvalue>0</returnvalue> on +success, <returnvalue>-1</returnvalue> on failure and the +<varname>errno</varname> is set appropriately. Possible error +codes:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is not a valid open file +descriptor.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-ioctl.xml b/linux/Documentation/DocBook/v4l/func-ioctl.xml new file mode 100644 index 000000000..00f9690e1 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-ioctl.xml @@ -0,0 +1,146 @@ +<refentry id="func-ioctl"> + <refmeta> + <refentrytitle>V4L2 ioctl()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-ioctl</refname> + <refpurpose>Program a V4L2 device</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <sys/ioctl.h></funcsynopsisinfo> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>void *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>V4L2 ioctl request code as defined in the <link +linkend="videodev">videodev.h</link> header file, for example +VIDIOC_QUERYCAP.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para>Pointer to a function parameter, usually a structure.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>The <function>ioctl()</function> function is used to program +V4L2 devices. The argument <parameter>fd</parameter> must be an open +file descriptor. An ioctl <parameter>request</parameter> has encoded +in it whether the argument is an input, output or read/write +parameter, and the size of the argument <parameter>argp</parameter> in +bytes. Macros and defines specifying V4L2 ioctl requests are located +in the <link linkend="videodev">videodev.h</link> header file. +Applications should use their own copy, not include the version in the +kernel sources on the system they compile on. All V4L2 ioctl requests, +their respective function and parameters are specified in <xref + linkend="user-func" />.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success the <function>ioctl()</function> function returns +<returnvalue>0</returnvalue> and does not reset the +<varname>errno</varname> variable. On failure +<returnvalue>-1</returnvalue> is returned, when the ioctl takes an +output or read/write parameter it remains unmodified, and the +<varname>errno</varname> variable is set appropriately. See below for +possible error codes. Generic errors like <errorcode>EBADF</errorcode> +or <errorcode>EFAULT</errorcode> are not listed in the sections +discussing individual ioctl requests.</para> + <para>Note ioctls may return undefined error codes. Since errors +may have side effects such as a driver reset applications should +abort on unexpected errors.</para> + + <variablelist> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is not a valid open file +descriptor.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The property cannot be changed right now. Typically +this error code is returned when I/O is in progress or the driver +supports multiple opens and another process locked the property.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EFAULT</errorcode></term> + <listitem> + <para><parameter>argp</parameter> references an inaccessible +memory area.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENOTTY</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is not associated with a +character special device.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <parameter>request</parameter> or the data pointed +to by <parameter>argp</parameter> is not valid. This is a very common +error code, see the individual ioctl requests listed in <xref + linkend="user-func" /> for actual causes.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENOMEM</errorcode></term> + <listitem> + <para>Not enough physical or virtual memory was available to +complete the request.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ERANGE</errorcode></term> + <listitem> + <para>The application attempted to set a control with the +&VIDIOC-S-CTRL; ioctl to a value which is out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-mmap.xml b/linux/Documentation/DocBook/v4l/func-mmap.xml new file mode 100644 index 000000000..2e2fc3933 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-mmap.xml @@ -0,0 +1,185 @@ +<refentry id="func-mmap"> + <refmeta> + <refentrytitle>V4L2 mmap()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-mmap</refname> + <refpurpose>Map device memory into application address space</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo> +#include <unistd.h> +#include <sys/mman.h></funcsynopsisinfo> + <funcprototype> + <funcdef>void *<function>mmap</function></funcdef> + <paramdef>void *<parameter>start</parameter></paramdef> + <paramdef>size_t <parameter>length</parameter></paramdef> + <paramdef>int <parameter>prot</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>off_t <parameter>offset</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + <variablelist> + <varlistentry> + <term><parameter>start</parameter></term> + <listitem> + <para>Map the buffer to this address in the +application's address space. When the <constant>MAP_FIXED</constant> +flag is specified, <parameter>start</parameter> must be a multiple of the +pagesize and mmap will fail when the specified address +cannot be used. Use of this option is discouraged; applications should +just specify a <constant>NULL</constant> pointer here.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>length</parameter></term> + <listitem> + <para>Length of the memory area to map. This must be the +same value as returned by the driver in the &v4l2-buffer; +<structfield>length</structfield> field.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>prot</parameter></term> + <listitem> + <para>The <parameter>prot</parameter> argument describes the +desired memory protection. Regardless of the device type and the +direction of data exchange it should be set to +<constant>PROT_READ</constant> | <constant>PROT_WRITE</constant>, +permitting read and write access to image buffers. Drivers should +support at least this combination of flags. Note the Linux +<filename>video-buf</filename> kernel module, which is used by the +bttv, saa7134, saa7146, cx88 and vivi driver supports only +<constant>PROT_READ</constant> | <constant>PROT_WRITE</constant>. When +the driver does not support the desired protection the +<function>mmap()</function> function fails.</para> + <para>Note device memory accesses (⪚ the memory on a +graphics card with video capturing hardware) may incur a performance +penalty compared to main memory accesses, or reads may be +significantly slower than writes or vice versa. Other I/O methods may +be more efficient in this case.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>flags</parameter></term> + <listitem> + <para>The <parameter>flags</parameter> parameter +specifies the type of the mapped object, mapping options and whether +modifications made to the mapped copy of the page are private to the +process or are to be shared with other references.</para> + <para><constant>MAP_FIXED</constant> requests that the +driver selects no other address than the one specified. If the +specified address cannot be used, <function>mmap()</function> will fail. If +<constant>MAP_FIXED</constant> is specified, +<parameter>start</parameter> must be a multiple of the pagesize. Use +of this option is discouraged.</para> + <para>One of the <constant>MAP_SHARED</constant> or +<constant>MAP_PRIVATE</constant> flags must be set. +<constant>MAP_SHARED</constant> allows applications to share the +mapped memory with other (⪚ child-) processes. Note the Linux +<filename>video-buf</filename> module which is used by the bttv, +saa7134, saa7146, cx88 and vivi driver supports only +<constant>MAP_SHARED</constant>. <constant>MAP_PRIVATE</constant> +requests copy-on-write semantics. V4L2 applications should not set the +<constant>MAP_PRIVATE</constant>, <constant>MAP_DENYWRITE</constant>, +<constant>MAP_EXECUTABLE</constant> or <constant>MAP_ANON</constant> +flag.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>offset</parameter></term> + <listitem> + <para>Offset of the buffer in device memory. This must be the +same value as returned by the driver in the &v4l2-buffer; +<structfield>m</structfield> union <structfield>offset</structfield> field.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>The <function>mmap()</function> function asks to map +<parameter>length</parameter> bytes starting at +<parameter>offset</parameter> in the memory of the device specified by +<parameter>fd</parameter> into the application address space, +preferably at address <parameter>start</parameter>. This latter +address is a hint only, and is usually specified as 0.</para> + + <para>Suitable length and offset parameters are queried with the +&VIDIOC-QUERYBUF; ioctl. Buffers must be allocated with the +&VIDIOC-REQBUFS; ioctl before they can be queried.</para> + + <para>To unmap buffers the &func-munmap; function is used.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success <function>mmap()</function> returns a pointer to +the mapped buffer. On error <constant>MAP_FAILED</constant> (-1) is +returned, and the <varname>errno</varname> variable is set +appropriately. Possible error codes are:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is not a valid file +descriptor.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EACCES</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is +not open for reading and writing.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <parameter>start</parameter> or +<parameter>length</parameter> or <parameter>offset</parameter> are not +suitable. (E. g. they are too large, or not aligned on a +<constant>PAGESIZE</constant> boundary.)</para> + <para>The <parameter>flags</parameter> or +<parameter>prot</parameter> value is not supported.</para> + <para>No buffers have been allocated with the +&VIDIOC-REQBUFS; ioctl.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENOMEM</errorcode></term> + <listitem> + <para>Not enough physical or virtual memory was available to +complete the request.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-munmap.xml b/linux/Documentation/DocBook/v4l/func-munmap.xml new file mode 100644 index 000000000..502ed4932 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-munmap.xml @@ -0,0 +1,83 @@ +<refentry id="func-munmap"> + <refmeta> + <refentrytitle>V4L2 munmap()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-munmap</refname> + <refpurpose>Unmap device memory</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo> +#include <unistd.h> +#include <sys/mman.h></funcsynopsisinfo> + <funcprototype> + <funcdef>int <function>munmap</function></funcdef> + <paramdef>void *<parameter>start</parameter></paramdef> + <paramdef>size_t <parameter>length</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + <refsect1> + <title>Arguments</title> + <variablelist> + <varlistentry> + <term><parameter>start</parameter></term> + <listitem> + <para>Address of the mapped buffer as returned by the +&func-mmap; function.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>length</parameter></term> + <listitem> + <para>Length of the mapped buffer. This must be the same +value as given to <function>mmap()</function> and returned by the +driver in the &v4l2-buffer; <structfield>length</structfield> +field.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Unmaps a previously with the &func-mmap; function mapped +buffer and frees it, if possible. <!-- ? This function (not freeing) +has no impact on I/O in progress, specifically it does not imply +&VIDIOC-STREAMOFF; to terminate I/O. Unmapped buffers can still be +enqueued, dequeued or queried, they are just not accessible by the +application.--></para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success <function>munmap()</function> returns 0, on +failure -1 and the <varname>errno</varname> variable is set +appropriately:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <parameter>start</parameter> or +<parameter>length</parameter> is incorrect, or no buffers have been +mapped yet.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-open.xml b/linux/Documentation/DocBook/v4l/func-open.xml new file mode 100644 index 000000000..7595d07a8 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-open.xml @@ -0,0 +1,121 @@ +<refentry id="func-open"> + <refmeta> + <refentrytitle>V4L2 open()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-open</refname> + <refpurpose>Open a V4L2 device</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <fcntl.h></funcsynopsisinfo> + <funcprototype> + <funcdef>int <function>open</function></funcdef> + <paramdef>const char *<parameter>device_name</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>device_name</parameter></term> + <listitem> + <para>Device to be opened.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>flags</parameter></term> + <listitem> + <para>Open flags. Access mode must be +<constant>O_RDWR</constant>. This is just a technicality, input devices +still support only reading and output devices only writing.</para> + <para>When the <constant>O_NONBLOCK</constant> flag is +given, the read() function and the &VIDIOC-DQBUF; ioctl will return +the &EAGAIN; when no data is available or no buffer is in the driver +outgoing queue, otherwise these functions block until data becomes +available. All V4L2 drivers exchanging data with applications must +support the <constant>O_NONBLOCK</constant> flag.</para> + <para>Other flags have no effect.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + <refsect1> + <title>Description</title> + + <para>To open a V4L2 device applications call +<function>open()</function> with the desired device name. This +function has no side effects; all data format parameters, current +input or output, control values or other properties remain unchanged. +At the first <function>open()</function> call after loading the driver +they will be reset to default values, drivers are never in an +undefined state.</para> + </refsect1> + <refsect1> + <title>Return Value</title> + + <para>On success <function>open</function> returns the new file +descriptor. On error -1 is returned, and the <varname>errno</varname> +variable is set appropriately. Possible error codes are:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EACCES</errorcode></term> + <listitem> + <para>The caller has no permission to access the +device.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The driver does not support multiple opens and the +device is already in use.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENXIO</errorcode></term> + <listitem> + <para>No device corresponding to this device special file +exists.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENOMEM</errorcode></term> + <listitem> + <para>Not enough kernel memory was available to complete the +request.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EMFILE</errorcode></term> + <listitem> + <para>The process already has the maximum number of +files open.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENFILE</errorcode></term> + <listitem> + <para>The limit on the total number of files open on the +system has been reached.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-poll.xml b/linux/Documentation/DocBook/v4l/func-poll.xml new file mode 100644 index 000000000..ec3c718f5 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-poll.xml @@ -0,0 +1,127 @@ +<refentry id="func-poll"> + <refmeta> + <refentrytitle>V4L2 poll()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-poll</refname> + <refpurpose>Wait for some event on a file descriptor</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <sys/poll.h></funcsynopsisinfo> + <funcprototype> + <funcdef>int <function>poll</function></funcdef> + <paramdef>struct pollfd *<parameter>ufds</parameter></paramdef> + <paramdef>unsigned int <parameter>nfds</parameter></paramdef> + <paramdef>int <parameter>timeout</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>With the <function>poll()</function> function applications +can suspend execution until the driver has captured data or is ready +to accept data for output.</para> + + <para>When streaming I/O has been negotiated this function waits +until a buffer has been filled or displayed and can be dequeued with +the &VIDIOC-DQBUF; ioctl. When buffers are already in the outgoing +queue of the driver the function returns immediately.</para> + + <para>On success <function>poll()</function> returns the number of +file descriptors that have been selected (that is, file descriptors +for which the <structfield>revents</structfield> field of the +respective <structname>pollfd</structname> structure is non-zero). +Capture devices set the <constant>POLLIN</constant> and +<constant>POLLRDNORM</constant> flags in the +<structfield>revents</structfield> field, output devices the +<constant>POLLOUT</constant> and <constant>POLLWRNORM</constant> +flags. When the function timed out it returns a value of zero, on +failure it returns <returnvalue>-1</returnvalue> and the +<varname>errno</varname> variable is set appropriately. When the +application did not call &VIDIOC-QBUF; or &VIDIOC-STREAMON; yet the +<function>poll()</function> function succeeds, but sets the +<constant>POLLERR</constant> flag in the +<structfield>revents</structfield> field.</para> + + <para>When use of the <function>read()</function> function has +been negotiated and the driver does not capture yet, the +<function>poll</function> function starts capturing. When that fails +it returns a <constant>POLLERR</constant> as above. Otherwise it waits +until data has been captured and can be read. When the driver captures +continuously (as opposed to, for example, still images) the function +may return immediately.</para> + + <para>When use of the <function>write()</function> function has +been negotiated the <function>poll</function> function just waits +until the driver is ready for a non-blocking +<function>write()</function> call.</para> + + <para>All drivers implementing the <function>read()</function> or +<function>write()</function> function or streaming I/O must also +support the <function>poll()</function> function.</para> + + <para>For more details see the +<function>poll()</function> manual page.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, <function>poll()</function> returns the number +structures which have non-zero <structfield>revents</structfield> +fields, or zero if the call timed out. On error +<returnvalue>-1</returnvalue> is returned, and the +<varname>errno</varname> variable is set appropriately:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para>One or more of the <parameter>ufds</parameter> members +specify an invalid file descriptor.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The driver does not support multiple read or write +streams and the device is already in use.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EFAULT</errorcode></term> + <listitem> + <para><parameter>ufds</parameter> references an inaccessible +memory area.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINTR</errorcode></term> + <listitem> + <para>The call was interrupted by a signal.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <parameter>nfds</parameter> argument is greater +than <constant>OPEN_MAX</constant>.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-read.xml b/linux/Documentation/DocBook/v4l/func-read.xml new file mode 100644 index 000000000..a5089bf88 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-read.xml @@ -0,0 +1,189 @@ +<refentry id="func-read"> + <refmeta> + <refentrytitle>V4L2 read()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-read</refname> + <refpurpose>Read from a V4L2 device</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <unistd.h></funcsynopsisinfo> + <funcprototype> + <funcdef>ssize_t <function>read</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>void *<parameter>buf</parameter></paramdef> + <paramdef>size_t <parameter>count</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>buf</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>count</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para><function>read()</function> attempts to read up to +<parameter>count</parameter> bytes from file descriptor +<parameter>fd</parameter> into the buffer starting at +<parameter>buf</parameter>. The layout of the data in the buffer is +discussed in the respective device interface section, see ##. If <parameter>count</parameter> is zero, +<function>read()</function> returns zero and has no other results. If +<parameter>count</parameter> is greater than +<constant>SSIZE_MAX</constant>, the result is unspecified. Regardless +of the <parameter>count</parameter> value each +<function>read()</function> call will provide at most one frame (two +fields) worth of data.</para> + + <para>By default <function>read()</function> blocks until data +becomes available. When the <constant>O_NONBLOCK</constant> flag was +given to the &func-open; function it +returns immediately with an &EAGAIN; when no data is available. The +&func-select; or &func-poll; functions +can always be used to suspend execution until data becomes available. All +drivers supporting the <function>read()</function> function must also +support <function>select()</function> and +<function>poll()</function>.</para> + + <para>Drivers can implement read functionality in different +ways, using a single or multiple buffers and discarding the oldest or +newest frames once the internal buffers are filled.</para> + + <para><function>read()</function> never returns a "snapshot" of a +buffer being filled. Using a single buffer the driver will stop +capturing when the application starts reading the buffer until the +read is finished. Thus only the period of the vertical blanking +interval is available for reading, or the capture rate must fall below +the nominal frame rate of the video standard.</para> + +<para>The behavior of +<function>read()</function> when called during the active picture +period or the vertical blanking separating the top and bottom field +depends on the discarding policy. A driver discarding the oldest +frames keeps capturing into an internal buffer, continuously +overwriting the previously, not read frame, and returns the frame +being received at the time of the <function>read()</function> call as +soon as it is complete.</para> + + <para>A driver discarding the newest frames stops capturing until +the next <function>read()</function> call. The frame being received at +<function>read()</function> time is discarded, returning the following +frame instead. Again this implies a reduction of the capture rate to +one half or less of the nominal frame rate. An example of this model +is the video read mode of the bttv driver, initiating a DMA to user +memory when <function>read()</function> is called and returning when +the DMA finished.</para> + + <para>In the multiple buffer model drivers maintain a ring of +internal buffers, automatically advancing to the next free buffer. +This allows continuous capturing when the application can empty the +buffers fast enough. Again, the behavior when the driver runs out of +free buffers depends on the discarding policy.</para> + + <para>Applications can get and set the number of buffers used +internally by the driver with the &VIDIOC-G-PARM; and &VIDIOC-S-PARM; +ioctls. They are optional, however. The discarding policy is not +reported and cannot be changed. For minimum requirements see <xref + linkend="devices" />.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, the number of bytes read is returned. It is not +an error if this number is smaller than the number of bytes requested, +or the amount of data required for one frame. This may happen for +example because <function>read()</function> was interrupted by a +signal. On error, -1 is returned, and the <varname>errno</varname> +variable is set appropriately. In this case the next read will start +at the beginning of a new frame. Possible error codes are:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EAGAIN</errorcode></term> + <listitem> + <para>Non-blocking I/O has been selected using +O_NONBLOCK and no data was immediately available for reading.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is not a valid file +descriptor or is not open for reading, or the process already has the +maximum number of files open.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The driver does not support multiple read streams and the +device is already in use.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EFAULT</errorcode></term> + <listitem> + <para><parameter>buf</parameter> references an inaccessible +memory area.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINTR</errorcode></term> + <listitem> + <para>The call was interrupted by a signal before any +data was read.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EIO</errorcode></term> + <listitem> + <para>I/O error. This indicates some hardware problem or a +failure to communicate with a remote device (USB camera etc.).</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <function>read()</function> function is not +supported by this driver, not on this device, or generally not on this +type of device.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-select.xml b/linux/Documentation/DocBook/v4l/func-select.xml new file mode 100644 index 000000000..b67136231 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-select.xml @@ -0,0 +1,138 @@ +<refentry id="func-select"> + <refmeta> + <refentrytitle>V4L2 select()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-select</refname> + <refpurpose>Synchronous I/O multiplexing</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo> +#include <sys/time.h> +#include <sys/types.h> +#include <unistd.h></funcsynopsisinfo> + <funcprototype> + <funcdef>int <function>select</function></funcdef> + <paramdef>int <parameter>nfds</parameter></paramdef> + <paramdef>fd_set *<parameter>readfds</parameter></paramdef> + <paramdef>fd_set *<parameter>writefds</parameter></paramdef> + <paramdef>fd_set *<parameter>exceptfds</parameter></paramdef> + <paramdef>struct timeval *<parameter>timeout</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>With the <function>select()</function> function applications +can suspend execution until the driver has captured data or is ready +to accept data for output.</para> + + <para>When streaming I/O has been negotiated this function waits +until a buffer has been filled or displayed and can be dequeued with +the &VIDIOC-DQBUF; ioctl. When buffers are already in the outgoing +queue of the driver the function returns immediately.</para> + + <para>On success <function>select()</function> returns the total +number of bits set in the <structname>fd_set</structname>s. When the +function timed out it returns a value of zero. On failure it returns +<returnvalue>-1</returnvalue> and the <varname>errno</varname> +variable is set appropriately. When the application did not call +&VIDIOC-QBUF; or &VIDIOC-STREAMON; yet the +<function>select()</function> function succeeds, setting the bit of +the file descriptor in <parameter>readfds</parameter> or +<parameter>writefds</parameter>, but subsequent &VIDIOC-DQBUF; calls +will fail.<footnote><para>The Linux kernel implements +<function>select()</function> like the &func-poll; function, but +<function>select()</function> cannot return a +<constant>POLLERR</constant>.</para> + </footnote></para> + + <para>When use of the <function>read()</function> function has +been negotiated and the driver does not capture yet, the +<function>select()</function> function starts capturing. When that +fails, <function>select()</function> returns successful and a +subsequent <function>read()</function> call, which also attempts to +start capturing, will return an appropriate error code. When the +driver captures continuously (as opposed to, for example, still +images) and data is already available the +<function>select()</function> function returns immediately.</para> + + <para>When use of the <function>write()</function> function has +been negotiated the <function>select()</function> function just waits +until the driver is ready for a non-blocking +<function>write()</function> call.</para> + + <para>All drivers implementing the <function>read()</function> or +<function>write()</function> function or streaming I/O must also +support the <function>select()</function> function.</para> + + <para>For more details see the <function>select()</function> +manual page.</para> + + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, <function>select()</function> returns the number +of descriptors contained in the three returned descriptor sets, which +will be zero if the timeout expired. On error +<returnvalue>-1</returnvalue> is returned, and the +<varname>errno</varname> variable is set appropriately; the sets and +<parameter>timeout</parameter> are undefined. Possible error codes +are:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para>One or more of the file descriptor sets specified a +file descriptor that is not open.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The driver does not support multiple read or write +streams and the device is already in use.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EFAULT</errorcode></term> + <listitem> + <para>The <parameter>readfds</parameter>, +<parameter>writefds</parameter>, <parameter>exceptfds</parameter> or +<parameter>timeout</parameter> pointer references an inaccessible memory +area.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINTR</errorcode></term> + <listitem> + <para>The call was interrupted by a signal.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <parameter>nfds</parameter> argument is less than +zero or greater than <constant>FD_SETSIZE</constant>.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/func-write.xml b/linux/Documentation/DocBook/v4l/func-write.xml new file mode 100644 index 000000000..2c09c0937 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/func-write.xml @@ -0,0 +1,136 @@ +<refentry id="func-write"> + <refmeta> + <refentrytitle>V4L2 write()</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>v4l2-write</refname> + <refpurpose>Write to a V4L2 device</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <unistd.h></funcsynopsisinfo> + <funcprototype> + <funcdef>ssize_t <function>write</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>void *<parameter>buf</parameter></paramdef> + <paramdef>size_t <parameter>count</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>buf</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>count</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para><function>write()</function> writes up to +<parameter>count</parameter> bytes to the device referenced by the +file descriptor <parameter>fd</parameter> from the buffer starting at +<parameter>buf</parameter>. When the hardware outputs are not active +yet, this function enables them. When <parameter>count</parameter> is +zero, <function>write()</function> returns +<returnvalue>0</returnvalue> without any other effect.</para> + + <para>When the application does not provide more data in time, the +previous video frame, raw VBI image, sliced VPS or WSS data is +displayed again. Sliced Teletext or Closed Caption data is not +repeated, the driver inserts a blank line instead.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>On success, the number of bytes written are returned. Zero +indicates nothing was written. On error, <returnvalue>-1</returnvalue> +is returned, and the <varname>errno</varname> variable is set +appropriately. In this case the next write will start at the beginning +of a new frame. Possible error codes are:</para> + + <variablelist> + <varlistentry> + <term><errorcode>EAGAIN</errorcode></term> + <listitem> + <para>Non-blocking I/O has been selected using the <link +linkend="func-open"><constant>O_NONBLOCK</constant></link> flag and no +buffer space was available to write the data immediately.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBADF</errorcode></term> + <listitem> + <para><parameter>fd</parameter> is not a valid file +descriptor or is not open for writing.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The driver does not support multiple write streams and the +device is already in use.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EFAULT</errorcode></term> + <listitem> + <para><parameter>buf</parameter> references an inaccessible +memory area.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINTR</errorcode></term> + <listitem> + <para>The call was interrupted by a signal before any +data was written.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EIO</errorcode></term> + <listitem> + <para>I/O error. This indicates some hardware problem.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <function>write()</function> function is not +supported by this driver, not on this device, or generally not on this +type of device.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/io.xml b/linux/Documentation/DocBook/v4l/io.xml new file mode 100644 index 000000000..f92f24323 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/io.xml @@ -0,0 +1,1073 @@ + <title>Input/Output</title> + + <para>The V4L2 API defines several different methods to read from or +write to a device. All drivers exchanging data with applications must +support at least one of them.</para> + + <para>The classic I/O method using the <function>read()</function> +and <function>write()</function> function is automatically selected +after opening a V4L2 device. When the driver does not support this +method attempts to read or write will fail at any time.</para> + + <para>Other methods must be negotiated. To select the streaming I/O +method with memory mapped or user buffers applications call the +&VIDIOC-REQBUFS; ioctl. The asynchronous I/O method is not defined +yet.</para> + + <para>Video overlay can be considered another I/O method, although +the application does not directly receive the image data. It is +selected by initiating video overlay with the &VIDIOC-S-FMT; ioctl. +For more information see <xref linkend="overlay" />.</para> + + <para>Generally exactly one I/O method, including overlay, is +associated with each file descriptor. The only exceptions are +applications not exchanging data with a driver ("panel applications", +see <xref linkend="open" />) and drivers permitting simultaneous video capturing +and overlay using the same file descriptor, for compatibility with V4L +and earlier versions of V4L2.</para> + + <para><constant>VIDIOC_S_FMT</constant> and +<constant>VIDIOC_REQBUFS</constant> would permit this to some degree, +but for simplicity drivers need not support switching the I/O method +(after first switching away from read/write) other than by closing +and reopening the device.</para> + + <para>The following sections describe the various I/O methods in +more detail.</para> + + <section id="rw"> + <title>Read/Write</title> + + <para>Input and output devices support the +<function>read()</function> and <function>write()</function> function, +respectively, when the <constant>V4L2_CAP_READWRITE</constant> flag in +the <structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl is set.</para> + + <para>Drivers may need the CPU to copy the data, but they may also +support DMA to or from user memory, so this I/O method is not +necessarily less efficient than other methods merely exchanging buffer +pointers. It is considered inferior though because no meta-information +like frame counters or timestamps are passed. This information is +necessary to recognize frame dropping and to synchronize with other +data streams. However this is also the simplest I/O method, requiring +little or no setup to exchange data. It permits command line stunts +like this (the <application>vidctrl</application> tool is +fictitious):</para> + + <informalexample> + <screen> +> vidctrl /dev/video --input=0 --format=YUYV --size=352x288 +> dd if=/dev/video of=myimage.422 bs=202752 count=1 +</screen> + </informalexample> + + <para>To read from the device applications use the +&func-read; function, to write the &func-write; function. +Drivers must implement one I/O method if they +exchange data with applications, but it need not be this.<footnote> + <para>It would be desirable if applications could depend on +drivers supporting all I/O interfaces, but as much as the complex +memory mapping I/O can be inadequate for some devices we have no +reason to require this interface, which is most useful for simple +applications capturing still images.</para> + </footnote> When reading or writing is supported, the driver +must also support the &func-select; and &func-poll; +function.<footnote> + <para>At the driver level <function>select()</function> and +<function>poll()</function> are the same, and +<function>select()</function> is too important to be optional.</para> + </footnote></para> + </section> + + <section id="mmap"> + <title>Streaming I/O (Memory Mapping)</title> + + <para>Input and output devices support this I/O method when the +<constant>V4L2_CAP_STREAMING</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl is set. There are two +streaming methods, to determine if the memory mapping flavor is +supported applications must call the &VIDIOC-REQBUFS; ioctl.</para> + + <para>Streaming is an I/O method where only pointers to buffers +are exchanged between application and driver, the data itself is not +copied. Memory mapping is primarily intended to map buffers in device +memory into the application's address space. Device memory can be for +example the video memory on a graphics card with a video capture +add-on. However, being the most efficient I/O method available for a +long time, many other drivers support streaming as well, allocating +buffers in DMA-able main memory.</para> + + <para>A driver can support many sets of buffers. Each set is +identified by a unique buffer type value. The sets are independent and +each set can hold a different type of data. To access different sets +at the same time different file descriptors must be used.<footnote> + <para>One could use one file descriptor and set the buffer +type field accordingly when calling &VIDIOC-QBUF; etc., but it makes +the <function>select()</function> function ambiguous. We also like the +clean approach of one file descriptor per logical stream. Video +overlay for example is also a logical stream, although the CPU is not +needed for continuous operation.</para> + </footnote></para> + + <para>To allocate device buffers applications call the +&VIDIOC-REQBUFS; ioctl with the desired number of buffers and buffer +type, for example <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>. +This ioctl can also be used to change the number of buffers or to free +the allocated memory, provided none of the buffers are still +mapped.</para> + + <para>Before applications can access the buffers they must map +them into their address space with the &func-mmap; function. The +location of the buffers in device memory can be determined with the +&VIDIOC-QUERYBUF; ioctl. The <structfield>m.offset</structfield> and +<structfield>length</structfield> returned in a &v4l2-buffer; are +passed as sixth and second parameter to the +<function>mmap()</function> function. The offset and length values +must not be modified. Remember the buffers are allocated in physical +memory, as opposed to virtual memory which can be swapped out to disk. +Applications should free the buffers as soon as possible with the +&func-munmap; function.</para> + + <example> + <title>Mapping buffers</title> + + <programlisting> +&v4l2-requestbuffers; reqbuf; +struct { + void *start; + size_t length; +} *buffers; +unsigned int i; + +memset (&reqbuf, 0, sizeof (reqbuf)); +reqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; +reqbuf.memory = V4L2_MEMORY_MMAP; +reqbuf.count = 20; + +if (-1 == ioctl (fd, &VIDIOC-REQBUFS;, &reqbuf)) { + if (errno == EINVAL) + printf ("Video capturing or mmap-streaming is not supported\n"); + else + perror ("VIDIOC_REQBUFS"); + + exit (EXIT_FAILURE); +} + +/* We want at least five buffers. */ + +if (reqbuf.count < 5) { + /* You may need to free the buffers here. */ + printf ("Not enough buffer memory\n"); + exit (EXIT_FAILURE); +} + +buffers = calloc (reqbuf.count, sizeof (*buffers)); +assert (buffers != NULL); + +for (i = 0; i < reqbuf.count; i++) { + &v4l2-buffer; buffer; + + memset (&buffer, 0, sizeof (buffer)); + buffer.type = reqbuf.type; + buffer.memory = V4L2_MEMORY_MMAP; + buffer.index = i; + + if (-1 == ioctl (fd, &VIDIOC-QUERYBUF;, &buffer)) { + perror ("VIDIOC_QUERYBUF"); + exit (EXIT_FAILURE); + } + + buffers[i].length = buffer.length; /* remember for munmap() */ + + buffers[i].start = mmap (NULL, buffer.length, + PROT_READ | PROT_WRITE, /* recommended */ + MAP_SHARED, /* recommended */ + fd, buffer.m.offset); + + if (MAP_FAILED == buffers[i].start) { + /* If you do not exit here you should unmap() and free() + the buffers mapped so far. */ + perror ("mmap"); + exit (EXIT_FAILURE); + } +} + +/* Cleanup. */ + +for (i = 0; i < reqbuf.count; i++) + munmap (buffers[i].start, buffers[i].length); + </programlisting> + </example> + + <para>Conceptually streaming drivers maintain two buffer queues, an incoming +and an outgoing queue. They separate the synchronous capture or output +operation locked to a video clock from the application which is +subject to random disk or network delays and preemption by +other processes, thereby reducing the probability of data loss. +The queues are organized as FIFOs, buffers will be +output in the order enqueued in the incoming FIFO, and were +captured in the order dequeued from the outgoing FIFO.</para> + + <para>The driver may require a minimum number of buffers enqueued +at all times to function, apart of this no limit exists on the number +of buffers applications can enqueue in advance, or dequeue and +process. They can also enqueue in a different order than buffers have +been dequeued, and the driver can <emphasis>fill</emphasis> enqueued +<emphasis>empty</emphasis> buffers in any order. <footnote> + <para>Random enqueue order permits applications processing +images out of order (such as video codecs) to return buffers earlier, +reducing the probability of data loss. Random fill order allows +drivers to reuse buffers on a LIFO-basis, taking advantage of caches +holding scatter-gather lists and the like.</para> + </footnote> The index number of a buffer (&v4l2-buffer; +<structfield>index</structfield>) plays no role here, it only +identifies the buffer.</para> + + <para>Initially all mapped buffers are in dequeued state, +inaccessible by the driver. For capturing applications it is customary +to first enqueue all mapped buffers, then to start capturing and enter +the read loop. Here the application waits until a filled buffer can be +dequeued, and re-enqueues the buffer when the data is no longer +needed. Output applications fill and enqueue buffers, when enough +buffers are stacked up the output is started with +<constant>VIDIOC_STREAMON</constant>. In the write loop, when +the application runs out of free buffers, it must wait until an empty +buffer can be dequeued and reused.</para> + + <para>To enqueue and dequeue a buffer applications use the +&VIDIOC-QBUF; and &VIDIOC-DQBUF; ioctl. The status of a buffer being +mapped, enqueued, full or empty can be determined at any time using the +&VIDIOC-QUERYBUF; ioctl. Two methods exist to suspend execution of the +application until one or more buffers can be dequeued. By default +<constant>VIDIOC_DQBUF</constant> blocks when no buffer is in the +outgoing queue. When the <constant>O_NONBLOCK</constant> flag was +given to the &func-open; function, <constant>VIDIOC_DQBUF</constant> +returns immediately with an &EAGAIN; when no buffer is available. The +&func-select; or &func-poll; function are always available.</para> + + <para>To start and stop capturing or output applications call the +&VIDIOC-STREAMON; and &VIDIOC-STREAMOFF; ioctl. Note +<constant>VIDIOC_STREAMOFF</constant> removes all buffers from both +queues as a side effect. Since there is no notion of doing anything +"now" on a multitasking system, if an application needs to synchronize +with another event it should examine the &v4l2-buffer; +<structfield>timestamp</structfield> of captured buffers, or set the +field before enqueuing buffers for output.</para> + + <para>Drivers implementing memory mapping I/O must +support the <constant>VIDIOC_REQBUFS</constant>, +<constant>VIDIOC_QUERYBUF</constant>, +<constant>VIDIOC_QBUF</constant>, <constant>VIDIOC_DQBUF</constant>, +<constant>VIDIOC_STREAMON</constant> and +<constant>VIDIOC_STREAMOFF</constant> ioctl, the +<function>mmap()</function>, <function>munmap()</function>, +<function>select()</function> and <function>poll()</function> +function.<footnote> + <para>At the driver level <function>select()</function> and +<function>poll()</function> are the same, and +<function>select()</function> is too important to be optional. The +rest should be evident.</para> + </footnote></para> + + <para>[capture example]</para> + + </section> + + <section id="userp"> + <title>Streaming I/O (User Pointers)</title> + + <para>Input and output devices support this I/O method when the +<constant>V4L2_CAP_STREAMING</constant> flag in the +<structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl is set. If the particular user +pointer method (not only memory mapping) is supported must be +determined by calling the &VIDIOC-REQBUFS; ioctl.</para> + + <para>This I/O method combines advantages of the read/write and +memory mapping methods. Buffers are allocated by the application +itself, and can reside for example in virtual or shared memory. Only +pointers to data are exchanged, these pointers and meta-information +are passed in &v4l2-buffer;. The driver must be switched +into user pointer I/O mode by calling the &VIDIOC-REQBUFS; with the +desired buffer type. No buffers are allocated beforehands, +consequently they are not indexed and cannot be queried like mapped +buffers with the <constant>VIDIOC_QUERYBUF</constant> ioctl.</para> + + <example> + <title>Initiating streaming I/O with user pointers</title> + + <programlisting> +&v4l2-requestbuffers; reqbuf; + +memset (&reqbuf, 0, sizeof (reqbuf)); +reqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; +reqbuf.memory = V4L2_MEMORY_USERPTR; + +if (ioctl (fd, &VIDIOC-REQBUFS;, &reqbuf) == -1) { + if (errno == EINVAL) + printf ("Video capturing or user pointer streaming is not supported\n"); + else + perror ("VIDIOC_REQBUFS"); + + exit (EXIT_FAILURE); +} + </programlisting> + </example> + + <para>Buffer addresses and sizes are passed on the fly with the +&VIDIOC-QBUF; ioctl. Although buffers are commonly cycled, +applications can pass different addresses and sizes at each +<constant>VIDIOC_QBUF</constant> call. If required by the hardware the +driver swaps memory pages within physical memory to create a +continuous area of memory. This happens transparently to the +application in the virtual memory subsystem of the kernel. When buffer +pages have been swapped out to disk they are brought back and finally +locked in physical memory for DMA.<footnote> + <para>We expect that frequently used buffers are typically not +swapped out. Anyway, the process of swapping, locking or generating +scatter-gather lists may be time consuming. The delay can be masked by +the depth of the incoming buffer queue, and perhaps by maintaining +caches assuming a buffer will be soon enqueued again. On the other +hand, to optimize memory usage drivers can limit the number of buffers +locked in advance and recycle the most recently used buffers first. Of +course, the pages of empty buffers in the incoming queue need not be +saved to disk. Output buffers must be saved on the incoming and +outgoing queue because an application may share them with other +processes.</para> + </footnote></para> + + <para>Filled or displayed buffers are dequeued with the +&VIDIOC-DQBUF; ioctl. The driver can unlock the memory pages at any +time between the completion of the DMA and this ioctl. The memory is +also unlocked when &VIDIOC-STREAMOFF; is called, &VIDIOC-REQBUFS;, or +when the device is closed. Applications must take care not to free +buffers without dequeuing. For once, the buffers remain locked until +further, wasting physical memory. Second the driver will not be +notified when the memory is returned to the application's free list +and subsequently reused for other purposes, possibly completing the +requested DMA and overwriting valuable data.</para> + + <para>For capturing applications it is customary to enqueue a +number of empty buffers, to start capturing and enter the read loop. +Here the application waits until a filled buffer can be dequeued, and +re-enqueues the buffer when the data is no longer needed. Output +applications fill and enqueue buffers, when enough buffers are stacked +up output is started. In the write loop, when the application +runs out of free buffers it must wait until an empty buffer can be +dequeued and reused. Two methods exist to suspend execution of the +application until one or more buffers can be dequeued. By default +<constant>VIDIOC_DQBUF</constant> blocks when no buffer is in the +outgoing queue. When the <constant>O_NONBLOCK</constant> flag was +given to the &func-open; function, <constant>VIDIOC_DQBUF</constant> +returns immediately with an &EAGAIN; when no buffer is available. The +&func-select; or &func-poll; function are always available.</para> + + <para>To start and stop capturing or output applications call the +&VIDIOC-STREAMON; and &VIDIOC-STREAMOFF; ioctl. Note +<constant>VIDIOC_STREAMOFF</constant> removes all buffers from both +queues and unlocks all buffers as a side effect. Since there is no +notion of doing anything "now" on a multitasking system, if an +application needs to synchronize with another event it should examine +the &v4l2-buffer; <structfield>timestamp</structfield> of captured +buffers, or set the field before enqueuing buffers for output.</para> + + <para>Drivers implementing user pointer I/O must +support the <constant>VIDIOC_REQBUFS</constant>, +<constant>VIDIOC_QBUF</constant>, <constant>VIDIOC_DQBUF</constant>, +<constant>VIDIOC_STREAMON</constant> and +<constant>VIDIOC_STREAMOFF</constant> ioctl, the +<function>select()</function> and <function>poll()</function> function.<footnote> + <para>At the driver level <function>select()</function> and +<function>poll()</function> are the same, and +<function>select()</function> is too important to be optional. The +rest should be evident.</para> + </footnote></para> + </section> + + <section id="async"> + <title>Asynchronous I/O</title> + + <para>This method is not defined yet.</para> + </section> + + <section id="buffer"> + <title>Buffers</title> + + <para>A buffer contains data exchanged by application and +driver using one of the Streaming I/O methods. Only pointers to +buffers are exchanged, the data itself is not copied. These pointers, +together with meta-information like timestamps or field parity, are +stored in a struct <structname>v4l2_buffer</structname>, argument to +the &VIDIOC-QUERYBUF;, &VIDIOC-QBUF; and &VIDIOC-DQBUF; ioctl.</para> + + <para>Nominally timestamps refer to the first data byte transmitted. +In practice however the wide range of hardware covered by the V4L2 API +limits timestamp accuracy. Often an interrupt routine will +sample the system clock shortly after the field or frame was stored +completely in memory. So applications must expect a constant +difference up to one field or frame period plus a small (few scan +lines) random error. The delay and error can be much +larger due to compression or transmission over an external bus when +the frames are not properly stamped by the sender. This is frequently +the case with USB cameras. Here timestamps refer to the instant the +field or frame was received by the driver, not the capture time. These +devices identify by not enumerating any video standards, see <xref +linkend="standard" />.</para> + + <para>Similar limitations apply to output timestamps. Typically +the video hardware locks to a clock controlling the video timing, the +horizontal and vertical synchronization pulses. At some point in the +line sequence, possibly the vertical blanking, an interrupt routine +samples the system clock, compares against the timestamp and programs +the hardware to repeat the previous field or frame, or to display the +buffer contents.</para> + + <para>Apart of limitations of the video device and natural +inaccuracies of all clocks, it should be noted system time itself is +not perfectly stable. It can be affected by power saving cycles, +warped to insert leap seconds, or even turned back or forth by the +system administrator affecting long term measurements. <footnote> + <para>Since no other Linux multimedia +API supports unadjusted time it would be foolish to introduce here. We +must use a universally supported clock to synchronize different media, +hence time of day.</para> + </footnote></para> + + <table frame="none" pgwide="1" id="v4l2-buffer"> + <title>struct <structname>v4l2_buffer</structname></title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry></entry> + <entry>Number of the buffer, set by the application. This +field is only used for <link linkend="mmap">memory mapping</link> I/O +and can range from zero to the number of buffers allocated +with the &VIDIOC-REQBUFS; ioctl (&v4l2-requestbuffers; <structfield>count</structfield>) minus one.</entry> + </row> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry></entry> + <entry>Type of the buffer, same as &v4l2-format; +<structfield>type</structfield> or &v4l2-requestbuffers; +<structfield>type</structfield>, set by the application.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>bytesused</structfield></entry> + <entry></entry> + <entry>The number of bytes occupied by the data in the +buffer. It depends on the negotiated data format and may change with +each buffer for compressed variable size data like JPEG images. +Drivers must set this field when <structfield>type</structfield> +refers to an input stream, applications when an output stream.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry></entry> + <entry>Flags set by the application or driver, see <xref +linkend="buffer-flags" />.</entry> + </row> + <row> + <entry>&v4l2-field;</entry> + <entry><structfield>field</structfield></entry> + <entry></entry> + <entry>Indicates the field order of the image in the +buffer, see <xref linkend="v4l2-field" />. This field is not used when +the buffer contains VBI data. Drivers must set it when +<structfield>type</structfield> refers to an input stream, +applications when an output stream.</entry> + </row> + <row> + <entry>struct timeval</entry> + <entry><structfield>timestamp</structfield></entry> + <entry></entry> + <entry><para>For input streams this is the +system time (as returned by the <function>gettimeofday()</function> +function) when the first data byte was captured. For output streams +the data will not be displayed before this time, secondary to the +nominal frame rate determined by the current video standard in +enqueued order. Applications can for example zero this field to +display frames as soon as possible. The driver stores the time at +which the first data byte was actually sent out in the +<structfield>timestamp</structfield> field. This permits +applications to monitor the drift between the video and system +clock.</para></entry> + </row> + <row> + <entry>&v4l2-timecode;</entry> + <entry><structfield>timecode</structfield></entry> + <entry></entry> + <entry>When <structfield>type</structfield> is +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant> and the +<constant>V4L2_BUF_FLAG_TIMECODE</constant> flag is set in +<structfield>flags</structfield>, this structure contains a frame +timecode. In <link linkend="v4l2-field">V4L2_FIELD_ALTERNATE</link> +mode the top and bottom field contain the same timecode. +Timecodes are intended to help video editing and are typically recorded on +video tapes, but also embedded in compressed formats like MPEG. This +field is independent of the <structfield>timestamp</structfield> and +<structfield>sequence</structfield> fields.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>sequence</structfield></entry> + <entry></entry> + <entry>Set by the driver, counting the frames in the +sequence.</entry> + </row> + <row> + <entry spanname="hspan"><para>In <link +linkend="v4l2-field">V4L2_FIELD_ALTERNATE</link> mode the top and +bottom field have the same sequence number. The count starts at zero +and includes dropped or repeated frames. A dropped frame was received +by an input device but could not be stored due to lack of free buffer +space. A repeated frame was displayed again by an output device +because the application did not pass new data in +time.</para><para>Note this may count the frames received +e.g. over USB, without taking into account the frames dropped by the +remote hardware due to limited compression throughput or bus +bandwidth. These devices identify by not enumerating any video +standards, see <xref linkend="standard" />.</para></entry> + </row> + <row> + <entry>&v4l2-memory;</entry> + <entry><structfield>memory</structfield></entry> + <entry></entry> + <entry>This field must be set by applications and/or drivers +in accordance with the selected I/O method.</entry> + </row> + <row> + <entry>union</entry> + <entry><structfield>m</structfield></entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>offset</structfield></entry> + <entry>When <structfield>memory</structfield> is +<constant>V4L2_MEMORY_MMAP</constant> this is the offset of the buffer +from the start of the device memory. The value is returned by the +driver and apart of serving as parameter to the &func-mmap; function +not useful for applications. See <xref linkend="mmap" /> for details.</entry> + </row> + <row> + <entry></entry> + <entry>unsigned long</entry> + <entry><structfield>userptr</structfield></entry> + <entry>When <structfield>memory</structfield> is +<constant>V4L2_MEMORY_USERPTR</constant> this is a pointer to the +buffer (casted to unsigned long type) in virtual memory, set by the +application. See <xref linkend="userp" /> for details.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>length</structfield></entry> + <entry></entry> + <entry>Size of the buffer (not the payload) in bytes.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>input</structfield></entry> + <entry></entry> + <entry>Some video capture drivers support rapid and +synchronous video input changes, a function useful for example in +video surveillance applications. For this purpose applications set the +<constant>V4L2_BUF_FLAG_INPUT</constant> flag, and this field to the +number of a video input as in &v4l2-input; field +<structfield>index</structfield>.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield></entry> + <entry></entry> + <entry>A place holder for future extensions and custom +(driver defined) buffer types +<constant>V4L2_BUF_TYPE_PRIVATE</constant> and higher.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-buf-type"> + <title>enum v4l2_buf_type</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant></entry> + <entry>1</entry> + <entry>Buffer of a video capture stream, see <xref + linkend="capture" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant></entry> + <entry>2</entry> + <entry>Buffer of a video output stream, see <xref + linkend="output" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant></entry> + <entry>3</entry> + <entry>Buffer for video overlay, see <xref linkend="overlay" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_VBI_CAPTURE</constant></entry> + <entry>4</entry> + <entry>Buffer of a raw VBI capture stream, see <xref + linkend="raw-vbi" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant></entry> + <entry>5</entry> + <entry>Buffer of a raw VBI output stream, see <xref + linkend="raw-vbi" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant></entry> + <entry>6</entry> + <entry>Buffer of a sliced VBI capture stream, see <xref + linkend="sliced" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant></entry> + <entry>7</entry> + <entry>Buffer of a sliced VBI output stream, see <xref + linkend="sliced" />.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant></entry> + <entry>8</entry> + <entry>Buffer for video output overlay (OSD), see <xref + linkend="osd" />. Status: <link +linkend="experimental">Experimental</link>.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_TYPE_PRIVATE</constant></entry> + <entry>0x80</entry> + <entry>This and higher values are reserved for custom +(driver defined) buffer types.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="buffer-flags"> + <title>Buffer Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_BUF_FLAG_MAPPED</constant></entry> + <entry>0x0001</entry> + <entry>The buffer resides in device memory and has been mapped +into the application's address space, see <xref linkend="mmap" /> for details. +Drivers set or clear this flag when the +<link linkend="vidioc-querybuf">VIDIOC_QUERYBUF</link>, <link + linkend="vidioc-qbuf">VIDIOC_QBUF</link> or <link + linkend="vidioc-qbuf">VIDIOC_DQBUF</link> ioctl is called. Set by the driver.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_QUEUED</constant></entry> + <entry>0x0002</entry> + <entry>Internally drivers maintain two buffer queues, an +incoming and outgoing queue. When this flag is set, the buffer is +currently on the incoming queue. It automatically moves to the +outgoing queue after the buffer has been filled (capture devices) or +displayed (output devices). Drivers set or clear this flag when the +<constant>VIDIOC_QUERYBUF</constant> ioctl is called. After +(successful) calling the <constant>VIDIOC_QBUF </constant>ioctl it is +always set and after <constant>VIDIOC_DQBUF</constant> always +cleared.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_DONE</constant></entry> + <entry>0x0004</entry> + <entry>When this flag is set, the buffer is currently on +the outgoing queue, ready to be dequeued from the driver. Drivers set +or clear this flag when the <constant>VIDIOC_QUERYBUF</constant> ioctl +is called. After calling the <constant>VIDIOC_QBUF</constant> or +<constant>VIDIOC_DQBUF</constant> it is always cleared. Of course a +buffer cannot be on both queues at the same time, the +<constant>V4L2_BUF_FLAG_QUEUED</constant> and +<constant>V4L2_BUF_FLAG_DONE</constant> flag are mutually exclusive. +They can be both cleared however, then the buffer is in "dequeued" +state, in the application domain to say so.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_KEYFRAME</constant></entry> + <entry>0x0008</entry> + <entry>Drivers set or clear this flag when calling the +<constant>VIDIOC_DQBUF</constant> ioctl. It may be set by video +capture devices when the buffer contains a compressed image which is a +key frame (or field), &ie; can be decompressed on its own.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_PFRAME</constant></entry> + <entry>0x0010</entry> + <entry>Similar to <constant>V4L2_BUF_FLAG_KEYFRAME</constant> +this flags predicted frames or fields which contain only differences to a +previous key frame.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_BFRAME</constant></entry> + <entry>0x0020</entry> + <entry>Similar to <constant>V4L2_BUF_FLAG_PFRAME</constant> + this is a bidirectional predicted frame or field. [ooc tbd]</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_TIMECODE</constant></entry> + <entry>0x0100</entry> + <entry>The <structfield>timecode</structfield> field is valid. +Drivers set or clear this flag when the <constant>VIDIOC_DQBUF</constant> +ioctl is called.</entry> + </row> + <row> + <entry><constant>V4L2_BUF_FLAG_INPUT</constant></entry> + <entry>0x0200</entry> + <entry>The <structfield>input</structfield> field is valid. +Applications set or clear this flag before calling the +<constant>VIDIOC_QBUF</constant> ioctl.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-memory"> + <title>enum v4l2_memory</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_MEMORY_MMAP</constant></entry> + <entry>1</entry> + <entry>The buffer is used for <link linkend="mmap">memory +mapping</link> I/O.</entry> + </row> + <row> + <entry><constant>V4L2_MEMORY_USERPTR</constant></entry> + <entry>2</entry> + <entry>The buffer is used for <link linkend="userp">user +pointer</link> I/O.</entry> + </row> + <row> + <entry><constant>V4L2_MEMORY_OVERLAY</constant></entry> + <entry>3</entry> + <entry>[to do]</entry> + </row> + </tbody> + </tgroup> + </table> + + <section> + <title>Timecodes</title> + + <para>The <structname>v4l2_timecode</structname> structure is +designed to hold a <xref linkend="smpte12m" /> or similar timecode. +(struct <structname>timeval</structname> timestamps are stored in +&v4l2-buffer; field <structfield>timestamp</structfield>.)</para> + + <table frame="none" pgwide="1" id="v4l2-timecode"> + <title>struct <structname>v4l2_timecode</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>Frame rate the timecodes are based on, see <xref + linkend="timecode-type" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Timecode flags, see <xref linkend="timecode-flags" />.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>frames</structfield></entry> + <entry>Frame count, 0 ... 23/24/29/49/59, depending on the + type of timecode.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>seconds</structfield></entry> + <entry>Seconds count, 0 ... 59. This is a binary, not BCD number.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>minutes</structfield></entry> + <entry>Minutes count, 0 ... 59. This is a binary, not BCD number.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>hours</structfield></entry> + <entry>Hours count, 0 ... 29. This is a binary, not BCD number.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>userbits</structfield>[4]</entry> + <entry>The "user group" bits from the timecode.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="timecode-type"> + <title>Timecode Types</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TC_TYPE_24FPS</constant></entry> + <entry>1</entry> + <entry>24 frames per second, i. e. film.</entry> + </row> + <row> + <entry><constant>V4L2_TC_TYPE_25FPS</constant></entry> + <entry>2</entry> + <entry>25 frames per second, &ie; PAL or SECAM video.</entry> + </row> + <row> + <entry><constant>V4L2_TC_TYPE_30FPS</constant></entry> + <entry>3</entry> + <entry>30 frames per second, &ie; NTSC video.</entry> + </row> + <row> + <entry><constant>V4L2_TC_TYPE_50FPS</constant></entry> + <entry>4</entry> + <entry></entry> + </row> + <row> + <entry><constant>V4L2_TC_TYPE_60FPS</constant></entry> + <entry>5</entry> + <entry></entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="timecode-flags"> + <title>Timecode Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TC_FLAG_DROPFRAME</constant></entry> + <entry>0x0001</entry> + <entry>Indicates "drop frame" semantics for counting frames +in 29.97 fps material. When set, frame numbers 0 and 1 at the start of +each minute, except minutes 0, 10, 20, 30, 40, 50 are omitted from the +count.</entry> + </row> + <row> + <entry><constant>V4L2_TC_FLAG_COLORFRAME</constant></entry> + <entry>0x0002</entry> + <entry>The "color frame" flag.</entry> + </row> + <row> + <entry><constant>V4L2_TC_USERBITS_field</constant></entry> + <entry>0x000C</entry> + <entry>Field mask for the "binary group flags".</entry> + </row> + <row> + <entry><constant>V4L2_TC_USERBITS_USERDEFINED</constant></entry> + <entry>0x0000</entry> + <entry>Unspecified format.</entry> + </row> + <row> + <entry><constant>V4L2_TC_USERBITS_8BITCHARS</constant></entry> + <entry>0x0008</entry> + <entry>8-bit ISO characters.</entry> + </row> + </tbody> + </tgroup> + </table> + </section> + </section> + + <section id="field-order"> + <title>Field Order</title> + + <para>We have to distinguish between progressive and interlaced +video. Progressive video transmits all lines of a video image +sequentially. Interlaced video divides an image into two fields, +containing only the odd and even lines of the image, respectively. +Alternating the so called odd and even field are transmitted, and due +to a small delay between fields a cathode ray TV displays the lines +interleaved, yielding the original frame. This curious technique was +invented because at refresh rates similar to film the image would +fade out too quickly. Transmitting fields reduces the flicker without +the necessity of doubling the frame rate and with it the bandwidth +required for each channel.</para> + + <para>It is important to understand a video camera does not expose +one frame at a time, merely transmitting the frames separated into +fields. The fields are in fact captured at two different instances in +time. An object on screen may well move between one field and the +next. For applications analysing motion it is of paramount importance +to recognize which field of a frame is older, the <emphasis>temporal +order</emphasis>.</para> + + <para>When the driver provides or accepts images field by field +rather than interleaved, it is also important applications understand +how the fields combine to frames. We distinguish between top and +bottom fields, the <emphasis>spatial order</emphasis>: The first line +of the top field is the first line of an interlaced frame, the first +line of the bottom field is the second line of that frame.</para> + + <para>However because fields were captured one after the other, +arguing whether a frame commences with the top or bottom field is +pointless. Any two successive top and bottom, or bottom and top fields +yield a valid frame. Only when the source was progressive to begin +with, ⪚ when transferring film to video, two fields may come from +the same frame, creating a natural order.</para> + + <para>Counter to intuition the top field is not necessarily the +older field. Whether the older field contains the top or bottom lines +is a convention determined by the video standard. Hence the +distinction between temporal and spatial order of fields. The diagrams +below should make this clearer.</para> + + <para>All video capture and output devices must report the current +field order. Some drivers may permit the selection of a different +order, to this end applications initialize the +<structfield>field</structfield> field of &v4l2-pix-format; before +calling the &VIDIOC-S-FMT; ioctl. If this is not desired it should +have the value <constant>V4L2_FIELD_ANY</constant> (0).</para> + + <table frame="none" pgwide="1" id="v4l2-field"> + <title>enum v4l2_field</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_FIELD_ANY</constant></entry> + <entry>0</entry> + <entry>Applications request this field order when any +one of the <constant>V4L2_FIELD_NONE</constant>, +<constant>V4L2_FIELD_TOP</constant>, +<constant>V4L2_FIELD_BOTTOM</constant>, or +<constant>V4L2_FIELD_INTERLACED</constant> formats is acceptable. +Drivers choose depending on hardware capabilities or e. g. the +requested image size, and return the actual field order. &v4l2-buffer; +<structfield>field</structfield> can never be +<constant>V4L2_FIELD_ANY</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_NONE</constant></entry> + <entry>1</entry> + <entry>Images are in progressive format, not interlaced. +The driver may also indicate this order when it cannot distinguish +between <constant>V4L2_FIELD_TOP</constant> and +<constant>V4L2_FIELD_BOTTOM</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_TOP</constant></entry> + <entry>2</entry> + <entry>Images consist of the top field only.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_BOTTOM</constant></entry> + <entry>3</entry> + <entry>Images consist of the bottom field only. +Applications may wish to prevent a device from capturing interlaced +images because they will have "comb" or "feathering" artefacts around +moving objects.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_INTERLACED</constant></entry> + <entry>4</entry> + <entry>Images contain both fields, interleaved line by +line. The temporal order of the fields (whether the top or bottom +field is first transmitted) depends on the current video standard. +M/NTSC transmits the bottom field first, all other standards the top +field first.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_SEQ_TB</constant></entry> + <entry>5</entry> + <entry>Images contain both fields, the top field lines +are stored first in memory, immediately followed by the bottom field +lines. Fields are always stored in temporal order, the older one first +in memory. Image sizes refer to the frame, not fields.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_SEQ_BT</constant></entry> + <entry>6</entry> + <entry>Images contain both fields, the bottom field +lines are stored first in memory, immediately followed by the top +field lines. Fields are always stored in temporal order, the older one +first in memory. Image sizes refer to the frame, not fields.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_ALTERNATE</constant></entry> + <entry>7</entry> + <entry>The two fields of a frame are passed in separate +buffers, in temporal order, &ie; the older one first. To indicate the field +parity (whether the current field is a top or bottom field) the driver +or application, depending on data direction, must set &v4l2-buffer; +<structfield>field</structfield> to +<constant>V4L2_FIELD_TOP</constant> or +<constant>V4L2_FIELD_BOTTOM</constant>. Any two successive fields pair +to build a frame. If fields are successive, without any dropped fields +between them (fields can drop individually), can be determined from +the &v4l2-buffer; <structfield>sequence</structfield> field. Image +sizes refer to the frame, not fields. This format cannot be selected +when using the read/write I/O method.<!-- Where it's indistinguishable +from V4L2_FIELD_SEQ_*. --></entry> + </row> + <row> + <entry><constant>V4L2_FIELD_INTERLACED_TB</constant></entry> + <entry>8</entry> + <entry>Images contain both fields, interleaved line by +line, top field first. The top field is transmitted first.</entry> + </row> + <row> + <entry><constant>V4L2_FIELD_INTERLACED_BT</constant></entry> + <entry>9</entry> + <entry>Images contain both fields, interleaved line by +line, top field first. The bottom field is transmitted first.</entry> + </row> + </tbody> + </tgroup> + </table> + + <figure id="fieldseq-tb"> + <title>Field Order, Top Field First Transmitted</title> + <mediaobject> + <imageobject> + <imagedata fileref="fieldseq_tb.pdf" format="PS" /> + </imageobject> + <imageobject> + <imagedata fileref="fieldseq_tb.gif" format="GIF" /> + </imageobject> + </mediaobject> + </figure> + + <figure id="fieldseq-bt"> + <title>Field Order, Bottom Field First Transmitted</title> + <mediaobject> + <imageobject> + <imagedata fileref="fieldseq_bt.pdf" format="PS" /> + </imageobject> + <imageobject> + <imagedata fileref="fieldseq_bt.gif" format="GIF" /> + </imageobject> + </mediaobject> + </figure> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/libv4l.xml b/linux/Documentation/DocBook/v4l/libv4l.xml new file mode 100644 index 000000000..c14fc3db2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/libv4l.xml @@ -0,0 +1,167 @@ +<title>Libv4l Userspace Library</title> +<section id="libv4l-introduction"> + <title>Introduction</title> + + <para>libv4l is a collection of libraries which adds a thin abstraction +layer on top of video4linux2 devices. The purpose of this (thin) layer +is to make it easy for application writers to support a wide variety of +devices without having to write separate code for different devices in the +same class.</para> +<para>An example of using libv4l is provided by +<link linkend='v4l2grab-example'>v4l2grab</link>. +</para> + + <para>libv4l consists of 3 different libraries:</para> + <section> + <title>libv4lconvert</title> + + <para>libv4lconvert is a library that converts several +different pixelformats found in V4L2 drivers into a few common RGB and +YUY formats.</para> + <para>It currently accepts the following V4L2 driver formats: +<link linkend="V4L2-PIX-FMT-BGR24"><constant>V4L2_PIX_FMT_BGR24</constant></link>, +<link linkend="V4L2-PIX-FMT-HM12"><constant>V4L2_PIX_FMT_HM12</constant></link>, +<link linkend="V4L2-PIX-FMT-JPEG"><constant>V4L2_PIX_FMT_JPEG</constant></link>, +<link linkend="V4L2-PIX-FMT-MJPEG"><constant>V4L2_PIX_FMT_MJPEG</constant></link>, +<link linkend="V4L2-PIX-FMT-MR97310A"><constant>V4L2_PIX_FMT_MR97310A</constant></link>, +<link linkend="V4L2-PIX-FMT-OV511"><constant>V4L2_PIX_FMT_OV511</constant></link>, +<link linkend="V4L2-PIX-FMT-OV518"><constant>V4L2_PIX_FMT_OV518</constant></link>, +<link linkend="V4L2-PIX-FMT-PAC207"><constant>V4L2_PIX_FMT_PAC207</constant></link>, +<link linkend="V4L2-PIX-FMT-PJPG"><constant>V4L2_PIX_FMT_PJPG</constant></link>, +<link linkend="V4L2-PIX-FMT-RGB24"><constant>V4L2_PIX_FMT_RGB24</constant></link>, +<link linkend="V4L2-PIX-FMT-SBGGR8"><constant>V4L2_PIX_FMT_SBGGR8</constant></link>, +<link linkend="V4L2-PIX-FMT-SGBRG8"><constant>V4L2_PIX_FMT_SGBRG8</constant></link>, +<link linkend="V4L2-PIX-FMT-SGRBG8"><constant>V4L2_PIX_FMT_SGRBG8</constant></link>, +<link linkend="V4L2-PIX-FMT-SN9C10X"><constant>V4L2_PIX_FMT_SN9C10X</constant></link>, +<link linkend="V4L2-PIX-FMT-SN9C20X-I420"><constant>V4L2_PIX_FMT_SN9C20X_I420</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA501"><constant>V4L2_PIX_FMT_SPCA501</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA505"><constant>V4L2_PIX_FMT_SPCA505</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA508"><constant>V4L2_PIX_FMT_SPCA508</constant></link>, +<link linkend="V4L2-PIX-FMT-SPCA561"><constant>V4L2_PIX_FMT_SPCA561</constant></link>, +<link linkend="V4L2-PIX-FMT-SQ905C"><constant>V4L2_PIX_FMT_SQ905C</constant></link>, +<constant>V4L2_PIX_FMT_SRGGB8</constant>, +<link linkend="V4L2-PIX-FMT-UYVY"><constant>V4L2_PIX_FMT_UYVY</constant></link>, +<link linkend="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></link>, +<link linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link>, +<link linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link>, +and <link linkend="V4L2-PIX-FMT-YVYU"><constant>V4L2_PIX_FMT_YVYU</constant></link>. +</para> + <para>Later on libv4lconvert was expanded to also be able to do +various video processing functions to improve webcam video quality. +The video processing is split in to 2 parts: libv4lconvert/control and +libv4lconvert/processing.</para> + + <para>The control part is used to offer video controls which can +be used to control the video processing functions made available by + libv4lconvert/processing. These controls are stored application wide +(until reboot) by using a persistent shared memory object.</para> + + <para>libv4lconvert/processing offers the actual video +processing functionality.</para> + </section> + <section> + <title>libv4l1</title> + <para>This library offers functions that can be used to quickly +make v4l1 applications work with v4l2 devices. These functions work exactly +like the normal open/close/etc, except that libv4l1 does full emulation of +the v4l1 api on top of v4l2 drivers, in case of v4l1 drivers it +will just pass calls through.</para> + <para>Since those functions are emulations of the old V4L1 API, +it shouldn't be used for new applications.</para> + </section> + <section> + <title>libv4l2</title> + <para>This library should be used for all modern V4L2 +applications.</para> + <para>It provides handles to call V4L2 open/ioctl/close/poll +methods. Instead of just providing the raw output of the device, it enhances +the calls in the sense that it will use libv4lconvert to provide more video +formats and to enhance the image quality.</para> + <para>In most cases, libv4l2 just passes the calls directly +through to the v4l2 driver, intercepting the calls to +<link linkend='vidioc-g-fmt'><constant>VIDIOC_TRY_FMT</constant></link>, +<link linkend='vidioc-g-fmt'><constant>VIDIOC_G_FMT</constant></link> +<link linkend='vidioc-g-fmt'><constant>VIDIOC_S_FMT</constant></link> +<link linkend='vidioc-enum-framesizes'><constant>VIDIOC_ENUM_FRAMESIZES</constant></link> +and <link linkend='vidioc-enum-frameintervals'><constant>VIDIOC_ENUM_FRAMEINTERVALS</constant></link> +in order to emulate the formats +<link linkend="V4L2-PIX-FMT-BGR24"><constant>V4L2_PIX_FMT_BGR24</constant></link>, +<link linkend="V4L2-PIX-FMT-RGB24"><constant>V4L2_PIX_FMT_RGB24</constant></link>, +<link linkend="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></link>, +and <link linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link>, +if they aren't available in the driver. +<link linkend='vidioc-enum-fmt'><constant>VIDIOC_ENUM_FMT</constant></link> +keeps enumerating the hardware supported formats, plus the emulated formats +offered by libv4l at the end. +</para> + <section id="libv4l-ops"> + <title>Libv4l device control functions</title> + <para>The common file operation methods are provided by +libv4l.</para> + <para>Those functions operate just like glibc +open/close/dup/ioctl/read/mmap/munmap:</para> +<itemizedlist><listitem> + <para>int v4l2_open(const char *file, int oflag, +...) - +operates like the standard <link linkend='func-open'>open()</link> function. +</para></listitem><listitem> + <para>int v4l2_close(int fd) - +operates like the standard <link linkend='func-close'>close()</link> function. +</para></listitem><listitem> + <para>int v4l2_dup(int fd) - +operates like the standard dup() function, duplicating a file handler. +</para></listitem><listitem> + <para>int v4l2_ioctl (int fd, unsigned long int request, ...) - +operates like the standard <link linkend='func-ioctl'>ioctl()</link> function. +</para></listitem><listitem> + <para>int v4l2_read (int fd, void* buffer, size_t n) - +operates like the standard <link linkend='func-read'>read()</link> function. +</para></listitem><listitem> + <para>void v4l2_mmap(void *start, size_t length, int prot, int flags, int fd, int64_t offset); - +operates like the standard <link linkend='func-mmap'>mmap()</link> function. +</para></listitem><listitem> + <para>int v4l2_munmap(void *_start, size_t length); - +operates like the standard <link linkend='func-munmap'>munmap()</link> function. +</para></listitem> +</itemizedlist> + <para>Those functions provide additional control:</para> +<itemizedlist><listitem> + <para>int v4l2_fd_open(int fd, int v4l2_flags) - +opens an already opened fd for further use through v4l2lib and possibly +modify libv4l2's default behavior through the v4l2_flags argument. +Currently, v4l2_flags can be <constant>V4L2_DISABLE_CONVERSION</constant>, +to disable format conversion. +</para></listitem><listitem> + <para>int v4l2_set_control(int fd, int cid, int value) - +This function takes a value of 0 - 65535, and then scales that range to +the actual range of the given v4l control id, and then if the cid exists +and is not locked sets the cid to the scaled value. +</para></listitem><listitem> + <para>int v4l2_get_control(int fd, int cid) - +This function returns a value of 0 - 65535, scaled to from the actual range +of the given v4l control id. when the cid does not exist, could not be +accessed for some reason, or some error occured 0 is returned. +</para></listitem> +</itemizedlist> + </section> + </section> + <section> + + <title>v4l1compat.so wrapper library</title> + + <para>This library intercepts calls to +open/close/ioctl/mmap/mmunmap operations and redirects them to the libv4l +counterparts, by using LD_PRELOAD=/usr/lib/v4l1compat.so. It also +emulates V4L1 calls via V4L2 API.</para> + <para>It allows usage of binary legacy applications that +still don't use libv4l.</para> + </section> + +</section> +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-grey.xml b/linux/Documentation/DocBook/v4l/pixfmt-grey.xml new file mode 100644 index 000000000..3b72bc6b2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-grey.xml @@ -0,0 +1,70 @@ + <refentry id="V4L2-PIX-FMT-GREY"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_GREY ('GREY')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_GREY</constant></refname> + <refpurpose>Grey-scale image</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is a grey-scale image. It is really a degenerate +Y'CbCr format which simply contains no Cb or Cr data.</para> + + <example> + <title><constant>V4L2_PIX_FMT_GREY</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-nv12.xml b/linux/Documentation/DocBook/v4l/pixfmt-nv12.xml new file mode 100644 index 000000000..873f67035 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-nv12.xml @@ -0,0 +1,151 @@ + <refentry> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_NV12 ('NV12'), V4L2_PIX_FMT_NV21 ('NV21')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname id="V4L2-PIX-FMT-NV12"><constant>V4L2_PIX_FMT_NV12</constant></refname> + <refname id="V4L2-PIX-FMT-NV21"><constant>V4L2_PIX_FMT_NV21</constant></refname> + <refpurpose>Formats with ½ horizontal and vertical +chroma resolution, also known as YUV 4:2:0. One luminance and one +chrominance plane with alternating chroma samples as opposed to +<constant>V4L2_PIX_FMT_YVU420</constant></refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>These are two-plane versions of the YUV 4:2:0 format. +The three components are separated into two sub-images or planes. The +Y plane is first. The Y plane has one byte per pixel. For +<constant>V4L2_PIX_FMT_NV12</constant>, a combined CbCr plane +immediately follows the Y plane in memory. The CbCr plane is the same +width, in bytes, as the Y plane (and of the image), but is half as +tall in pixels. Each CbCr pair belongs to four pixels. For example, +Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to +Y'<subscript>00</subscript>, Y'<subscript>01</subscript>, +Y'<subscript>10</subscript>, Y'<subscript>11</subscript>. +<constant>V4L2_PIX_FMT_NV21</constant> is the same except the Cb and +Cr bytes are swapped, the CrCb plane starts with a Cr byte.</para> + + <para>If the Y plane has pad bytes after each row, then the +CbCr plane has as many pad bytes after its rows.</para> + + <example> + <title><constant>V4L2_PIX_FMT_NV12</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 20:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-nv16.xml b/linux/Documentation/DocBook/v4l/pixfmt-nv16.xml new file mode 100644 index 000000000..26094035f --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-nv16.xml @@ -0,0 +1,174 @@ + <refentry> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_NV16 ('NV16'), V4L2_PIX_FMT_NV61 ('NV61')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname id="V4L2-PIX-FMT-NV16"><constant>V4L2_PIX_FMT_NV16</constant></refname> + <refname id="V4L2-PIX-FMT-NV61"><constant>V4L2_PIX_FMT_NV61</constant></refname> + <refpurpose>Formats with ½ horizontal +chroma resolution, also known as YUV 4:2:2. One luminance and one +chrominance plane with alternating chroma samples as opposed to +<constant>V4L2_PIX_FMT_YVU420</constant></refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>These are two-plane versions of the YUV 4:2:2 format. +The three components are separated into two sub-images or planes. The +Y plane is first. The Y plane has one byte per pixel. For +<constant>V4L2_PIX_FMT_NV16</constant>, a combined CbCr plane +immediately follows the Y plane in memory. The CbCr plane is the same +width and height, in bytes, as the Y plane (and of the image). +Each CbCr pair belongs to two pixels. For example, +Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to +Y'<subscript>00</subscript>, Y'<subscript>01</subscript>. +<constant>V4L2_PIX_FMT_NV61</constant> is the same except the Cb and +Cr bytes are swapped, the CrCb plane starts with a Cr byte.</para> + + <para>If the Y plane has pad bytes after each row, then the +CbCr plane has as many pad bytes after its rows.</para> + + <example> + <title><constant>V4L2_PIX_FMT_NV16</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 20:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + </row> + <row> + <entry>start + 28:</entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-packed-rgb.xml b/linux/Documentation/DocBook/v4l/pixfmt-packed-rgb.xml new file mode 100644 index 000000000..d2dd697a8 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-packed-rgb.xml @@ -0,0 +1,862 @@ +<refentry id="packed-rgb"> + <refmeta> + <refentrytitle>Packed RGB formats</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname>Packed RGB formats</refname> + <refpurpose>Packed RGB formats</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>These formats are designed to match the pixel formats of +typical PC graphics frame buffers. They occupy 8, 16, 24 or 32 bits +per pixel. These are all packed-pixel formats, meaning all the data +for a pixel lie next to each other in memory.</para> + + <para>When one of these formats is used, drivers shall report the +colorspace <constant>V4L2_COLORSPACE_SRGB</constant>.</para> + + <table pgwide="1" frame="none" id="rgb-formats"> + <title>Packed RGB Image Formats</title> + <tgroup cols="37" align="center"> + <colspec colname="id" align="left" /> + <colspec colname="fourcc" /> + <colspec colname="bit" /> + + <colspec colnum="4" colname="b07" align="center" /> + <colspec colnum="5" colname="b06" align="center" /> + <colspec colnum="6" colname="b05" align="center" /> + <colspec colnum="7" colname="b04" align="center" /> + <colspec colnum="8" colname="b03" align="center" /> + <colspec colnum="9" colname="b02" align="center" /> + <colspec colnum="10" colname="b01" align="center" /> + <colspec colnum="11" colname="b00" align="center" /> + + <colspec colnum="13" colname="b17" align="center" /> + <colspec colnum="14" colname="b16" align="center" /> + <colspec colnum="15" colname="b15" align="center" /> + <colspec colnum="16" colname="b14" align="center" /> + <colspec colnum="17" colname="b13" align="center" /> + <colspec colnum="18" colname="b12" align="center" /> + <colspec colnum="19" colname="b11" align="center" /> + <colspec colnum="20" colname="b10" align="center" /> + + <colspec colnum="22" colname="b27" align="center" /> + <colspec colnum="23" colname="b26" align="center" /> + <colspec colnum="24" colname="b25" align="center" /> + <colspec colnum="25" colname="b24" align="center" /> + <colspec colnum="26" colname="b23" align="center" /> + <colspec colnum="27" colname="b22" align="center" /> + <colspec colnum="28" colname="b21" align="center" /> + <colspec colnum="29" colname="b20" align="center" /> + + <colspec colnum="31" colname="b37" align="center" /> + <colspec colnum="32" colname="b36" align="center" /> + <colspec colnum="33" colname="b35" align="center" /> + <colspec colnum="34" colname="b34" align="center" /> + <colspec colnum="35" colname="b33" align="center" /> + <colspec colnum="36" colname="b32" align="center" /> + <colspec colnum="37" colname="b31" align="center" /> + <colspec colnum="38" colname="b30" align="center" /> + + <spanspec namest="b07" nameend="b00" spanname="b0" /> + <spanspec namest="b17" nameend="b10" spanname="b1" /> + <spanspec namest="b27" nameend="b20" spanname="b2" /> + <spanspec namest="b37" nameend="b30" spanname="b3" /> + <thead> + <row> + <entry>Identifier</entry> + <entry>Code</entry> + <entry> </entry> + <entry spanname="b0">Byte 0 in memory</entry> + <entry spanname="b1">Byte 1</entry> + <entry spanname="b2">Byte 2</entry> + <entry spanname="b3">Byte 3</entry> + </row> + <row> + <entry> </entry> + <entry> </entry> + <entry>Bit</entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + </row> + </thead> + <tbody valign="top"> + <row id="V4L2-PIX-FMT-RGB332"> + <entry><constant>V4L2_PIX_FMT_RGB332</constant></entry> + <entry>'RGB1'</entry> + <entry></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB444"> + <entry><constant>V4L2_PIX_FMT_RGB444</constant></entry> + <entry>'R444'</entry> + <entry></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB555"> + <entry><constant>V4L2_PIX_FMT_RGB555</constant></entry> + <entry>'RGBO'</entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>a</entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB565"> + <entry><constant>V4L2_PIX_FMT_RGB565</constant></entry> + <entry>'RGBP'</entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB555X"> + <entry><constant>V4L2_PIX_FMT_RGB555X</constant></entry> + <entry>'RGBQ'</entry> + <entry></entry> + <entry>a</entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB565X"> + <entry><constant>V4L2_PIX_FMT_RGB565X</constant></entry> + <entry>'RGBR'</entry> + <entry></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-BGR24"> + <entry><constant>V4L2_PIX_FMT_BGR24</constant></entry> + <entry>'BGR3'</entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB24"> + <entry><constant>V4L2_PIX_FMT_RGB24</constant></entry> + <entry>'RGB3'</entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-BGR32"> + <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry> + <entry>'BGR4'</entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>a<subscript>7</subscript></entry> + <entry>a<subscript>6</subscript></entry> + <entry>a<subscript>5</subscript></entry> + <entry>a<subscript>4</subscript></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + </row> + <row id="V4L2-PIX-FMT-RGB32"> + <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry> + <entry>'RGB4'</entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>a<subscript>7</subscript></entry> + <entry>a<subscript>6</subscript></entry> + <entry>a<subscript>5</subscript></entry> + <entry>a<subscript>4</subscript></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Bit 7 is the most significant bit. The value of a = alpha +bits is undefined when reading from the driver, ignored when writing +to the driver, except when alpha blending has been negotiated for a +<link linkend="overlay">Video Overlay</link> or <link +linkend="osd">Video Output Overlay</link>.</para> + + <example> + <title><constant>V4L2_PIX_FMT_BGR24</constant> 4 × 4 pixel +image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="13" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>B<subscript>00</subscript></entry> + <entry>G<subscript>00</subscript></entry> + <entry>R<subscript>00</subscript></entry> + <entry>B<subscript>01</subscript></entry> + <entry>G<subscript>01</subscript></entry> + <entry>R<subscript>01</subscript></entry> + <entry>B<subscript>02</subscript></entry> + <entry>G<subscript>02</subscript></entry> + <entry>R<subscript>02</subscript></entry> + <entry>B<subscript>03</subscript></entry> + <entry>G<subscript>03</subscript></entry> + <entry>R<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>B<subscript>10</subscript></entry> + <entry>G<subscript>10</subscript></entry> + <entry>R<subscript>10</subscript></entry> + <entry>B<subscript>11</subscript></entry> + <entry>G<subscript>11</subscript></entry> + <entry>R<subscript>11</subscript></entry> + <entry>B<subscript>12</subscript></entry> + <entry>G<subscript>12</subscript></entry> + <entry>R<subscript>12</subscript></entry> + <entry>B<subscript>13</subscript></entry> + <entry>G<subscript>13</subscript></entry> + <entry>R<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>B<subscript>20</subscript></entry> + <entry>G<subscript>20</subscript></entry> + <entry>R<subscript>20</subscript></entry> + <entry>B<subscript>21</subscript></entry> + <entry>G<subscript>21</subscript></entry> + <entry>R<subscript>21</subscript></entry> + <entry>B<subscript>22</subscript></entry> + <entry>G<subscript>22</subscript></entry> + <entry>R<subscript>22</subscript></entry> + <entry>B<subscript>23</subscript></entry> + <entry>G<subscript>23</subscript></entry> + <entry>R<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 36:</entry> + <entry>B<subscript>30</subscript></entry> + <entry>G<subscript>30</subscript></entry> + <entry>R<subscript>30</subscript></entry> + <entry>B<subscript>31</subscript></entry> + <entry>G<subscript>31</subscript></entry> + <entry>R<subscript>31</subscript></entry> + <entry>B<subscript>32</subscript></entry> + <entry>G<subscript>32</subscript></entry> + <entry>R<subscript>32</subscript></entry> + <entry>B<subscript>33</subscript></entry> + <entry>G<subscript>33</subscript></entry> + <entry>R<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + + <important> + <para>Drivers may interpret these formats differently.</para> + </important> + + <para>Some RGB formats above are uncommon and were probably +defined in error. Drivers may interpret them as in <xref + linkend="rgb-formats-corrected" />.</para> + + <table pgwide="1" frame="none" id="rgb-formats-corrected"> + <title>Packed RGB Image Formats (corrected)</title> + <tgroup cols="37" align="center"> + <colspec colname="id" align="left" /> + <colspec colname="fourcc" /> + <colspec colname="bit" /> + + <colspec colnum="4" colname="b07" align="center" /> + <colspec colnum="5" colname="b06" align="center" /> + <colspec colnum="6" colname="b05" align="center" /> + <colspec colnum="7" colname="b04" align="center" /> + <colspec colnum="8" colname="b03" align="center" /> + <colspec colnum="9" colname="b02" align="center" /> + <colspec colnum="10" colname="b01" align="center" /> + <colspec colnum="11" colname="b00" align="center" /> + + <colspec colnum="13" colname="b17" align="center" /> + <colspec colnum="14" colname="b16" align="center" /> + <colspec colnum="15" colname="b15" align="center" /> + <colspec colnum="16" colname="b14" align="center" /> + <colspec colnum="17" colname="b13" align="center" /> + <colspec colnum="18" colname="b12" align="center" /> + <colspec colnum="19" colname="b11" align="center" /> + <colspec colnum="20" colname="b10" align="center" /> + + <colspec colnum="22" colname="b27" align="center" /> + <colspec colnum="23" colname="b26" align="center" /> + <colspec colnum="24" colname="b25" align="center" /> + <colspec colnum="25" colname="b24" align="center" /> + <colspec colnum="26" colname="b23" align="center" /> + <colspec colnum="27" colname="b22" align="center" /> + <colspec colnum="28" colname="b21" align="center" /> + <colspec colnum="29" colname="b20" align="center" /> + + <colspec colnum="31" colname="b37" align="center" /> + <colspec colnum="32" colname="b36" align="center" /> + <colspec colnum="33" colname="b35" align="center" /> + <colspec colnum="34" colname="b34" align="center" /> + <colspec colnum="35" colname="b33" align="center" /> + <colspec colnum="36" colname="b32" align="center" /> + <colspec colnum="37" colname="b31" align="center" /> + <colspec colnum="38" colname="b30" align="center" /> + + <spanspec namest="b07" nameend="b00" spanname="b0" /> + <spanspec namest="b17" nameend="b10" spanname="b1" /> + <spanspec namest="b27" nameend="b20" spanname="b2" /> + <spanspec namest="b37" nameend="b30" spanname="b3" /> + <thead> + <row> + <entry>Identifier</entry> + <entry>Code</entry> + <entry> </entry> + <entry spanname="b0">Byte 0 in memory</entry> + <entry spanname="b1">Byte 1</entry> + <entry spanname="b2">Byte 2</entry> + <entry spanname="b3">Byte 3</entry> + </row> + <row> + <entry> </entry> + <entry> </entry> + <entry>Bit</entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + </row> + </thead> + <tbody valign="top"> + <row><!-- id="V4L2-PIX-FMT-RGB332" --> + <entry><constant>V4L2_PIX_FMT_RGB332</constant></entry> + <entry>'RGB1'</entry> + <entry></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB444" --> + <entry><constant>V4L2_PIX_FMT_RGB444</constant></entry> + <entry>'R444'</entry> + <entry></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB555" --> + <entry><constant>V4L2_PIX_FMT_RGB555</constant></entry> + <entry>'RGBO'</entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>a</entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB565" --> + <entry><constant>V4L2_PIX_FMT_RGB565</constant></entry> + <entry>'RGBP'</entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB555X" --> + <entry><constant>V4L2_PIX_FMT_RGB555X</constant></entry> + <entry>'RGBQ'</entry> + <entry></entry> + <entry>a</entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB565X" --> + <entry><constant>V4L2_PIX_FMT_RGB565X</constant></entry> + <entry>'RGBR'</entry> + <entry></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-BGR24" --> + <entry><constant>V4L2_PIX_FMT_BGR24</constant></entry> + <entry>'BGR3'</entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB24" --> + <entry><constant>V4L2_PIX_FMT_RGB24</constant></entry> + <entry>'RGB3'</entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-BGR32" --> + <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry> + <entry>'BGR4'</entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>a<subscript>7</subscript></entry> + <entry>a<subscript>6</subscript></entry> + <entry>a<subscript>5</subscript></entry> + <entry>a<subscript>4</subscript></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + </row> + <row><!-- id="V4L2-PIX-FMT-RGB32" --> + <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry> + <entry>'RGB4'</entry> + <entry></entry> + <entry>a<subscript>7</subscript></entry> + <entry>a<subscript>6</subscript></entry> + <entry>a<subscript>5</subscript></entry> + <entry>a<subscript>4</subscript></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + <entry></entry> + <entry>r<subscript>7</subscript></entry> + <entry>r<subscript>6</subscript></entry> + <entry>r<subscript>5</subscript></entry> + <entry>r<subscript>4</subscript></entry> + <entry>r<subscript>3</subscript></entry> + <entry>r<subscript>2</subscript></entry> + <entry>r<subscript>1</subscript></entry> + <entry>r<subscript>0</subscript></entry> + <entry></entry> + <entry>g<subscript>7</subscript></entry> + <entry>g<subscript>6</subscript></entry> + <entry>g<subscript>5</subscript></entry> + <entry>g<subscript>4</subscript></entry> + <entry>g<subscript>3</subscript></entry> + <entry>g<subscript>2</subscript></entry> + <entry>g<subscript>1</subscript></entry> + <entry>g<subscript>0</subscript></entry> + <entry></entry> + <entry>b<subscript>7</subscript></entry> + <entry>b<subscript>6</subscript></entry> + <entry>b<subscript>5</subscript></entry> + <entry>b<subscript>4</subscript></entry> + <entry>b<subscript>3</subscript></entry> + <entry>b<subscript>2</subscript></entry> + <entry>b<subscript>1</subscript></entry> + <entry>b<subscript>0</subscript></entry> + </row> + </tbody> + </tgroup> + </table> + + <para>A test utility to determine which RGB formats a driver +actually supports is available from the LinuxTV v4l-dvb repository. +See &v4l-dvb; for access instructions.</para> + + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-packed-yuv.xml b/linux/Documentation/DocBook/v4l/pixfmt-packed-yuv.xml new file mode 100644 index 000000000..3cab5d0ca --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-packed-yuv.xml @@ -0,0 +1,244 @@ +<refentry id="packed-yuv"> + <refmeta> + <refentrytitle>Packed YUV formats</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname>Packed YUV formats</refname> + <refpurpose>Packed YUV formats</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>Similar to the packed RGB formats these formats store +the Y, Cb and Cr component of each pixel in one 16 or 32 bit +word.</para> + + <table pgwide="1" frame="none"> + <title>Packed YUV Image Formats</title> + <tgroup cols="37" align="center"> + <colspec colname="id" align="left" /> + <colspec colname="fourcc" /> + <colspec colname="bit" /> + + <colspec colnum="4" colname="b07" align="center" /> + <colspec colnum="5" colname="b06" align="center" /> + <colspec colnum="6" colname="b05" align="center" /> + <colspec colnum="7" colname="b04" align="center" /> + <colspec colnum="8" colname="b03" align="center" /> + <colspec colnum="9" colname="b02" align="center" /> + <colspec colnum="10" colname="b01" align="center" /> + <colspec colnum="11" colname="b00" align="center" /> + + <colspec colnum="13" colname="b17" align="center" /> + <colspec colnum="14" colname="b16" align="center" /> + <colspec colnum="15" colname="b15" align="center" /> + <colspec colnum="16" colname="b14" align="center" /> + <colspec colnum="17" colname="b13" align="center" /> + <colspec colnum="18" colname="b12" align="center" /> + <colspec colnum="19" colname="b11" align="center" /> + <colspec colnum="20" colname="b10" align="center" /> + + <colspec colnum="22" colname="b27" align="center" /> + <colspec colnum="23" colname="b26" align="center" /> + <colspec colnum="24" colname="b25" align="center" /> + <colspec colnum="25" colname="b24" align="center" /> + <colspec colnum="26" colname="b23" align="center" /> + <colspec colnum="27" colname="b22" align="center" /> + <colspec colnum="28" colname="b21" align="center" /> + <colspec colnum="29" colname="b20" align="center" /> + + <colspec colnum="31" colname="b37" align="center" /> + <colspec colnum="32" colname="b36" align="center" /> + <colspec colnum="33" colname="b35" align="center" /> + <colspec colnum="34" colname="b34" align="center" /> + <colspec colnum="35" colname="b33" align="center" /> + <colspec colnum="36" colname="b32" align="center" /> + <colspec colnum="37" colname="b31" align="center" /> + <colspec colnum="38" colname="b30" align="center" /> + + <spanspec namest="b07" nameend="b00" spanname="b0" /> + <spanspec namest="b17" nameend="b10" spanname="b1" /> + <spanspec namest="b27" nameend="b20" spanname="b2" /> + <spanspec namest="b37" nameend="b30" spanname="b3" /> + <thead> + <row> + <entry>Identifier</entry> + <entry>Code</entry> + <entry> </entry> + <entry spanname="b0">Byte 0 in memory</entry> + <entry spanname="b1">Byte 1</entry> + <entry spanname="b2">Byte 2</entry> + <entry spanname="b3">Byte 3</entry> + </row> + <row> + <entry> </entry> + <entry> </entry> + <entry>Bit</entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + <entry> </entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + </row> + </thead> + <tbody valign="top"> + <row id="V4L2-PIX-FMT-YUV444"> + <entry><constant>V4L2_PIX_FMT_YUV444</constant></entry> + <entry>'Y444'</entry> + <entry></entry> + <entry>Cb<subscript>3</subscript></entry> + <entry>Cb<subscript>2</subscript></entry> + <entry>Cb<subscript>1</subscript></entry> + <entry>Cb<subscript>0</subscript></entry> + <entry>Cr<subscript>3</subscript></entry> + <entry>Cr<subscript>2</subscript></entry> + <entry>Cr<subscript>1</subscript></entry> + <entry>Cr<subscript>0</subscript></entry> + <entry></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + <entry>Y'<subscript>3</subscript></entry> + <entry>Y'<subscript>2</subscript></entry> + <entry>Y'<subscript>1</subscript></entry> + <entry>Y'<subscript>0</subscript></entry> + </row> + + <row id="V4L2-PIX-FMT-YUV555"> + <entry><constant>V4L2_PIX_FMT_YUV555</constant></entry> + <entry>'YUVO'</entry> + <entry></entry> + <entry>Cb<subscript>2</subscript></entry> + <entry>Cb<subscript>1</subscript></entry> + <entry>Cb<subscript>0</subscript></entry> + <entry>Cr<subscript>4</subscript></entry> + <entry>Cr<subscript>3</subscript></entry> + <entry>Cr<subscript>2</subscript></entry> + <entry>Cr<subscript>1</subscript></entry> + <entry>Cr<subscript>0</subscript></entry> + <entry></entry> + <entry>a</entry> + <entry>Y'<subscript>4</subscript></entry> + <entry>Y'<subscript>3</subscript></entry> + <entry>Y'<subscript>2</subscript></entry> + <entry>Y'<subscript>1</subscript></entry> + <entry>Y'<subscript>0</subscript></entry> + <entry>Cb<subscript>4</subscript></entry> + <entry>Cb<subscript>3</subscript></entry> + </row> + + <row id="V4L2-PIX-FMT-YUV565"> + <entry><constant>V4L2_PIX_FMT_YUV565</constant></entry> + <entry>'YUVP'</entry> + <entry></entry> + <entry>Cb<subscript>2</subscript></entry> + <entry>Cb<subscript>1</subscript></entry> + <entry>Cb<subscript>0</subscript></entry> + <entry>Cr<subscript>4</subscript></entry> + <entry>Cr<subscript>3</subscript></entry> + <entry>Cr<subscript>2</subscript></entry> + <entry>Cr<subscript>1</subscript></entry> + <entry>Cr<subscript>0</subscript></entry> + <entry></entry> + <entry>Y'<subscript>4</subscript></entry> + <entry>Y'<subscript>3</subscript></entry> + <entry>Y'<subscript>2</subscript></entry> + <entry>Y'<subscript>1</subscript></entry> + <entry>Y'<subscript>0</subscript></entry> + <entry>Cb<subscript>5</subscript></entry> + <entry>Cb<subscript>4</subscript></entry> + <entry>Cb<subscript>3</subscript></entry> + </row> + + <row id="V4L2-PIX-FMT-YUV32"> + <entry><constant>V4L2_PIX_FMT_YUV32</constant></entry> + <entry>'YUV4'</entry> + <entry></entry> + <entry>a<subscript>7</subscript></entry> + <entry>a<subscript>6</subscript></entry> + <entry>a<subscript>5</subscript></entry> + <entry>a<subscript>4</subscript></entry> + <entry>a<subscript>3</subscript></entry> + <entry>a<subscript>2</subscript></entry> + <entry>a<subscript>1</subscript></entry> + <entry>a<subscript>0</subscript></entry> + <entry></entry> + <entry>Y'<subscript>7</subscript></entry> + <entry>Y'<subscript>6</subscript></entry> + <entry>Y'<subscript>5</subscript></entry> + <entry>Y'<subscript>4</subscript></entry> + <entry>Y'<subscript>3</subscript></entry> + <entry>Y'<subscript>2</subscript></entry> + <entry>Y'<subscript>1</subscript></entry> + <entry>Y'<subscript>0</subscript></entry> + <entry></entry> + <entry>Cb<subscript>7</subscript></entry> + <entry>Cb<subscript>6</subscript></entry> + <entry>Cb<subscript>5</subscript></entry> + <entry>Cb<subscript>4</subscript></entry> + <entry>Cb<subscript>3</subscript></entry> + <entry>Cb<subscript>2</subscript></entry> + <entry>Cb<subscript>1</subscript></entry> + <entry>Cb<subscript>0</subscript></entry> + <entry></entry> + <entry>Cr<subscript>7</subscript></entry> + <entry>Cr<subscript>6</subscript></entry> + <entry>Cr<subscript>5</subscript></entry> + <entry>Cr<subscript>4</subscript></entry> + <entry>Cr<subscript>3</subscript></entry> + <entry>Cr<subscript>2</subscript></entry> + <entry>Cr<subscript>1</subscript></entry> + <entry>Cr<subscript>0</subscript></entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Bit 7 is the most significant bit. The value of a = alpha +bits is undefined when reading from the driver, ignored when writing +to the driver, except when alpha blending has been negotiated for a +<link linkend="overlay">Video Overlay</link> or <link +linkend="osd">Video Output Overlay</link>.</para> + + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-sbggr16.xml b/linux/Documentation/DocBook/v4l/pixfmt-sbggr16.xml new file mode 100644 index 000000000..519a9efba --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-sbggr16.xml @@ -0,0 +1,91 @@ +<refentry id="V4L2-PIX-FMT-SBGGR16"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_SBGGR16 ('BYR2')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_SBGGR16</constant></refname> + <refpurpose>Bayer RGB format</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This format is similar to <link +linkend="V4L2-PIX-FMT-SBGGR8"> +<constant>V4L2_PIX_FMT_SBGGR8</constant></link>, except each pixel has +a depth of 16 bits. The least significant byte is stored at lower +memory addresses (little-endian). Note the actual sampling precision +may be lower than 16 bits, for example 10 bits per pixel with values +in range 0 to 1023.</para> + + <example> + <title><constant>V4L2_PIX_FMT_SBGGR16</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>B<subscript>00low</subscript></entry> + <entry>B<subscript>00high</subscript></entry> + <entry>G<subscript>01low</subscript></entry> + <entry>G<subscript>01high</subscript></entry> + <entry>B<subscript>02low</subscript></entry> + <entry>B<subscript>02high</subscript></entry> + <entry>G<subscript>03low</subscript></entry> + <entry>G<subscript>03high</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>G<subscript>10low</subscript></entry> + <entry>G<subscript>10high</subscript></entry> + <entry>R<subscript>11low</subscript></entry> + <entry>R<subscript>11high</subscript></entry> + <entry>G<subscript>12low</subscript></entry> + <entry>G<subscript>12high</subscript></entry> + <entry>R<subscript>13low</subscript></entry> + <entry>R<subscript>13high</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>B<subscript>20low</subscript></entry> + <entry>B<subscript>20high</subscript></entry> + <entry>G<subscript>21low</subscript></entry> + <entry>G<subscript>21high</subscript></entry> + <entry>B<subscript>22low</subscript></entry> + <entry>B<subscript>22high</subscript></entry> + <entry>G<subscript>23low</subscript></entry> + <entry>G<subscript>23high</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>G<subscript>30low</subscript></entry> + <entry>G<subscript>30high</subscript></entry> + <entry>R<subscript>31low</subscript></entry> + <entry>R<subscript>31high</subscript></entry> + <entry>G<subscript>32low</subscript></entry> + <entry>G<subscript>32high</subscript></entry> + <entry>R<subscript>33low</subscript></entry> + <entry>R<subscript>33high</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> +</refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-sbggr8.xml b/linux/Documentation/DocBook/v4l/pixfmt-sbggr8.xml new file mode 100644 index 000000000..5fe84ecc2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-sbggr8.xml @@ -0,0 +1,75 @@ + <refentry id="V4L2-PIX-FMT-SBGGR8"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_SBGGR8 ('BA81')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_SBGGR8</constant></refname> + <refpurpose>Bayer RGB format</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is commonly the native format of digital cameras, +reflecting the arrangement of sensors on the CCD device. Only one red, +green or blue value is given for each pixel. Missing components must +be interpolated from neighbouring pixels. From left to right the first +row consists of a blue and green value, the second row of a green and +red value. This scheme repeats to the right and down for every two +columns and rows.</para> + + <example> + <title><constant>V4L2_PIX_FMT_SBGGR8</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>B<subscript>00</subscript></entry> + <entry>G<subscript>01</subscript></entry> + <entry>B<subscript>02</subscript></entry> + <entry>G<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>G<subscript>10</subscript></entry> + <entry>R<subscript>11</subscript></entry> + <entry>G<subscript>12</subscript></entry> + <entry>R<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>B<subscript>20</subscript></entry> + <entry>G<subscript>21</subscript></entry> + <entry>B<subscript>22</subscript></entry> + <entry>G<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>G<subscript>30</subscript></entry> + <entry>R<subscript>31</subscript></entry> + <entry>G<subscript>32</subscript></entry> + <entry>R<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-sgbrg8.xml b/linux/Documentation/DocBook/v4l/pixfmt-sgbrg8.xml new file mode 100644 index 000000000..d67a472b0 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-sgbrg8.xml @@ -0,0 +1,75 @@ + <refentry id="V4L2-PIX-FMT-SGBRG8"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_SGBRG8 ('GBRG')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_SGBRG8</constant></refname> + <refpurpose>Bayer RGB format</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is commonly the native format of digital cameras, +reflecting the arrangement of sensors on the CCD device. Only one red, +green or blue value is given for each pixel. Missing components must +be interpolated from neighbouring pixels. From left to right the first +row consists of a green and blue value, the second row of a red and +green value. This scheme repeats to the right and down for every two +columns and rows.</para> + + <example> + <title><constant>V4L2_PIX_FMT_SGBRG8</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>G<subscript>00</subscript></entry> + <entry>B<subscript>01</subscript></entry> + <entry>G<subscript>02</subscript></entry> + <entry>B<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>R<subscript>10</subscript></entry> + <entry>G<subscript>11</subscript></entry> + <entry>R<subscript>12</subscript></entry> + <entry>G<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>G<subscript>20</subscript></entry> + <entry>B<subscript>21</subscript></entry> + <entry>G<subscript>22</subscript></entry> + <entry>B<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>R<subscript>30</subscript></entry> + <entry>G<subscript>31</subscript></entry> + <entry>R<subscript>32</subscript></entry> + <entry>G<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-sgrbg8.xml b/linux/Documentation/DocBook/v4l/pixfmt-sgrbg8.xml new file mode 100644 index 000000000..0cdf13b8a --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-sgrbg8.xml @@ -0,0 +1,75 @@ + <refentry id="V4L2-PIX-FMT-SGRBG8"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_SGRBG8 ('GRBG')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_SGRBG8</constant></refname> + <refpurpose>Bayer RGB format</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is commonly the native format of digital cameras, +reflecting the arrangement of sensors on the CCD device. Only one red, +green or blue value is given for each pixel. Missing components must +be interpolated from neighbouring pixels. From left to right the first +row consists of a green and blue value, the second row of a red and +green value. This scheme repeats to the right and down for every two +columns and rows.</para> + + <example> + <title><constant>V4L2_PIX_FMT_SGRBG8</constant> 4 × +4 pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>G<subscript>00</subscript></entry> + <entry>R<subscript>01</subscript></entry> + <entry>G<subscript>02</subscript></entry> + <entry>R<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>R<subscript>10</subscript></entry> + <entry>B<subscript>11</subscript></entry> + <entry>R<subscript>12</subscript></entry> + <entry>B<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>G<subscript>20</subscript></entry> + <entry>R<subscript>21</subscript></entry> + <entry>G<subscript>22</subscript></entry> + <entry>R<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>R<subscript>30</subscript></entry> + <entry>B<subscript>31</subscript></entry> + <entry>R<subscript>32</subscript></entry> + <entry>B<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-uyvy.xml b/linux/Documentation/DocBook/v4l/pixfmt-uyvy.xml new file mode 100644 index 000000000..816c8d467 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-uyvy.xml @@ -0,0 +1,128 @@ + <refentry id="V4L2-PIX-FMT-UYVY"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_UYVY ('UYVY')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_UYVY</constant></refname> + <refpurpose>Variation of +<constant>V4L2_PIX_FMT_YUYV</constant> with different order of samples +in memory</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>In this format each four bytes is two pixels. Each four +bytes is two Y's, a Cb and a Cr. Each Y goes to one of the pixels, and +the Cb and Cr belong to both pixels. As you can see, the Cr and Cb +components have half the horizontal resolution of the Y +component.</para> + + <example> + <title><constant>V4L2_PIX_FMT_UYVY</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="9" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-vyuy.xml b/linux/Documentation/DocBook/v4l/pixfmt-vyuy.xml new file mode 100644 index 000000000..61f12a5e6 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-vyuy.xml @@ -0,0 +1,128 @@ + <refentry id="V4L2-PIX-FMT-VYUY"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_VYUY ('VYUY')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_VYUY</constant></refname> + <refpurpose>Variation of +<constant>V4L2_PIX_FMT_YUYV</constant> with different order of samples +in memory</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>In this format each four bytes is two pixels. Each four +bytes is two Y's, a Cb and a Cr. Each Y goes to one of the pixels, and +the Cb and Cr belong to both pixels. As you can see, the Cr and Cb +components have half the horizontal resolution of the Y +component.</para> + + <example> + <title><constant>V4L2_PIX_FMT_VYUY</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="9" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-y16.xml b/linux/Documentation/DocBook/v4l/pixfmt-y16.xml new file mode 100644 index 000000000..d58404015 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-y16.xml @@ -0,0 +1,89 @@ +<refentry id="V4L2-PIX-FMT-Y16"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_Y16 ('Y16 ')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_Y16</constant></refname> + <refpurpose>Grey-scale image</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is a grey-scale image with a depth of 16 bits per +pixel. The least significant byte is stored at lower memory addresses +(little-endian). Note the actual sampling precision may be lower than +16 bits, for example 10 bits per pixel with values in range 0 to +1023.</para> + + <example> + <title><constant>V4L2_PIX_FMT_Y16</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="9" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00low</subscript></entry> + <entry>Y'<subscript>00high</subscript></entry> + <entry>Y'<subscript>01low</subscript></entry> + <entry>Y'<subscript>01high</subscript></entry> + <entry>Y'<subscript>02low</subscript></entry> + <entry>Y'<subscript>02high</subscript></entry> + <entry>Y'<subscript>03low</subscript></entry> + <entry>Y'<subscript>03high</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>10low</subscript></entry> + <entry>Y'<subscript>10high</subscript></entry> + <entry>Y'<subscript>11low</subscript></entry> + <entry>Y'<subscript>11high</subscript></entry> + <entry>Y'<subscript>12low</subscript></entry> + <entry>Y'<subscript>12high</subscript></entry> + <entry>Y'<subscript>13low</subscript></entry> + <entry>Y'<subscript>13high</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Y'<subscript>20low</subscript></entry> + <entry>Y'<subscript>20high</subscript></entry> + <entry>Y'<subscript>21low</subscript></entry> + <entry>Y'<subscript>21high</subscript></entry> + <entry>Y'<subscript>22low</subscript></entry> + <entry>Y'<subscript>22high</subscript></entry> + <entry>Y'<subscript>23low</subscript></entry> + <entry>Y'<subscript>23high</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Y'<subscript>30low</subscript></entry> + <entry>Y'<subscript>30high</subscript></entry> + <entry>Y'<subscript>31low</subscript></entry> + <entry>Y'<subscript>31high</subscript></entry> + <entry>Y'<subscript>32low</subscript></entry> + <entry>Y'<subscript>32high</subscript></entry> + <entry>Y'<subscript>33low</subscript></entry> + <entry>Y'<subscript>33high</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> +</refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-y41p.xml b/linux/Documentation/DocBook/v4l/pixfmt-y41p.xml new file mode 100644 index 000000000..73c8536ef --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-y41p.xml @@ -0,0 +1,157 @@ + <refentry id="V4L2-PIX-FMT-Y41P"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_Y41P ('Y41P')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_Y41P</constant></refname> + <refpurpose>Format with ¼ horizontal chroma +resolution, also known as YUV 4:1:1</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>In this format each 12 bytes is eight pixels. In the +twelve bytes are two CbCr pairs and eight Y's. The first CbCr pair +goes with the first four Y's, and the second CbCr pair goes with the +other four Y's. The Cb and Cr components have one fourth the +horizontal resolution of the Y component.</para> + + <para>Do not confuse this format with <link +linkend="V4L2-PIX-FMT-YUV411P"><constant>V4L2_PIX_FMT_YUV411P</constant></link>. +Y41P is derived from "YUV 4:1:1 <emphasis>packed</emphasis>", while +YUV411P stands for "YUV 4:1:1 <emphasis>planar</emphasis>".</para> + + <example> + <title><constant>V4L2_PIX_FMT_Y41P</constant> 8 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="13" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + <entry>Y'<subscript>04</subscript></entry> + <entry>Y'<subscript>05</subscript></entry> + <entry>Y'<subscript>06</subscript></entry> + <entry>Y'<subscript>07</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + <entry>Y'<subscript>14</subscript></entry> + <entry>Y'<subscript>15</subscript></entry> + <entry>Y'<subscript>16</subscript></entry> + <entry>Y'<subscript>17</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + <entry>Y'<subscript>24</subscript></entry> + <entry>Y'<subscript>25</subscript></entry> + <entry>Y'<subscript>26</subscript></entry> + <entry>Y'<subscript>27</subscript></entry> + </row> + <row> + <entry>start + 36:</entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + <entry>Y'<subscript>34</subscript></entry> + <entry>Y'<subscript>35</subscript></entry> + <entry>Y'<subscript>36</subscript></entry> + <entry>Y'<subscript>37</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable></para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="15" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry><entry></entry> + <entry>4</entry><entry></entry><entry>5</entry><entry></entry> + <entry>6</entry><entry></entry><entry>7</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-yuv410.xml b/linux/Documentation/DocBook/v4l/pixfmt-yuv410.xml new file mode 100644 index 000000000..8eb4a193d --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-yuv410.xml @@ -0,0 +1,141 @@ + <refentry> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YVU410 ('YVU9'), V4L2_PIX_FMT_YUV410 ('YUV9')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname id="V4L2-PIX-FMT-YVU410"><constant>V4L2_PIX_FMT_YVU410</constant></refname> + <refname id="V4L2-PIX-FMT-YUV410"><constant>V4L2_PIX_FMT_YUV410</constant></refname> + <refpurpose>Planar formats with ¼ horizontal and +vertical chroma resolution, also known as YUV 4:1:0</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>These are planar formats, as opposed to a packed format. +The three components are separated into three sub-images or planes. +The Y plane is first. The Y plane has one byte per pixel. For +<constant>V4L2_PIX_FMT_YVU410</constant>, the Cr plane immediately +follows the Y plane in memory. The Cr plane is ¼ the width and +¼ the height of the Y plane (and of the image). Each Cr belongs +to 16 pixels, a four-by-four square of the image. Following the Cr +plane is the Cb plane, just like the Cr plane. +<constant>V4L2_PIX_FMT_YUV410</constant> is the same, except the Cb +plane comes first, then the Cr plane.</para> + + <para>If the Y plane has pad bytes after each row, then the Cr +and Cb planes have ¼ as many pad bytes after their rows. In +other words, four Cx rows (including padding) are exactly as long as +one Y row (including padding).</para> + + <example> + <title><constant>V4L2_PIX_FMT_YVU410</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cr<subscript>00</subscript></entry> + </row> + <row> + <entry>start + 17:</entry> + <entry>Cb<subscript>00</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry></entry><entry></entry><entry>C</entry> + <entry></entry><entry></entry><entry></entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-yuv411p.xml b/linux/Documentation/DocBook/v4l/pixfmt-yuv411p.xml new file mode 100644 index 000000000..00e0960a9 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-yuv411p.xml @@ -0,0 +1,155 @@ + <refentry id="V4L2-PIX-FMT-YUV411P"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YUV411P ('411P')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_YUV411P</constant></refname> + <refpurpose>Format with ¼ horizontal chroma resolution, +also known as YUV 4:1:1. Planar layout as opposed to +<constant>V4L2_PIX_FMT_Y41P</constant></refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This format is not commonly used. This is a planar +format similar to the 4:2:2 planar format except with half as many +chroma. The three components are separated into three sub-images or +planes. The Y plane is first. The Y plane has one byte per pixel. The +Cb plane immediately follows the Y plane in memory. The Cb plane is +¼ the width of the Y plane (and of the image). Each Cb belongs +to 4 pixels all on the same row. For example, +Cb<subscript>0</subscript> belongs to Y'<subscript>00</subscript>, +Y'<subscript>01</subscript>, Y'<subscript>02</subscript> and +Y'<subscript>03</subscript>. Following the Cb plane is the Cr plane, +just like the Cb plane.</para> + + <para>If the Y plane has pad bytes after each row, then the Cr +and Cb planes have ¼ as many pad bytes after their rows. In +other words, four C x rows (including padding) is exactly as long as +one Y row (including padding).</para> + + <example> + <title><constant>V4L2_PIX_FMT_YUV411P</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cb<subscript>00</subscript></entry> + </row> + <row> + <entry>start + 17:</entry> + <entry>Cb<subscript>10</subscript></entry> + </row> + <row> + <entry>start + 18:</entry> + <entry>Cb<subscript>20</subscript></entry> + </row> + <row> + <entry>start + 19:</entry> + <entry>Cb<subscript>30</subscript></entry> + </row> + <row> + <entry>start + 20:</entry> + <entry>Cr<subscript>00</subscript></entry> + </row> + <row> + <entry>start + 21:</entry> + <entry>Cr<subscript>10</subscript></entry> + </row> + <row> + <entry>start + 22:</entry> + <entry>Cr<subscript>20</subscript></entry> + </row> + <row> + <entry>start + 23:</entry> + <entry>Cr<subscript>30</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry>C</entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-yuv420.xml b/linux/Documentation/DocBook/v4l/pixfmt-yuv420.xml new file mode 100644 index 000000000..42d7de5e4 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-yuv420.xml @@ -0,0 +1,157 @@ + <refentry> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YVU420 ('YV12'), V4L2_PIX_FMT_YUV420 ('YU12')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname id="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></refname> + <refname id="V4L2-PIX-FMT-YUV420"><constant>V4L2_PIX_FMT_YUV420</constant></refname> + <refpurpose>Planar formats with ½ horizontal and +vertical chroma resolution, also known as YUV 4:2:0</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>These are planar formats, as opposed to a packed format. +The three components are separated into three sub- images or planes. +The Y plane is first. The Y plane has one byte per pixel. For +<constant>V4L2_PIX_FMT_YVU420</constant>, the Cr plane immediately +follows the Y plane in memory. The Cr plane is half the width and half +the height of the Y plane (and of the image). Each Cr belongs to four +pixels, a two-by-two square of the image. For example, +Cr<subscript>0</subscript> belongs to Y'<subscript>00</subscript>, +Y'<subscript>01</subscript>, Y'<subscript>10</subscript>, and +Y'<subscript>11</subscript>. Following the Cr plane is the Cb plane, +just like the Cr plane. <constant>V4L2_PIX_FMT_YUV420</constant> is +the same except the Cb plane comes first, then the Cr plane.</para> + + <para>If the Y plane has pad bytes after each row, then the Cr +and Cb planes have half as many pad bytes after their rows. In other +words, two Cx rows (including padding) is exactly as long as one Y row +(including padding).</para> + + <example> + <title><constant>V4L2_PIX_FMT_YVU420</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 18:</entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + </row> + <row> + <entry>start + 20:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 22:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + <row> + <entry></entry> + <entry></entry><entry>C</entry><entry></entry><entry></entry> + <entry></entry><entry>C</entry><entry></entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry></entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-yuv422p.xml b/linux/Documentation/DocBook/v4l/pixfmt-yuv422p.xml new file mode 100644 index 000000000..4348bd9f0 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-yuv422p.xml @@ -0,0 +1,161 @@ + <refentry id="V4L2-PIX-FMT-YUV422P"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YUV422P ('422P')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_YUV422P</constant></refname> + <refpurpose>Format with ½ horizontal chroma resolution, +also known as YUV 4:2:2. Planar layout as opposed to +<constant>V4L2_PIX_FMT_YUYV</constant></refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This format is not commonly used. This is a planar +version of the YUYV format. The three components are separated into +three sub-images or planes. The Y plane is first. The Y plane has one +byte per pixel. The Cb plane immediately follows the Y plane in +memory. The Cb plane is half the width of the Y plane (and of the +image). Each Cb belongs to two pixels. For example, +Cb<subscript>0</subscript> belongs to Y'<subscript>00</subscript>, +Y'<subscript>01</subscript>. Following the Cb plane is the Cr plane, +just like the Cb plane.</para> + + <para>If the Y plane has pad bytes after each row, then the Cr +and Cb planes have half as many pad bytes after their rows. In other +words, two Cx rows (including padding) is exactly as long as one Y row +(including padding).</para> + + <example> + <title><constant>V4L2_PIX_FMT_YUV422P</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="5" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + </row> + <row> + <entry>start + 4:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + </row> + <row> + <entry>start + 12:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 18:</entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + </row> + <row> + <entry>start + 20:</entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + </row> + <row> + <entry>start + 22:</entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 26:</entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + </row> + <row> + <entry>start + 28:</entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + </row> + <row> + <entry>start + 30:</entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-yuyv.xml b/linux/Documentation/DocBook/v4l/pixfmt-yuyv.xml new file mode 100644 index 000000000..bdb2ffacb --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-yuyv.xml @@ -0,0 +1,128 @@ + <refentry id="V4L2-PIX-FMT-YUYV"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YUYV ('YUYV')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_YUYV</constant></refname> + <refpurpose>Packed format with ½ horizontal chroma +resolution, also known as YUV 4:2:2</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>In this format each four bytes is two pixels. Each four +bytes is two Y's, a Cb and a Cr. Each Y goes to one of the pixels, and +the Cb and Cr belong to both pixels. As you can see, the Cr and Cb +components have half the horizontal resolution of the Y component. +<constant>V4L2_PIX_FMT_YUYV </constant> is known in the Windows +environment as YUY2.</para> + + <example> + <title><constant>V4L2_PIX_FMT_YUYV</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="9" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt-yvyu.xml b/linux/Documentation/DocBook/v4l/pixfmt-yvyu.xml new file mode 100644 index 000000000..40d17ae39 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt-yvyu.xml @@ -0,0 +1,128 @@ + <refentry id="V4L2-PIX-FMT-YVYU"> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_YVYU ('YVYU')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname><constant>V4L2_PIX_FMT_YVYU</constant></refname> + <refpurpose>Variation of +<constant>V4L2_PIX_FMT_YUYV</constant> with different order of samples +in memory</refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>In this format each four bytes is two pixels. Each four +bytes is two Y's, a Cb and a Cr. Each Y goes to one of the pixels, and +the Cb and Cr belong to both pixels. As you can see, the Cr and Cb +components have half the horizontal resolution of the Y +component.</para> + + <example> + <title><constant>V4L2_PIX_FMT_YVYU</constant> 4 × 4 +pixel image</title> + + <formalpara> + <title>Byte Order.</title> + <para>Each cell is one byte. + <informaltable frame="none"> + <tgroup cols="9" align="center"> + <colspec align="left" colwidth="2*" /> + <tbody valign="top"> + <row> + <entry>start + 0:</entry> + <entry>Y'<subscript>00</subscript></entry> + <entry>Cr<subscript>00</subscript></entry> + <entry>Y'<subscript>01</subscript></entry> + <entry>Cb<subscript>00</subscript></entry> + <entry>Y'<subscript>02</subscript></entry> + <entry>Cr<subscript>01</subscript></entry> + <entry>Y'<subscript>03</subscript></entry> + <entry>Cb<subscript>01</subscript></entry> + </row> + <row> + <entry>start + 8:</entry> + <entry>Y'<subscript>10</subscript></entry> + <entry>Cr<subscript>10</subscript></entry> + <entry>Y'<subscript>11</subscript></entry> + <entry>Cb<subscript>10</subscript></entry> + <entry>Y'<subscript>12</subscript></entry> + <entry>Cr<subscript>11</subscript></entry> + <entry>Y'<subscript>13</subscript></entry> + <entry>Cb<subscript>11</subscript></entry> + </row> + <row> + <entry>start + 16:</entry> + <entry>Y'<subscript>20</subscript></entry> + <entry>Cr<subscript>20</subscript></entry> + <entry>Y'<subscript>21</subscript></entry> + <entry>Cb<subscript>20</subscript></entry> + <entry>Y'<subscript>22</subscript></entry> + <entry>Cr<subscript>21</subscript></entry> + <entry>Y'<subscript>23</subscript></entry> + <entry>Cb<subscript>21</subscript></entry> + </row> + <row> + <entry>start + 24:</entry> + <entry>Y'<subscript>30</subscript></entry> + <entry>Cr<subscript>30</subscript></entry> + <entry>Y'<subscript>31</subscript></entry> + <entry>Cb<subscript>30</subscript></entry> + <entry>Y'<subscript>32</subscript></entry> + <entry>Cr<subscript>31</subscript></entry> + <entry>Y'<subscript>33</subscript></entry> + <entry>Cb<subscript>31</subscript></entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + + <formalpara> + <title>Color Sample Location.</title> + <para> + <informaltable frame="none"> + <tgroup cols="7" align="center"> + <tbody valign="top"> + <row> + <entry></entry> + <entry>0</entry><entry></entry><entry>1</entry><entry></entry> + <entry>2</entry><entry></entry><entry>3</entry> + </row> + <row> + <entry>0</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>1</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>2</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + <row> + <entry>3</entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry><entry></entry> + <entry>Y</entry><entry>C</entry><entry>Y</entry> + </row> + </tbody> + </tgroup> + </informaltable> + </para> + </formalpara> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/pixfmt.xml b/linux/Documentation/DocBook/v4l/pixfmt.xml new file mode 100644 index 000000000..7d396a378 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/pixfmt.xml @@ -0,0 +1,801 @@ + <title>Image Formats</title> + + <para>The V4L2 API was primarily designed for devices exchanging +image data with applications. The +<structname>v4l2_pix_format</structname> structure defines the format +and layout of an image in memory. Image formats are negotiated with +the &VIDIOC-S-FMT; ioctl. (The explanations here focus on video +capturing and output, for overlay frame buffer formats see also +&VIDIOC-G-FBUF;.)</para> + + <table pgwide="1" frame="none" id="v4l2-pix-format"> + <title>struct <structname>v4l2_pix_format</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>width</structfield></entry> + <entry>Image width in pixels.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>height</structfield></entry> + <entry>Image height in pixels.</entry> + </row> + <row> + <entry spanname="hspan">Applications set these fields to +request an image size, drivers return the closest possible values. In +case of planar formats the <structfield>width</structfield> and +<structfield>height</structfield> applies to the largest plane. To +avoid ambiguities drivers must return values rounded up to a multiple +of the scale factor of any smaller planes. For example when the image +format is YUV 4:2:0, <structfield>width</structfield> and +<structfield>height</structfield> must be multiples of two.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>pixelformat</structfield></entry> + <entry>The pixel format or type of compression, set by the +application. This is a little endian <link +linkend="v4l2-fourcc">four character code</link>. V4L2 defines +standard RGB formats in <xref linkend="rgb-formats" />, YUV formats in <xref +linkend="yuv-formats" />, and reserved codes in <xref +linkend="reserved-formats" /></entry> + </row> + <row> + <entry>&v4l2-field;</entry> + <entry><structfield>field</structfield></entry> + <entry>Video images are typically interlaced. Applications +can request to capture or output only the top or bottom field, or both +fields interlaced or sequentially stored in one buffer or alternating +in separate buffers. Drivers return the actual field order selected. +For details see <xref linkend="field-order" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>bytesperline</structfield></entry> + <entry>Distance in bytes between the leftmost pixels in two +adjacent lines.</entry> + </row> + <row> + <entry spanname="hspan"><para>Both applications and drivers +can set this field to request padding bytes at the end of each line. +Drivers however may ignore the value requested by the application, +returning <structfield>width</structfield> times bytes per pixel or a +larger value required by the hardware. That implies applications can +just set this field to zero to get a reasonable +default.</para><para>Video hardware may access padding bytes, +therefore they must reside in accessible memory. Consider cases where +padding bytes after the last line of an image cross a system page +boundary. Input devices may write padding bytes, the value is +undefined. Output devices ignore the contents of padding +bytes.</para><para>When the image format is planar the +<structfield>bytesperline</structfield> value applies to the largest +plane and is divided by the same factor as the +<structfield>width</structfield> field for any smaller planes. For +example the Cb and Cr planes of a YUV 4:2:0 image have half as many +padding bytes following each line as the Y plane. To avoid ambiguities +drivers must return a <structfield>bytesperline</structfield> value +rounded up to a multiple of the scale factor.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>sizeimage</structfield></entry> + <entry>Size in bytes of the buffer to hold a complete image, +set by the driver. Usually this is +<structfield>bytesperline</structfield> times +<structfield>height</structfield>. When the image consists of variable +length compressed data this is the maximum number of bytes required to +hold an image.</entry> + </row> + <row> + <entry>&v4l2-colorspace;</entry> + <entry><structfield>colorspace</structfield></entry> + <entry>This information supplements the +<structfield>pixelformat</structfield> and must be set by the driver, +see <xref linkend="colorspaces" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>priv</structfield></entry> + <entry>Reserved for custom (driver defined) additional +information about formats. When not used drivers and applications must +set this field to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <section> + <title>Standard Image Formats</title> + + <para>In order to exchange images between drivers and +applications, it is necessary to have standard image data formats +which both sides will interpret the same way. V4L2 includes several +such formats, and this section is intended to be an unambiguous +specification of the standard image data formats in V4L2.</para> + + <para>V4L2 drivers are not limited to these formats, however. +Driver-specific formats are possible. In that case the application may +depend on a codec to convert images to one of the standard formats +when needed. But the data can still be stored and retrieved in the +proprietary format. For example, a device may support a proprietary +compressed format. Applications can still capture and save the data in +the compressed format, saving much disk space, and later use a codec +to convert the images to the X Windows screen format when the video is +to be displayed.</para> + + <para>Even so, ultimately, some standard formats are needed, so +the V4L2 specification would not be complete without well-defined +standard formats.</para> + + <para>The V4L2 standard formats are mainly uncompressed formats. The +pixels are always arranged in memory from left to right, and from top +to bottom. The first byte of data in the image buffer is always for +the leftmost pixel of the topmost row. Following that is the pixel +immediately to its right, and so on until the end of the top row of +pixels. Following the rightmost pixel of the row there may be zero or +more bytes of padding to guarantee that each row of pixel data has a +certain alignment. Following the pad bytes, if any, is data for the +leftmost pixel of the second row from the top, and so on. The last row +has just as many pad bytes after it as the other rows.</para> + + <para>In V4L2 each format has an identifier which looks like +<constant>PIX_FMT_XXX</constant>, defined in the <link +linkend="videodev">videodev.h</link> header file. These identifiers +represent <link linkend="v4l2-fourcc">four character codes</link> +which are also listed below, however they are not the same as those +used in the Windows world.</para> + </section> + + <section id="colorspaces"> + <title>Colorspaces</title> + + <para>[intro]</para> + + <!-- See proposal by Billy Biggs, video4linux-list@redhat.com +on 11 Oct 2002, subject: "Re: [V4L] Re: v4l2 api", and +http://vektor.theorem.ca/graphics/ycbcr/ and +http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html --> + + <para> + <variablelist> + <varlistentry> + <term>Gamma Correction</term> + <listitem> + <para>[to do]</para> + <para>E'<subscript>R</subscript> = f(R)</para> + <para>E'<subscript>G</subscript> = f(G)</para> + <para>E'<subscript>B</subscript> = f(B)</para> + </listitem> + </varlistentry> + <varlistentry> + <term>Construction of luminance and color-difference +signals</term> + <listitem> + <para>[to do]</para> + <para>E'<subscript>Y</subscript> = +Coeff<subscript>R</subscript> E'<subscript>R</subscript> ++ Coeff<subscript>G</subscript> E'<subscript>G</subscript> ++ Coeff<subscript>B</subscript> E'<subscript>B</subscript></para> + <para>(E'<subscript>R</subscript> - E'<subscript>Y</subscript>) = E'<subscript>R</subscript> +- Coeff<subscript>R</subscript> E'<subscript>R</subscript> +- Coeff<subscript>G</subscript> E'<subscript>G</subscript> +- Coeff<subscript>B</subscript> E'<subscript>B</subscript></para> + <para>(E'<subscript>B</subscript> - E'<subscript>Y</subscript>) = E'<subscript>B</subscript> +- Coeff<subscript>R</subscript> E'<subscript>R</subscript> +- Coeff<subscript>G</subscript> E'<subscript>G</subscript> +- Coeff<subscript>B</subscript> E'<subscript>B</subscript></para> + </listitem> + </varlistentry> + <varlistentry> + <term>Re-normalized color-difference signals</term> + <listitem> + <para>The color-difference signals are scaled back to unity +range [-0.5;+0.5]:</para> + <para>K<subscript>B</subscript> = 0.5 / (1 - Coeff<subscript>B</subscript>)</para> + <para>K<subscript>R</subscript> = 0.5 / (1 - Coeff<subscript>R</subscript>)</para> + <para>P<subscript>B</subscript> = +K<subscript>B</subscript> (E'<subscript>B</subscript> - E'<subscript>Y</subscript>) = + 0.5 (Coeff<subscript>R</subscript> / Coeff<subscript>B</subscript>) E'<subscript>R</subscript> ++ 0.5 (Coeff<subscript>G</subscript> / Coeff<subscript>B</subscript>) E'<subscript>G</subscript> ++ 0.5 E'<subscript>B</subscript></para> + <para>P<subscript>R</subscript> = +K<subscript>R</subscript> (E'<subscript>R</subscript> - E'<subscript>Y</subscript>) = + 0.5 E'<subscript>R</subscript> ++ 0.5 (Coeff<subscript>G</subscript> / Coeff<subscript>R</subscript>) E'<subscript>G</subscript> ++ 0.5 (Coeff<subscript>B</subscript> / Coeff<subscript>R</subscript>) E'<subscript>B</subscript></para> + </listitem> + </varlistentry> + <varlistentry> + <term>Quantization</term> + <listitem> + <para>[to do]</para> + <para>Y' = (Lum. Levels - 1) · E'<subscript>Y</subscript> + Lum. Offset</para> + <para>C<subscript>B</subscript> = (Chrom. Levels - 1) +· P<subscript>B</subscript> + Chrom. Offset</para> + <para>C<subscript>R</subscript> = (Chrom. Levels - 1) +· P<subscript>R</subscript> + Chrom. Offset</para> + <para>Rounding to the nearest integer and clamping to the range +[0;255] finally yields the digital color components Y'CbCr +stored in YUV images.</para> + </listitem> + </varlistentry> + </variablelist> + </para> + + <example> + <title>ITU-R Rec. BT.601 color conversion</title> + + <para>Forward Transformation</para> + + <programlisting> +int ER, EG, EB; /* gamma corrected RGB input [0;255] */ +int Y1, Cb, Cr; /* output [0;255] */ + +double r, g, b; /* temporaries */ +double y1, pb, pr; + +int +clamp (double x) +{ + int r = x; /* round to nearest */ + + if (r < 0) return 0; + else if (r > 255) return 255; + else return r; +} + +r = ER / 255.0; +g = EG / 255.0; +b = EB / 255.0; + +y1 = 0.299 * r + 0.587 * g + 0.114 * b; +pb = -0.169 * r - 0.331 * g + 0.5 * b; +pr = 0.5 * r - 0.419 * g - 0.081 * b; + +Y1 = clamp (219 * y1 + 16); +Cb = clamp (224 * pb + 128); +Cr = clamp (224 * pr + 128); + +/* or shorter */ + +y1 = 0.299 * ER + 0.587 * EG + 0.114 * EB; + +Y1 = clamp ( (219 / 255.0) * y1 + 16); +Cb = clamp (((224 / 255.0) / (2 - 2 * 0.114)) * (EB - y1) + 128); +Cr = clamp (((224 / 255.0) / (2 - 2 * 0.299)) * (ER - y1) + 128); + </programlisting> + + <para>Inverse Transformation</para> + + <programlisting> +int Y1, Cb, Cr; /* gamma pre-corrected input [0;255] */ +int ER, EG, EB; /* output [0;255] */ + +double r, g, b; /* temporaries */ +double y1, pb, pr; + +int +clamp (double x) +{ + int r = x; /* round to nearest */ + + if (r < 0) return 0; + else if (r > 255) return 255; + else return r; +} + +y1 = (255 / 219.0) * (Y1 - 16); +pb = (255 / 224.0) * (Cb - 128); +pr = (255 / 224.0) * (Cr - 128); + +r = 1.0 * y1 + 0 * pb + 1.402 * pr; +g = 1.0 * y1 - 0.344 * pb - 0.714 * pr; +b = 1.0 * y1 + 1.772 * pb + 0 * pr; + +ER = clamp (r * 255); /* [ok? one should prob. limit y1,pb,pr] */ +EG = clamp (g * 255); +EB = clamp (b * 255); + </programlisting> + </example> + + <table pgwide="1" id="v4l2-colorspace" orient="land"> + <title>enum v4l2_colorspace</title> + <tgroup cols="11" align="center"> + <colspec align="left" /> + <colspec align="center" /> + <colspec align="left" /> + <colspec colname="cr" /> + <colspec colname="cg" /> + <colspec colname="cb" /> + <colspec colname="wp" /> + <colspec colname="gc" /> + <colspec colname="lum" /> + <colspec colname="qy" /> + <colspec colname="qc" /> + <spanspec namest="cr" nameend="cb" spanname="chrom" /> + <spanspec namest="qy" nameend="qc" spanname="quant" /> + <spanspec namest="lum" nameend="qc" spanname="spam" /> + <thead> + <row> + <entry morerows="1">Identifier</entry> + <entry morerows="1">Value</entry> + <entry morerows="1">Description</entry> + <entry spanname="chrom">Chromaticities<footnote> + <para>The coordinates of the color primaries are +given in the CIE system (1931)</para> + </footnote></entry> + <entry morerows="1">White Point</entry> + <entry morerows="1">Gamma Correction</entry> + <entry morerows="1">Luminance E'<subscript>Y</subscript></entry> + <entry spanname="quant">Quantization</entry> + </row> + <row> + <entry>Red</entry> + <entry>Green</entry> + <entry>Blue</entry> + <entry>Y'</entry> + <entry>Cb, Cr</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_COLORSPACE_SMPTE170M</constant></entry> + <entry>1</entry> + <entry>NTSC/PAL according to <xref linkend="smpte170m" />, +<xref linkend="itu601" /></entry> + <entry>x = 0.630, y = 0.340</entry> + <entry>x = 0.310, y = 0.595</entry> + <entry>x = 0.155, y = 0.070</entry> + <entry>x = 0.3127, y = 0.3290, + Illuminant D<subscript>65</subscript></entry> + <entry>E' = 4.5 I for I ≤0.018, +1.099 I<superscript>0.45</superscript> - 0.099 for 0.018 < I</entry> + <entry>0.299 E'<subscript>R</subscript> ++ 0.587 E'<subscript>G</subscript> ++ 0.114 E'<subscript>B</subscript></entry> + <entry>219 E'<subscript>Y</subscript> + 16</entry> + <entry>224 P<subscript>B,R</subscript> + 128</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_SMPTE240M</constant></entry> + <entry>2</entry> + <entry>1125-Line (US) HDTV, see <xref +linkend="smpte240m" /></entry> + <entry>x = 0.630, y = 0.340</entry> + <entry>x = 0.310, y = 0.595</entry> + <entry>x = 0.155, y = 0.070</entry> + <entry>x = 0.3127, y = 0.3290, + Illuminant D<subscript>65</subscript></entry> + <entry>E' = 4 I for I ≤0.0228, +1.1115 I<superscript>0.45</superscript> - 0.1115 for 0.0228 < I</entry> + <entry>0.212 E'<subscript>R</subscript> ++ 0.701 E'<subscript>G</subscript> ++ 0.087 E'<subscript>B</subscript></entry> + <entry>219 E'<subscript>Y</subscript> + 16</entry> + <entry>224 P<subscript>B,R</subscript> + 128</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_REC709</constant></entry> + <entry>3</entry> + <entry>HDTV and modern devices, see <xref +linkend="itu709" /></entry> + <entry>x = 0.640, y = 0.330</entry> + <entry>x = 0.300, y = 0.600</entry> + <entry>x = 0.150, y = 0.060</entry> + <entry>x = 0.3127, y = 0.3290, + Illuminant D<subscript>65</subscript></entry> + <entry>E' = 4.5 I for I ≤0.018, +1.099 I<superscript>0.45</superscript> - 0.099 for 0.018 < I</entry> + <entry>0.2125 E'<subscript>R</subscript> ++ 0.7154 E'<subscript>G</subscript> ++ 0.0721 E'<subscript>B</subscript></entry> + <entry>219 E'<subscript>Y</subscript> + 16</entry> + <entry>224 P<subscript>B,R</subscript> + 128</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_BT878</constant></entry> + <entry>4</entry> + <entry>Broken Bt878 extents<footnote> + <para>The ubiquitous Bt878 video capture chip +quantizes E'<subscript>Y</subscript> to 238 levels, yielding a range +of Y' = 16 … 253, unlike Rec. 601 Y' = 16 … +235. This is not a typo in the Bt878 documentation, it has been +implemented in silicon. The chroma extents are unclear.</para> + </footnote>, <xref linkend="itu601" /></entry> + <entry>?</entry> + <entry>?</entry> + <entry>?</entry> + <entry>?</entry> + <entry>?</entry> + <entry>0.299 E'<subscript>R</subscript> ++ 0.587 E'<subscript>G</subscript> ++ 0.114 E'<subscript>B</subscript></entry> + <entry><emphasis>237</emphasis> E'<subscript>Y</subscript> + 16</entry> + <entry>224 P<subscript>B,R</subscript> + 128 (probably)</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_470_SYSTEM_M</constant></entry> + <entry>5</entry> + <entry>M/NTSC<footnote> + <para>No identifier exists for M/PAL which uses +the chromaticities of M/NTSC, the remaining parameters are equal to B and +G/PAL.</para> + </footnote> according to <xref linkend="itu470" />, <xref + linkend="itu601" /></entry> + <entry>x = 0.67, y = 0.33</entry> + <entry>x = 0.21, y = 0.71</entry> + <entry>x = 0.14, y = 0.08</entry> + <entry>x = 0.310, y = 0.316, Illuminant C</entry> + <entry>?</entry> + <entry>0.299 E'<subscript>R</subscript> ++ 0.587 E'<subscript>G</subscript> ++ 0.114 E'<subscript>B</subscript></entry> + <entry>219 E'<subscript>Y</subscript> + 16</entry> + <entry>224 P<subscript>B,R</subscript> + 128</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant></entry> + <entry>6</entry> + <entry>625-line PAL and SECAM systems according to <xref +linkend="itu470" />, <xref linkend="itu601" /></entry> + <entry>x = 0.64, y = 0.33</entry> + <entry>x = 0.29, y = 0.60</entry> + <entry>x = 0.15, y = 0.06</entry> + <entry>x = 0.313, y = 0.329, +Illuminant D<subscript>65</subscript></entry> + <entry>?</entry> + <entry>0.299 E'<subscript>R</subscript> ++ 0.587 E'<subscript>G</subscript> ++ 0.114 E'<subscript>B</subscript></entry> + <entry>219 E'<subscript>Y</subscript> + 16</entry> + <entry>224 P<subscript>B,R</subscript> + 128</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_JPEG</constant></entry> + <entry>7</entry> + <entry>JPEG Y'CbCr, see <xref linkend="jfif" />, <xref linkend="itu601" /></entry> + <entry>?</entry> + <entry>?</entry> + <entry>?</entry> + <entry>?</entry> + <entry>?</entry> + <entry>0.299 E'<subscript>R</subscript> ++ 0.587 E'<subscript>G</subscript> ++ 0.114 E'<subscript>B</subscript></entry> + <entry>256 E'<subscript>Y</subscript> + 16<footnote> + <para>Note JFIF quantizes +Y'P<subscript>B</subscript>P<subscript>R</subscript> in range [0;+1] and +[-0.5;+0.5] to <emphasis>257</emphasis> levels, however Y'CbCr signals +are still clamped to [0;255].</para> + </footnote></entry> + <entry>256 P<subscript>B,R</subscript> + 128</entry> + </row> + <row> + <entry><constant>V4L2_COLORSPACE_SRGB</constant></entry> + <entry>8</entry> + <entry>[?]</entry> + <entry>x = 0.640, y = 0.330</entry> + <entry>x = 0.300, y = 0.600</entry> + <entry>x = 0.150, y = 0.060</entry> + <entry>x = 0.3127, y = 0.3290, + Illuminant D<subscript>65</subscript></entry> + <entry>E' = 4.5 I for I ≤0.018, +1.099 I<superscript>0.45</superscript> - 0.099 for 0.018 < I</entry> + <entry spanname="spam">n/a</entry> + </row> + </tbody> + </tgroup> + </table> + </section> + + <section id="pixfmt-indexed"> + <title>Indexed Format</title> + + <para>In this format each pixel is represented by an 8 bit index +into a 256 entry ARGB palette. It is intended for <link +linkend="osd">Video Output Overlays</link> only. There are no ioctls to +access the palette, this must be done with ioctls of the Linux framebuffer API.</para> + + <table pgwide="0" frame="none"> + <title>Indexed Image Format</title> + <tgroup cols="37" align="center"> + <colspec colname="id" align="left" /> + <colspec colname="fourcc" /> + <colspec colname="bit" /> + + <colspec colnum="4" colname="b07" align="center" /> + <colspec colnum="5" colname="b06" align="center" /> + <colspec colnum="6" colname="b05" align="center" /> + <colspec colnum="7" colname="b04" align="center" /> + <colspec colnum="8" colname="b03" align="center" /> + <colspec colnum="9" colname="b02" align="center" /> + <colspec colnum="10" colname="b01" align="center" /> + <colspec colnum="11" colname="b00" align="center" /> + + <spanspec namest="b07" nameend="b00" spanname="b0" /> + <spanspec namest="b17" nameend="b10" spanname="b1" /> + <spanspec namest="b27" nameend="b20" spanname="b2" /> + <spanspec namest="b37" nameend="b30" spanname="b3" /> + <thead> + <row> + <entry>Identifier</entry> + <entry>Code</entry> + <entry> </entry> + <entry spanname="b0">Byte 0</entry> + </row> + <row> + <entry> </entry> + <entry> </entry> + <entry>Bit</entry> + <entry>7</entry> + <entry>6</entry> + <entry>5</entry> + <entry>4</entry> + <entry>3</entry> + <entry>2</entry> + <entry>1</entry> + <entry>0</entry> + </row> + </thead> + <tbody valign="top"> + <row id="V4L2-PIX-FMT-PAL8"> + <entry><constant>V4L2_PIX_FMT_PAL8</constant></entry> + <entry>'PAL8'</entry> + <entry></entry> + <entry>i<subscript>7</subscript></entry> + <entry>i<subscript>6</subscript></entry> + <entry>i<subscript>5</subscript></entry> + <entry>i<subscript>4</subscript></entry> + <entry>i<subscript>3</subscript></entry> + <entry>i<subscript>2</subscript></entry> + <entry>i<subscript>1</subscript></entry> + <entry>i<subscript>0</subscript></entry> + </row> + </tbody> + </tgroup> + </table> + </section> + + <section id="pixfmt-rgb"> + <title>RGB Formats</title> + + &sub-packed-rgb; + &sub-sbggr8; + &sub-sgbrg8; + &sub-sgrbg8; + &sub-sbggr16; + </section> + + <section id="yuv-formats"> + <title>YUV Formats</title> + + <para>YUV is the format native to TV broadcast and composite video +signals. It separates the brightness information (Y) from the color +information (U and V or Cb and Cr). The color information consists of +red and blue <emphasis>color difference</emphasis> signals, this way +the green component can be reconstructed by subtracting from the +brightness component. See <xref linkend="colorspaces" /> for conversion +examples. YUV was chosen because early television would only transmit +brightness information. To add color in a way compatible with existing +receivers a new signal carrier was added to transmit the color +difference signals. Secondary in the YUV format the U and V components +usually have lower resolution than the Y component. This is an analog +video compression technique taking advantage of a property of the +human visual system, being more sensitive to brightness +information.</para> + + &sub-packed-yuv; + &sub-grey; + &sub-y16; + &sub-yuyv; + &sub-uyvy; + &sub-yvyu; + &sub-vyuy; + &sub-y41p; + &sub-yuv420; + &sub-yuv410; + &sub-yuv422p; + &sub-yuv411p; + &sub-nv12; + &sub-nv16; + </section> + + <section> + <title>Compressed Formats</title> + + <table pgwide="1" frame="none" id="compressed-formats"> + <title>Compressed Image Formats</title> + <tgroup cols="3" align="left"> + &cs-def; + <thead> + <row> + <entry>Identifier</entry> + <entry>Code</entry> + <entry>Details</entry> + </row> + </thead> + <tbody valign="top"> + <row id="V4L2-PIX-FMT-JPEG"> + <entry><constant>V4L2_PIX_FMT_JPEG</constant></entry> + <entry>'JPEG'</entry> + <entry>TBD. See also &VIDIOC-G-JPEGCOMP;, + &VIDIOC-S-JPEGCOMP;.</entry> + </row> + <row id="V4L2-PIX-FMT-MPEG"> + <entry><constant>V4L2_PIX_FMT_MPEG</constant></entry> + <entry>'MPEG'</entry> + <entry>MPEG stream. The actual format is determined by +extended control <constant>V4L2_CID_MPEG_STREAM_TYPE</constant>, see +<xref linkend="mpeg-control-id" />.</entry> + </row> + </tbody> + </tgroup> + </table> + </section> + + <section id="pixfmt-reserved"> + <title>Reserved Format Identifiers</title> + + <para>These formats are not defined by this specification, they +are just listed for reference and to avoid naming conflicts. If you +want to register your own format, send an e-mail to the linux-media mailing +list &v4l-ml; for inclusion in the <filename>videodev2.h</filename> +file. If you want to share your format with other developers add a +link to your documentation and send a copy to the linux-media mailing list +for inclusion in this section. If you think your format should be listed +in a standard format section please make a proposal on the linux-media mailing +list.</para> + + <table pgwide="1" frame="none" id="reserved-formats"> + <title>Reserved Image Formats</title> + <tgroup cols="3" align="left"> + &cs-def; + <thead> + <row> + <entry>Identifier</entry> + <entry>Code</entry> + <entry>Details</entry> + </row> + </thead> + <tbody valign="top"> + <row id="V4L2-PIX-FMT-DV"> + <entry><constant>V4L2_PIX_FMT_DV</constant></entry> + <entry>'dvsd'</entry> + <entry>unknown</entry> + </row> + <row id="V4L2-PIX-FMT-ET61X251"> + <entry><constant>V4L2_PIX_FMT_ET61X251</constant></entry> + <entry>'E625'</entry> + <entry>Compressed format of the ET61X251 driver.</entry> + </row> + <row id="V4L2-PIX-FMT-HI240"> + <entry><constant>V4L2_PIX_FMT_HI240</constant></entry> + <entry>'HI24'</entry> + <entry><para>8 bit RGB format used by the BTTV driver.</para></entry> + </row> + <row id="V4L2-PIX-FMT-HM12"> + <entry><constant>V4L2_PIX_FMT_HM12</constant></entry> + <entry>'HM12'</entry> + <entry><para>YUV 4:2:0 format used by the +IVTV driver, <ulink url="http://www.ivtvdriver.org/"> +http://www.ivtvdriver.org/</ulink></para><para>The format is documented in the +kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.hm12</filename> +</para></entry> + </row> + <row id="V4L2-PIX-FMT-SPCA501"> + <entry><constant>V4L2_PIX_FMT_SPCA501</constant></entry> + <entry>'S501'</entry> + <entry>YUYV per line used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SPCA505"> + <entry><constant>V4L2_PIX_FMT_SPCA505</constant></entry> + <entry>'S505'</entry> + <entry>YYUV per line used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SPCA508"> + <entry><constant>V4L2_PIX_FMT_SPCA508</constant></entry> + <entry>'S508'</entry> + <entry>YUVY per line used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SPCA561"> + <entry><constant>V4L2_PIX_FMT_SPCA561</constant></entry> + <entry>'S561'</entry> + <entry>Compressed GBRG Bayer format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SGRBG10"> + <entry><constant>V4L2_PIX_FMT_SGRBG10</constant></entry> + <entry>'DA10'</entry> + <entry>10 bit raw Bayer, expanded to 16 bits.</entry> + </row> + <row id="V4L2-PIX-FMT-SGRBG10DPCM8"> + <entry><constant>V4L2_PIX_FMT_SGRBG10DPCM8</constant></entry> + <entry>'DB10'</entry> + <entry>10 bit raw Bayer DPCM compressed to 8 bits.</entry> + </row> + <row id="V4L2-PIX-FMT-PAC207"> + <entry><constant>V4L2_PIX_FMT_PAC207</constant></entry> + <entry>'P207'</entry> + <entry>Compressed BGGR Bayer format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-MR97310A"> + <entry><constant>V4L2_PIX_FMT_MR97310A</constant></entry> + <entry>'M310'</entry> + <entry>Compressed BGGR Bayer format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-OV511"> + <entry><constant>V4L2_PIX_FMT_OV511</constant></entry> + <entry>'O511'</entry> + <entry>OV511 JPEG format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-OV518"> + <entry><constant>V4L2_PIX_FMT_OV518</constant></entry> + <entry>'O518'</entry> + <entry>OV518 JPEG format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-PJPG"> + <entry><constant>V4L2_PIX_FMT_PJPG</constant></entry> + <entry>'PJPG'</entry> + <entry>Pixart 73xx JPEG format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SQ905C"> + <entry><constant>V4L2_PIX_FMT_SQ905C</constant></entry> + <entry>'905C'</entry> + <entry>Compressed RGGB bayer format used by the gspca driver.</entry> + </row> + <row id="V4L2-PIX-FMT-MJPEG"> + <entry><constant>V4L2_PIX_FMT_MJPEG</constant></entry> + <entry>'MJPG'</entry> + <entry>Compressed format used by the Zoran driver</entry> + </row> + <row id="V4L2-PIX-FMT-PWC1"> + <entry><constant>V4L2_PIX_FMT_PWC1</constant></entry> + <entry>'PWC1'</entry> + <entry>Compressed format of the PWC driver.</entry> + </row> + <row id="V4L2-PIX-FMT-PWC2"> + <entry><constant>V4L2_PIX_FMT_PWC2</constant></entry> + <entry>'PWC2'</entry> + <entry>Compressed format of the PWC driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SN9C10X"> + <entry><constant>V4L2_PIX_FMT_SN9C10X</constant></entry> + <entry>'S910'</entry> + <entry>Compressed format of the SN9C102 driver.</entry> + </row> + <row id="V4L2-PIX-FMT-SN9C20X-I420"> + <entry><constant>V4L2_PIX_FMT_SN9C20X_I420</constant></entry> + <entry>'S920'</entry> + <entry>YUV 4:2:0 format of the gspca sn9c20x driver.</entry> + </row> + <row id="V4L2-PIX-FMT-WNVA"> + <entry><constant>V4L2_PIX_FMT_WNVA</constant></entry> + <entry>'WNVA'</entry> + <entry><para>Used by the Winnov Videum driver, <ulink +url="http://www.thedirks.org/winnov/"> +http://www.thedirks.org/winnov/</ulink></para></entry> + </row> + <row id="V4L2-PIX-FMT-TM6000"> + <entry><constant>V4L2_PIX_FMT_TM6000</constant></entry> + <entry>'TM60'</entry> + <entry><para>Used by Trident tm6000</para></entry> + </row> + <row id="V4L2-PIX-FMT-YYUV"> + <entry><constant>V4L2_PIX_FMT_YYUV</constant></entry> + <entry>'YYUV'</entry> + <entry>unknown</entry> + </row> + </tbody> + </tgroup> + </table> + </section> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> diff --git a/linux/Documentation/DocBook/v4l/remote_controllers.xml b/linux/Documentation/DocBook/v4l/remote_controllers.xml new file mode 100644 index 000000000..73f5eab09 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/remote_controllers.xml @@ -0,0 +1,175 @@ +<title>Remote Controllers</title> +<section id="Remote_controllers_Intro"> +<title>Introduction</title> + +<para>Currently, most analog and digital devices have a Infrared input for remote controllers. Each +manufacturer has their own type of control. It is not rare for the same manufacturer to ship different +types of controls, depending on the device.</para> +<para>Unfortunately, for several years, there was no effort to create uniform IR keycodes for +different devices. This caused the same IR keyname to be mapped completely differently on +different IR devices. This resulted that the same IR keyname to be mapped completely different on +different IR's. Due to that, V4L2 API now specifies a standard for mapping Media keys on IR.</para> +<para>This standard should be used by both V4L/DVB drivers and userspace applications</para> +<para>The modules register the remote as keyboard within the linux input layer. This means that the IR key strokes will look like normal keyboard key strokes (if CONFIG_INPUT_KEYBOARD is enabled). Using the event devices (CONFIG_INPUT_EVDEV) it is possible for applications to access the remote via /dev/input/event devices.</para> + +<table pgwide="1" frame="none" id="rc_standard_keymap"> +<title>IR default keymapping</title> +<tgroup cols="3"> +&cs-str; +<tbody valign="top"> +<row> +<entry>Key code</entry> +<entry>Meaning</entry> +<entry>Key examples on IR</entry> +</row> + +<row><entry><emphasis role="bold">Numeric keys</emphasis></entry></row> + +<row><entry><constant>KEY_0</constant></entry><entry>Keyboard digit 0</entry><entry>0</entry></row> +<row><entry><constant>KEY_1</constant></entry><entry>Keyboard digit 1</entry><entry>1</entry></row> +<row><entry><constant>KEY_2</constant></entry><entry>Keyboard digit 2</entry><entry>2</entry></row> +<row><entry><constant>KEY_3</constant></entry><entry>Keyboard digit 3</entry><entry>3</entry></row> +<row><entry><constant>KEY_4</constant></entry><entry>Keyboard digit 4</entry><entry>4</entry></row> +<row><entry><constant>KEY_5</constant></entry><entry>Keyboard digit 5</entry><entry>5</entry></row> +<row><entry><constant>KEY_6</constant></entry><entry>Keyboard digit 6</entry><entry>6</entry></row> +<row><entry><constant>KEY_7</constant></entry><entry>Keyboard digit 7</entry><entry>7</entry></row> +<row><entry><constant>KEY_8</constant></entry><entry>Keyboard digit 8</entry><entry>8</entry></row> +<row><entry><constant>KEY_9</constant></entry><entry>Keyboard digit 9</entry><entry>9</entry></row> + +<row><entry><emphasis role="bold">Movie play control</emphasis></entry></row> + +<row><entry><constant>KEY_FORWARD</constant></entry><entry>Instantly advance in time</entry><entry>>> / FORWARD</entry></row> +<row><entry><constant>KEY_BACK</constant></entry><entry>Instantly go back in time</entry><entry><<< / BACK</entry></row> +<row><entry><constant>KEY_FASTFORWARD</constant></entry><entry>Play movie faster</entry><entry>>>> / FORWARD</entry></row> +<row><entry><constant>KEY_REWIND</constant></entry><entry>Play movie back</entry><entry>REWIND / BACKWARD</entry></row> +<row><entry><constant>KEY_NEXT</constant></entry><entry>Select next chapter / sub-chapter / interval</entry><entry>NEXT / SKIP</entry></row> +<row><entry><constant>KEY_PREVIOUS</constant></entry><entry>Select previous chapter / sub-chapter / interval</entry><entry><< / PREV / PREVIOUS</entry></row> +<row><entry><constant>KEY_AGAIN</constant></entry><entry>Repeat the video or a video interval</entry><entry>REPEAT / LOOP / RECALL</entry></row> +<row><entry><constant>KEY_PAUSE</constant></entry><entry>Pause sroweam</entry><entry>PAUSE / FREEZE</entry></row> +<row><entry><constant>KEY_PLAY</constant></entry><entry>Play movie at the normal timeshift</entry><entry>NORMAL TIMESHIFT / LIVE / ></entry></row> +<row><entry><constant>KEY_PLAYPAUSE</constant></entry><entry>Alternate between play and pause</entry><entry>PLAY / PAUSE</entry></row> +<row><entry><constant>KEY_STOP</constant></entry><entry>Stop sroweam</entry><entry>STOP</entry></row> +<row><entry><constant>KEY_RECORD</constant></entry><entry>Start/stop recording sroweam</entry><entry>CAPTURE / REC / RECORD/PAUSE</entry></row> +<row><entry><constant>KEY_CAMERA</constant></entry><entry>Take a picture of the image</entry><entry>CAMERA ICON / CAPTURE / SNAPSHOT</entry></row> +<row><entry><constant>KEY_SHUFFLE</constant></entry><entry>Enable shuffle mode</entry><entry>SHUFFLE</entry></row> +<row><entry><constant>KEY_TIME</constant></entry><entry>Activate time shift mode</entry><entry>TIME SHIFT</entry></row> +<row><entry><constant>KEY_TITLE</constant></entry><entry>Allow changing the chapter</entry><entry>CHAPTER</entry></row> +<row><entry><constant>KEY_SUBTITLE</constant></entry><entry>Allow changing the subtitle</entry><entry>SUBTITLE</entry></row> + +<row><entry><emphasis role="bold">Image control</emphasis></entry></row> + +<row><entry><constant>KEY_BRIGHTNESSDOWN</constant></entry><entry>Decrease Brightness</entry><entry>BRIGHTNESS DECREASE</entry></row> +<row><entry><constant>KEY_BRIGHTNESSUP</constant></entry><entry>Increase Brightness</entry><entry>BRIGHTNESS INCREASE</entry></row> + +<row><entry><constant>KEY_ANGLE</constant></entry><entry>Switch video camera angle (on videos with more than one angle stored)</entry><entry>ANGLE / SWAP</entry></row> +<row><entry><constant>KEY_EPG</constant></entry><entry>Open the Elecrowonic Play Guide (EPG)</entry><entry>EPG / GUIDE</entry></row> +<row><entry><constant>KEY_TEXT</constant></entry><entry>Activate/change closed caption mode</entry><entry>CLOSED CAPTION/TELETEXT / DVD TEXT / TELETEXT / TTX</entry></row> + +<row><entry><emphasis role="bold">Audio control</emphasis></entry></row> + +<row><entry><constant>KEY_AUDIO</constant></entry><entry>Change audio source</entry><entry>AUDIO SOURCE / AUDIO / MUSIC</entry></row> +<row><entry><constant>KEY_MUTE</constant></entry><entry>Mute/unmute audio</entry><entry>MUTE / DEMUTE / UNMUTE</entry></row> +<row><entry><constant>KEY_VOLUMEDOWN</constant></entry><entry>Decrease volume</entry><entry>VOLUME- / VOLUME DOWN</entry></row> +<row><entry><constant>KEY_VOLUMEUP</constant></entry><entry>Increase volume</entry><entry>VOLUME+ / VOLUME UP</entry></row> +<row><entry><constant>KEY_MODE</constant></entry><entry>Change sound mode</entry><entry>MONO/STEREO</entry></row> +<row><entry><constant>KEY_LANGUAGE</constant></entry><entry>Select Language</entry><entry>1ST / 2ND LANGUAGE / DVD LANG / MTS/SAP / MTS SEL</entry></row> + +<row><entry><emphasis role="bold">Channel control</emphasis></entry></row> + +<row><entry><constant>KEY_CHANNEL</constant></entry><entry>Go to the next favorite channel</entry><entry>ALT / CHANNEL / CH SURFING / SURF / FAV</entry></row> +<row><entry><constant>KEY_CHANNELDOWN</constant></entry><entry>Decrease channel sequencially</entry><entry>CHANNEL - / CHANNEL DOWN / DOWN</entry></row> +<row><entry><constant>KEY_CHANNELUP</constant></entry><entry>Increase channel sequencially</entry><entry>CHANNEL + / CHANNEL UP / UP</entry></row> +<row><entry><constant>KEY_DIGITS</constant></entry><entry>Use more than one digit for channel</entry><entry>PLUS / 100/ 1xx / xxx / -/-- / Single Double Triple Digit</entry></row> +<row><entry><constant>KEY_SEARCH</constant></entry><entry>Start channel autoscan</entry><entry>SCAN / AUTOSCAN</entry></row> + +<row><entry><emphasis role="bold">Colored keys</emphasis></entry></row> + +<row><entry><constant>KEY_BLUE</constant></entry><entry>IR Blue key</entry><entry>BLUE</entry></row> +<row><entry><constant>KEY_GREEN</constant></entry><entry>IR Green Key</entry><entry>GREEN</entry></row> +<row><entry><constant>KEY_RED</constant></entry><entry>IR Red key</entry><entry>RED</entry></row> +<row><entry><constant>KEY_YELLOW</constant></entry><entry>IR Yellow key</entry><entry> YELLOW</entry></row> + +<row><entry><emphasis role="bold">Media selection</emphasis></entry></row> + +<row><entry><constant>KEY_CD</constant></entry><entry>Change input source to Compact Disc</entry><entry>CD</entry></row> +<row><entry><constant>KEY_DVD</constant></entry><entry>Change input to DVD</entry><entry>DVD / DVD MENU</entry></row> +<row><entry><constant>KEY_EJECTCLOSECD</constant></entry><entry>Open/close the CD/DVD player</entry><entry>-> ) / CLOSE / OPEN</entry></row> + +<row><entry><constant>KEY_MEDIA</constant></entry><entry>Turn on/off Media application</entry><entry>PC/TV / TURN ON/OFF APP</entry></row> +<row><entry><constant>KEY_PC</constant></entry><entry>Selects from TV to PC</entry><entry>PC</entry></row> +<row><entry><constant>KEY_RADIO</constant></entry><entry>Put into AM/FM radio mode</entry><entry>RADIO / TV/FM / TV/RADIO / FM / FM/RADIO</entry></row> +<row><entry><constant>KEY_TV</constant></entry><entry>Select tv mode</entry><entry>TV / LIVE TV</entry></row> +<row><entry><constant>KEY_TV2</constant></entry><entry>Select Cable mode</entry><entry>AIR/CBL</entry></row> +<row><entry><constant>KEY_VCR</constant></entry><entry>Select VCR mode</entry><entry>VCR MODE / DTR</entry></row> +<row><entry><constant>KEY_VIDEO</constant></entry><entry>Alternate between input modes</entry><entry>SOURCE / SELECT / DISPLAY / SWITCH INPUTS / VIDEO</entry></row> + +<row><entry><emphasis role="bold">Power control</emphasis></entry></row> + +<row><entry><constant>KEY_POWER</constant></entry><entry>Turn on/off computer</entry><entry>SYSTEM POWER / COMPUTER POWER</entry></row> +<row><entry><constant>KEY_POWER2</constant></entry><entry>Turn on/off application</entry><entry>TV ON/OFF / POWER</entry></row> +<row><entry><constant>KEY_SLEEP</constant></entry><entry>Activate sleep timer</entry><entry>SLEEP / SLEEP TIMER</entry></row> +<row><entry><constant>KEY_SUSPEND</constant></entry><entry>Put computer into suspend mode</entry><entry>STANDBY / SUSPEND</entry></row> + +<row><entry><emphasis role="bold">Window control</emphasis></entry></row> + +<row><entry><constant>KEY_CLEAR</constant></entry><entry>Stop sroweam and return to default input video/audio</entry><entry>CLEAR / RESET / BOSS KEY</entry></row> +<row><entry><constant>KEY_CYCLEWINDOWS</constant></entry><entry>Minimize windows and move to the next one</entry><entry>ALT-TAB / MINIMIZE / DESKTOP</entry></row> +<row><entry><constant>KEY_FAVORITES</constant></entry><entry>Open the favorites sroweam window</entry><entry>TV WALL / Favorites</entry></row> +<row><entry><constant>KEY_MENU</constant></entry><entry>Call application menu</entry><entry>2ND CONTROLS (USA: MENU) / DVD/MENU / SHOW/HIDE CTRL</entry></row> +<row><entry><constant>KEY_NEW</constant></entry><entry>Open/Close Picture in Picture</entry><entry>PIP</entry></row> +<row><entry><constant>KEY_OK</constant></entry><entry>Send a confirmation code to application</entry><entry>OK / ENTER / RETURN</entry></row> +<row><entry><constant>KEY_SCREEN</constant></entry><entry>Select screen aspect ratio</entry><entry>4:3 16:9 SELECT</entry></row> +<row><entry><constant>KEY_ZOOM</constant></entry><entry>Put device into zoom/full screen mode</entry><entry>ZOOM / FULL SCREEN / ZOOM+ / HIDE PANNEL / SWITCH</entry></row> + +<row><entry><emphasis role="bold">Navigation keys</emphasis></entry></row> + +<row><entry><constant>KEY_ESC</constant></entry><entry>Cancel current operation</entry><entry>CANCEL / BACK</entry></row> +<row><entry><constant>KEY_HELP</constant></entry><entry>Open a Help window</entry><entry>HELP</entry></row> +<row><entry><constant>KEY_HOMEPAGE</constant></entry><entry>Navigate to Homepage</entry><entry>HOME</entry></row> +<row><entry><constant>KEY_INFO</constant></entry><entry>Open On Screen Display</entry><entry>DISPLAY INFORMATION / OSD</entry></row> +<row><entry><constant>KEY_WWW</constant></entry><entry>Open the default browser</entry><entry>WEB</entry></row> +<row><entry><constant>KEY_UP</constant></entry><entry>Up key</entry><entry>UP</entry></row> +<row><entry><constant>KEY_DOWN</constant></entry><entry>Down key</entry><entry>DOWN</entry></row> +<row><entry><constant>KEY_LEFT</constant></entry><entry>Left key</entry><entry>LEFT</entry></row> +<row><entry><constant>KEY_RIGHT</constant></entry><entry>Right key</entry><entry>RIGHT</entry></row> + +<row><entry><emphasis role="bold">Miscelaneous keys</emphasis></entry></row> + +<row><entry><constant>KEY_DOT</constant></entry><entry>Return a dot</entry><entry>.</entry></row> +<row><entry><constant>KEY_FN</constant></entry><entry>Select a function</entry><entry>FUNCTION</entry></row> + +</tbody> +</tgroup> +</table> + +<para>It should be noticed that, sometimes, there some fundamental missing keys at some cheaper IR's. Due to that, it is recommended to:</para> + +<table pgwide="1" frame="none" id="rc_keymap_notes"> +<title>Notes</title> +<tgroup cols="1"> +&cs-str; +<tbody valign="top"> +<row> +<entry>On simpler IR's, without separate channel keys, you need to map UP as <constant>KEY_CHANNELUP</constant></entry> +</row><row> +<entry>On simpler IR's, without separate channel keys, you need to map DOWN as <constant>KEY_CHANNELDOWN</constant></entry> +</row><row> +<entry>On simpler IR's, without separate volume keys, you need to map LEFT as <constant>KEY_VOLUMEDOWN</constant></entry> +</row><row> +<entry>On simpler IR's, without separate volume keys, you need to map RIGHT as <constant>KEY_VOLUMEUP</constant></entry> +</row> +</tbody> +</tgroup> +</table> + +</section> + +<section id="Remote_controllers_table_change"> +<title>Changing default Remote Controller mappings</title> +<para>The event interface provides two ioctls to be used against +the /dev/input/event device, to allow changing the default +keymapping.</para> + +<para>This program demonstrates how to replace the keymap tables.</para> +&sub-keytable-c; +</section> diff --git a/linux/Documentation/DocBook/v4l/v4l2.xml b/linux/Documentation/DocBook/v4l/v4l2.xml new file mode 100644 index 000000000..937b4157a --- /dev/null +++ b/linux/Documentation/DocBook/v4l/v4l2.xml @@ -0,0 +1,479 @@ + <partinfo> + <authorgroup> + <author> + <firstname>Michael</firstname> + <surname>Schimek</surname> + <othername role="mi">H</othername> + <affiliation> + <address> + <email>mschimek@gmx.at</email> + </address> + </affiliation> + </author> + + <author> + <firstname>Bill</firstname> + <surname>Dirks</surname> + <!-- Commented until Bill opts in to be spammed. + <affiliation> + <address> + <email>bill@thedirks.org</email> + </address> + </affiliation> --> + <contrib>Original author of the V4L2 API and +documentation.</contrib> + </author> + + <author> + <firstname>Hans</firstname> + <surname>Verkuil</surname> + <contrib>Designed and documented the VIDIOC_LOG_STATUS ioctl, +the extended control ioctls and major parts of the sliced VBI +API.</contrib> + <affiliation> + <address> + <email>hverkuil@xs4all.nl</email> + </address> + </affiliation> + </author> + + <author> + <firstname>Martin</firstname> + <surname>Rubli</surname> + <!-- + <affiliation> + <address> + <email>martin_rubli@logitech.com</email> + </address> + </affiliation> --> + <contrib>Designed and documented the VIDIOC_ENUM_FRAMESIZES +and VIDIOC_ENUM_FRAMEINTERVALS ioctls.</contrib> + </author> + + <author> + <firstname>Andy</firstname> + <surname>Walls</surname> + <contrib>Documented the fielded V4L2_MPEG_STREAM_VBI_FMT_IVTV +MPEG stream embedded, sliced VBI data format in this specification. +</contrib> + <affiliation> + <address> + <email>awalls@radix.net</email> + </address> + </affiliation> + </author> + + <author> + <firstname>Mauro</firstname> + <surname>Carvalho Chehab</surname> + <contrib>Documented libv4l, designed and added v4l2grab example, +Remote Controller chapter.</contrib> + <affiliation> + <address> + <email>mchehab@redhat.com</email> + </address> + </affiliation> + </author> + </authorgroup> + + <copyright> + <year>1999</year> + <year>2000</year> + <year>2001</year> + <year>2002</year> + <year>2003</year> + <year>2004</year> + <year>2005</year> + <year>2006</year> + <year>2007</year> + <year>2008</year> + <year>2009</year> + <holder>Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin +Rubli, Andy Walls, Mauro Carvalho Chehab</holder> + </copyright> + <legalnotice> + <para>Except when explicitly stated as GPL, programming examples within + this part can be used and distributed without restrictions.</para> + </legalnotice> + <revhistory> + <!-- Put document revisions here, newest first. --> + <!-- API revisions (changes and additions of defines, enums, +structs, ioctls) must be noted in more detail in the history chapter +(compat.sgml), along with the possible impact on existing drivers and +applications. --> + + <revision> + <revnumber>2.6.32</revnumber> + <date>2009-08-31</date> + <authorinitials>mcc</authorinitials> + <revremark>Now, revisions will match the kernel version where +the V4L2 API changes will be used by the Linux Kernel. +Also added Remote Controller chapter.</revremark> + </revision> + + <revision> + <revnumber>0.29</revnumber> + <date>2009-08-26</date> + <authorinitials>ev</authorinitials> + <revremark>Added documentation for string controls and for FM Transmitter controls.</revremark> + </revision> + + <revision> + <revnumber>0.28</revnumber> + <date>2009-08-26</date> + <authorinitials>gl</authorinitials> + <revremark>Added V4L2_CID_BAND_STOP_FILTER documentation.</revremark> + </revision> + + <revision> + <revnumber>0.27</revnumber> + <date>2009-08-15</date> + <authorinitials>mcc</authorinitials> + <revremark>Added libv4l and Remote Controller documentation; +added v4l2grab and keytable application examples.</revremark> + </revision> + + <revision> + <revnumber>0.26</revnumber> + <date>2009-07-23</date> + <authorinitials>hv</authorinitials> + <revremark>Finalized the RDS capture API. Added modulator and RDS encoder +capabilities. Added support for string controls.</revremark> + </revision> + + <revision> + <revnumber>0.25</revnumber> + <date>2009-01-18</date> + <authorinitials>hv</authorinitials> + <revremark>Added pixel formats VYUY, NV16 and NV61, and changed +the debug ioctls VIDIOC_DBG_G/S_REGISTER and VIDIOC_DBG_G_CHIP_IDENT. +Added camera controls V4L2_CID_ZOOM_ABSOLUTE, V4L2_CID_ZOOM_RELATIVE, +V4L2_CID_ZOOM_CONTINUOUS and V4L2_CID_PRIVACY.</revremark> + </revision> + + <revision> + <revnumber>0.24</revnumber> + <date>2008-03-04</date> + <authorinitials>mhs</authorinitials> + <revremark>Added pixel formats Y16 and SBGGR16, new controls +and a camera controls class. Removed VIDIOC_G/S_MPEGCOMP.</revremark> + </revision> + + <revision> + <revnumber>0.23</revnumber> + <date>2007-08-30</date> + <authorinitials>mhs</authorinitials> + <revremark>Fixed a typo in VIDIOC_DBG_G/S_REGISTER. +Clarified the byte order of packed pixel formats.</revremark> + </revision> + + <revision> + <revnumber>0.22</revnumber> + <date>2007-08-29</date> + <authorinitials>mhs</authorinitials> + <revremark>Added the Video Output Overlay interface, new MPEG +controls, V4L2_FIELD_INTERLACED_TB and V4L2_FIELD_INTERLACED_BT, +VIDIOC_DBG_G/S_REGISTER, VIDIOC_(TRY_)ENCODER_CMD, +VIDIOC_G_CHIP_IDENT, VIDIOC_G_ENC_INDEX, new pixel formats. +Clarifications in the cropping chapter, about RGB pixel formats, the +mmap(), poll(), select(), read() and write() functions. Typographical +fixes.</revremark> + </revision> + + <revision> + <revnumber>0.21</revnumber> + <date>2006-12-19</date> + <authorinitials>mhs</authorinitials> + <revremark>Fixed a link in the VIDIOC_G_EXT_CTRLS section.</revremark> + </revision> + + <revision> + <revnumber>0.20</revnumber> + <date>2006-11-24</date> + <authorinitials>mhs</authorinitials> + <revremark>Clarified the purpose of the audioset field in +struct v4l2_input and v4l2_output.</revremark> + </revision> + + <revision> + <revnumber>0.19</revnumber> + <date>2006-10-19</date> + <authorinitials>mhs</authorinitials> + <revremark>Documented V4L2_PIX_FMT_RGB444.</revremark> + </revision> + + <revision> + <revnumber>0.18</revnumber> + <date>2006-10-18</date> + <authorinitials>mhs</authorinitials> + <revremark>Added the description of extended controls by Hans +Verkuil. Linked V4L2_PIX_FMT_MPEG to V4L2_CID_MPEG_STREAM_TYPE.</revremark> + </revision> + + <revision> + <revnumber>0.17</revnumber> + <date>2006-10-12</date> + <authorinitials>mhs</authorinitials> + <revremark>Corrected V4L2_PIX_FMT_HM12 description.</revremark> + </revision> + + <revision> + <revnumber>0.16</revnumber> + <date>2006-10-08</date> + <authorinitials>mhs</authorinitials> + <revremark>VIDIOC_ENUM_FRAMESIZES and +VIDIOC_ENUM_FRAMEINTERVALS are now part of the API.</revremark> + </revision> + + <revision> + <revnumber>0.15</revnumber> + <date>2006-09-23</date> + <authorinitials>mhs</authorinitials> + <revremark>Cleaned up the bibliography, added BT.653 and +BT.1119. capture.c/start_capturing() for user pointer I/O did not +initialize the buffer index. Documented the V4L MPEG and MJPEG +VID_TYPEs and V4L2_PIX_FMT_SBGGR8. Updated the list of reserved pixel +formats. See the history chapter for API changes.</revremark> + </revision> + + <revision> + <revnumber>0.14</revnumber> + <date>2006-09-14</date> + <authorinitials>mr</authorinitials> + <revremark>Added VIDIOC_ENUM_FRAMESIZES and +VIDIOC_ENUM_FRAMEINTERVALS proposal for frame format enumeration of +digital devices.</revremark> + </revision> + + <revision> + <revnumber>0.13</revnumber> + <date>2006-04-07</date> + <authorinitials>mhs</authorinitials> + <revremark>Corrected the description of struct v4l2_window +clips. New V4L2_STD_ and V4L2_TUNER_MODE_LANG1_LANG2 +defines.</revremark> + </revision> + + <revision> + <revnumber>0.12</revnumber> + <date>2006-02-03</date> + <authorinitials>mhs</authorinitials> + <revremark>Corrected the description of struct +v4l2_captureparm and v4l2_outputparm.</revremark> + </revision> + + <revision> + <revnumber>0.11</revnumber> + <date>2006-01-27</date> + <authorinitials>mhs</authorinitials> + <revremark>Improved the description of struct +v4l2_tuner.</revremark> + </revision> + + <revision> + <revnumber>0.10</revnumber> + <date>2006-01-10</date> + <authorinitials>mhs</authorinitials> + <revremark>VIDIOC_G_INPUT and VIDIOC_S_PARM +clarifications.</revremark> + </revision> + + <revision> + <revnumber>0.9</revnumber> + <date>2005-11-27</date> + <authorinitials>mhs</authorinitials> + <revremark>Improved the 525 line numbering diagram. Hans +Verkuil and I rewrote the sliced VBI section. He also contributed a +VIDIOC_LOG_STATUS page. Fixed VIDIOC_S_STD call in the video standard +selection example. Various updates.</revremark> + </revision> + + <revision> + <revnumber>0.8</revnumber> + <date>2004-10-04</date> + <authorinitials>mhs</authorinitials> + <revremark>Somehow a piece of junk slipped into the capture +example, removed.</revremark> + </revision> + + <revision> + <revnumber>0.7</revnumber> + <date>2004-09-19</date> + <authorinitials>mhs</authorinitials> + <revremark>Fixed video standard selection, control +enumeration, downscaling and aspect example. Added read and user +pointer i/o to video capture example.</revremark> + </revision> + + <revision> + <revnumber>0.6</revnumber> + <date>2004-08-01</date> + <authorinitials>mhs</authorinitials> + <revremark>v4l2_buffer changes, added video capture example, +various corrections.</revremark> + </revision> + + <revision> + <revnumber>0.5</revnumber> + <date>2003-11-05</date> + <authorinitials>mhs</authorinitials> + <revremark>Pixel format erratum.</revremark> + </revision> + + <revision> + <revnumber>0.4</revnumber> + <date>2003-09-17</date> + <authorinitials>mhs</authorinitials> + <revremark>Corrected source and Makefile to generate a PDF. +SGML fixes. Added latest API changes. Closed gaps in the history +chapter.</revremark> + </revision> + + <revision> + <revnumber>0.3</revnumber> + <date>2003-02-05</date> + <authorinitials>mhs</authorinitials> + <revremark>Another draft, more corrections.</revremark> + </revision> + + <revision> + <revnumber>0.2</revnumber> + <date>2003-01-15</date> + <authorinitials>mhs</authorinitials> + <revremark>Second draft, with corrections pointed out by Gerd +Knorr.</revremark> + </revision> + + <revision> + <revnumber>0.1</revnumber> + <date>2002-12-01</date> + <authorinitials>mhs</authorinitials> + <revremark>First draft, based on documentation by Bill Dirks +and discussions on the V4L mailing list.</revremark> + </revision> + </revhistory> +</partinfo> + +<title>Video for Linux Two API Specification</title> + <subtitle>Revision 2.6.32</subtitle> + + <chapter id="common"> + &sub-common; + </chapter> + + <chapter id="pixfmt"> + &sub-pixfmt; + </chapter> + + <chapter id="io"> + &sub-io; + </chapter> + + <chapter id="devices"> + <title>Interfaces</title> + + <section id="capture"> &sub-dev-capture; </section> + <section id="overlay"> &sub-dev-overlay; </section> + <section id="output"> &sub-dev-output; </section> + <section id="osd"> &sub-dev-osd; </section> + <section id="codec"> &sub-dev-codec; </section> + <section id="effect"> &sub-dev-effect; </section> + <section id="raw-vbi"> &sub-dev-raw-vbi; </section> + <section id="sliced"> &sub-dev-sliced-vbi; </section> + <section id="ttx"> &sub-dev-teletext; </section> + <section id="radio"> &sub-dev-radio; </section> + <section id="rds"> &sub-dev-rds; </section> + </chapter> + + <chapter id="driver"> + &sub-driver; + </chapter> + + <chapter id="libv4l"> + &sub-libv4l; + </chapter> + + <chapter id="compat"> + &sub-compat; + </chapter> + + <appendix id="user-func"> + <title>Function Reference</title> + + <!-- Keep this alphabetically sorted. --> + + &sub-close; + &sub-ioctl; + <!-- All ioctls go here. --> + &sub-cropcap; + &sub-dbg-g-chip-ident; + &sub-dbg-g-register; + &sub-encoder-cmd; + &sub-enumaudio; + &sub-enumaudioout; + &sub-enum-fmt; + &sub-enum-framesizes; + &sub-enum-frameintervals; + &sub-enuminput; + &sub-enumoutput; + &sub-enumstd; + &sub-g-audio; + &sub-g-audioout; + &sub-g-crop; + &sub-g-ctrl; + &sub-g-enc-index; + &sub-g-ext-ctrls; + &sub-g-fbuf; + &sub-g-fmt; + &sub-g-frequency; + &sub-g-input; + &sub-g-jpegcomp; + &sub-g-modulator; + &sub-g-output; + &sub-g-parm; + &sub-g-priority; + &sub-g-sliced-vbi-cap; + &sub-g-std; + &sub-g-tuner; + &sub-log-status; + &sub-overlay; + &sub-qbuf; + &sub-querybuf; + &sub-querycap; + &sub-queryctrl; + &sub-querystd; + &sub-reqbufs; + &sub-s-hw-freq-seek; + &sub-streamon; + <!-- End of ioctls. --> + &sub-mmap; + &sub-munmap; + &sub-open; + &sub-poll; + &sub-read; + &sub-select; + &sub-write; + </appendix> + + <appendix id="videodev"> + <title>Video For Linux Two Header File</title> + &sub-videodev2-h; + </appendix> + + <appendix id="capture-example"> + <title>Video Capture Example</title> + &sub-capture-c; + </appendix> + + <appendix id="v4l2grab-example"> + <title>Video Grabber example using libv4l</title> + <para>This program demonstrates how to grab V4L2 images in ppm format by +using libv4l handlers. The advantage is that this grabber can potentially work +with any V4L2 driver.</para> + &sub-v4l2grab-c; + </appendix> + + &sub-media-indices; + + &sub-biblio; + diff --git a/linux/Documentation/DocBook/v4l/vbi_525.gif b/linux/Documentation/DocBook/v4l/vbi_525.gif Binary files differnew file mode 100644 index 000000000..5580b690d --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vbi_525.gif diff --git a/linux/Documentation/DocBook/v4l/vbi_525.pdf b/linux/Documentation/DocBook/v4l/vbi_525.pdf Binary files differnew file mode 100644 index 000000000..9e72c25b2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vbi_525.pdf diff --git a/linux/Documentation/DocBook/v4l/vbi_625.gif b/linux/Documentation/DocBook/v4l/vbi_625.gif Binary files differnew file mode 100644 index 000000000..34e325198 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vbi_625.gif diff --git a/linux/Documentation/DocBook/v4l/vbi_625.pdf b/linux/Documentation/DocBook/v4l/vbi_625.pdf Binary files differnew file mode 100644 index 000000000..765235e33 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vbi_625.pdf diff --git a/linux/Documentation/DocBook/v4l/vbi_hsync.gif b/linux/Documentation/DocBook/v4l/vbi_hsync.gif Binary files differnew file mode 100644 index 000000000..b02434d3b --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vbi_hsync.gif diff --git a/linux/Documentation/DocBook/v4l/vbi_hsync.pdf b/linux/Documentation/DocBook/v4l/vbi_hsync.pdf Binary files differnew file mode 100644 index 000000000..200b66818 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vbi_hsync.pdf diff --git a/linux/Documentation/DocBook/v4l/vidioc-cropcap.xml b/linux/Documentation/DocBook/v4l/vidioc-cropcap.xml new file mode 100644 index 000000000..816e90e28 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-cropcap.xml @@ -0,0 +1,174 @@ +<refentry id="vidioc-cropcap"> + <refmeta> + <refentrytitle>ioctl VIDIOC_CROPCAP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_CROPCAP</refname> + <refpurpose>Information about the video cropping and scaling abilities</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_cropcap +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_CROPCAP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Applications use this function to query the cropping +limits, the pixel aspect of images and to calculate scale factors. +They set the <structfield>type</structfield> field of a v4l2_cropcap +structure to the respective buffer (stream) type and call the +<constant>VIDIOC_CROPCAP</constant> ioctl with a pointer to this +structure. Drivers fill the rest of the structure. The results are +constant except when switching the video standard. Remember this +switch can occur implicit when switching the video input or +output.</para> + + <table pgwide="1" frame="none" id="v4l2-cropcap"> + <title>struct <structname>v4l2_cropcap</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the data stream, set by the application. +Only these types are valid here: +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver +defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant> +and higher.</entry> + </row> + <row> + <entry>struct <link linkend="v4l2-rect-crop">v4l2_rect</link></entry> + <entry><structfield>bounds</structfield></entry> + <entry>Defines the window within capturing or output is +possible, this may exclude for example the horizontal and vertical +blanking areas. The cropping rectangle cannot exceed these limits. +Width and height are defined in pixels, the driver writer is free to +choose origin and units of the coordinate system in the analog +domain.</entry> + </row> + <row> + <entry>struct <link linkend="v4l2-rect-crop">v4l2_rect</link></entry> + <entry><structfield>defrect</structfield></entry> + <entry>Default cropping rectangle, it shall cover the +"whole picture". Assuming pixel aspect 1/1 this could be for example a +640 × 480 rectangle for NTSC, a +768 × 576 rectangle for PAL and SECAM centered over +the active picture area. The same co-ordinate system as for + <structfield>bounds</structfield> is used.</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>pixelaspect</structfield></entry> + <entry><para>This is the pixel aspect (y / x) when no +scaling is applied, the ratio of the actual sampling +frequency and the frequency required to get square +pixels.</para><para>When cropping coordinates refer to square pixels, +the driver sets <structfield>pixelaspect</structfield> to 1/1. Other +common values are 54/59 for PAL and SECAM, 11/10 for NTSC sampled +according to [<xref linkend="itu601" />].</para></entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- NB this table is duplicated in the overlay chapter. --> + + <table pgwide="1" frame="none" id="v4l2-rect-crop"> + <title>struct <structname>v4l2_rect</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__s32</entry> + <entry><structfield>left</structfield></entry> + <entry>Horizontal offset of the top, left corner of the +rectangle, in pixels.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>top</structfield></entry> + <entry>Vertical offset of the top, left corner of the +rectangle, in pixels.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>width</structfield></entry> + <entry>Width of the rectangle, in pixels.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>height</structfield></entry> + <entry>Height of the rectangle, in pixels. Width +and height cannot be negative, the fields are signed for +hysterical reasons. <!-- video4linux-list@redhat.com +on 22 Oct 2002 subject "Re:[V4L][patches!] Re:v4l2/kernel-2.5" --> +</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-cropcap; <structfield>type</structfield> is +invalid or the ioctl is not supported. This is not permitted for +video capture, output and overlay devices, which must support +<constant>VIDIOC_CROPCAP</constant>.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-dbg-g-chip-ident.xml b/linux/Documentation/DocBook/v4l/vidioc-dbg-g-chip-ident.xml new file mode 100644 index 000000000..4a09e203a --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-dbg-g-chip-ident.xml @@ -0,0 +1,275 @@ +<refentry id="vidioc-dbg-g-chip-ident"> + <refmeta> + <refentrytitle>ioctl VIDIOC_DBG_G_CHIP_IDENT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_DBG_G_CHIP_IDENT</refname> + <refpurpose>Identify the chips on a TV card</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_dbg_chip_ident +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_DBG_G_CHIP_IDENT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + + <para>This is an <link +linkend="experimental">experimental</link> interface and may change in +the future.</para> + </note> + + <para>For driver debugging purposes this ioctl allows test +applications to query the driver about the chips present on the TV +card. Regular applications must not use it. When you found a chip +specific bug, please contact the linux-media mailing list (&v4l-ml;) +so it can be fixed.</para> + + <para>To query the driver applications must initialize the +<structfield>match.type</structfield> and +<structfield>match.addr</structfield> or <structfield>match.name</structfield> +fields of a &v4l2-dbg-chip-ident; +and call <constant>VIDIOC_DBG_G_CHIP_IDENT</constant> with a pointer to +this structure. On success the driver stores information about the +selected chip in the <structfield>ident</structfield> and +<structfield>revision</structfield> fields. On failure the structure +remains unchanged.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_HOST</constant>, +<structfield>match.addr</structfield> selects the nth non-&i2c; chip +on the TV card. You can enumerate all chips by starting at zero and +incrementing <structfield>match.addr</structfield> by one until +<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;. +The number zero always selects the host chip, ⪚ the chip connected +to the PCI or USB bus.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant>, +<structfield>match.name</structfield> contains the I2C driver name. +For instance +<constant>"saa7127"</constant> will match any chip +supported by the saa7127 driver, regardless of its &i2c; bus address. +When multiple chips supported by the same driver are present, the +ioctl will return <constant>V4L2_IDENT_AMBIGUOUS</constant> in the +<structfield>ident</structfield> field.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_I2C_ADDR</constant>, +<structfield>match.addr</structfield> selects a chip by its 7 bit +&i2c; bus address.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_AC97</constant>, +<structfield>match.addr</structfield> selects the nth AC97 chip +on the TV card. You can enumerate all chips by starting at zero and +incrementing <structfield>match.addr</structfield> by one until +<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.</para> + + <para>On success, the <structfield>ident</structfield> field will +contain a chip ID from the Linux +<filename>media/v4l2-chip-ident.h</filename> header file, and the +<structfield>revision</structfield> field will contain a driver +specific value, or zero if no particular revision is associated with +this chip.</para> + + <para>When the driver could not identify the selected chip, +<structfield>ident</structfield> will contain +<constant>V4L2_IDENT_UNKNOWN</constant>. When no chip matched +the ioctl will succeed but the +<structfield>ident</structfield> field will contain +<constant>V4L2_IDENT_NONE</constant>. If multiple chips matched, +<structfield>ident</structfield> will contain +<constant>V4L2_IDENT_AMBIGUOUS</constant>. In all these cases the +<structfield>revision</structfield> field remains unchanged.</para> + + <para>This ioctl is optional, not all drivers may support it. It +was introduced in Linux 2.6.21, but the API was changed to the +one described here in 2.6.29.</para> + + <para>We recommended the <application>v4l2-dbg</application> +utility over calling this ioctl directly. It is available from the +LinuxTV v4l-dvb repository; see <ulink +url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for +access instructions.</para> + + <!-- Note for convenience vidioc-dbg-g-register.sgml + contains a duplicate of this table. --> + <table pgwide="1" frame="none" id="ident-v4l2-dbg-match"> + <title>struct <structname>v4l2_dbg_match</structname></title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>See <xref linkend="ident-chip-match-types" /> for a list of +possible types.</entry> + </row> + <row> + <entry>union</entry> + <entry>(anonymous)</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>addr</structfield></entry> + <entry>Match a chip by this number, interpreted according +to the <structfield>type</structfield> field.</entry> + </row> + <row> + <entry></entry> + <entry>char</entry> + <entry><structfield>name[32]</structfield></entry> + <entry>Match a chip by this name, interpreted according +to the <structfield>type</structfield> field.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-dbg-chip-ident"> + <title>struct <structname>v4l2_dbg_chip_ident</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>struct v4l2_dbg_match</entry> + <entry><structfield>match</structfield></entry> + <entry>How to match the chip, see <xref linkend="ident-v4l2-dbg-match" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>ident</structfield></entry> + <entry>A chip identifier as defined in the Linux +<filename>media/v4l2-chip-ident.h</filename> header file, or one of +the values from <xref linkend="chip-ids" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>revision</structfield></entry> + <entry>A chip revision, chip and driver specific.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- Note for convenience vidioc-dbg-g-register.sgml + contains a duplicate of this table. --> + <table pgwide="1" frame="none" id="ident-chip-match-types"> + <title>Chip Match Types</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_CHIP_MATCH_HOST</constant></entry> + <entry>0</entry> + <entry>Match the nth chip on the card, zero for the + host chip. Does not match &i2c; chips.</entry> + </row> + <row> + <entry><constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant></entry> + <entry>1</entry> + <entry>Match an &i2c; chip by its driver name.</entry> + </row> + <row> + <entry><constant>V4L2_CHIP_MATCH_I2C_ADDR</constant></entry> + <entry>2</entry> + <entry>Match a chip by its 7 bit &i2c; bus address.</entry> + </row> + <row> + <entry><constant>V4L2_CHIP_MATCH_AC97</constant></entry> + <entry>3</entry> + <entry>Match the nth anciliary AC97 chip.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- This is an anonymous enum in media/v4l2-chip-ident.h. --> + <table pgwide="1" frame="none" id="chip-ids"> + <title>Chip Identifiers</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_IDENT_NONE</constant></entry> + <entry>0</entry> + <entry>No chip matched.</entry> + </row> + <row> + <entry><constant>V4L2_IDENT_AMBIGUOUS</constant></entry> + <entry>1</entry> + <entry>Multiple chips matched.</entry> + </row> + <row> + <entry><constant>V4L2_IDENT_UNKNOWN</constant></entry> + <entry>2</entry> + <entry>A chip is present at this address, but the driver +could not identify it.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The driver does not support this ioctl, or the +<structfield>match_type</structfield> is invalid.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-dbg-g-register.xml b/linux/Documentation/DocBook/v4l/vidioc-dbg-g-register.xml new file mode 100644 index 000000000..980c7f3e2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-dbg-g-register.xml @@ -0,0 +1,275 @@ +<refentry id="vidioc-dbg-g-register"> + <refmeta> + <refentrytitle>ioctl VIDIOC_DBG_G_REGISTER, VIDIOC_DBG_S_REGISTER</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_DBG_G_REGISTER</refname> + <refname>VIDIOC_DBG_S_REGISTER</refname> + <refpurpose>Read or write hardware registers</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_dbg_register *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_dbg_register +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_DBG_G_REGISTER, VIDIOC_DBG_S_REGISTER</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + + <para>This is an <link linkend="experimental">experimental</link> +interface and may change in the future.</para> + </note> + + <para>For driver debugging purposes these ioctls allow test +applications to access hardware registers directly. Regular +applications must not use them.</para> + + <para>Since writing or even reading registers can jeopardize the +system security, its stability and damage the hardware, both ioctls +require superuser privileges. Additionally the Linux kernel must be +compiled with the <constant>CONFIG_VIDEO_ADV_DEBUG</constant> option +to enable these ioctls.</para> + + <para>To write a register applications must initialize all fields +of a &v4l2-dbg-register; and call +<constant>VIDIOC_DBG_S_REGISTER</constant> with a pointer to this +structure. The <structfield>match.type</structfield> and +<structfield>match.addr</structfield> or <structfield>match.name</structfield> +fields select a chip on the TV +card, the <structfield>reg</structfield> field specifies a register +number and the <structfield>val</structfield> field the value to be +written into the register.</para> + + <para>To read a register applications must initialize the +<structfield>match.type</structfield>, +<structfield>match.chip</structfield> or <structfield>match.name</structfield> and +<structfield>reg</structfield> fields, and call +<constant>VIDIOC_DBG_G_REGISTER</constant> with a pointer to this +structure. On success the driver stores the register value in the +<structfield>val</structfield> field. On failure the structure remains +unchanged.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_HOST</constant>, +<structfield>match.addr</structfield> selects the nth non-&i2c; chip +on the TV card. The number zero always selects the host chip, ⪚ the +chip connected to the PCI or USB bus. You can find out which chips are +present with the &VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant>, +<structfield>match.name</structfield> contains the I2C driver name. +For instance +<constant>"saa7127"</constant> will match any chip +supported by the saa7127 driver, regardless of its &i2c; bus address. +When multiple chips supported by the same driver are present, the +effect of these ioctls is undefined. Again with the +&VIDIOC-DBG-G-CHIP-IDENT; ioctl you can find out which &i2c; chips are +present.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_I2C_ADDR</constant>, +<structfield>match.addr</structfield> selects a chip by its 7 bit &i2c; +bus address.</para> + + <para>When <structfield>match.type</structfield> is +<constant>V4L2_CHIP_MATCH_AC97</constant>, +<structfield>match.addr</structfield> selects the nth AC97 chip +on the TV card.</para> + + <note> + <title>Success not guaranteed</title> + + <para>Due to a flaw in the Linux &i2c; bus driver these ioctls may +return successfully without actually reading or writing a register. To +catch the most likely failure we recommend a &VIDIOC-DBG-G-CHIP-IDENT; +call confirming the presence of the selected &i2c; chip.</para> + </note> + + <para>These ioctls are optional, not all drivers may support them. +However when a driver supports these ioctls it must also support +&VIDIOC-DBG-G-CHIP-IDENT;. Conversely it may support +<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> but not these ioctls.</para> + + <para><constant>VIDIOC_DBG_G_REGISTER</constant> and +<constant>VIDIOC_DBG_S_REGISTER</constant> were introduced in Linux +2.6.21, but their API was changed to the one described here in kernel 2.6.29.</para> + + <para>We recommended the <application>v4l2-dbg</application> +utility over calling these ioctls directly. It is available from the +LinuxTV v4l-dvb repository; see <ulink +url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for +access instructions.</para> + + <!-- Note for convenience vidioc-dbg-g-chip-ident.sgml + contains a duplicate of this table. --> + <table pgwide="1" frame="none" id="v4l2-dbg-match"> + <title>struct <structname>v4l2_dbg_match</structname></title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>See <xref linkend="ident-chip-match-types" /> for a list of +possible types.</entry> + </row> + <row> + <entry>union</entry> + <entry>(anonymous)</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>addr</structfield></entry> + <entry>Match a chip by this number, interpreted according +to the <structfield>type</structfield> field.</entry> + </row> + <row> + <entry></entry> + <entry>char</entry> + <entry><structfield>name[32]</structfield></entry> + <entry>Match a chip by this name, interpreted according +to the <structfield>type</structfield> field.</entry> + </row> + </tbody> + </tgroup> + </table> + + + <table pgwide="1" frame="none" id="v4l2-dbg-register"> + <title>struct <structname>v4l2_dbg_register</structname></title> + <tgroup cols="4"> + <colspec colname="c1" /> + <colspec colname="c2" /> + <colspec colname="c4" /> + <tbody valign="top"> + <row> + <entry>struct v4l2_dbg_match</entry> + <entry><structfield>match</structfield></entry> + <entry>How to match the chip, see <xref linkend="v4l2-dbg-match" />.</entry> + </row> + <row> + <entry>__u64</entry> + <entry><structfield>reg</structfield></entry> + <entry>A register number.</entry> + </row> + <row> + <entry>__u64</entry> + <entry><structfield>val</structfield></entry> + <entry>The value read from, or to be written into the +register.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- Note for convenience vidioc-dbg-g-chip-ident.sgml + contains a duplicate of this table. --> + <table pgwide="1" frame="none" id="chip-match-types"> + <title>Chip Match Types</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_CHIP_MATCH_HOST</constant></entry> + <entry>0</entry> + <entry>Match the nth chip on the card, zero for the + host chip. Does not match &i2c; chips.</entry> + </row> + <row> + <entry><constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant></entry> + <entry>1</entry> + <entry>Match an &i2c; chip by its driver name.</entry> + </row> + <row> + <entry><constant>V4L2_CHIP_MATCH_I2C_ADDR</constant></entry> + <entry>2</entry> + <entry>Match a chip by its 7 bit &i2c; bus address.</entry> + </row> + <row> + <entry><constant>V4L2_CHIP_MATCH_AC97</constant></entry> + <entry>3</entry> + <entry>Match the nth anciliary AC97 chip.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The driver does not support this ioctl, or the kernel +was not compiled with the <constant>CONFIG_VIDEO_ADV_DEBUG</constant> +option, or the <structfield>match_type</structfield> is invalid, or the +selected chip or register does not exist.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EPERM</errorcode></term> + <listitem> + <para>Insufficient permissions. Root privileges are required +to execute these ioctls.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-encoder-cmd.xml b/linux/Documentation/DocBook/v4l/vidioc-encoder-cmd.xml new file mode 100644 index 000000000..b0dde9438 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-encoder-cmd.xml @@ -0,0 +1,204 @@ +<refentry id="vidioc-encoder-cmd"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENCODER_CMD</refname> + <refname>VIDIOC_TRY_ENCODER_CMD</refname> + <refpurpose>Execute an encoder command</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_encoder_cmd *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENCODER_CMD, VIDIOC_TRY_ENCODER_CMD</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + + <para>This is an <link linkend="experimental">experimental</link> +interface and may change in the future.</para> + </note> + + <para>These ioctls control an audio/video (usually MPEG-) encoder. +<constant>VIDIOC_ENCODER_CMD</constant> sends a command to the +encoder, <constant>VIDIOC_TRY_ENCODER_CMD</constant> can be used to +try a command without actually executing it.</para> + + <para>To send a command applications must initialize all fields of a + &v4l2-encoder-cmd; and call + <constant>VIDIOC_ENCODER_CMD</constant> or + <constant>VIDIOC_TRY_ENCODER_CMD</constant> with a pointer to this + structure.</para> + + <para>The <structfield>cmd</structfield> field must contain the +command code. The <structfield>flags</structfield> field is currently +only used by the STOP command and contains one bit: If the +<constant>V4L2_ENC_CMD_STOP_AT_GOP_END</constant> flag is set, +encoding will continue until the end of the current <wordasword>Group +Of Pictures</wordasword>, otherwise it will stop immediately.</para> + + <para>A <function>read</function>() call sends a START command to +the encoder if it has not been started yet. After a STOP command, +<function>read</function>() calls will read the remaining data +buffered by the driver. When the buffer is empty, +<function>read</function>() will return zero and the next +<function>read</function>() call will restart the encoder.</para> + + <para>A <function>close</function>() call sends an immediate STOP +to the encoder, and all buffered data is discarded.</para> + + <para>These ioctls are optional, not all drivers may support +them. They were introduced in Linux 2.6.21.</para> + + <table pgwide="1" frame="none" id="v4l2-encoder-cmd"> + <title>struct <structname>v4l2_encoder_cmd</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>cmd</structfield></entry> + <entry>The encoder command, see <xref linkend="encoder-cmds" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Flags to go with the command, see <xref + linkend="encoder-flags" />. If no flags are defined for +this command, drivers and applications must set this field to +zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>data</structfield>[8]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="encoder-cmds"> + <title>Encoder Commands</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_ENC_CMD_START</constant></entry> + <entry>0</entry> + <entry>Start the encoder. When the encoder is already +running or paused, this command does nothing. No flags are defined for +this command.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_CMD_STOP</constant></entry> + <entry>1</entry> + <entry>Stop the encoder. When the +<constant>V4L2_ENC_CMD_STOP_AT_GOP_END</constant> flag is set, +encoding will continue until the end of the current <wordasword>Group +Of Pictures</wordasword>, otherwise encoding will stop immediately. +When the encoder is already stopped, this command does +nothing.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_CMD_PAUSE</constant></entry> + <entry>2</entry> + <entry>Pause the encoder. When the encoder has not been +started yet, the driver will return an &EPERM;. When the encoder is +already paused, this command does nothing. No flags are defined for +this command.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_CMD_RESUME</constant></entry> + <entry>3</entry> + <entry>Resume encoding after a PAUSE command. When the +encoder has not been started yet, the driver will return an &EPERM;. +When the encoder is already running, this command does nothing. No +flags are defined for this command.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="encoder-flags"> + <title>Encoder Command Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_ENC_CMD_STOP_AT_GOP_END</constant></entry> + <entry>0x0001</entry> + <entry>Stop encoding at the end of the current <wordasword>Group Of +Pictures</wordasword>, rather than immediately.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The driver does not support this ioctl, or the +<structfield>cmd</structfield> field is invalid.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EPERM</errorcode></term> + <listitem> + <para>The application sent a PAUSE or RESUME command when +the encoder was not running.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enum-fmt.xml b/linux/Documentation/DocBook/v4l/vidioc-enum-fmt.xml new file mode 100644 index 000000000..960d44615 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enum-fmt.xml @@ -0,0 +1,164 @@ +<refentry id="vidioc-enum-fmt"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUM_FMT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUM_FMT</refname> + <refpurpose>Enumerate image formats</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_fmtdesc +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUM_FMT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To enumerate image formats applications initialize the +<structfield>type</structfield> and <structfield>index</structfield> +field of &v4l2-fmtdesc; and call the +<constant>VIDIOC_ENUM_FMT</constant> ioctl with a pointer to this +structure. Drivers fill the rest of the structure or return an +&EINVAL;. All formats are enumerable by beginning at index zero and +incrementing by one until <errorcode>EINVAL</errorcode> is +returned.</para> + + <table pgwide="1" frame="none" id="v4l2-fmtdesc"> + <title>struct <structname>v4l2_fmtdesc</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Number of the format in the enumeration, set by +the application. This is in no way related to the <structfield> +pixelformat</structfield> field.</entry> + </row> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the data stream, set by the application. +Only these types are valid here: +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver +defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant> +and higher.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>See <xref linkend="fmtdesc-flags" /></entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>description</structfield>[32]</entry> + <entry>Description of the format, a NUL-terminated ASCII +string. This information is intended for the user, for example: "YUV +4:2:2".</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>pixelformat</structfield></entry> + <entry>The image format identifier. This is a +four character code as computed by the v4l2_fourcc() +macro:</entry> + </row> + <row> + <entry spanname="hspan"><para><programlisting id="v4l2-fourcc"> +#define v4l2_fourcc(a,b,c,d) (((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24)) +</programlisting></para><para>Several image formats are already +defined by this specification in <xref linkend="pixfmt" />. Note these +codes are not the same as those used in the Windows world.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers must set +the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="fmtdesc-flags"> + <title>Image Format Description Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_FMT_FLAG_COMPRESSED</constant></entry> + <entry>0x0001</entry> + <entry>This is a compressed format.</entry> + </row> + <row> + <entry><constant>V4L2_FMT_FLAG_EMULATED</constant></entry> + <entry>0x0002</entry> + <entry>This format is not native to the device but emulated +through software (usually libv4l2), where possible try to use a native format +instead for better performance.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-fmtdesc; <structfield>type</structfield> +is not supported or the <structfield>index</structfield> is out of +bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enum-frameintervals.xml b/linux/Documentation/DocBook/v4l/vidioc-enum-frameintervals.xml new file mode 100644 index 000000000..3c216e113 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enum-frameintervals.xml @@ -0,0 +1,270 @@ +<refentry id="vidioc-enum-frameintervals"> + + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUM_FRAMEINTERVALS</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUM_FRAMEINTERVALS</refname> + <refpurpose>Enumerate frame intervals</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_frmivalenum *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUM_FRAMEINTERVALS</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para>Pointer to a &v4l2-frmivalenum; structure that +contains a pixel format and size and receives a frame interval.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>This ioctl allows applications to enumerate all frame +intervals that the device supports for the given pixel format and +frame size.</para> + <para>The supported pixel formats and frame sizes can be obtained +by using the &VIDIOC-ENUM-FMT; and &VIDIOC-ENUM-FRAMESIZES; +functions.</para> + <para>The return value and the content of the +<structfield>v4l2_frmivalenum.type</structfield> field depend on the +type of frame intervals the device supports. Here are the semantics of +the function for the different cases:</para> + <itemizedlist> + <listitem> + <para><emphasis role="bold">Discrete:</emphasis> The function +returns success if the given index value (zero-based) is valid. The +application should increase the index by one for each call until +<constant>EINVAL</constant> is returned. The `v4l2_frmivalenum.type` +field is set to `V4L2_FRMIVAL_TYPE_DISCRETE` by the driver. Of the +union only the `discrete` member is valid.</para> + </listitem> + <listitem> + <para><emphasis role="bold">Step-wise:</emphasis> The function +returns success if the given index value is zero and +<constant>EINVAL</constant> for any other index value. The +<structfield>v4l2_frmivalenum.type</structfield> field is set to +<constant>V4L2_FRMIVAL_TYPE_STEPWISE</constant> by the driver. Of the +union only the <structfield>stepwise</structfield> member is +valid.</para> + </listitem> + <listitem> + <para><emphasis role="bold">Continuous:</emphasis> This is a +special case of the step-wise type above. The function returns success +if the given index value is zero and <constant>EINVAL</constant> for +any other index value. The +<structfield>v4l2_frmivalenum.type</structfield> field is set to +<constant>V4L2_FRMIVAL_TYPE_CONTINUOUS</constant> by the driver. Of +the union only the <structfield>stepwise</structfield> member is valid +and the <structfield>step</structfield> value is set to 1.</para> + </listitem> + </itemizedlist> + + <para>When the application calls the function with index zero, it +must check the <structfield>type</structfield> field to determine the +type of frame interval enumeration the device supports. Only for the +<constant>V4L2_FRMIVAL_TYPE_DISCRETE</constant> type does it make +sense to increase the index value to receive more frame +intervals.</para> + <para>Note that the order in which the frame intervals are +returned has no special meaning. In particular does it not say +anything about potential default frame intervals.</para> + <para>Applications can assume that the enumeration data does not +change without any interaction from the application itself. This means +that the enumeration data is consistent if the application does not +perform any other ioctl calls while it runs the frame interval +enumeration.</para> + </refsect1> + + <refsect1> + <title>Notes</title> + + <itemizedlist> + <listitem> + <para><emphasis role="bold">Frame intervals and frame +rates:</emphasis> The V4L2 API uses frame intervals instead of frame +rates. Given the frame interval the frame rate can be computed as +follows:<screen>frame_rate = 1 / frame_interval</screen></para> + </listitem> + </itemizedlist> + + </refsect1> + + <refsect1> + <title>Structs</title> + + <para>In the structs below, <emphasis>IN</emphasis> denotes a +value that has to be filled in by the application, +<emphasis>OUT</emphasis> denotes values that the driver fills in. The +application should zero out all members except for the +<emphasis>IN</emphasis> fields.</para> + + <table pgwide="1" frame="none" id="v4l2-frmival-stepwise"> + <title>struct <structname>v4l2_frmival_stepwise</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>min</structfield></entry> + <entry>Minimum frame interval [s].</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>max</structfield></entry> + <entry>Maximum frame interval [s].</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>step</structfield></entry> + <entry>Frame interval step size [s].</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-frmivalenum"> + <title>struct <structname>v4l2_frmivalenum</structname></title> + <tgroup cols="4"> + <colspec colname="c1" /> + <colspec colname="c2" /> + <colspec colname="c3" /> + <colspec colname="c4" /> + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry></entry> + <entry>IN: Index of the given frame interval in the +enumeration.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>pixel_format</structfield></entry> + <entry></entry> + <entry>IN: Pixel format for which the frame intervals are +enumerated.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>width</structfield></entry> + <entry></entry> + <entry>IN: Frame width for which the frame intervals are +enumerated.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>height</structfield></entry> + <entry></entry> + <entry>IN: Frame height for which the frame intervals are +enumerated.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry></entry> + <entry>OUT: Frame interval type the device supports.</entry> + </row> + <row> + <entry>union</entry> + <entry></entry> + <entry></entry> + <entry>OUT: Frame interval with the given index.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-fract;</entry> + <entry><structfield>discrete</structfield></entry> + <entry>Frame interval [s].</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-frmival-stepwise;</entry> + <entry><structfield>stepwise</structfield></entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved[2]</structfield></entry> + <entry></entry> + <entry>Reserved space for future use.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + <title>Enums</title> + + <table pgwide="1" frame="none" id="v4l2-frmivaltypes"> + <title>enum <structname>v4l2_frmivaltypes</structname></title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_FRMIVAL_TYPE_DISCRETE</constant></entry> + <entry>1</entry> + <entry>Discrete frame interval.</entry> + </row> + <row> + <entry><constant>V4L2_FRMIVAL_TYPE_CONTINUOUS</constant></entry> + <entry>2</entry> + <entry>Continuous frame interval.</entry> + </row> + <row> + <entry><constant>V4L2_FRMIVAL_TYPE_STEPWISE</constant></entry> + <entry>3</entry> + <entry>Step-wise defined frame interval.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <para>See the description section above for a list of return +values that <varname>errno</varname> can have.</para> + </refsect1> + +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enum-framesizes.xml b/linux/Documentation/DocBook/v4l/vidioc-enum-framesizes.xml new file mode 100644 index 000000000..6afa4542c --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enum-framesizes.xml @@ -0,0 +1,282 @@ +<refentry id="vidioc-enum-framesizes"> + + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUM_FRAMESIZES</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUM_FRAMESIZES</refname> + <refpurpose>Enumerate frame sizes</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_frmsizeenum *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUM_FRAMESIZES</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para>Pointer to a &v4l2-frmsizeenum; that contains an index +and pixel format and receives a frame width and height.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + + <para>This is an <link linkend="experimental">experimental</link> +interface and may change in the future.</para> + </note> + + <para>This ioctl allows applications to enumerate all frame sizes +(&ie; width and height in pixels) that the device supports for the +given pixel format.</para> + <para>The supported pixel formats can be obtained by using the +&VIDIOC-ENUM-FMT; function.</para> + <para>The return value and the content of the +<structfield>v4l2_frmsizeenum.type</structfield> field depend on the +type of frame sizes the device supports. Here are the semantics of the +function for the different cases:</para> + + <itemizedlist> + <listitem> + <para><emphasis role="bold">Discrete:</emphasis> The function +returns success if the given index value (zero-based) is valid. The +application should increase the index by one for each call until +<constant>EINVAL</constant> is returned. The +<structfield>v4l2_frmsizeenum.type</structfield> field is set to +<constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> by the driver. Of the +union only the <structfield>discrete</structfield> member is +valid.</para> + </listitem> + <listitem> + <para><emphasis role="bold">Step-wise:</emphasis> The function +returns success if the given index value is zero and +<constant>EINVAL</constant> for any other index value. The +<structfield>v4l2_frmsizeenum.type</structfield> field is set to +<constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant> by the driver. Of the +union only the <structfield>stepwise</structfield> member is +valid.</para> + </listitem> + <listitem> + <para><emphasis role="bold">Continuous:</emphasis> This is a +special case of the step-wise type above. The function returns success +if the given index value is zero and <constant>EINVAL</constant> for +any other index value. The +<structfield>v4l2_frmsizeenum.type</structfield> field is set to +<constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant> by the driver. Of +the union only the <structfield>stepwise</structfield> member is valid +and the <structfield>step_width</structfield> and +<structfield>step_height</structfield> values are set to 1.</para> + </listitem> + </itemizedlist> + + <para>When the application calls the function with index zero, it +must check the <structfield>type</structfield> field to determine the +type of frame size enumeration the device supports. Only for the +<constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> type does it make +sense to increase the index value to receive more frame sizes.</para> + <para>Note that the order in which the frame sizes are returned +has no special meaning. In particular does it not say anything about +potential default format sizes.</para> + <para>Applications can assume that the enumeration data does not +change without any interaction from the application itself. This means +that the enumeration data is consistent if the application does not +perform any other ioctl calls while it runs the frame size +enumeration.</para> + </refsect1> + + <refsect1> + <title>Structs</title> + + <para>In the structs below, <emphasis>IN</emphasis> denotes a +value that has to be filled in by the application, +<emphasis>OUT</emphasis> denotes values that the driver fills in. The +application should zero out all members except for the +<emphasis>IN</emphasis> fields.</para> + + <table pgwide="1" frame="none" id="v4l2-frmsize-discrete"> + <title>struct <structname>v4l2_frmsize_discrete</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>width</structfield></entry> + <entry>Width of the frame [pixel].</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>height</structfield></entry> + <entry>Height of the frame [pixel].</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-frmsize-stepwise"> + <title>struct <structname>v4l2_frmsize_stepwise</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>min_width</structfield></entry> + <entry>Minimum frame width [pixel].</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>max_width</structfield></entry> + <entry>Maximum frame width [pixel].</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>step_width</structfield></entry> + <entry>Frame width step size [pixel].</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>min_height</structfield></entry> + <entry>Minimum frame height [pixel].</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>max_height</structfield></entry> + <entry>Maximum frame height [pixel].</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>step_height</structfield></entry> + <entry>Frame height step size [pixel].</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-frmsizeenum"> + <title>struct <structname>v4l2_frmsizeenum</structname></title> + <tgroup cols="4"> + <colspec colname="c1" /> + <colspec colname="c2" /> + <colspec colname="c3" /> + <colspec colname="c4" /> + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry></entry> + <entry>IN: Index of the given frame size in the enumeration.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>pixel_format</structfield></entry> + <entry></entry> + <entry>IN: Pixel format for which the frame sizes are enumerated.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry></entry> + <entry>OUT: Frame size type the device supports.</entry> + </row> + <row> + <entry>union</entry> + <entry></entry> + <entry></entry> + <entry>OUT: Frame size with the given index.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-frmsize-discrete;</entry> + <entry><structfield>discrete</structfield></entry> + <entry></entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-frmsize-stepwise;</entry> + <entry><structfield>stepwise</structfield></entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved[2]</structfield></entry> + <entry></entry> + <entry>Reserved space for future use.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + <title>Enums</title> + + <table pgwide="1" frame="none" id="v4l2-frmsizetypes"> + <title>enum <structname>v4l2_frmsizetypes</structname></title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant></entry> + <entry>1</entry> + <entry>Discrete frame size.</entry> + </row> + <row> + <entry><constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant></entry> + <entry>2</entry> + <entry>Continuous frame size.</entry> + </row> + <row> + <entry><constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant></entry> + <entry>3</entry> + <entry>Step-wise defined frame size.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <para>See the description section above for a list of return +values that <varname>errno</varname> can have.</para> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enumaudio.xml b/linux/Documentation/DocBook/v4l/vidioc-enumaudio.xml new file mode 100644 index 000000000..9ae8f2d3a --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enumaudio.xml @@ -0,0 +1,86 @@ +<refentry id="vidioc-enumaudio"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUMAUDIO</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUMAUDIO</refname> + <refpurpose>Enumerate audio inputs</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_audio *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUMAUDIO</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of an audio input applications +initialize the <structfield>index</structfield> field and zero out the +<structfield>reserved</structfield> array of a &v4l2-audio; +and call the <constant>VIDIOC_ENUMAUDIO</constant> ioctl with a pointer +to this structure. Drivers fill the rest of the structure or return an +&EINVAL; when the index is out of bounds. To enumerate all audio +inputs applications shall begin at index zero, incrementing by one +until the driver returns <errorcode>EINVAL</errorcode>.</para> + + <para>See <xref linkend="vidioc-g-audio" /> for a description of +&v4l2-audio;.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The number of the audio input is out of bounds, or +there are no audio inputs at all and this ioctl is not +supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enumaudioout.xml b/linux/Documentation/DocBook/v4l/vidioc-enumaudioout.xml new file mode 100644 index 000000000..d3d7c0ab1 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enumaudioout.xml @@ -0,0 +1,89 @@ +<refentry id="vidioc-enumaudioout"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUMAUDOUT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUMAUDOUT</refname> + <refpurpose>Enumerate audio outputs</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_audioout *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUMAUDOUT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of an audio output applications +initialize the <structfield>index</structfield> field and zero out the +<structfield>reserved</structfield> array of a &v4l2-audioout; and +call the <constant>VIDIOC_G_AUDOUT</constant> ioctl with a pointer +to this structure. Drivers fill the rest of the structure or return an +&EINVAL; when the index is out of bounds. To enumerate all audio +outputs applications shall begin at index zero, incrementing by one +until the driver returns <errorcode>EINVAL</errorcode>.</para> + + <para>Note connectors on a TV card to loop back the received audio +signal to a sound card are not audio outputs in this sense.</para> + + <para>See <xref linkend="vidioc-g-audioout" /> for a description of +&v4l2-audioout;.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The number of the audio output is out of bounds, or +there are no audio outputs at all and this ioctl is not +supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enuminput.xml b/linux/Documentation/DocBook/v4l/vidioc-enuminput.xml new file mode 100644 index 000000000..414856b82 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enuminput.xml @@ -0,0 +1,287 @@ +<refentry id="vidioc-enuminput"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUMINPUT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUMINPUT</refname> + <refpurpose>Enumerate video inputs</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_input +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUMINPUT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of a video input applications +initialize the <structfield>index</structfield> field of &v4l2-input; +and call the <constant>VIDIOC_ENUMINPUT</constant> ioctl with a +pointer to this structure. Drivers fill the rest of the structure or +return an &EINVAL; when the index is out of bounds. To enumerate all +inputs applications shall begin at index zero, incrementing by one +until the driver returns <errorcode>EINVAL</errorcode>.</para> + + <table frame="none" pgwide="1" id="v4l2-input"> + <title>struct <structname>v4l2_input</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Identifies the input, set by the +application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the video input, a NUL-terminated ASCII +string, for example: "Vin (Composite 2)". This information is intended +for the user, preferably the connector label on the device itself.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the input, see <xref + linkend="input-type" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>audioset</structfield></entry> + <entry><para>Drivers can enumerate up to 32 video and +audio inputs. This field shows which audio inputs were selectable as +audio source if this was the currently selected video input. It is a +bit mask. The LSB corresponds to audio input 0, the MSB to input 31. +Any number of bits can be set, or none.</para><para>When the driver +does not enumerate audio inputs no bits must be set. Applications +shall not interpret this as lack of audio support. Some drivers +automatically select audio sources and do not enumerate them since +there is no choice anyway.</para><para>For details on audio inputs and +how to select the current input see <xref + linkend="audio" />.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>tuner</structfield></entry> + <entry>Capture devices can have zero or more tuners (RF +demodulators). When the <structfield>type</structfield> is set to +<constant>V4L2_INPUT_TYPE_TUNER</constant> this is an RF connector and +this field identifies the tuner. It corresponds to +&v4l2-tuner; field <structfield>index</structfield>. For details on +tuners see <xref linkend="tuner" />.</entry> + </row> + <row> + <entry>&v4l2-std-id;</entry> + <entry><structfield>std</structfield></entry> + <entry>Every video input supports one or more different +video standards. This field is a set of all supported standards. For +details on video standards and how to switch see <xref +linkend="standard" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>status</structfield></entry> + <entry>This field provides status information about the +input. See <xref linkend="input-status" /> for flags. +With the exception of the sensor orientation bits <structfield>status</structfield> is only valid when this is the +current input.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers must set +the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="input-type"> + <title>Input Types</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_INPUT_TYPE_TUNER</constant></entry> + <entry>1</entry> + <entry>This input uses a tuner (RF demodulator).</entry> + </row> + <row> + <entry><constant>V4L2_INPUT_TYPE_CAMERA</constant></entry> + <entry>2</entry> + <entry>Analog baseband input, for example CVBS / +Composite Video, S-Video, RGB.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- Status flags based on proposal by Mark McClelland, +video4linux-list@redhat.com on 18 Oct 2002, subject "Re: [V4L] Re: +v4l2 api". "Why are some of them inverted? So that the driver doesn't +have to lie about the status in cases where it can't tell one way or +the other. Plus, a status of zero would generally mean that everything +is OK." --> + + <table frame="none" pgwide="1" id="input-status"> + <title>Input Status Flags</title> + <tgroup cols="3"> + <colspec colname="c1" /> + <colspec colname="c2" align="center" /> + <colspec colname="c3" /> + <spanspec namest="c1" nameend="c3" spanname="hspan" + align="left" /> + <tbody valign="top"> + <row> + <entry spanname="hspan">General</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_POWER</constant></entry> + <entry>0x00000001</entry> + <entry>Attached device is off.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_SIGNAL</constant></entry> + <entry>0x00000002</entry> + <entry></entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_COLOR</constant></entry> + <entry>0x00000004</entry> + <entry>The hardware supports color decoding, but does not +detect color modulation in the signal.</entry> + </row> + <row> + <entry spanname="hspan">Sensor Orientation</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_HFLIP</constant></entry> + <entry>0x00000010</entry> + <entry>The input is connected to a device that produces a signal +that is flipped horizontally and does not correct this before passing the +signal to userspace.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_VFLIP</constant></entry> + <entry>0x00000020</entry> + <entry>The input is connected to a device that produces a signal +that is flipped vertically and does not correct this before passing the +signal to userspace. Note that a 180 degree rotation is the same as HFLIP | VFLIP</entry> + </row> + <row> + <entry spanname="hspan">Analog Video</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_H_LOCK</constant></entry> + <entry>0x00000100</entry> + <entry>No horizontal sync lock.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_COLOR_KILL</constant></entry> + <entry>0x00000200</entry> + <entry>A color killer circuit automatically disables color +decoding when it detects no color modulation. When this flag is set +the color killer is enabled <emphasis>and</emphasis> has shut off +color decoding.</entry> + </row> + <row> + <entry spanname="hspan">Digital Video</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_SYNC</constant></entry> + <entry>0x00010000</entry> + <entry>No synchronization lock.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_EQU</constant></entry> + <entry>0x00020000</entry> + <entry>No equalizer lock.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_CARRIER</constant></entry> + <entry>0x00040000</entry> + <entry>Carrier recovery failed.</entry> + </row> + <row> + <entry spanname="hspan">VCR and Set-Top Box</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_MACROVISION</constant></entry> + <entry>0x01000000</entry> + <entry>Macrovision is an analog copy prevention system +mangling the video signal to confuse video recorders. When this +flag is set Macrovision has been detected.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_NO_ACCESS</constant></entry> + <entry>0x02000000</entry> + <entry>Conditional access denied.</entry> + </row> + <row> + <entry><constant>V4L2_IN_ST_VTR</constant></entry> + <entry>0x04000000</entry> + <entry>VTR time constant. [?]</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-input; <structfield>index</structfield> is +out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enumoutput.xml b/linux/Documentation/DocBook/v4l/vidioc-enumoutput.xml new file mode 100644 index 000000000..e8d16dcd5 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enumoutput.xml @@ -0,0 +1,172 @@ +<refentry id="vidioc-enumoutput"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUMOUTPUT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUMOUTPUT</refname> + <refpurpose>Enumerate video outputs</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_output *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUMOUTPUT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of a video outputs applications +initialize the <structfield>index</structfield> field of &v4l2-output; +and call the <constant>VIDIOC_ENUMOUTPUT</constant> ioctl with a +pointer to this structure. Drivers fill the rest of the structure or +return an &EINVAL; when the index is out of bounds. To enumerate all +outputs applications shall begin at index zero, incrementing by one +until the driver returns <errorcode>EINVAL</errorcode>.</para> + + <table frame="none" pgwide="1" id="v4l2-output"> + <title>struct <structname>v4l2_output</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Identifies the output, set by the +application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the video output, a NUL-terminated ASCII +string, for example: "Vout". This information is intended for the +user, preferably the connector label on the device itself.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the output, see <xref + linkend="output-type" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>audioset</structfield></entry> + <entry><para>Drivers can enumerate up to 32 video and +audio outputs. This field shows which audio outputs were +selectable as the current output if this was the currently selected +video output. It is a bit mask. The LSB corresponds to audio output 0, +the MSB to output 31. Any number of bits can be set, or +none.</para><para>When the driver does not enumerate audio outputs no +bits must be set. Applications shall not interpret this as lack of +audio support. Drivers may automatically select audio outputs without +enumerating them.</para><para>For details on audio outputs and how to +select the current output see <xref linkend="audio" />.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>modulator</structfield></entry> + <entry>Output devices can have zero or more RF modulators. +When the <structfield>type</structfield> is +<constant>V4L2_OUTPUT_TYPE_MODULATOR</constant> this is an RF +connector and this field identifies the modulator. It corresponds to +&v4l2-modulator; field <structfield>index</structfield>. For details +on modulators see <xref linkend="tuner" />.</entry> + </row> + <row> + <entry>&v4l2-std-id;</entry> + <entry><structfield>std</structfield></entry> + <entry>Every video output supports one or more different +video standards. This field is a set of all supported standards. For +details on video standards and how to switch see <xref + linkend="standard" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers must set +the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="output-type"> + <title>Output Type</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_OUTPUT_TYPE_MODULATOR</constant></entry> + <entry>1</entry> + <entry>This output is an analog TV modulator.</entry> + </row> + <row> + <entry><constant>V4L2_OUTPUT_TYPE_ANALOG</constant></entry> + <entry>2</entry> + <entry>Analog baseband output, for example Composite / +CVBS, S-Video, RGB.</entry> + </row> + <row> + <entry><constant>V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY</constant></entry> + <entry>3</entry> + <entry>[?]</entry> + </row> + </tbody> + </tgroup> + </table> + + </refsect1> + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-output; <structfield>index</structfield> +is out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-enumstd.xml b/linux/Documentation/DocBook/v4l/vidioc-enumstd.xml new file mode 100644 index 000000000..95803fe2c --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-enumstd.xml @@ -0,0 +1,391 @@ +<refentry id="vidioc-enumstd"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUMSTD</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUMSTD</refname> + <refpurpose>Enumerate supported video standards</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_standard *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_ENUMSTD</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of a video standard, +especially a custom (driver defined) one, applications initialize the +<structfield>index</structfield> field of &v4l2-standard; and call the +<constant>VIDIOC_ENUMSTD</constant> ioctl with a pointer to this +structure. Drivers fill the rest of the structure or return an +&EINVAL; when the index is out of bounds. To enumerate all standards +applications shall begin at index zero, incrementing by one until the +driver returns <errorcode>EINVAL</errorcode>. Drivers may enumerate a +different set of standards after switching the video input or +output.<footnote> + <para>The supported standards may overlap and we need an +unambiguous set to find the current standard returned by +<constant>VIDIOC_G_STD</constant>.</para> + </footnote></para> + + <table pgwide="1" frame="none" id="v4l2-standard"> + <title>struct <structname>v4l2_standard</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Number of the video standard, set by the +application.</entry> + </row> + <row> + <entry>&v4l2-std-id;</entry> + <entry><structfield>id</structfield></entry> + <entry>The bits in this field identify the standard as +one of the common standards listed in <xref linkend="v4l2-std-id" />, +or if bits 32 to 63 are set as custom standards. Multiple bits can be +set if the hardware does not distinguish between these standards, +however separate indices do not indicate the opposite. The +<structfield>id</structfield> must be unique. No other enumerated +<structname>v4l2_standard</structname> structure, for this input or +output anyway, can contain the same set of bits.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[24]</entry> + <entry>Name of the standard, a NUL-terminated ASCII +string, for example: "PAL-B/G", "NTSC Japan". This information is +intended for the user.</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>frameperiod</structfield></entry> + <entry>The frame period (not field period) is numerator +/ denominator. For example M/NTSC has a frame period of 1001 / +30000 seconds.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>framelines</structfield></entry> + <entry>Total lines per frame including blanking, +e. g. 625 for B/PAL.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers must set +the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-fract"> + <title>struct <structname>v4l2_fract</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>numerator</structfield></entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>denominator</structfield></entry> + <entry></entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-std-id"> + <title>typedef <structname>v4l2_std_id</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u64</entry> + <entry><structfield>v4l2_std_id</structfield></entry> + <entry>This type is a set, each bit representing another +video standard as listed below and in <xref +linkend="video-standards" />. The 32 most significant bits are reserved +for custom (driver defined) video standards.</entry> + </row> + </tbody> + </tgroup> + </table> + + <para><programlisting> +#define V4L2_STD_PAL_B ((v4l2_std_id)0x00000001) +#define V4L2_STD_PAL_B1 ((v4l2_std_id)0x00000002) +#define V4L2_STD_PAL_G ((v4l2_std_id)0x00000004) +#define V4L2_STD_PAL_H ((v4l2_std_id)0x00000008) +#define V4L2_STD_PAL_I ((v4l2_std_id)0x00000010) +#define V4L2_STD_PAL_D ((v4l2_std_id)0x00000020) +#define V4L2_STD_PAL_D1 ((v4l2_std_id)0x00000040) +#define V4L2_STD_PAL_K ((v4l2_std_id)0x00000080) + +#define V4L2_STD_PAL_M ((v4l2_std_id)0x00000100) +#define V4L2_STD_PAL_N ((v4l2_std_id)0x00000200) +#define V4L2_STD_PAL_Nc ((v4l2_std_id)0x00000400) +#define V4L2_STD_PAL_60 ((v4l2_std_id)0x00000800) +</programlisting></para><para><constant>V4L2_STD_PAL_60</constant> is +a hybrid standard with 525 lines, 60 Hz refresh rate, and PAL color +modulation with a 4.43 MHz color subcarrier. Some PAL video recorders +can play back NTSC tapes in this mode for display on a 50/60 Hz agnostic +PAL TV.</para><para><programlisting> +#define V4L2_STD_NTSC_M ((v4l2_std_id)0x00001000) +#define V4L2_STD_NTSC_M_JP ((v4l2_std_id)0x00002000) +#define V4L2_STD_NTSC_443 ((v4l2_std_id)0x00004000) +</programlisting></para><para><constant>V4L2_STD_NTSC_443</constant> +is a hybrid standard with 525 lines, 60 Hz refresh rate, and NTSC +color modulation with a 4.43 MHz color +subcarrier.</para><para><programlisting> +#define V4L2_STD_NTSC_M_KR ((v4l2_std_id)0x00008000) + +#define V4L2_STD_SECAM_B ((v4l2_std_id)0x00010000) +#define V4L2_STD_SECAM_D ((v4l2_std_id)0x00020000) +#define V4L2_STD_SECAM_G ((v4l2_std_id)0x00040000) +#define V4L2_STD_SECAM_H ((v4l2_std_id)0x00080000) +#define V4L2_STD_SECAM_K ((v4l2_std_id)0x00100000) +#define V4L2_STD_SECAM_K1 ((v4l2_std_id)0x00200000) +#define V4L2_STD_SECAM_L ((v4l2_std_id)0x00400000) +#define V4L2_STD_SECAM_LC ((v4l2_std_id)0x00800000) + +/* ATSC/HDTV */ +#define V4L2_STD_ATSC_8_VSB ((v4l2_std_id)0x01000000) +#define V4L2_STD_ATSC_16_VSB ((v4l2_std_id)0x02000000) +</programlisting></para><para><!-- ATSC proposal by Mark McClelland, +video4linux-list@redhat.com on 17 Oct 2002 +--><constant>V4L2_STD_ATSC_8_VSB</constant> and +<constant>V4L2_STD_ATSC_16_VSB</constant> are U.S. terrestrial digital +TV standards. Presently the V4L2 API does not support digital TV. See +also the Linux DVB API at <ulink +url="http://linuxtv.org">http://linuxtv.org</ulink>.</para> +<para><programlisting> +#define V4L2_STD_PAL_BG (V4L2_STD_PAL_B |\ + V4L2_STD_PAL_B1 |\ + V4L2_STD_PAL_G) +#define V4L2_STD_B (V4L2_STD_PAL_B |\ + V4L2_STD_PAL_B1 |\ + V4L2_STD_SECAM_B) +#define V4L2_STD_GH (V4L2_STD_PAL_G |\ + V4L2_STD_PAL_H |\ + V4L2_STD_SECAM_G |\ + V4L2_STD_SECAM_H) +#define V4L2_STD_PAL_DK (V4L2_STD_PAL_D |\ + V4L2_STD_PAL_D1 |\ + V4L2_STD_PAL_K) +#define V4L2_STD_PAL (V4L2_STD_PAL_BG |\ + V4L2_STD_PAL_DK |\ + V4L2_STD_PAL_H |\ + V4L2_STD_PAL_I) +#define V4L2_STD_NTSC (V4L2_STD_NTSC_M |\ + V4L2_STD_NTSC_M_JP |\ + V4L2_STD_NTSC_M_KR) +#define V4L2_STD_MN (V4L2_STD_PAL_M |\ + V4L2_STD_PAL_N |\ + V4L2_STD_PAL_Nc |\ + V4L2_STD_NTSC) +#define V4L2_STD_SECAM_DK (V4L2_STD_SECAM_D |\ + V4L2_STD_SECAM_K |\ + V4L2_STD_SECAM_K1) +#define V4L2_STD_DK (V4L2_STD_PAL_DK |\ + V4L2_STD_SECAM_DK) + +#define V4L2_STD_SECAM (V4L2_STD_SECAM_B |\ + V4L2_STD_SECAM_G |\ + V4L2_STD_SECAM_H |\ + V4L2_STD_SECAM_DK |\ + V4L2_STD_SECAM_L |\ + V4L2_STD_SECAM_LC) + +#define V4L2_STD_525_60 (V4L2_STD_PAL_M |\ + V4L2_STD_PAL_60 |\ + V4L2_STD_NTSC |\ + V4L2_STD_NTSC_443) +#define V4L2_STD_625_50 (V4L2_STD_PAL |\ + V4L2_STD_PAL_N |\ + V4L2_STD_PAL_Nc |\ + V4L2_STD_SECAM) + +#define V4L2_STD_UNKNOWN 0 +#define V4L2_STD_ALL (V4L2_STD_525_60 |\ + V4L2_STD_625_50) +</programlisting></para> + + <table pgwide="1" id="video-standards" orient="land"> + <title>Video Standards (based on [<xref linkend="itu470" />])</title> + <tgroup cols="12" colsep="1" rowsep="1" align="center"> + <colspec colname="c1" align="left" /> + <colspec colname="c2" /> + <colspec colname="c3" /> + <colspec colname="c4" /> + <colspec colname="c5" /> + <colspec colnum="7" colname="c7" /> + <colspec colnum="9" colname="c9" /> + <colspec colnum="12" colname="c12" /> + <spanspec namest="c2" nameend="c3" spanname="m" align="center" /> + <spanspec namest="c4" nameend="c12" spanname="x" align="center" /> + <spanspec namest="c5" nameend="c7" spanname="b" align="center" /> + <spanspec namest="c9" nameend="c12" spanname="s" align="center" /> + <thead> + <row> + <entry>Characteristics</entry> + <entry><para>M/NTSC<footnote><para>Japan uses a standard +similar to M/NTSC +(V4L2_STD_NTSC_M_JP).</para></footnote></para></entry> + <entry>M/PAL</entry> + <entry><para>N/PAL<footnote><para> The values in +brackets apply to the combination N/PAL a.k.a. +N<subscript>C</subscript> used in Argentina +(V4L2_STD_PAL_Nc).</para></footnote></para></entry> + <entry align="center">B, B1, G/PAL</entry> + <entry align="center">D, D1, K/PAL</entry> + <entry align="center">H/PAL</entry> + <entry align="center">I/PAL</entry> + <entry align="center">B, G/SECAM</entry> + <entry align="center">D, K/SECAM</entry> + <entry align="center">K1/SECAM</entry> + <entry align="center">L/SECAM</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry>Frame lines</entry> + <entry spanname="m">525</entry> + <entry spanname="x">625</entry> + </row> + <row> + <entry>Frame period (s)</entry> + <entry spanname="m">1001/30000</entry> + <entry spanname="x">1/25</entry> + </row> + <row> + <entry>Chrominance sub-carrier frequency (Hz)</entry> + <entry>3579545 ± 10</entry> + <entry>3579611.49 ± 10</entry> + <entry>4433618.75 ± 5 (3582056.25 +± 5)</entry> + <entry spanname="b">4433618.75 ± 5</entry> + <entry>4433618.75 ± 1</entry> + <entry spanname="s">f<subscript>OR</subscript> = +4406250 ± 2000, f<subscript>OB</subscript> = 4250000 +± 2000</entry> + </row> + <row> + <entry>Nominal radio-frequency channel bandwidth +(MHz)</entry> + <entry>6</entry> + <entry>6</entry> + <entry>6</entry> + <entry>B: 7; B1, G: 8</entry> + <entry>8</entry> + <entry>8</entry> + <entry>8</entry> + <entry>8</entry> + <entry>8</entry> + <entry>8</entry> + <entry>8</entry> + </row> + <row> + <entry>Sound carrier relative to vision carrier +(MHz)</entry> + <entry>+ 4.5</entry> + <entry>+ 4.5</entry> + <entry>+ 4.5</entry> + <entry><para>+ 5.5 ± 0.001 +<footnote><para>In the Federal Republic of Germany, Austria, Italy, +the Netherlands, Slovakia and Switzerland a system of two sound +carriers is used, the frequency of the second carrier being +242.1875 kHz above the frequency of the first sound carrier. For +stereophonic sound transmissions a similar system is used in +Australia.</para></footnote> <footnote><para>New Zealand uses a sound +carrier displaced 5.4996 ± 0.0005 MHz from the vision +carrier.</para></footnote> <footnote><para>In Denmark, Finland, New +Zealand, Sweden and Spain a system of two sound carriers is used. In +Iceland, Norway and Poland the same system is being introduced. The +second carrier is 5.85 MHz above the vision carrier and is DQPSK +modulated with 728 kbit/s sound and data multiplex. (NICAM +system)</para></footnote> <footnote><para>In the United Kingdom, a +system of two sound carriers is used. The second sound carrier is +6.552 MHz above the vision carrier and is DQPSK modulated with a +728 kbit/s sound and data multiplex able to carry two sound +channels. (NICAM system)</para></footnote></para></entry> + <entry>+ 6.5 ± 0.001</entry> + <entry>+ 5.5</entry> + <entry>+ 5.9996 ± 0.0005</entry> + <entry>+ 5.5 ± 0.001</entry> + <entry>+ 6.5 ± 0.001</entry> + <entry>+ 6.5</entry> + <entry><para>+ 6.5 <footnote><para>In France, a +digital carrier 5.85 MHz away from the vision carrier may be used in +addition to the main sound carrier. It is modulated in differentially +encoded QPSK with a 728 kbit/s sound and data multiplexer capable of +carrying two sound channels. (NICAM +system)</para></footnote></para></entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-standard; <structfield>index</structfield> +is out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-audio.xml b/linux/Documentation/DocBook/v4l/vidioc-g-audio.xml new file mode 100644 index 000000000..65361a8c2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-audio.xml @@ -0,0 +1,188 @@ +<refentry id="vidioc-g-audio"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_AUDIO</refname> + <refname>VIDIOC_S_AUDIO</refname> + <refpurpose>Query or select the current audio input and its +attributes</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_audio *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_audio *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_AUDIO, VIDIOC_S_AUDIO</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the current audio input applications zero out the +<structfield>reserved</structfield> array of a &v4l2-audio; +and call the <constant>VIDIOC_G_AUDIO</constant> ioctl with a pointer +to this structure. Drivers fill the rest of the structure or return an +&EINVAL; when the device has no audio inputs, or none which combine +with the current video input.</para> + + <para>Audio inputs have one writable property, the audio mode. To +select the current audio input <emphasis>and</emphasis> change the +audio mode, applications initialize the +<structfield>index</structfield> and <structfield>mode</structfield> +fields, and the +<structfield>reserved</structfield> array of a +<structname>v4l2_audio</structname> structure and call the +<constant>VIDIOC_S_AUDIO</constant> ioctl. Drivers may switch to a +different audio mode if the request cannot be satisfied. However, this +is a write-only ioctl, it does not return the actual new audio +mode.</para> + + <table pgwide="1" frame="none" id="v4l2-audio"> + <title>struct <structname>v4l2_audio</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Identifies the audio input, set by the +driver or application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the audio input, a NUL-terminated ASCII +string, for example: "Line In". This information is intended for the +user, preferably the connector label on the device itself.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry>Audio capability flags, see <xref + linkend="audio-capability" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>mode</structfield></entry> + <entry>Audio mode flags set by drivers and applications (on + <constant>VIDIOC_S_AUDIO</constant> ioctl), see <xref linkend="audio-mode" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="audio-capability"> + <title>Audio Capability Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_AUDCAP_STEREO</constant></entry> + <entry>0x00001</entry> + <entry>This is a stereo input. The flag is intended to +automatically disable stereo recording etc. when the signal is always +monaural. The API provides no means to detect if stereo is +<emphasis>received</emphasis>, unless the audio input belongs to a +tuner.</entry> + </row> + <row> + <entry><constant>V4L2_AUDCAP_AVL</constant></entry> + <entry>0x00002</entry> + <entry>Automatic Volume Level mode is supported.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="audio-mode"> + <title>Audio Mode Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_AUDMODE_AVL</constant></entry> + <entry>0x00001</entry> + <entry>AVL mode is on.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>No audio inputs combine with the current video input, +or the number of the selected audio input is out of bounds or it does +not combine, or there are no audio inputs at all and the ioctl is not +supported.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>I/O is in progress, the input cannot be +switched.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-audioout.xml b/linux/Documentation/DocBook/v4l/vidioc-g-audioout.xml new file mode 100644 index 000000000..3632730c5 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-audioout.xml @@ -0,0 +1,154 @@ +<refentry id="vidioc-g-audioout"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_AUDOUT</refname> + <refname>VIDIOC_S_AUDOUT</refname> + <refpurpose>Query or select the current audio output</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_audioout *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_audioout *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the current audio output applications zero out the +<structfield>reserved</structfield> array of a &v4l2-audioout; and +call the <constant>VIDIOC_G_AUDOUT</constant> ioctl with a pointer +to this structure. Drivers fill the rest of the structure or return an +&EINVAL; when the device has no audio inputs, or none which combine +with the current video output.</para> + + <para>Audio outputs have no writable properties. Nevertheless, to +select the current audio output applications can initialize the +<structfield>index</structfield> field and +<structfield>reserved</structfield> array (which in the future may +contain writable properties) of a +<structname>v4l2_audioout</structname> structure and call the +<constant>VIDIOC_S_AUDOUT</constant> ioctl. Drivers switch to the +requested output or return the &EINVAL; when the index is out of +bounds. This is a write-only ioctl, it does not return the current +audio output attributes as <constant>VIDIOC_G_AUDOUT</constant> +does.</para> + + <para>Note connectors on a TV card to loop back the received audio +signal to a sound card are not audio outputs in this sense.</para> + + <table pgwide="1" frame="none" id="v4l2-audioout"> + <title>struct <structname>v4l2_audioout</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Identifies the audio output, set by the +driver or application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the audio output, a NUL-terminated ASCII +string, for example: "Line Out". This information is intended for the +user, preferably the connector label on the device itself.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry>Audio capability flags, none defined yet. Drivers +must set this field to zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>mode</structfield></entry> + <entry>Audio mode, none defined yet. Drivers and +applications (on <constant>VIDIOC_S_AUDOUT</constant>) must set this +field to zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>No audio outputs combine with the current video +output, or the number of the selected audio output is out of bounds or +it does not combine, or there are no audio outputs at all and the +ioctl is not supported.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>I/O is in progress, the output cannot be +switched.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-crop.xml b/linux/Documentation/DocBook/v4l/vidioc-g-crop.xml new file mode 100644 index 000000000..d235b1ded --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-crop.xml @@ -0,0 +1,143 @@ +<refentry id="vidioc-g-crop"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_CROP, VIDIOC_S_CROP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_CROP</refname> + <refname>VIDIOC_S_CROP</refname> + <refpurpose>Get or set the current cropping rectangle</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_crop *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_crop *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_CROP, VIDIOC_S_CROP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the cropping rectangle size and position +applications set the <structfield>type</structfield> field of a +<structname>v4l2_crop</structname> structure to the respective buffer +(stream) type and call the <constant>VIDIOC_G_CROP</constant> ioctl +with a pointer to this structure. The driver fills the rest of the +structure or returns the &EINVAL; if cropping is not supported.</para> + + <para>To change the cropping rectangle applications initialize the +<structfield>type</structfield> and &v4l2-rect; substructure named +<structfield>c</structfield> of a v4l2_crop structure and call the +<constant>VIDIOC_S_CROP</constant> ioctl with a pointer to this +structure.</para> + + <para>The driver first adjusts the requested dimensions against +hardware limits, &ie; the bounds given by the capture/output window, +and it rounds to the closest possible values of horizontal and +vertical offset, width and height. In particular the driver must round +the vertical offset of the cropping rectangle to frame lines modulo +two, such that the field order cannot be confused.</para> + + <para>Second the driver adjusts the image size (the opposite +rectangle of the scaling process, source or target depending on the +data direction) to the closest size possible while maintaining the +current horizontal and vertical scaling factor.</para> + + <para>Finally the driver programs the hardware with the actual +cropping and image parameters. <constant>VIDIOC_S_CROP</constant> is a +write-only ioctl, it does not return the actual parameters. To query +them applications must call <constant>VIDIOC_G_CROP</constant> and +&VIDIOC-G-FMT;. When the parameters are unsuitable the application may +modify the cropping or image parameters and repeat the cycle until +satisfactory parameters have been negotiated.</para> + + <para>When cropping is not supported then no parameters are +changed and <constant>VIDIOC_S_CROP</constant> returns the +&EINVAL;.</para> + + <table pgwide="1" frame="none" id="v4l2-crop"> + <title>struct <structname>v4l2_crop</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the data stream, set by the application. +Only these types are valid here: <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>, +<constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>, and custom (driver +defined) types with code <constant>V4L2_BUF_TYPE_PRIVATE</constant> +and higher.</entry> + </row> + <row> + <entry>&v4l2-rect;</entry> + <entry><structfield>c</structfield></entry> + <entry>Cropping rectangle. The same co-ordinate system as +for &v4l2-cropcap; <structfield>bounds</structfield> is used.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>Cropping is not supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-ctrl.xml b/linux/Documentation/DocBook/v4l/vidioc-g-ctrl.xml new file mode 100644 index 000000000..8b5e6ff7f --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-ctrl.xml @@ -0,0 +1,130 @@ +<refentry id="vidioc-g-ctrl"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_CTRL</refname> + <refname>VIDIOC_S_CTRL</refname> + <refpurpose>Get or set the value of a control</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_control +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_CTRL, VIDIOC_S_CTRL</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To get the current value of a control applications +initialize the <structfield>id</structfield> field of a struct +<structname>v4l2_control</structname> and call the +<constant>VIDIOC_G_CTRL</constant> ioctl with a pointer to this +structure. To change the value of a control applications initialize +the <structfield>id</structfield> and <structfield>value</structfield> +fields of a struct <structname>v4l2_control</structname> and call the +<constant>VIDIOC_S_CTRL</constant> ioctl.</para> + + <para>When the <structfield>id</structfield> is invalid drivers +return an &EINVAL;. When the <structfield>value</structfield> is out +of bounds drivers can choose to take the closest valid value or return +an &ERANGE;, whatever seems more appropriate. However, +<constant>VIDIOC_S_CTRL</constant> is a write-only ioctl, it does not +return the actual new value.</para> + + <para>These ioctls work only with user controls. For other +control classes the &VIDIOC-G-EXT-CTRLS;, &VIDIOC-S-EXT-CTRLS; or +&VIDIOC-TRY-EXT-CTRLS; must be used.</para> + + <table pgwide="1" frame="none" id="v4l2-control"> + <title>struct <structname>v4l2_control</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry>Identifies the control, set by the +application.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>value</structfield></entry> + <entry>New value or current value.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-control; <structfield>id</structfield> is +invalid.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ERANGE</errorcode></term> + <listitem> + <para>The &v4l2-control; <structfield>value</structfield> +is out of bounds.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The control is temporarily not changeable, possibly +because another applications took over control of the device function +this control belongs to.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-enc-index.xml b/linux/Documentation/DocBook/v4l/vidioc-g-enc-index.xml new file mode 100644 index 000000000..9f242e4b2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-enc-index.xml @@ -0,0 +1,213 @@ +<refentry id="vidioc-g-enc-index"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_ENC_INDEX</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_ENC_INDEX</refname> + <refpurpose>Get meta data about a compressed video stream</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_enc_idx *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_ENC_INDEX</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + + <para>This is an <link linkend="experimental">experimental</link> +interface and may change in the future.</para> + </note> + + <para>The <constant>VIDIOC_G_ENC_INDEX</constant> ioctl provides +meta data about a compressed video stream the same or another +application currently reads from the driver, which is useful for +random access into the stream without decoding it.</para> + + <para>To read the data applications must call +<constant>VIDIOC_G_ENC_INDEX</constant> with a pointer to a +&v4l2-enc-idx;. On success the driver fills the +<structfield>entry</structfield> array, stores the number of elements +written in the <structfield>entries</structfield> field, and +initializes the <structfield>entries_cap</structfield> field.</para> + + <para>Each element of the <structfield>entry</structfield> array +contains meta data about one picture. A +<constant>VIDIOC_G_ENC_INDEX</constant> call reads up to +<constant>V4L2_ENC_IDX_ENTRIES</constant> entries from a driver +buffer, which can hold up to <structfield>entries_cap</structfield> +entries. This number can be lower or higher than +<constant>V4L2_ENC_IDX_ENTRIES</constant>, but not zero. When the +application fails to read the meta data in time the oldest entries +will be lost. When the buffer is empty or no capturing/encoding is in +progress, <structfield>entries</structfield> will be zero.</para> + + <para>Currently this ioctl is only defined for MPEG-2 program +streams and video elementary streams.</para> + + <table pgwide="1" frame="none" id="v4l2-enc-idx"> + <title>struct <structname>v4l2_enc_idx</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>entries</structfield></entry> + <entry>The number of entries the driver stored in the +<structfield>entry</structfield> array.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>entries_cap</structfield></entry> + <entry>The number of entries the driver can +buffer. Must be greater than zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry spanname="hspan">Reserved for future extensions. +Drivers must set the array to zero.</entry> + </row> + <row> + <entry>&v4l2-enc-idx-entry;</entry> + <entry><structfield>entry</structfield>[<constant>V4L2_ENC_IDX_ENTRIES</constant>]</entry> + <entry>Meta data about a compressed video stream. Each +element of the array corresponds to one picture, sorted in ascending +order by their <structfield>offset</structfield>.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-enc-idx-entry"> + <title>struct <structname>v4l2_enc_idx_entry</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u64</entry> + <entry><structfield>offset</structfield></entry> + <entry>The offset in bytes from the beginning of the +compressed video stream to the beginning of this picture, that is a +<wordasword>PES packet header</wordasword> as defined in <xref + linkend="mpeg2part1" /> or a <wordasword>picture +header</wordasword> as defined in <xref linkend="mpeg2part2" />. When +the encoder is stopped, the driver resets the offset to zero.</entry> + </row> + <row> + <entry>__u64</entry> + <entry><structfield>pts</structfield></entry> + <entry>The 33 bit <wordasword>Presentation Time +Stamp</wordasword> of this picture as defined in <xref + linkend="mpeg2part1" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>length</structfield></entry> + <entry>The length of this picture in bytes.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Flags containing the coding type of this picture, see <xref + linkend="enc-idx-flags" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>Reserved for future extensions. +Drivers must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="enc-idx-flags"> + <title>Index Entry Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_ENC_IDX_FRAME_I</constant></entry> + <entry>0x00</entry> + <entry>This is an Intra-coded picture.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_IDX_FRAME_P</constant></entry> + <entry>0x01</entry> + <entry>This is a Predictive-coded picture.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_IDX_FRAME_B</constant></entry> + <entry>0x02</entry> + <entry>This is a Bidirectionally predictive-coded +picture.</entry> + </row> + <row> + <entry><constant>V4L2_ENC_IDX_FRAME_MASK</constant></entry> + <entry>0x0F</entry> + <entry><wordasword>AND</wordasword> the flags field with +this mask to obtain the picture coding type.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The driver does not support this ioctl.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-ext-ctrls.xml b/linux/Documentation/DocBook/v4l/vidioc-g-ext-ctrls.xml new file mode 100644 index 000000000..3aa7f8f9f --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-ext-ctrls.xml @@ -0,0 +1,307 @@ +<refentry id="vidioc-g-ext-ctrls"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, +VIDIOC_TRY_EXT_CTRLS</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_EXT_CTRLS</refname> + <refname>VIDIOC_S_EXT_CTRLS</refname> + <refname>VIDIOC_TRY_EXT_CTRLS</refname> + <refpurpose>Get or set the value of several controls, try control +values</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_ext_controls +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, +VIDIOC_TRY_EXT_CTRLS</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>These ioctls allow the caller to get or set multiple +controls atomically. Control IDs are grouped into control classes (see +<xref linkend="ctrl-class" />) and all controls in the control array +must belong to the same control class.</para> + + <para>Applications must always fill in the +<structfield>count</structfield>, +<structfield>ctrl_class</structfield>, +<structfield>controls</structfield> and +<structfield>reserved</structfield> fields of &v4l2-ext-controls;, and +initialize the &v4l2-ext-control; array pointed to by the +<structfield>controls</structfield> fields.</para> + + <para>To get the current value of a set of controls applications +initialize the <structfield>id</structfield>, +<structfield>size</structfield> and <structfield>reserved2</structfield> fields +of each &v4l2-ext-control; and call the +<constant>VIDIOC_G_EXT_CTRLS</constant> ioctl. String controls controls +must also set the <structfield>string</structfield> field.</para> + + <para>If the <structfield>size</structfield> is too small to +receive the control result (only relevant for pointer-type controls +like strings), then the driver will set <structfield>size</structfield> +to a valid value and return an &ENOSPC;. You should re-allocate the +string memory to this new size and try again. It is possible that the +same issue occurs again if the string has grown in the meantime. It is +recommended to call &VIDIOC-QUERYCTRL; first and use +<structfield>maximum</structfield>+1 as the new <structfield>size</structfield> +value. It is guaranteed that that is sufficient memory. +</para> + + <para>To change the value of a set of controls applications +initialize the <structfield>id</structfield>, <structfield>size</structfield>, +<structfield>reserved2</structfield> and +<structfield>value/string</structfield> fields of each &v4l2-ext-control; and +call the <constant>VIDIOC_S_EXT_CTRLS</constant> ioctl. The controls +will only be set if <emphasis>all</emphasis> control values are +valid.</para> + + <para>To check if a set of controls have correct values applications +initialize the <structfield>id</structfield>, <structfield>size</structfield>, +<structfield>reserved2</structfield> and +<structfield>value/string</structfield> fields of each &v4l2-ext-control; and +call the <constant>VIDIOC_TRY_EXT_CTRLS</constant> ioctl. It is up to +the driver whether wrong values are automatically adjusted to a valid +value or if an error is returned.</para> + + <para>When the <structfield>id</structfield> or +<structfield>ctrl_class</structfield> is invalid drivers return an +&EINVAL;. When the value is out of bounds drivers can choose to take +the closest valid value or return an &ERANGE;, whatever seems more +appropriate. In the first case the new value is set in +&v4l2-ext-control;.</para> + + <para>The driver will only set/get these controls if all control +values are correct. This prevents the situation where only some of the +controls were set/get. Only low-level errors (⪚ a failed i2c +command) can still cause this situation.</para> + + <table pgwide="1" frame="none" id="v4l2-ext-control"> + <title>struct <structname>v4l2_ext_control</structname></title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry></entry> + <entry>Identifies the control, set by the +application.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>size</structfield></entry> + <entry></entry> + <entry>The total size in bytes of the payload of this +control. This is normally 0, but for pointer controls this should be +set to the size of the memory containing the payload, or that will +receive the payload. If <constant>VIDIOC_G_EXT_CTRLS</constant> finds +that this value is less than is required to store +the payload result, then it is set to a value large enough to store the +payload result and ENOSPC is returned. Note that for string controls +this <structfield>size</structfield> field should not be confused with the length of the string. +This field refers to the size of the memory that contains the string. +The actual <emphasis>length</emphasis> of the string may well be much smaller. +</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved2</structfield>[1]</entry> + <entry></entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + <row> + <entry>union</entry> + <entry>(anonymous)</entry> + </row> + <row> + <entry></entry> + <entry>__s32</entry> + <entry><structfield>value</structfield></entry> + <entry>New value or current value.</entry> + </row> + <row> + <entry></entry> + <entry>__s64</entry> + <entry><structfield>value64</structfield></entry> + <entry>New value or current value.</entry> + </row> + <row> + <entry></entry> + <entry>char *</entry> + <entry><structfield>string</structfield></entry> + <entry>A pointer to a string.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-ext-controls"> + <title>struct <structname>v4l2_ext_controls</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>ctrl_class</structfield></entry> + <entry>The control class to which all controls belong, see +<xref linkend="ctrl-class" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>count</structfield></entry> + <entry>The number of controls in the controls array. May +also be zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>error_idx</structfield></entry> + <entry>Set by the driver in case of an error. It is the +index of the control causing the error or equal to 'count' when the +error is not associated with a particular control. Undefined when the +ioctl returns 0 (success).</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + <row> + <entry>&v4l2-ext-control; *</entry> + <entry><structfield>controls</structfield></entry> + <entry>Pointer to an array of +<structfield>count</structfield> v4l2_ext_control structures. Ignored +if <structfield>count</structfield> equals zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="ctrl-class"> + <title>Control classes</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_CTRL_CLASS_USER</constant></entry> + <entry>0x980000</entry> + <entry>The class containing user controls. These controls +are described in <xref linkend="control" />. All controls that can be set +using the &VIDIOC-S-CTRL; and &VIDIOC-G-CTRL; ioctl belong to this +class.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_CLASS_MPEG</constant></entry> + <entry>0x990000</entry> + <entry>The class containing MPEG compression controls. +These controls are described in <xref + linkend="mpeg-controls" />.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_CLASS_CAMERA</constant></entry> + <entry>0x9a0000</entry> + <entry>The class containing camera controls. +These controls are described in <xref + linkend="camera-controls" />.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_CLASS_FM_TX</constant></entry> + <entry>0x9b0000</entry> + <entry>The class containing FM Transmitter (FM TX) controls. +These controls are described in <xref + linkend="fm-tx-controls" />.</entry> + </row> + </tbody> + </tgroup> + </table> + + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-ext-control; <structfield>id</structfield> +is invalid or the &v4l2-ext-controls; +<structfield>ctrl_class</structfield> is invalid. This error code is +also returned by the <constant>VIDIOC_S_EXT_CTRLS</constant> and +<constant>VIDIOC_TRY_EXT_CTRLS</constant> ioctls if two or more +control values are in conflict.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ERANGE</errorcode></term> + <listitem> + <para>The &v4l2-ext-control; <structfield>value</structfield> +is out of bounds.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The control is temporarily not changeable, possibly +because another applications took over control of the device function +this control belongs to.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENOSPC</errorcode></term> + <listitem> + <para>The space reserved for the control's payload is insufficient. +The field <structfield>size</structfield> is set to a value that is enough +to store the payload and this error code is returned.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-fbuf.xml b/linux/Documentation/DocBook/v4l/vidioc-g-fbuf.xml new file mode 100644 index 000000000..f70170626 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-fbuf.xml @@ -0,0 +1,456 @@ +<refentry id="vidioc-g-fbuf"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_FBUF, VIDIOC_S_FBUF</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_FBUF</refname> + <refname>VIDIOC_S_FBUF</refname> + <refpurpose>Get or set frame buffer overlay parameters</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_framebuffer *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_framebuffer *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_FBUF, VIDIOC_S_FBUF</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Applications can use the <constant>VIDIOC_G_FBUF</constant> and +<constant>VIDIOC_S_FBUF</constant> ioctl to get and set the +framebuffer parameters for a <link linkend="overlay">Video +Overlay</link> or <link linkend="osd">Video Output Overlay</link> +(OSD). The type of overlay is implied by the device type (capture or +output device) and can be determined with the &VIDIOC-QUERYCAP; ioctl. +One <filename>/dev/videoN</filename> device must not support both +kinds of overlay.</para> + + <para>The V4L2 API distinguishes destructive and non-destructive +overlays. A destructive overlay copies captured video images into the +video memory of a graphics card. A non-destructive overlay blends +video images into a VGA signal or graphics into a video signal. +<wordasword>Video Output Overlays</wordasword> are always +non-destructive.</para> + + <para>To get the current parameters applications call the +<constant>VIDIOC_G_FBUF</constant> ioctl with a pointer to a +<structname>v4l2_framebuffer</structname> structure. The driver fills +all fields of the structure or returns an &EINVAL; when overlays are +not supported.</para> + + <para>To set the parameters for a <wordasword>Video Output +Overlay</wordasword>, applications must initialize the +<structfield>flags</structfield> field of a struct +<structname>v4l2_framebuffer</structname>. Since the framebuffer is +implemented on the TV card all other parameters are determined by the +driver. When an application calls <constant>VIDIOC_S_FBUF</constant> +with a pointer to this structure, the driver prepares for the overlay +and returns the framebuffer parameters as +<constant>VIDIOC_G_FBUF</constant> does, or it returns an error +code.</para> + + <para>To set the parameters for a <wordasword>non-destructive +Video Overlay</wordasword>, applications must initialize the +<structfield>flags</structfield> field, the +<structfield>fmt</structfield> substructure, and call +<constant>VIDIOC_S_FBUF</constant>. Again the driver prepares for the +overlay and returns the framebuffer parameters as +<constant>VIDIOC_G_FBUF</constant> does, or it returns an error +code.</para> + + <para>For a <wordasword>destructive Video Overlay</wordasword> +applications must additionally provide a +<structfield>base</structfield> address. Setting up a DMA to a +random memory location can jeopardize the system security, its +stability or even damage the hardware, therefore only the superuser +can set the parameters for a destructive video overlay.</para> + + <!-- NB v4l2_pix_format is also specified in pixfmt.sgml.--> + + <table pgwide="1" frame="none" id="v4l2-framebuffer"> + <title>struct <structname>v4l2_framebuffer</structname></title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry></entry> + <entry>Overlay capability flags set by the driver, see +<xref linkend="framebuffer-cap" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry></entry> + <entry>Overlay control flags set by application and +driver, see <xref linkend="framebuffer-flags" /></entry> + </row> + <row> + <entry>void *</entry> + <entry><structfield>base</structfield></entry> + <entry></entry> + <entry>Physical base address of the framebuffer, +that is the address of the pixel in the top left corner of the +framebuffer.<footnote><para>A physical base address may not suit all +platforms. GK notes in theory we should pass something like PCI device ++ memory region + offset instead. If you encounter problems please +discuss on the linux-media mailing list: &v4l-ml;.</para></footnote></entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry></entry> + <entry>This field is irrelevant to +<wordasword>non-destructive Video Overlays</wordasword>. For +<wordasword>destructive Video Overlays</wordasword> applications must +provide a base address. The driver may accept only base addresses +which are a multiple of two, four or eight bytes. For +<wordasword>Video Output Overlays</wordasword> the driver must return +a valid base address, so applications can find the corresponding Linux +framebuffer device (see <xref linkend="osd" />).</entry> + </row> + <row> + <entry>&v4l2-pix-format;</entry> + <entry><structfield>fmt</structfield></entry> + <entry></entry> + <entry>Layout of the frame buffer. The +<structname>v4l2_pix_format</structname> structure is defined in <xref +linkend="pixfmt" />, for clarification the fields and acceptable values + are listed below:</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>width</structfield></entry> + <entry>Width of the frame buffer in pixels.</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>height</structfield></entry> + <entry>Height of the frame buffer in pixels.</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>pixelformat</structfield></entry> + <entry>The pixel format of the +framebuffer.</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry></entry> + <entry>For <wordasword>non-destructive Video +Overlays</wordasword> this field only defines a format for the +&v4l2-window; <structfield>chromakey</structfield> field.</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry></entry> + <entry>For <wordasword>destructive Video +Overlays</wordasword> applications must initialize this field. For +<wordasword>Video Output Overlays</wordasword> the driver must return +a valid format.</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry></entry> + <entry>Usually this is an RGB format (for example +<link linkend="V4L2-PIX-FMT-RGB565"><constant>V4L2_PIX_FMT_RGB565</constant></link>) +but YUV formats (only packed YUV formats when chroma keying is used, +not including <constant>V4L2_PIX_FMT_YUYV</constant> and +<constant>V4L2_PIX_FMT_UYVY</constant>) and the +<constant>V4L2_PIX_FMT_PAL8</constant> format are also permitted. The +behavior of the driver when an application requests a compressed +format is undefined. See <xref linkend="pixfmt" /> for information on +pixel formats.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-field;</entry> + <entry><structfield>field</structfield></entry> + <entry>Drivers and applications shall ignore this field. +If applicable, the field order is selected with the &VIDIOC-S-FMT; +ioctl, using the <structfield>field</structfield> field of +&v4l2-window;.</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>bytesperline</structfield></entry> + <entry>Distance in bytes between the leftmost pixels in +two adjacent lines.</entry> + </row> + <row> + <entry spanname="hspan"><para>This field is irrelevant to +<wordasword>non-destructive Video +Overlays</wordasword>.</para><para>For <wordasword>destructive Video +Overlays</wordasword> both applications and drivers can set this field +to request padding bytes at the end of each line. Drivers however may +ignore the requested value, returning <structfield>width</structfield> +times bytes-per-pixel or a larger value required by the hardware. That +implies applications can just set this field to zero to get a +reasonable default.</para><para>For <wordasword>Video Output +Overlays</wordasword> the driver must return a valid +value.</para><para>Video hardware may access padding bytes, therefore +they must reside in accessible memory. Consider for example the case +where padding bytes after the last line of an image cross a system +page boundary. Capture devices may write padding bytes, the value is +undefined. Output devices ignore the contents of padding +bytes.</para><para>When the image format is planar the +<structfield>bytesperline</structfield> value applies to the largest +plane and is divided by the same factor as the +<structfield>width</structfield> field for any smaller planes. For +example the Cb and Cr planes of a YUV 4:2:0 image have half as many +padding bytes following each line as the Y plane. To avoid ambiguities +drivers must return a <structfield>bytesperline</structfield> value +rounded up to a multiple of the scale factor.</para></entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>sizeimage</structfield></entry> + <entry><para>This field is irrelevant to +<wordasword>non-destructive Video Overlays</wordasword>. For +<wordasword>destructive Video Overlays</wordasword> applications must +initialize this field. For <wordasword>Video Output +Overlays</wordasword> the driver must return a valid +format.</para><para>Together with <structfield>base</structfield> it +defines the framebuffer memory accessible by the +driver.</para></entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-colorspace;</entry> + <entry><structfield>colorspace</structfield></entry> + <entry>This information supplements the +<structfield>pixelformat</structfield> and must be set by the driver, +see <xref linkend="colorspaces" />.</entry> + </row> + <row> + <entry></entry> + <entry>__u32</entry> + <entry><structfield>priv</structfield></entry> + <entry>Reserved for additional information about custom +(driver defined) formats. When not used drivers and applications must +set this field to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="framebuffer-cap"> + <title>Frame Buffer Capability Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_FBUF_CAP_EXTERNOVERLAY</constant></entry> + <entry>0x0001</entry> + <entry>The device is capable of non-destructive overlays. +When the driver clears this flag, only destructive overlays are +supported. There are no drivers yet which support both destructive and +non-destructive overlays.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_CAP_CHROMAKEY</constant></entry> + <entry>0x0002</entry> + <entry>The device supports clipping by chroma-keying the +images. That is, image pixels replace pixels in the VGA or video +signal only where the latter assume a certain color. Chroma-keying +makes no sense for destructive overlays.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant></entry> + <entry>0x0004</entry> + <entry>The device supports clipping using a list of clip +rectangles.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant></entry> + <entry>0x0008</entry> + <entry>The device supports clipping using a bit mask.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_CAP_LOCAL_ALPHA</constant></entry> + <entry>0x0010</entry> + <entry>The device supports clipping/blending using the +alpha channel of the framebuffer or VGA signal. Alpha blending makes +no sense for destructive overlays.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_CAP_GLOBAL_ALPHA</constant></entry> + <entry>0x0020</entry> + <entry>The device supports alpha blending using a global +alpha value. Alpha blending makes no sense for destructive overlays.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_CAP_LOCAL_INV_ALPHA</constant></entry> + <entry>0x0040</entry> + <entry>The device supports clipping/blending using the +inverted alpha channel of the framebuffer or VGA signal. Alpha +blending makes no sense for destructive overlays.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="framebuffer-flags"> + <title>Frame Buffer Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_FBUF_FLAG_PRIMARY</constant></entry> + <entry>0x0001</entry> + <entry>The framebuffer is the primary graphics surface. +In other words, the overlay is destructive. [?]</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_FLAG_OVERLAY</constant></entry> + <entry>0x0002</entry> + <entry>The frame buffer is an overlay surface the same +size as the capture. [?]</entry> + </row> + <row> + <entry spanname="hspan">The purpose of +<constant>V4L2_FBUF_FLAG_PRIMARY</constant> and +<constant>V4L2_FBUF_FLAG_OVERLAY</constant> was never quite clear. +Most drivers seem to ignore these flags. For compatibility with the +<wordasword>bttv</wordasword> driver applications should set the +<constant>V4L2_FBUF_FLAG_OVERLAY</constant> flag.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_FLAG_CHROMAKEY</constant></entry> + <entry>0x0004</entry> + <entry>Use chroma-keying. The chroma-key color is +determined by the <structfield>chromakey</structfield> field of +&v4l2-window; and negotiated with the &VIDIOC-S-FMT; ioctl, see <xref + linkend="overlay" /> +and + <xref linkend="osd" />.</entry> + </row> + <row> + <entry spanname="hspan">There are no flags to enable +clipping using a list of clip rectangles or a bitmap. These methods +are negotiated with the &VIDIOC-S-FMT; ioctl, see <xref + linkend="overlay" /> and <xref linkend="osd" />.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_FLAG_LOCAL_ALPHA</constant></entry> + <entry>0x0008</entry> + <entry>Use the alpha channel of the framebuffer to clip or +blend framebuffer pixels with video images. The blend +function is: output = framebuffer pixel * alpha + video pixel * (1 - +alpha). The actual alpha depth depends on the framebuffer pixel +format.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_FLAG_GLOBAL_ALPHA</constant></entry> + <entry>0x0010</entry> + <entry>Use a global alpha value to blend the framebuffer +with video images. The blend function is: output = (framebuffer pixel +* alpha + video pixel * (255 - alpha)) / 255. The alpha value is +determined by the <structfield>global_alpha</structfield> field of +&v4l2-window; and negotiated with the &VIDIOC-S-FMT; ioctl, see <xref + linkend="overlay" /> +and <xref linkend="osd" />.</entry> + </row> + <row> + <entry><constant>V4L2_FBUF_FLAG_LOCAL_INV_ALPHA</constant></entry> + <entry>0x0020</entry> + <entry>Like +<constant>V4L2_FBUF_FLAG_LOCAL_ALPHA</constant>, use the alpha channel +of the framebuffer to clip or blend framebuffer pixels with video +images, but with an inverted alpha value. The blend function is: +output = framebuffer pixel * (1 - alpha) + video pixel * alpha. The +actual alpha depth depends on the framebuffer pixel format.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EPERM</errorcode></term> + <listitem> + <para><constant>VIDIOC_S_FBUF</constant> can only be called +by a privileged user to negotiate the parameters for a destructive +overlay.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The framebuffer parameters cannot be changed at this +time because overlay is already enabled, or capturing is enabled +and the hardware cannot capture and overlay simultaneously.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The ioctl is not supported or the +<constant>VIDIOC_S_FBUF</constant> parameters are unsuitable.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-fmt.xml b/linux/Documentation/DocBook/v4l/vidioc-g-fmt.xml new file mode 100644 index 000000000..7c7d1b72c --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-fmt.xml @@ -0,0 +1,201 @@ +<refentry id="vidioc-g-fmt"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_FMT, VIDIOC_S_FMT, +VIDIOC_TRY_FMT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_FMT</refname> + <refname>VIDIOC_S_FMT</refname> + <refname>VIDIOC_TRY_FMT</refname> + <refpurpose>Get or set the data format, try a format</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_format +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_FMT, VIDIOC_S_FMT, VIDIOC_TRY_FMT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>These ioctls are used to negotiate the format of data +(typically image format) exchanged between driver and +application.</para> + + <para>To query the current parameters applications set the +<structfield>type</structfield> field of a struct +<structname>v4l2_format</structname> to the respective buffer (stream) +type. For example video capture devices use +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>. When the application +calls the <constant>VIDIOC_G_FMT</constant> ioctl with a pointer to +this structure the driver fills the respective member of the +<structfield>fmt</structfield> union. In case of video capture devices +that is the &v4l2-pix-format; <structfield>pix</structfield> member. +When the requested buffer type is not supported drivers return an +&EINVAL;.</para> + + <para>To change the current format parameters applications +initialize the <structfield>type</structfield> field and all +fields of the respective <structfield>fmt</structfield> +union member. For details see the documentation of the various devices +types in <xref linkend="devices" />. Good practice is to query the +current parameters first, and to +modify only those parameters not suitable for the application. When +the application calls the <constant>VIDIOC_S_FMT</constant> ioctl +with a pointer to a <structname>v4l2_format</structname> structure +the driver checks +and adjusts the parameters against hardware abilities. Drivers +should not return an error code unless the input is ambiguous, this is +a mechanism to fathom device capabilities and to approach parameters +acceptable for both the application and driver. On success the driver +may program the hardware, allocate resources and generally prepare for +data exchange. +Finally the <constant>VIDIOC_S_FMT</constant> ioctl returns the +current format parameters as <constant>VIDIOC_G_FMT</constant> does. +Very simple, inflexible devices may even ignore all input and always +return the default parameters. However all V4L2 devices exchanging +data with the application must implement the +<constant>VIDIOC_G_FMT</constant> and +<constant>VIDIOC_S_FMT</constant> ioctl. When the requested buffer +type is not supported drivers return an &EINVAL; on a +<constant>VIDIOC_S_FMT</constant> attempt. When I/O is already in +progress or the resource is not available for other reasons drivers +return the &EBUSY;.</para> + + <para>The <constant>VIDIOC_TRY_FMT</constant> ioctl is equivalent +to <constant>VIDIOC_S_FMT</constant> with one exception: it does not +change driver state. It can also be called at any time, never +returning <errorcode>EBUSY</errorcode>. This function is provided to +negotiate parameters, to learn about hardware limitations, without +disabling I/O or possibly time consuming hardware preparations. +Although strongly recommended drivers are not required to implement +this ioctl.</para> + + <table pgwide="1" frame="none" id="v4l2-format"> + <title>struct <structname>v4l2_format</structname></title> + <tgroup cols="4"> + <colspec colname="c1" /> + <colspec colname="c2" /> + <colspec colname="c3" /> + <colspec colname="c4" /> + <tbody valign="top"> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry></entry> + <entry>Type of the data stream, see <xref + linkend="v4l2-buf-type" />.</entry> + </row> + <row> + <entry>union</entry> + <entry><structfield>fmt</structfield></entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-pix-format;</entry> + <entry><structfield>pix</structfield></entry> + <entry>Definition of an image format, see <xref + linkend="pixfmt" />, used by video capture and output +devices.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-window;</entry> + <entry><structfield>win</structfield></entry> + <entry>Definition of an overlaid image, see <xref + linkend="overlay" />, used by video overlay devices.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-vbi-format;</entry> + <entry><structfield>vbi</structfield></entry> + <entry>Raw VBI capture or output parameters. This is +discussed in more detail in <xref linkend="raw-vbi" />. Used by raw VBI +capture and output devices.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-sliced-vbi-format;</entry> + <entry><structfield>sliced</structfield></entry> + <entry>Sliced VBI capture or output parameters. See +<xref linkend="sliced" /> for details. Used by sliced VBI +capture and output devices.</entry> + </row> + <row> + <entry></entry> + <entry>__u8</entry> + <entry><structfield>raw_data</structfield>[200]</entry> + <entry>Place holder for future extensions and custom +(driver defined) formats with <structfield>type</structfield> +<constant>V4L2_BUF_TYPE_PRIVATE</constant> and higher.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The data format cannot be changed at this +time, for example because I/O is already in progress.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-format; <structfield>type</structfield> +field is invalid, the requested buffer type not supported, or +<constant>VIDIOC_TRY_FMT</constant> was called and is not +supported with this buffer type.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-frequency.xml b/linux/Documentation/DocBook/v4l/vidioc-g-frequency.xml new file mode 100644 index 000000000..062d72069 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-frequency.xml @@ -0,0 +1,145 @@ +<refentry id="vidioc-g-frequency"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_FREQUENCY</refname> + <refname>VIDIOC_S_FREQUENCY</refname> + <refpurpose>Get or set tuner or modulator radio +frequency</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_frequency +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_frequency +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To get the current tuner or modulator radio frequency +applications set the <structfield>tuner</structfield> field of a +&v4l2-frequency; to the respective tuner or modulator number (only +input devices have tuners, only output devices have modulators), zero +out the <structfield>reserved</structfield> array and +call the <constant>VIDIOC_G_FREQUENCY</constant> ioctl with a pointer +to this structure. The driver stores the current frequency in the +<structfield>frequency</structfield> field.</para> + + <para>To change the current tuner or modulator radio frequency +applications initialize the <structfield>tuner</structfield>, +<structfield>type</structfield> and +<structfield>frequency</structfield> fields, and the +<structfield>reserved</structfield> array of a &v4l2-frequency; and +call the <constant>VIDIOC_S_FREQUENCY</constant> ioctl with a pointer +to this structure. When the requested frequency is not possible the +driver assumes the closest possible value. However +<constant>VIDIOC_S_FREQUENCY</constant> is a write-only ioctl, it does +not return the actual new frequency.</para> + + <table pgwide="1" frame="none" id="v4l2-frequency"> + <title>struct <structname>v4l2_frequency</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>tuner</structfield></entry> + <entry>The tuner or modulator index number. This is the +same value as in the &v4l2-input; <structfield>tuner</structfield> +field and the &v4l2-tuner; <structfield>index</structfield> field, or +the &v4l2-output; <structfield>modulator</structfield> field and the +&v4l2-modulator; <structfield>index</structfield> field.</entry> + </row> + <row> + <entry>&v4l2-tuner-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>The tuner type. This is the same value as in the +&v4l2-tuner; <structfield>type</structfield> field. The field is not +applicable to modulators, &ie; ignored by drivers.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>frequency</structfield></entry> + <entry>Tuning frequency in units of 62.5 kHz, or if the +&v4l2-tuner; or &v4l2-modulator; <structfield>capabilities</structfield> flag +<constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5 +Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[8]</entry> + <entry>Reserved for future extensions. Drivers and + applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <structfield>tuner</structfield> index is out of +bounds or the value in the <structfield>type</structfield> field is +wrong.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-input.xml b/linux/Documentation/DocBook/v4l/vidioc-g-input.xml new file mode 100644 index 000000000..ed076e927 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-input.xml @@ -0,0 +1,100 @@ +<refentry id="vidioc-g-input"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_INPUT</refname> + <refname>VIDIOC_S_INPUT</refname> + <refpurpose>Query or select the current video input</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>int *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_INPUT, VIDIOC_S_INPUT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the current video input applications call the +<constant>VIDIOC_G_INPUT</constant> ioctl with a pointer to an integer +where the driver stores the number of the input, as in the +&v4l2-input; <structfield>index</structfield> field. This ioctl will +fail only when there are no video inputs, returning +<errorcode>EINVAL</errorcode>.</para> + + <para>To select a video input applications store the number of the +desired input in an integer and call the +<constant>VIDIOC_S_INPUT</constant> ioctl with a pointer to this +integer. Side effects are possible. For example inputs may support +different video standards, so the driver may implicitly switch the +current standard. It is good practice to select an input before +querying or negotiating any other parameters.</para> + + <para>Information about video inputs is available using the +&VIDIOC-ENUMINPUT; ioctl.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The number of the video input is out of bounds, or +there are no video inputs at all and this ioctl is not +supported.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>I/O is in progress, the input cannot be +switched.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-jpegcomp.xml b/linux/Documentation/DocBook/v4l/vidioc-g-jpegcomp.xml new file mode 100644 index 000000000..77394b287 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-jpegcomp.xml @@ -0,0 +1,180 @@ +<refentry id="vidioc-g-jpegcomp"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_JPEGCOMP</refname> + <refname>VIDIOC_S_JPEGCOMP</refname> + <refpurpose></refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>v4l2_jpegcompression *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const v4l2_jpegcompression *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>[to do]</para> + + <para>Ronald Bultje elaborates:</para> + + <!-- See video4linux-list@redhat.com on 16 Oct 2002, subject +"Re: [V4L] Re: v4l2 api / Zoran v4l2_jpegcompression" --> + + <para>APP is some application-specific information. The +application can set it itself, and it'll be stored in the JPEG-encoded +fields (eg; interlacing information for in an AVI or so). COM is the +same, but it's comments, like 'encoded by me' or so.</para> + + <para>jpeg_markers describes whether the huffman tables, +quantization tables and the restart interval information (all +JPEG-specific stuff) should be stored in the JPEG-encoded fields. +These define how the JPEG field is encoded. If you omit them, +applications assume you've used standard encoding. You usually do want +to add them.</para> + + <!-- NB VIDIOC_S_JPEGCOMP is w/o. --> + + <table pgwide="1" frame="none" id="v4l2-jpegcompression"> + <title>struct <structname>v4l2_jpegcompression</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>int</entry> + <entry><structfield>quality</structfield></entry> + <entry></entry> + </row> + <row> + <entry>int</entry> + <entry><structfield>APPn</structfield></entry> + <entry></entry> + </row> + <row> + <entry>int</entry> + <entry><structfield>APP_len</structfield></entry> + <entry></entry> + </row> + <row> + <entry>char</entry> + <entry><structfield>APP_data</structfield>[60]</entry> + <entry></entry> + </row> + <row> + <entry>int</entry> + <entry><structfield>COM_len</structfield></entry> + <entry></entry> + </row> + <row> + <entry>char</entry> + <entry><structfield>COM_data</structfield>[60]</entry> + <entry></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>jpeg_markers</structfield></entry> + <entry>See <xref linkend="jpeg-markers" />.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="jpeg-markers"> + <title>JPEG Markers Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_JPEG_MARKER_DHT</constant></entry> + <entry>(1<<3)</entry> + <entry>Define Huffman Tables</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_DQT</constant></entry> + <entry>(1<<4)</entry> + <entry>Define Quantization Tables</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_DRI</constant></entry> + <entry>(1<<5)</entry> + <entry>Define Restart Interval</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_COM</constant></entry> + <entry>(1<<6)</entry> + <entry>Comment segment</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_APP</constant></entry> + <entry>(1<<7)</entry> + <entry>App segment, driver will always use APP0</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>This ioctl is not supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-modulator.xml b/linux/Documentation/DocBook/v4l/vidioc-g-modulator.xml new file mode 100644 index 000000000..15ce660f0 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-modulator.xml @@ -0,0 +1,246 @@ +<refentry id="vidioc-g-modulator"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_MODULATOR</refname> + <refname>VIDIOC_S_MODULATOR</refname> + <refpurpose>Get or set modulator attributes</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_modulator +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_modulator +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of a modulator applications initialize +the <structfield>index</structfield> field and zero out the +<structfield>reserved</structfield> array of a &v4l2-modulator; and +call the <constant>VIDIOC_G_MODULATOR</constant> ioctl with a pointer +to this structure. Drivers fill the rest of the structure or return an +&EINVAL; when the index is out of bounds. To enumerate all modulators +applications shall begin at index zero, incrementing by one until the +driver returns <errorcode>EINVAL</errorcode>.</para> + + <para>Modulators have two writable properties, an audio +modulation set and the radio frequency. To change the modulated audio +subprograms, applications initialize the <structfield>index +</structfield> and <structfield>txsubchans</structfield> fields and the +<structfield>reserved</structfield> array and call the +<constant>VIDIOC_S_MODULATOR</constant> ioctl. Drivers may choose a +different audio modulation if the request cannot be satisfied. However +this is a write-only ioctl, it does not return the actual audio +modulation selected.</para> + + <para>To change the radio frequency the &VIDIOC-S-FREQUENCY; ioctl +is available.</para> + + <table pgwide="1" frame="none" id="v4l2-modulator"> + <title>struct <structname>v4l2_modulator</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Identifies the modulator, set by the +application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the modulator, a NUL-terminated ASCII +string. This information is intended for the user.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry>Modulator capability flags. No flags are defined +for this field, the tuner flags in &v4l2-tuner; +are used accordingly. The audio flags indicate the ability +to encode audio subprograms. They will <emphasis>not</emphasis> +change for example with the current video standard.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>rangelow</structfield></entry> + <entry>The lowest tunable frequency in units of 62.5 +KHz, or if the <structfield>capability</structfield> flag +<constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5 +Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>rangehigh</structfield></entry> + <entry>The highest tunable frequency in units of 62.5 +KHz, or if the <structfield>capability</structfield> flag +<constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5 +Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>txsubchans</structfield></entry> + <entry>With this field applications can determine how +audio sub-carriers shall be modulated. It contains a set of flags as +defined in <xref linkend="modulator-txsubchans" />. Note the tuner +<structfield>rxsubchans</structfield> flags are reused, but the +semantics are different. Video output devices are assumed to have an +analog or PCM audio input with 1-3 channels. The +<structfield>txsubchans</structfield> flags select one or more +channels for modulation, together with some audio subprogram +indicator, for example a stereo pilot tone.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="modulator-txsubchans"> + <title>Modulator Audio Transmission Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry> + <entry>0x0001</entry> + <entry>Modulate channel 1 as mono audio, when the input +has more channels, a down-mix of channel 1 and 2. This flag does not +combine with <constant>V4L2_TUNER_SUB_STEREO</constant> or +<constant>V4L2_TUNER_SUB_LANG1</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_STEREO</constant></entry> + <entry>0x0002</entry> + <entry>Modulate channel 1 and 2 as left and right +channel of a stereo audio signal. When the input has only one channel +or two channels and <constant>V4L2_TUNER_SUB_SAP</constant> is also +set, channel 1 is encoded as left and right channel. This flag does +not combine with <constant>V4L2_TUNER_SUB_MONO</constant> or +<constant>V4L2_TUNER_SUB_LANG1</constant>. When the driver does not +support stereo audio it shall fall back to mono.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_LANG1</constant></entry> + <entry>0x0008</entry> + <entry>Modulate channel 1 and 2 as primary and secondary +language of a bilingual audio signal. When the input has only one +channel it is used for both languages. It is not possible to encode +the primary or secondary language only. This flag does not combine +with <constant>V4L2_TUNER_SUB_MONO</constant>, +<constant>V4L2_TUNER_SUB_STEREO</constant> or +<constant>V4L2_TUNER_SUB_SAP</constant>. If the hardware does not +support the respective audio matrix, or the current video standard +does not permit bilingual audio the +<constant>VIDIOC_S_MODULATOR</constant> ioctl shall return an &EINVAL; +and the driver shall fall back to mono or stereo mode.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_LANG2</constant></entry> + <entry>0x0004</entry> + <entry>Same effect as +<constant>V4L2_TUNER_SUB_SAP</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_SAP</constant></entry> + <entry>0x0004</entry> + <entry>When combined with <constant>V4L2_TUNER_SUB_MONO +</constant> the first channel is encoded as mono audio, the last +channel as Second Audio Program. When the input has only one channel +it is used for both audio tracks. When the input has three channels +the mono track is a down-mix of channel 1 and 2. When combined with +<constant>V4L2_TUNER_SUB_STEREO</constant> channel 1 and 2 are +encoded as left and right stereo audio, channel 3 as Second Audio +Program. When the input has only two channels, the first is encoded as +left and right channel and the second as SAP. When the input has only +one channel it is used for all audio tracks. It is not possible to +encode a Second Audio Program only. This flag must combine with +<constant>V4L2_TUNER_SUB_MONO</constant> or +<constant>V4L2_TUNER_SUB_STEREO</constant>. If the hardware does not +support the respective audio matrix, or the current video standard +does not permit SAP the <constant>VIDIOC_S_MODULATOR</constant> ioctl +shall return an &EINVAL; and driver shall fall back to mono or stereo +mode.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_RDS</constant></entry> + <entry>0x0010</entry> + <entry>Enable the RDS encoder for a radio FM transmitter.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-modulator; +<structfield>index</structfield> is out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-output.xml b/linux/Documentation/DocBook/v4l/vidioc-g-output.xml new file mode 100644 index 000000000..3ea8c0ed8 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-output.xml @@ -0,0 +1,100 @@ +<refentry id="vidioc-g-output"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_OUTPUT</refname> + <refname>VIDIOC_S_OUTPUT</refname> + <refpurpose>Query or select the current video output</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>int *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the current video output applications call the +<constant>VIDIOC_G_OUTPUT</constant> ioctl with a pointer to an integer +where the driver stores the number of the output, as in the +&v4l2-output; <structfield>index</structfield> field. This ioctl +will fail only when there are no video outputs, returning the +&EINVAL;.</para> + + <para>To select a video output applications store the number of the +desired output in an integer and call the +<constant>VIDIOC_S_OUTPUT</constant> ioctl with a pointer to this integer. +Side effects are possible. For example outputs may support different +video standards, so the driver may implicitly switch the current +standard. It is good practice to select an output before querying or +negotiating any other parameters.</para> + + <para>Information about video outputs is available using the +&VIDIOC-ENUMOUTPUT; ioctl.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The number of the video output is out of bounds, or +there are no video outputs at all and this ioctl is not +supported.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>I/O is in progress, the output cannot be +switched.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-parm.xml b/linux/Documentation/DocBook/v4l/vidioc-g-parm.xml new file mode 100644 index 000000000..78332d365 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-parm.xml @@ -0,0 +1,332 @@ +<refentry id="vidioc-g-parm"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_PARM, VIDIOC_S_PARM</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_PARM</refname> + <refname>VIDIOC_S_PARM</refname> + <refpurpose>Get or set streaming parameters</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>v4l2_streamparm *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_PARM, VIDIOC_S_PARM</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>The current video standard determines a nominal number of +frames per second. If less than this number of frames is to be +captured or output, applications can request frame skipping or +duplicating on the driver side. This is especially useful when using +the <function>read()</function> or <function>write()</function>, which +are not augmented by timestamps or sequence counters, and to avoid +unneccessary data copying.</para> + + <para>Further these ioctls can be used to determine the number of +buffers used internally by a driver in read/write mode. For +implications see the section discussing the &func-read; +function.</para> + + <para>To get and set the streaming parameters applications call +the <constant>VIDIOC_G_PARM</constant> and +<constant>VIDIOC_S_PARM</constant> ioctl, respectively. They take a +pointer to a struct <structname>v4l2_streamparm</structname> which +contains a union holding separate parameters for input and output +devices.</para> + + <table pgwide="1" frame="none" id="v4l2-streamparm"> + <title>struct <structname>v4l2_streamparm</structname></title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry></entry> + <entry>The buffer (stream) type, same as &v4l2-format; +<structfield>type</structfield>, set by the application.</entry> + </row> + <row> + <entry>union</entry> + <entry><structfield>parm</structfield></entry> + <entry></entry> + <entry></entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-captureparm;</entry> + <entry><structfield>capture</structfield></entry> + <entry>Parameters for capture devices, used when +<structfield>type</structfield> is +<constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant>.</entry> + </row> + <row> + <entry></entry> + <entry>&v4l2-outputparm;</entry> + <entry><structfield>output</structfield></entry> + <entry>Parameters for output devices, used when +<structfield>type</structfield> is +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant>.</entry> + </row> + <row> + <entry></entry> + <entry>__u8</entry> + <entry><structfield>raw_data</structfield>[200]</entry> + <entry>A place holder for future extensions and custom +(driver defined) buffer types <constant>V4L2_BUF_TYPE_PRIVATE</constant> and +higher.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-captureparm"> + <title>struct <structname>v4l2_captureparm</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry>See <xref linkend="parm-caps" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capturemode</structfield></entry> + <entry>Set by drivers and applications, see <xref linkend="parm-flags" />.</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>timeperframe</structfield></entry> + <entry><para>This is is the desired period between +successive frames captured by the driver, in seconds. The +field is intended to skip frames on the driver side, saving I/O +bandwidth.</para><para>Applications store here the desired frame +period, drivers return the actual frame period, which must be greater +or equal to the nominal frame period determined by the current video +standard (&v4l2-standard; <structfield>frameperiod</structfield> +field). Changing the video standard (also implicitly by switching the +video input) may reset this parameter to the nominal frame period. To +reset manually applications can just set this field to +zero.</para><para>Drivers support this function only when they set the +<constant>V4L2_CAP_TIMEPERFRAME</constant> flag in the +<structfield>capability</structfield> field.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>extendedmode</structfield></entry> + <entry>Custom (driver specific) streaming parameters. When +unused, applications and drivers must set this field to zero. +Applications using this field should check the driver name and +version, see <xref linkend="querycap" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>readbuffers</structfield></entry> + <entry>Applications set this field to the desired number +of buffers used internally by the driver in &func-read; mode. Drivers +return the actual number of buffers. When an application requests zero +buffers, drivers should just return the current setting rather than +the minimum or an error code. For details see <xref + linkend="rw" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-outputparm"> + <title>struct <structname>v4l2_outputparm</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry>See <xref linkend="parm-caps" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>outputmode</structfield></entry> + <entry>Set by drivers and applications, see <xref + linkend="parm-flags" />.</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>timeperframe</structfield></entry> + <entry>This is is the desired period between +successive frames output by the driver, in seconds.</entry> + </row> + <row> + <entry spanname="hspan"><para>The field is intended to +repeat frames on the driver side in &func-write; mode (in streaming +mode timestamps can be used to throttle the output), saving I/O +bandwidth.</para><para>Applications store here the desired frame +period, drivers return the actual frame period, which must be greater +or equal to the nominal frame period determined by the current video +standard (&v4l2-standard; <structfield>frameperiod</structfield> +field). Changing the video standard (also implicitly by switching the +video output) may reset this parameter to the nominal frame period. To +reset manually applications can just set this field to +zero.</para><para>Drivers support this function only when they set the +<constant>V4L2_CAP_TIMEPERFRAME</constant> flag in the +<structfield>capability</structfield> field.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>extendedmode</structfield></entry> + <entry>Custom (driver specific) streaming parameters. When +unused, applications and drivers must set this field to zero. +Applications using this field should check the driver name and +version, see <xref linkend="querycap" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>writebuffers</structfield></entry> + <entry>Applications set this field to the desired number +of buffers used internally by the driver in +<function>write()</function> mode. Drivers return the actual number of +buffers. When an application requests zero buffers, drivers should +just return the current setting rather than the minimum or an error +code. For details see <xref linkend="rw" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="parm-caps"> + <title>Streaming Parameters Capabilites</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_CAP_TIMEPERFRAME</constant></entry> + <entry>0x1000</entry> + <entry>The frame skipping/repeating controlled by the +<structfield>timeperframe</structfield> field is supported.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="parm-flags"> + <title>Capture Parameters Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_MODE_HIGHQUALITY</constant></entry> + <entry>0x0001</entry> + <entry><para>High quality imaging mode. High quality mode +is intended for still imaging applications. The idea is to get the +best possible image quality that the hardware can deliver. It is not +defined how the driver writer may achieve that; it will depend on the +hardware and the ingenuity of the driver writer. High quality mode is +a different mode from the the regular motion video capture modes. In +high quality mode:<itemizedlist> + <listitem> + <para>The driver may be able to capture higher +resolutions than for motion capture.</para> + </listitem> + <listitem> + <para>The driver may support fewer pixel formats +than motion capture (eg; true color).</para> + </listitem> + <listitem> + <para>The driver may capture and arithmetically +combine multiple successive fields or frames to remove color edge +artifacts and reduce the noise in the video data. +</para> + </listitem> + <listitem> + <para>The driver may capture images in slices like +a scanner in order to handle larger format images than would otherwise +be possible. </para> + </listitem> + <listitem> + <para>An image capture operation may be +significantly slower than motion capture. </para> + </listitem> + <listitem> + <para>Moving objects in the image might have +excessive motion blur. </para> + </listitem> + <listitem> + <para>Capture might only work through the +<function>read()</function> call.</para> + </listitem> + </itemizedlist></para></entry> + </row> + </tbody> + </tgroup> + </table> + + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>This ioctl is not supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-priority.xml b/linux/Documentation/DocBook/v4l/vidioc-g-priority.xml new file mode 100644 index 000000000..5fb001978 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-priority.xml @@ -0,0 +1,144 @@ +<refentry id="vidioc-g-priority"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_PRIORITY</refname> + <refname>VIDIOC_S_PRIORITY</refname> + <refpurpose>Query or request the access priority associated with a +file descriptor</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>enum v4l2_priority *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const enum v4l2_priority *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_PRIORITY, VIDIOC_S_PRIORITY</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para>Pointer to an enum v4l2_priority type.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the current access priority +applications call the <constant>VIDIOC_G_PRIORITY</constant> ioctl +with a pointer to an enum v4l2_priority variable where the driver stores +the current priority.</para> + + <para>To request an access priority applications store the +desired priority in an enum v4l2_priority variable and call +<constant>VIDIOC_S_PRIORITY</constant> ioctl with a pointer to this +variable.</para> + + <table frame="none" pgwide="1" id="v4l2-priority"> + <title>enum v4l2_priority</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_PRIORITY_UNSET</constant></entry> + <entry>0</entry> + <entry></entry> + </row> + <row> + <entry><constant>V4L2_PRIORITY_BACKGROUND</constant></entry> + <entry>1</entry> + <entry>Lowest priority, usually applications running in +background, for example monitoring VBI transmissions. A proxy +application running in user space will be necessary if multiple +applications want to read from a device at this priority.</entry> + </row> + <row> + <entry><constant>V4L2_PRIORITY_INTERACTIVE</constant></entry> + <entry>2</entry> + <entry></entry> + </row> + <row> + <entry><constant>V4L2_PRIORITY_DEFAULT</constant></entry> + <entry>2</entry> + <entry>Medium priority, usually applications started and +interactively controlled by the user. For example TV viewers, Teletext +browsers, or just "panel" applications to change the channel or video +controls. This is the default priority unless an application requests +another.</entry> + </row> + <row> + <entry><constant>V4L2_PRIORITY_RECORD</constant></entry> + <entry>3</entry> + <entry>Highest priority. Only one file descriptor can have +this priority, it blocks any other fd from changing device properties. +Usually applications which must not be interrupted, like video +recording.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The requested priority value is invalid, or the +driver does not support access priorities.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>Another application already requested higher +priority.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-sliced-vbi-cap.xml b/linux/Documentation/DocBook/v4l/vidioc-g-sliced-vbi-cap.xml new file mode 100644 index 000000000..10e721b17 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-sliced-vbi-cap.xml @@ -0,0 +1,264 @@ +<refentry id="vidioc-g-sliced-vbi-cap"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_SLICED_VBI_CAP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_SLICED_VBI_CAP</refname> + <refpurpose>Query sliced VBI capabilities</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_sliced_vbi_cap *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_SLICED_VBI_CAP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To find out which data services are supported by a sliced +VBI capture or output device, applications initialize the +<structfield>type</structfield> field of a &v4l2-sliced-vbi-cap;, +clear the <structfield>reserved</structfield> array and +call the <constant>VIDIOC_G_SLICED_VBI_CAP</constant> ioctl. The +driver fills in the remaining fields or returns an &EINVAL; if the +sliced VBI API is unsupported or <structfield>type</structfield> +is invalid.</para> + + <para>Note the <structfield>type</structfield> field was added, +and the ioctl changed from read-only to write-read, in Linux 2.6.19.</para> + + <table pgwide="1" frame="none" id="v4l2-sliced-vbi-cap"> + <title>struct <structname>v4l2_sliced_vbi_cap</structname></title> + <tgroup cols="5"> + <colspec colname="c1" colwidth="3*" /> + <colspec colname="c2" colwidth="3*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="2*" /> + <colspec colname="c5" colwidth="2*" /> + <spanspec spanname="hspan" namest="c3" nameend="c5" /> + <tbody valign="top"> + <row> + <entry>__u16</entry> + <entry><structfield>service_set</structfield></entry> + <entry spanname="hspan">A set of all data services +supported by the driver. Equal to the union of all elements of the +<structfield>service_lines </structfield> array.</entry> + </row> + <row> + <entry>__u16</entry> + <entry><structfield>service_lines</structfield>[2][24]</entry> + <entry spanname="hspan">Each element of this array +contains a set of data services the hardware can look for or insert +into a particular scan line. Data services are defined in <xref + linkend="vbi-services" />. Array indices map to ITU-R +line numbers (see also <xref + linkend="vbi-525" /> and <xref +linkend="vbi-625" />) as follows:</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry>Element</entry> + <entry>525 line systems</entry> + <entry>625 line systems</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[0][1]</entry> + <entry align="center">1</entry> + <entry align="center">1</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[0][23]</entry> + <entry align="center">23</entry> + <entry align="center">23</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[1][1]</entry> + <entry align="center">264</entry> + <entry align="center">314</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[1][23]</entry> + <entry align="center">286</entry> + <entry align="center">336</entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry spanname="hspan">The number of VBI lines the +hardware can capture or output per frame, or the number of services it +can identify on a given line may be limited. For example on PAL line +16 the hardware may be able to look for a VPS or Teletext signal, but +not both at the same time. Applications can learn about these limits +using the &VIDIOC-S-FMT; ioctl as described in <xref + linkend="sliced" />.</entry> + </row> + <row> + <entry></entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry spanname="hspan">Drivers must set +<structfield>service_lines</structfield>[0][0] and +<structfield>service_lines</structfield>[1][0] to zero.</entry> + </row> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the data stream, see <xref + linkend="v4l2-buf-type" />. Should be +<constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> or +<constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant>.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[3]</entry> + <entry spanname="hspan">This array is reserved for future +extensions. Applications and drivers must set it to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- See also dev-sliced-vbi.sgml --> + <table pgwide="1" frame="none" id="vbi-services"> + <title>Sliced VBI services</title> + <tgroup cols="5"> + <colspec colname="c1" colwidth="2*" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colname="c3" colwidth="1*" /> + <colspec colname="c4" colwidth="2*" /> + <colspec colname="c5" colwidth="2*" /> + <spanspec spanname='rlp' namest='c3' nameend='c5' /> + <thead> + <row> + <entry>Symbol</entry> + <entry>Value</entry> + <entry>Reference</entry> + <entry>Lines, usually</entry> + <entry>Payload</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_SLICED_TELETEXT_B</constant> (Teletext +System B)</entry> + <entry>0x0001</entry> + <entry><xref linkend="ets300706" />, <xref linkend="itu653" /></entry> + <entry>PAL/SECAM line 7-22, 320-335 (second field 7-22)</entry> + <entry>Last 42 of the 45 byte Teletext packet, that is +without clock run-in and framing code, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VPS</constant></entry> + <entry>0x0400</entry> + <entry><xref linkend="ets300231" /></entry> + <entry>PAL line 16</entry> + <entry>Byte number 3 to 15 according to Figure 9 of +ETS 300 231, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_CAPTION_525</constant></entry> + <entry>0x1000</entry> + <entry><xref linkend="eia608" /></entry> + <entry>NTSC line 21, 284 (second field 21)</entry> + <entry>Two bytes in transmission order, including parity +bit, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_WSS_625</constant></entry> + <entry>0x4000</entry> + <entry><xref linkend="en300294" />, <xref linkend="itu1119" /></entry> + <entry>PAL/SECAM line 23</entry> + <entry><screen> +Byte 0 1 + msb lsb msb lsb +Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9 +</screen></entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VBI_525</constant></entry> + <entry>0x1000</entry> + <entry spanname="rlp">Set of services applicable to 525 +line systems.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VBI_625</constant></entry> + <entry>0x4401</entry> + <entry spanname="rlp">Set of services applicable to 625 +line systems.</entry> + </row> + </tbody> + </tgroup> + </table> + + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The device does not support sliced VBI capturing or +output, or the value in the <structfield>type</structfield> field is +wrong.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-std.xml b/linux/Documentation/DocBook/v4l/vidioc-g-std.xml new file mode 100644 index 000000000..b6f5d267e --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-std.xml @@ -0,0 +1,99 @@ +<refentry id="vidioc-g-std"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_STD, VIDIOC_S_STD</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_STD</refname> + <refname>VIDIOC_S_STD</refname> + <refpurpose>Query or select the video standard of the current input</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>v4l2_std_id +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const v4l2_std_id +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_STD, VIDIOC_S_STD</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query and select the current video standard applications +use the <constant>VIDIOC_G_STD</constant> and <constant>VIDIOC_S_STD</constant> ioctls which take a pointer to a +&v4l2-std-id; type as argument. <constant>VIDIOC_G_STD</constant> can +return a single flag or a set of flags as in &v4l2-standard; field +<structfield>id</structfield>. The flags must be unambiguous such +that they appear in only one enumerated <structname>v4l2_standard</structname> structure.</para> + + <para><constant>VIDIOC_S_STD</constant> accepts one or more +flags, being a write-only ioctl it does not return the actual new standard as +<constant>VIDIOC_G_STD</constant> does. When no flags are given or +the current input does not support the requested standard the driver +returns an &EINVAL;. When the standard set is ambiguous drivers may +return <errorcode>EINVAL</errorcode> or choose any of the requested +standards.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>This ioctl is not supported, or the +<constant>VIDIOC_S_STD</constant> parameter was unsuitable.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-g-tuner.xml b/linux/Documentation/DocBook/v4l/vidioc-g-tuner.xml new file mode 100644 index 000000000..bd98c734c --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-g-tuner.xml @@ -0,0 +1,535 @@ +<refentry id="vidioc-g-tuner"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_TUNER</refname> + <refname>VIDIOC_S_TUNER</refname> + <refpurpose>Get or set tuner attributes</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_tuner +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_tuner +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_G_TUNER, VIDIOC_S_TUNER</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of a tuner applications initialize the +<structfield>index</structfield> field and zero out the +<structfield>reserved</structfield> array of a &v4l2-tuner; and call the +<constant>VIDIOC_G_TUNER</constant> ioctl with a pointer to this +structure. Drivers fill the rest of the structure or return an +&EINVAL; when the index is out of bounds. To enumerate all tuners +applications shall begin at index zero, incrementing by one until the +driver returns <errorcode>EINVAL</errorcode>.</para> + + <para>Tuners have two writable properties, the audio mode and +the radio frequency. To change the audio mode, applications initialize +the <structfield>index</structfield>, +<structfield>audmode</structfield> and +<structfield>reserved</structfield> fields and call the +<constant>VIDIOC_S_TUNER</constant> ioctl. This will +<emphasis>not</emphasis> change the current tuner, which is determined +by the current video input. Drivers may choose a different audio mode +if the requested mode is invalid or unsupported. Since this is a +<!-- FIXME -->write-only ioctl, it does not return the actually +selected audio mode.</para> + + <para>To change the radio frequency the &VIDIOC-S-FREQUENCY; ioctl +is available.</para> + + <table pgwide="1" frame="none" id="v4l2-tuner"> + <title>struct <structname>v4l2_tuner</structname></title> + <tgroup cols="3"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colname="c3" colwidth="1*" /> + <colspec colname="c4" colwidth="1*" /> + <spanspec spanname="hspan" namest="c3" nameend="c4" /> + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry spanname="hspan">Identifies the tuner, set by the +application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry spanname="hspan"><para>Name of the tuner, a +NUL-terminated ASCII string. This information is intended for the +user.<!-- FIXME Video inputs already have a name, the purpose of this +field is not quite clear.--></para></entry> + </row> + <row> + <entry>&v4l2-tuner-type;</entry> + <entry><structfield>type</structfield></entry> + <entry spanname="hspan">Type of the tuner, see <xref + linkend="v4l2-tuner-type" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry spanname="hspan"><para>Tuner capability flags, see +<xref linkend="tuner-capability" />. Audio flags indicate the ability +to decode audio subprograms. They will <emphasis>not</emphasis> +change, for example with the current video standard.</para><para>When +the structure refers to a radio tuner only the +<constant>V4L2_TUNER_CAP_LOW</constant>, +<constant>V4L2_TUNER_CAP_STEREO</constant> and +<constant>V4L2_TUNER_CAP_RDS</constant> flags can be set.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>rangelow</structfield></entry> + <entry spanname="hspan">The lowest tunable frequency in +units of 62.5 kHz, or if the <structfield>capability</structfield> +flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5 +Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>rangehigh</structfield></entry> + <entry spanname="hspan">The highest tunable frequency in +units of 62.5 kHz, or if the <structfield>capability</structfield> +flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5 +Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>rxsubchans</structfield></entry> + <entry spanname="hspan"><para>Some tuners or audio +decoders can determine the received audio subprograms by analyzing +audio carriers, pilot tones or other indicators. To pass this +information drivers set flags defined in <xref + linkend="tuner-rxsubchans" /> in this field. For +example:</para></entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry> + <entry>receiving mono audio</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><constant>STEREO | SAP</constant></entry> + <entry>receiving stereo audio and a secondary audio +program</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><constant>MONO | STEREO</constant></entry> + <entry>receiving mono or stereo audio, the hardware cannot +distinguish</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><constant>LANG1 | LANG2</constant></entry> + <entry>receiving bilingual audio</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><constant>MONO | STEREO | LANG1 | LANG2</constant></entry> + <entry>receiving mono, stereo or bilingual +audio</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry spanname="hspan"><para>When the +<constant>V4L2_TUNER_CAP_STEREO</constant>, +<constant>_LANG1</constant>, <constant>_LANG2</constant> or +<constant>_SAP</constant> flag is cleared in the +<structfield>capability</structfield> field, the corresponding +<constant>V4L2_TUNER_SUB_</constant> flag must not be set +here.</para><para>This field is valid only if this is the tuner of the +current video input, or when the structure refers to a radio +tuner.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>audmode</structfield></entry> + <entry spanname="hspan"><para>The selected audio mode, see +<xref linkend="tuner-audmode" /> for valid values. The audio mode does +not affect audio subprogram detection, and like a <link +linkend="control">control</link> it does not automatically change +unless the requested mode is invalid or unsupported. See <xref + linkend="tuner-matrix" /> for possible results when +the selected and received audio programs do not +match.</para><para>Currently this is the only field of struct +<structname>v4l2_tuner</structname> applications can +change.</para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>signal</structfield></entry> + <entry spanname="hspan">The signal strength if known, ranging +from 0 to 65535. Higher values indicate a better signal.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>afc</structfield></entry> + <entry spanname="hspan">Automatic frequency control: When the +<structfield>afc</structfield> value is negative, the frequency is too +low, when positive too high.<!-- FIXME need example what to do when it never +settles at zero, &ie; range is what? --></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry spanname="hspan">Reserved for future extensions. Drivers and +applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-tuner-type"> + <title>enum v4l2_tuner_type</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TUNER_RADIO</constant></entry> + <entry>1</entry> + <entry></entry> + </row> + <row> + <entry><constant>V4L2_TUNER_ANALOG_TV</constant></entry> + <entry>2</entry> + <entry></entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="tuner-capability"> + <title>Tuner and Modulator Capability Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TUNER_CAP_LOW</constant></entry> + <entry>0x0001</entry> + <entry>When set, tuning frequencies are expressed in units of +62.5 Hz, otherwise in units of 62.5 kHz.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_CAP_NORM</constant></entry> + <entry>0x0002</entry> + <entry>This is a multi-standard tuner; the video standard +can or must be switched. (B/G PAL tuners for example are typically not + considered multi-standard because the video standard is automatically + determined from the frequency band.) The set of supported video + standards is available from the &v4l2-input; pointing to this tuner, + see the description of ioctl &VIDIOC-ENUMINPUT; for details. Only + <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_CAP_STEREO</constant></entry> + <entry>0x0010</entry> + <entry>Stereo audio reception is supported.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_CAP_LANG1</constant></entry> + <entry>0x0040</entry> + <entry>Reception of the primary language of a bilingual +audio program is supported. Bilingual audio is a feature of +two-channel systems, transmitting the primary language monaural on the +main audio carrier and a secondary language monaural on a second +carrier. Only + <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_CAP_LANG2</constant></entry> + <entry>0x0020</entry> + <entry>Reception of the secondary language of a bilingual +audio program is supported. Only + <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_CAP_SAP</constant></entry> + <entry>0x0020</entry> + <entry><para>Reception of a secondary audio program is +supported. This is a feature of the BTSC system which accompanies the +NTSC video standard. Two audio carriers are available for mono or +stereo transmissions of a primary language, and an independent third +carrier for a monaural secondary language. Only + <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</para><para>Note the +<constant>V4L2_TUNER_CAP_LANG2</constant> and +<constant>V4L2_TUNER_CAP_SAP</constant> flags are synonyms. +<constant>V4L2_TUNER_CAP_SAP</constant> applies when the tuner +supports the <constant>V4L2_STD_NTSC_M</constant> video +standard.</para><!-- FIXME what if PAL+NTSC and Bi but not SAP? --></entry> + </row> + <row> + <entry><constant>V4L2_TUNER_CAP_RDS</constant></entry> + <entry>0x0080</entry> + <entry>RDS capture is supported. This capability is only valid for +radio tuners.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="tuner-rxsubchans"> + <title>Tuner Audio Reception Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry> + <entry>0x0001</entry> + <entry>The tuner receives a mono audio signal.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_STEREO</constant></entry> + <entry>0x0002</entry> + <entry>The tuner receives a stereo audio signal.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_LANG1</constant></entry> + <entry>0x0008</entry> + <entry>The tuner receives the primary language of a +bilingual audio signal. Drivers must clear this flag when the current +video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_LANG2</constant></entry> + <entry>0x0004</entry> + <entry>The tuner receives the secondary language of a +bilingual audio signal (or a second audio program).</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_SAP</constant></entry> + <entry>0x0004</entry> + <entry>The tuner receives a Second Audio Program. Note the +<constant>V4L2_TUNER_SUB_LANG2</constant> and +<constant>V4L2_TUNER_SUB_SAP</constant> flags are synonyms. The +<constant>V4L2_TUNER_SUB_SAP</constant> flag applies when the +current video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_SUB_RDS</constant></entry> + <entry>0x0010</entry> + <entry>The tuner receives an RDS channel.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="tuner-audmode"> + <title>Tuner Audio Modes</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_TUNER_MODE_MONO</constant></entry> + <entry>0</entry> + <entry>Play mono audio. When the tuner receives a stereo +signal this a down-mix of the left and right channel. When the tuner +receives a bilingual or SAP signal this mode selects the primary +language.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_MODE_STEREO</constant></entry> + <entry>1</entry> + <entry><para>Play stereo audio. When the tuner receives +bilingual audio it may play different languages on the left and right +channel or the primary language is played on both channels.</para><para>Playing +different languages in this mode is +deprecated. New drivers should do this only in +<constant>MODE_LANG1_LANG2</constant>.</para><para>When the tuner +receives no stereo signal or does not support stereo reception the +driver shall fall back to <constant>MODE_MONO</constant>.</para></entry> + </row> + <row> + <entry><constant>V4L2_TUNER_MODE_LANG1</constant></entry> + <entry>3</entry> + <entry>Play the primary language, mono or stereo. Only +<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this +mode.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_MODE_LANG2</constant></entry> + <entry>2</entry> + <entry>Play the secondary language, mono. When the tuner +receives no bilingual audio or SAP, or their reception is not +supported the driver shall fall back to mono or stereo mode. Only +<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this +mode.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_MODE_SAP</constant></entry> + <entry>2</entry> + <entry>Play the Second Audio Program. When the tuner +receives no bilingual audio or SAP, or their reception is not +supported the driver shall fall back to mono or stereo mode. Only +<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this mode. +Note the <constant>V4L2_TUNER_MODE_LANG2</constant> and +<constant>V4L2_TUNER_MODE_SAP</constant> are synonyms.</entry> + </row> + <row> + <entry><constant>V4L2_TUNER_MODE_LANG1_LANG2</constant></entry> + <entry>4</entry> + <entry>Play the primary language on the left channel, the +secondary language on the right channel. When the tuner receives no +bilingual audio or SAP, it shall fall back to +<constant>MODE_LANG1</constant> or <constant>MODE_MONO</constant>. +Only <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this +mode.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="all" id="tuner-matrix"> + <title>Tuner Audio Matrix</title> + <tgroup cols="6" align="center"> + <colspec align="left" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colwidth="1*" /> + <colspec colwidth="1*" /> + <colspec colnum="6" colname="c6" colwidth="1*" /> + <spanspec namest="c2" nameend="c6" spanname="hspan" align="center" /> + <thead> + <row> + <entry></entry> + <entry spanname="hspan">Selected +<constant>V4L2_TUNER_MODE_</constant></entry> + </row> + <row> + <entry>Received <constant>V4L2_TUNER_SUB_</constant></entry> + <entry><constant>MONO</constant></entry> + <entry><constant>STEREO</constant></entry> + <entry><constant>LANG1</constant></entry> + <entry><constant>LANG2 = SAP</constant></entry> + <entry><constant>LANG1_LANG2</constant><footnote><para>This +mode has been added in Linux 2.6.17 and may not be supported by older +drivers.</para></footnote></entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>MONO</constant></entry> + <entry>Mono</entry> + <entry>Mono/Mono</entry> + <entry>Mono</entry> + <entry>Mono</entry> + <entry>Mono/Mono</entry> + </row> + <row> + <entry><constant>MONO | SAP</constant></entry> + <entry>Mono</entry> + <entry>Mono/Mono</entry> + <entry>Mono</entry> + <entry>SAP</entry> + <entry>Mono/SAP (preferred) or Mono/Mono</entry> + </row> + <row> + <entry><constant>STEREO</constant></entry> + <entry>L+R</entry> + <entry>L/R</entry> + <entry>Stereo L/R (preferred) or Mono L+R</entry> + <entry>Stereo L/R (preferred) or Mono L+R</entry> + <entry>L/R (preferred) or L+R/L+R</entry> + </row> + <row> + <entry><constant>STEREO | SAP</constant></entry> + <entry>L+R</entry> + <entry>L/R</entry> + <entry>Stereo L/R (preferred) or Mono L+R</entry> + <entry>SAP</entry> + <entry>L+R/SAP (preferred) or L/R or L+R/L+R</entry> + </row> + <row> + <entry><constant>LANG1 | LANG2</constant></entry> + <entry>Language 1</entry> + <entry>Lang1/Lang2 (deprecated<footnote><para>Playback of +both languages in <constant>MODE_STEREO</constant> is deprecated. In +the future drivers should produce only the primary language in this +mode. Applications should request +<constant>MODE_LANG1_LANG2</constant> to record both languages or a +stereo signal.</para></footnote>) or +Lang1/Lang1</entry> + <entry>Language 1</entry> + <entry>Language 2</entry> + <entry>Lang1/Lang2 (preferred) or Lang1/Lang1</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-tuner; <structfield>index</structfield> is +out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-log-status.xml b/linux/Documentation/DocBook/v4l/vidioc-log-status.xml new file mode 100644 index 000000000..2634b7c88 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-log-status.xml @@ -0,0 +1,58 @@ +<refentry id="vidioc-log-status"> + <refmeta> + <refentrytitle>ioctl VIDIOC_LOG_STATUS</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_LOG_STATUS</refname> + <refpurpose>Log driver status information</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>As the video/audio devices become more complicated it +becomes harder to debug problems. When this ioctl is called the driver +will output the current device status to the kernel log. This is +particular useful when dealing with problems like no sound, no video +and incorrectly tuned channels. Also many modern devices autodetect +video and audio standards and this ioctl will report what the device +thinks what the standard is. Mismatches may give an indication where +the problem is.</para> + + <para>This ioctl is optional and not all drivers support it. It +was introduced in Linux 2.6.15.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The driver does not support this ioctl.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-overlay.xml b/linux/Documentation/DocBook/v4l/vidioc-overlay.xml new file mode 100644 index 000000000..1036c582c --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-overlay.xml @@ -0,0 +1,83 @@ +<refentry id="vidioc-overlay"> + <refmeta> + <refentrytitle>ioctl VIDIOC_OVERLAY</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_OVERLAY</refname> + <refpurpose>Start or stop video overlay</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const int *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_OVERLAY</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>This ioctl is part of the <link linkend="overlay">video + overlay</link> I/O method. Applications call + <constant>VIDIOC_OVERLAY</constant> to start or stop the + overlay. It takes a pointer to an integer which must be set to + zero by the application to stop overlay, to one to start.</para> + + <para>Drivers do not support &VIDIOC-STREAMON; or +&VIDIOC-STREAMOFF; with <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>Video overlay is not supported, or the +parameters have not been set up. See <xref +linkend="overlay" /> for the necessary steps.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-qbuf.xml b/linux/Documentation/DocBook/v4l/vidioc-qbuf.xml new file mode 100644 index 000000000..187081778 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-qbuf.xml @@ -0,0 +1,168 @@ +<refentry id="vidioc-qbuf"> + <refmeta> + <refentrytitle>ioctl VIDIOC_QBUF, VIDIOC_DQBUF</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_QBUF</refname> + <refname>VIDIOC_DQBUF</refname> + <refpurpose>Exchange a buffer with the driver</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_buffer *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_QBUF, VIDIOC_DQBUF</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Applications call the <constant>VIDIOC_QBUF</constant> ioctl +to enqueue an empty (capturing) or filled (output) buffer in the +driver's incoming queue. The semantics depend on the selected I/O +method.</para> + + <para>To enqueue a <link linkend="mmap">memory mapped</link> +buffer applications set the <structfield>type</structfield> field of a +&v4l2-buffer; to the same buffer type as previously &v4l2-format; +<structfield>type</structfield> and &v4l2-requestbuffers; +<structfield>type</structfield>, the <structfield>memory</structfield> +field to <constant>V4L2_MEMORY_MMAP</constant> and the +<structfield>index</structfield> field. Valid index numbers range from +zero to the number of buffers allocated with &VIDIOC-REQBUFS; +(&v4l2-requestbuffers; <structfield>count</structfield>) minus one. The +contents of the struct <structname>v4l2_buffer</structname> returned +by a &VIDIOC-QUERYBUF; ioctl will do as well. When the buffer is +intended for output (<structfield>type</structfield> is +<constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant> or +<constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant>) applications must also +initialize the <structfield>bytesused</structfield>, +<structfield>field</structfield> and +<structfield>timestamp</structfield> fields. See <xref + linkend="buffer" /> for details. When +<constant>VIDIOC_QBUF</constant> is called with a pointer to this +structure the driver sets the +<constant>V4L2_BUF_FLAG_MAPPED</constant> and +<constant>V4L2_BUF_FLAG_QUEUED</constant> flags and clears the +<constant>V4L2_BUF_FLAG_DONE</constant> flag in the +<structfield>flags</structfield> field, or it returns an +&EINVAL;.</para> + + <para>To enqueue a <link linkend="userp">user pointer</link> +buffer applications set the <structfield>type</structfield> field of a +&v4l2-buffer; to the same buffer type as previously &v4l2-format; +<structfield>type</structfield> and &v4l2-requestbuffers; +<structfield>type</structfield>, the <structfield>memory</structfield> +field to <constant>V4L2_MEMORY_USERPTR</constant> and the +<structfield>m.userptr</structfield> field to the address of the +buffer and <structfield>length</structfield> to its size. When the +buffer is intended for output additional fields must be set as above. +When <constant>VIDIOC_QBUF</constant> is called with a pointer to this +structure the driver sets the <constant>V4L2_BUF_FLAG_QUEUED</constant> +flag and clears the <constant>V4L2_BUF_FLAG_MAPPED</constant> and +<constant>V4L2_BUF_FLAG_DONE</constant> flags in the +<structfield>flags</structfield> field, or it returns an error code. +This ioctl locks the memory pages of the buffer in physical memory, +they cannot be swapped out to disk. Buffers remain locked until +dequeued, until the &VIDIOC-STREAMOFF; or &VIDIOC-REQBUFS; ioctl are +called, or until the device is closed.</para> + + <para>Applications call the <constant>VIDIOC_DQBUF</constant> +ioctl to dequeue a filled (capturing) or displayed (output) buffer +from the driver's outgoing queue. They just set the +<structfield>type</structfield> and <structfield>memory</structfield> +fields of a &v4l2-buffer; as above, when <constant>VIDIOC_DQBUF</constant> +is called with a pointer to this structure the driver fills the +remaining fields or returns an error code.</para> + + <para>By default <constant>VIDIOC_DQBUF</constant> blocks when no +buffer is in the outgoing queue. When the +<constant>O_NONBLOCK</constant> flag was given to the &func-open; +function, <constant>VIDIOC_DQBUF</constant> returns immediately +with an &EAGAIN; when no buffer is available.</para> + + <para>The <structname>v4l2_buffer</structname> structure is +specified in <xref linkend="buffer" />.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EAGAIN</errorcode></term> + <listitem> + <para>Non-blocking I/O has been selected using +<constant>O_NONBLOCK</constant> and no buffer was in the outgoing +queue.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The buffer <structfield>type</structfield> is not +supported, or the <structfield>index</structfield> is out of bounds, +or no buffers have been allocated yet, or the +<structfield>userptr</structfield> or +<structfield>length</structfield> are invalid.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>ENOMEM</errorcode></term> + <listitem> + <para>Not enough physical or virtual memory was available to +enqueue a user pointer buffer.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EIO</errorcode></term> + <listitem> + <para><constant>VIDIOC_DQBUF</constant> failed due to an +internal error. Can also indicate temporary problems like signal +loss. Note the driver might dequeue an (empty) buffer despite +returning an error, or even stop capturing.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-querybuf.xml b/linux/Documentation/DocBook/v4l/vidioc-querybuf.xml new file mode 100644 index 000000000..d834993e6 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-querybuf.xml @@ -0,0 +1,103 @@ +<refentry id="vidioc-querybuf"> + <refmeta> + <refentrytitle>ioctl VIDIOC_QUERYBUF</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_QUERYBUF</refname> + <refpurpose>Query the status of a buffer</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_buffer *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_QUERYBUF</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>This ioctl is part of the <link linkend="mmap">memory +mapping</link> I/O method. It can be used to query the status of a +buffer at any time after buffers have been allocated with the +&VIDIOC-REQBUFS; ioctl.</para> + + <para>Applications set the <structfield>type</structfield> field + of a &v4l2-buffer; to the same buffer type as previously +&v4l2-format; <structfield>type</structfield> and &v4l2-requestbuffers; +<structfield>type</structfield>, and the <structfield>index</structfield> + field. Valid index numbers range from zero +to the number of buffers allocated with &VIDIOC-REQBUFS; + (&v4l2-requestbuffers; <structfield>count</structfield>) minus one. +After calling <constant>VIDIOC_QUERYBUF</constant> with a pointer to + this structure drivers return an error code or fill the rest of +the structure.</para> + + <para>In the <structfield>flags</structfield> field the +<constant>V4L2_BUF_FLAG_MAPPED</constant>, +<constant>V4L2_BUF_FLAG_QUEUED</constant> and +<constant>V4L2_BUF_FLAG_DONE</constant> flags will be valid. The +<structfield>memory</structfield> field will be set to +<constant>V4L2_MEMORY_MMAP</constant>, the <structfield>m.offset</structfield> +contains the offset of the buffer from the start of the device memory, +the <structfield>length</structfield> field its size. The driver may +or may not set the remaining fields and flags, they are meaningless in +this context.</para> + + <para>The <structname>v4l2_buffer</structname> structure is + specified in <xref linkend="buffer" />.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The buffer <structfield>type</structfield> is not +supported, or the <structfield>index</structfield> is out of bounds.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-querycap.xml b/linux/Documentation/DocBook/v4l/vidioc-querycap.xml new file mode 100644 index 000000000..6ab7e25b3 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-querycap.xml @@ -0,0 +1,284 @@ +<refentry id="vidioc-querycap"> + <refmeta> + <refentrytitle>ioctl VIDIOC_QUERYCAP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_QUERYCAP</refname> + <refpurpose>Query device capabilities</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_capability *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_QUERYCAP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>All V4L2 devices support the +<constant>VIDIOC_QUERYCAP</constant> ioctl. It is used to identify +kernel devices compatible with this specification and to obtain +information about driver and hardware capabilities. The ioctl takes a +pointer to a &v4l2-capability; which is filled by the driver. When the +driver is not compatible with this specification the ioctl returns an +&EINVAL;.</para> + + <table pgwide="1" frame="none" id="v4l2-capability"> + <title>struct <structname>v4l2_capability</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u8</entry> + <entry><structfield>driver</structfield>[16]</entry> + <entry><para>Name of the driver, a unique NUL-terminated +ASCII string. For example: "bttv". Driver specific applications can +use this information to verify the driver identity. It is also useful +to work around known bugs, or to identify drivers in error reports. +The driver version is stored in the <structfield>version</structfield> +field.</para><para>Storing strings in fixed sized arrays is bad +practice but unavoidable here. Drivers and applications should take +precautions to never read or write beyond the end of the array and to +make sure the strings are properly NUL-terminated.</para></entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>card</structfield>[32]</entry> + <entry>Name of the device, a NUL-terminated ASCII string. +For example: "Yoyodyne TV/FM". One driver may support different brands +or models of video hardware. This information is intended for users, +for example in a menu of available devices. Since multiple TV cards of +the same brand may be installed which are supported by the same +driver, this name should be combined with the character device file +name (⪚ <filename>/dev/video2</filename>) or the +<structfield>bus_info</structfield> string to avoid +ambiguities.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>bus_info</structfield>[32]</entry> + <entry>Location of the device in the system, a +NUL-terminated ASCII string. For example: "PCI Slot 4". This +information is intended for users, to distinguish multiple +identical devices. If no such information is available the field may +simply count the devices controlled by the driver, or contain the +empty string (<structfield>bus_info</structfield>[0] = 0).<!-- XXX pci_dev->slot_name example --></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>version</structfield></entry> + <entry><para>Version number of the driver. Together with +the <structfield>driver</structfield> field this identifies a +particular driver. The version number is formatted using the +<constant>KERNEL_VERSION()</constant> macro:</para></entry> + </row> + <row> + <entry spanname="hspan"><para> +<programlisting> +#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c)) + +__u32 version = KERNEL_VERSION(0, 8, 1); + +printf ("Version: %u.%u.%u\n", + (version >> 16) & 0xFF, + (version >> 8) & 0xFF, + version & 0xFF); +</programlisting></para></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capabilities</structfield></entry> + <entry>Device capabilities, see <xref + linkend="device-capabilities" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[4]</entry> + <entry>Reserved for future extensions. Drivers must set +this array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="device-capabilities"> + <title>Device Capabilities Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_CAP_VIDEO_CAPTURE</constant></entry> + <entry>0x00000001</entry> + <entry>The device supports the <link +linkend="capture">Video Capture</link> interface.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_VIDEO_OUTPUT</constant></entry> + <entry>0x00000002</entry> + <entry>The device supports the <link +linkend="output">Video Output</link> interface.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_VIDEO_OVERLAY</constant></entry> + <entry>0x00000004</entry> + <entry>The device supports the <link +linkend="overlay">Video Overlay</link> interface. A video overlay device +typically stores captured images directly in the video memory of a +graphics card, with hardware clipping and scaling.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_VBI_CAPTURE</constant></entry> + <entry>0x00000010</entry> + <entry>The device supports the <link linkend="raw-vbi">Raw +VBI Capture</link> interface, providing Teletext and Closed Caption +data.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_VBI_OUTPUT</constant></entry> + <entry>0x00000020</entry> + <entry>The device supports the <link linkend="raw-vbi">Raw VBI Output</link> interface.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_SLICED_VBI_CAPTURE</constant></entry> + <entry>0x00000040</entry> + <entry>The device supports the <link linkend="sliced">Sliced VBI Capture</link> interface.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_SLICED_VBI_OUTPUT</constant></entry> + <entry>0x00000080</entry> + <entry>The device supports the <link linkend="sliced">Sliced VBI Output</link> interface.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_RDS_CAPTURE</constant></entry> + <entry>0x00000100</entry> + <entry>The device supports the <link linkend="rds">RDS</link> interface.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant></entry> + <entry>0x00000200</entry> + <entry>The device supports the <link linkend="osd">Video +Output Overlay</link> (OSD) interface. Unlike the <wordasword>Video +Overlay</wordasword> interface, this is a secondary function of video +output devices and overlays an image onto an outgoing video signal. +When the driver sets this flag, it must clear the +<constant>V4L2_CAP_VIDEO_OVERLAY</constant> flag and vice +versa.<footnote><para>The &v4l2-framebuffer; lacks an +&v4l2-buf-type; field, therefore the type of overlay is implied by the +driver capabilities.</para></footnote></entry> + </row> + <row> + <entry><constant>V4L2_CAP_HW_FREQ_SEEK</constant></entry> + <entry>0x00000400</entry> + <entry>The device supports the &VIDIOC-S-HW-FREQ-SEEK; ioctl for +hardware frequency seeking.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_TUNER</constant></entry> + <entry>0x00010000</entry> + <entry>The device has some sort of tuner to +receive RF-modulated video signals. For more information about +tuner programming see +<xref linkend="tuner" />.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_AUDIO</constant></entry> + <entry>0x00020000</entry> + <entry>The device has audio inputs or outputs. It may or +may not support audio recording or playback, in PCM or compressed +formats. PCM audio support must be implemented as ALSA or OSS +interface. For more information on audio inputs and outputs see <xref + linkend="audio" />.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_RADIO</constant></entry> + <entry>0x00040000</entry> + <entry>This is a radio receiver.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_MODULATOR</constant></entry> + <entry>0x00080000</entry> + <entry>The device has some sort of modulator to +emit RF-modulated video/audio signals. For more information about +modulator programming see +<xref linkend="tuner" />.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_READWRITE</constant></entry> + <entry>0x01000000</entry> + <entry>The device supports the <link +linkend="rw">read()</link> and/or <link linkend="rw">write()</link> +I/O methods.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_ASYNCIO</constant></entry> + <entry>0x02000000</entry> + <entry>The device supports the <link +linkend="async">asynchronous</link> I/O methods.</entry> + </row> + <row> + <entry><constant>V4L2_CAP_STREAMING</constant></entry> + <entry>0x04000000</entry> + <entry>The device supports the <link +linkend="mmap">streaming</link> I/O method.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The device is not compatible with this +specification.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> + diff --git a/linux/Documentation/DocBook/v4l/vidioc-queryctrl.xml b/linux/Documentation/DocBook/v4l/vidioc-queryctrl.xml new file mode 100644 index 000000000..4876ff1a1 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-queryctrl.xml @@ -0,0 +1,428 @@ +<refentry id="vidioc-queryctrl"> + <refmeta> + <refentrytitle>ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_QUERYCTRL</refname> + <refname>VIDIOC_QUERYMENU</refname> + <refpurpose>Enumerate controls and menu control items</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_queryctrl *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_querymenu *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To query the attributes of a control applications set the +<structfield>id</structfield> field of a &v4l2-queryctrl; and call the +<constant>VIDIOC_QUERYCTRL</constant> ioctl with a pointer to this +structure. The driver fills the rest of the structure or returns an +&EINVAL; when the <structfield>id</structfield> is invalid.</para> + + <para>It is possible to enumerate controls by calling +<constant>VIDIOC_QUERYCTRL</constant> with successive +<structfield>id</structfield> values starting from +<constant>V4L2_CID_BASE</constant> up to and exclusive +<constant>V4L2_CID_BASE_LASTP1</constant>. Drivers may return +<errorcode>EINVAL</errorcode> if a control in this range is not +supported. Further applications can enumerate private controls, which +are not defined in this specification, by starting at +<constant>V4L2_CID_PRIVATE_BASE</constant> and incrementing +<structfield>id</structfield> until the driver returns +<errorcode>EINVAL</errorcode>.</para> + + <para>In both cases, when the driver sets the +<constant>V4L2_CTRL_FLAG_DISABLED</constant> flag in the +<structfield>flags</structfield> field this control is permanently +disabled and should be ignored by the application.<footnote> + <para><constant>V4L2_CTRL_FLAG_DISABLED</constant> was +intended for two purposes: Drivers can skip predefined controls not +supported by the hardware (although returning EINVAL would do as +well), or disable predefined and private controls after hardware +detection without the trouble of reordering control arrays and indices +(EINVAL cannot be used to skip private controls because it would +prematurely end the enumeration).</para></footnote></para> + + <para>When the application ORs <structfield>id</structfield> with +<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> the driver returns the +next supported control, or <errorcode>EINVAL</errorcode> if there is +none. Drivers which do not support this flag yet always return +<errorcode>EINVAL</errorcode>.</para> + + <para>Additional information is required for menu controls: the +names of the menu items. To query them applications set the +<structfield>id</structfield> and <structfield>index</structfield> +fields of &v4l2-querymenu; and call the +<constant>VIDIOC_QUERYMENU</constant> ioctl with a pointer to this +structure. The driver fills the rest of the structure or returns an +&EINVAL; when the <structfield>id</structfield> or +<structfield>index</structfield> is invalid. Menu items are enumerated +by calling <constant>VIDIOC_QUERYMENU</constant> with successive +<structfield>index</structfield> values from &v4l2-queryctrl; +<structfield>minimum</structfield> (0) to +<structfield>maximum</structfield>, inclusive.</para> + + <para>See also the examples in <xref linkend="control" />.</para> + + <table pgwide="1" frame="none" id="v4l2-queryctrl"> + <title>struct <structname>v4l2_queryctrl</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry>Identifies the control, set by the application. See +<xref linkend="control-id" /> for predefined IDs. When the ID is ORed +with V4L2_CTRL_FLAG_NEXT_CTRL the driver clears the flag and returns +the first control with a higher ID. Drivers which do not support this +flag yet always return an &EINVAL;.</entry> + </row> + <row> + <entry>&v4l2-ctrl-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of control, see <xref + linkend="v4l2-ctrl-type" />.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the control, a NUL-terminated ASCII +string. This information is intended for the user.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>minimum</structfield></entry> + <entry>Minimum value, inclusive. This field gives a lower +bound for <constant>V4L2_CTRL_TYPE_INTEGER</constant> controls and the +lowest valid index (always 0) for <constant>V4L2_CTRL_TYPE_MENU</constant> controls. +For <constant>V4L2_CTRL_TYPE_STRING</constant> controls the minimum value +gives the minimum length of the string. This length <emphasis>does not include the terminating +zero</emphasis>. It may not be valid for any other type of control, including +<constant>V4L2_CTRL_TYPE_INTEGER64</constant> controls. Note that this is a +signed value.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>maximum</structfield></entry> + <entry>Maximum value, inclusive. This field gives an upper +bound for <constant>V4L2_CTRL_TYPE_INTEGER</constant> controls and the +highest valid index for <constant>V4L2_CTRL_TYPE_MENU</constant> +controls. +For <constant>V4L2_CTRL_TYPE_STRING</constant> controls the maximum value +gives the maximum length of the string. This length <emphasis>does not include the terminating +zero</emphasis>. It may not be valid for any other type of control, including +<constant>V4L2_CTRL_TYPE_INTEGER64</constant> controls. Note that this is a +signed value.</entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>step</structfield></entry> + <entry><para>This field gives a step size for +<constant>V4L2_CTRL_TYPE_INTEGER</constant> controls. For +<constant>V4L2_CTRL_TYPE_STRING</constant> controls this field refers to +the string length that has to be a multiple of this step size. +It may not be valid for any other type of control, including +<constant>V4L2_CTRL_TYPE_INTEGER64</constant> +controls.</para><para>Generally drivers should not scale hardware +control values. It may be necessary for example when the +<structfield>name</structfield> or <structfield>id</structfield> imply +a particular unit and the hardware actually accepts only multiples of +said unit. If so, drivers must take care values are properly rounded +when scaling, such that errors will not accumulate on repeated +read-write cycles.</para><para>This field gives the smallest change of +an integer control actually affecting hardware. Often the information +is needed when the user can change controls by keyboard or GUI +buttons, rather than a slider. When for example a hardware register +accepts values 0-511 and the driver reports 0-65535, step should be +128.</para><para>Note that although signed, the step value is supposed to +be always positive.</para></entry> + </row> + <row> + <entry>__s32</entry> + <entry><structfield>default_value</structfield></entry> + <entry>The default value of a +<constant>V4L2_CTRL_TYPE_INTEGER</constant>, +<constant>_BOOLEAN</constant> or <constant>_MENU</constant> control. +Not valid for other types of controls. Drivers reset controls only +when the driver is loaded, not later, in particular not when the +func-open; is called.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>flags</structfield></entry> + <entry>Control flags, see <xref + linkend="control-flags" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>Reserved for future extensions. Drivers must set +the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-querymenu"> + <title>struct <structname>v4l2_querymenu</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry>Identifies the control, set by the application +from the respective &v4l2-queryctrl; +<structfield>id</structfield>.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Index of the menu item, starting at zero, set by + the application.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>name</structfield>[32]</entry> + <entry>Name of the menu item, a NUL-terminated ASCII +string. This information is intended for the user.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield></entry> + <entry>Reserved for future extensions. Drivers must set +the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="v4l2-ctrl-type"> + <title>enum v4l2_ctrl_type</title> + <tgroup cols="5" align="left"> + <colspec colwidth="30*" /> + <colspec colwidth="5*" align="center" /> + <colspec colwidth="5*" align="center" /> + <colspec colwidth="5*" align="center" /> + <colspec colwidth="55*" /> + <thead> + <row> + <entry>Type</entry> + <entry><structfield>minimum</structfield></entry> + <entry><structfield>step</structfield></entry> + <entry><structfield>maximum</structfield></entry> + <entry>Description</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_CTRL_TYPE_INTEGER</constant></entry> + <entry>any</entry> + <entry>any</entry> + <entry>any</entry> + <entry>An integer-valued control ranging from minimum to +maximum inclusive. The step value indicates the increment between +values which are actually different on the hardware.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_TYPE_BOOLEAN</constant></entry> + <entry>0</entry> + <entry>1</entry> + <entry>1</entry> + <entry>A boolean-valued control. Zero corresponds to +"disabled", and one means "enabled".</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_TYPE_MENU</constant></entry> + <entry>0</entry> + <entry>1</entry> + <entry>N-1</entry> + <entry>The control has a menu of N choices. The names of +the menu items can be enumerated with the +<constant>VIDIOC_QUERYMENU</constant> ioctl.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_TYPE_BUTTON</constant></entry> + <entry>0</entry> + <entry>0</entry> + <entry>0</entry> + <entry>A control which performs an action when set. +Drivers must ignore the value passed with +<constant>VIDIOC_S_CTRL</constant> and return an &EINVAL; on a +<constant>VIDIOC_G_CTRL</constant> attempt.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_TYPE_INTEGER64</constant></entry> + <entry>n/a</entry> + <entry>n/a</entry> + <entry>n/a</entry> + <entry>A 64-bit integer valued control. Minimum, maximum +and step size cannot be queried.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_TYPE_STRING</constant></entry> + <entry>≥ 0</entry> + <entry>≥ 1</entry> + <entry>≥ 0</entry> + <entry>The minimum and maximum string lengths. The step size +means that the string must be (minimum + N * step) characters long for +N ≥ 0. These lengths do not include the terminating zero, so in order to +pass a string of length 8 to &VIDIOC-S-EXT-CTRLS; you need to set the +<structfield>size</structfield> field of &v4l2-ext-control; to 9. For &VIDIOC-G-EXT-CTRLS; you can +set the <structfield>size</structfield> field to <structfield>maximum</structfield> + 1. +Which character encoding is used will depend on the string control itself and +should be part of the control documentation.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant></entry> + <entry>n/a</entry> + <entry>n/a</entry> + <entry>n/a</entry> + <entry>This is not a control. When +<constant>VIDIOC_QUERYCTRL</constant> is called with a control ID +equal to a control class code (see <xref linkend="ctrl-class" />), the +ioctl returns the name of the control class and this control type. +Older drivers which do not support this feature return an +&EINVAL;.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="control-flags"> + <title>Control Flags</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_CTRL_FLAG_DISABLED</constant></entry> + <entry>0x0001</entry> + <entry>This control is permanently disabled and should be +ignored by the application. Any attempt to change the control will +result in an &EINVAL;.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_FLAG_GRABBED</constant></entry> + <entry>0x0002</entry> + <entry>This control is temporarily unchangeable, for +example because another application took over control of the +respective resource. Such controls may be displayed specially in a +user interface. Attempts to change the control may result in an +&EBUSY;.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_FLAG_READ_ONLY</constant></entry> + <entry>0x0004</entry> + <entry>This control is permanently readable only. Any +attempt to change the control will result in an &EINVAL;.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_FLAG_UPDATE</constant></entry> + <entry>0x0008</entry> + <entry>A hint that changing this control may affect the +value of other controls within the same control class. Applications +should update their user interface accordingly.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_FLAG_INACTIVE</constant></entry> + <entry>0x0010</entry> + <entry>This control is not applicable to the current +configuration and should be displayed accordingly in a user interface. +For example the flag may be set on a MPEG audio level 2 bitrate +control when MPEG audio encoding level 1 was selected with another +control.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_FLAG_SLIDER</constant></entry> + <entry>0x0020</entry> + <entry>A hint that this control is best represented as a +slider-like element in a user interface.</entry> + </row> + <row> + <entry><constant>V4L2_CTRL_FLAG_WRITE_ONLY</constant></entry> + <entry>0x0040</entry> + <entry>This control is permanently writable only. Any +attempt to read the control will result in an &EACCES; error code. This +flag is typically present for relative controls or action controls where +writing a value will cause the device to carry out a given action +(⪚ motor control) but no meaningful value can be returned.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-queryctrl; <structfield>id</structfield> +is invalid. The &v4l2-querymenu; <structfield>id</structfield> or +<structfield>index</structfield> is invalid.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EACCES</errorcode></term> + <listitem> + <para>An attempt was made to read a write-only control.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-querystd.xml b/linux/Documentation/DocBook/v4l/vidioc-querystd.xml new file mode 100644 index 000000000..b5a7ff934 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-querystd.xml @@ -0,0 +1,83 @@ +<refentry id="vidioc-querystd"> + <refmeta> + <refentrytitle>ioctl VIDIOC_QUERYSTD</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_QUERYSTD</refname> + <refpurpose>Sense the video standard received by the current +input</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>v4l2_std_id *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_QUERYSTD</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>The hardware may be able to detect the current video +standard automatically. To do so, applications call <constant> +VIDIOC_QUERYSTD</constant> with a pointer to a &v4l2-std-id; type. The +driver stores here a set of candidates, this can be a single flag or a +set of supported standards if for example the hardware can only +distinguish between 50 and 60 Hz systems. When detection is not +possible or fails, the set must contain all standards supported by the +current video input or output.</para> + + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>This ioctl is not supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-reqbufs.xml b/linux/Documentation/DocBook/v4l/vidioc-reqbufs.xml new file mode 100644 index 000000000..bab380844 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-reqbufs.xml @@ -0,0 +1,160 @@ +<refentry id="vidioc-reqbufs"> + <refmeta> + <refentrytitle>ioctl VIDIOC_REQBUFS</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_REQBUFS</refname> + <refpurpose>Initiate Memory Mapping or User Pointer I/O</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_requestbuffers *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_REQBUFS</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>This ioctl is used to initiate <link linkend="mmap">memory +mapped</link> or <link linkend="userp">user pointer</link> +I/O. Memory mapped buffers are located in device memory and must be +allocated with this ioctl before they can be mapped into the +application's address space. User buffers are allocated by +applications themselves, and this ioctl is merely used to switch the +driver into user pointer I/O mode.</para> + + <para>To allocate device buffers applications initialize three +fields of a <structname>v4l2_requestbuffers</structname> structure. +They set the <structfield>type</structfield> field to the respective +stream or buffer type, the <structfield>count</structfield> field to +the desired number of buffers, and <structfield>memory</structfield> +must be set to <constant>V4L2_MEMORY_MMAP</constant>. When the ioctl +is called with a pointer to this structure the driver attempts to +allocate the requested number of buffers and stores the actual number +allocated in the <structfield>count</structfield> field. It can be +smaller than the number requested, even zero, when the driver runs out +of free memory. A larger number is possible when the driver requires +more buffers to function correctly.<footnote> + <para>For example video output requires at least two buffers, +one displayed and one filled by the application.</para> + </footnote> When memory mapping I/O is not supported the ioctl +returns an &EINVAL;.</para> + + <para>Applications can call <constant>VIDIOC_REQBUFS</constant> +again to change the number of buffers, however this cannot succeed +when any buffers are still mapped. A <structfield>count</structfield> +value of zero frees all buffers, after aborting or finishing any DMA +in progress, an implicit &VIDIOC-STREAMOFF;. <!-- mhs: I see no +reason why munmap()ping one or even all buffers must imply +streamoff.--></para> + + <para>To negotiate user pointer I/O, applications initialize only +the <structfield>type</structfield> field and set +<structfield>memory</structfield> to +<constant>V4L2_MEMORY_USERPTR</constant>. When the ioctl is called +with a pointer to this structure the driver prepares for user pointer +I/O, when this I/O method is not supported the ioctl returns an +&EINVAL;.</para> + + <table pgwide="1" frame="none" id="v4l2-requestbuffers"> + <title>struct <structname>v4l2_requestbuffers</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>count</structfield></entry> + <entry>The number of buffers requested or granted. This +field is only used when <structfield>memory</structfield> is set to +<constant>V4L2_MEMORY_MMAP</constant>.</entry> + </row> + <row> + <entry>&v4l2-buf-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>Type of the stream or buffers, this is the same +as the &v4l2-format; <structfield>type</structfield> field. See <xref + linkend="v4l2-buf-type" /> for valid values.</entry> + </row> + <row> + <entry>&v4l2-memory;</entry> + <entry><structfield>memory</structfield></entry> + <entry>Applications set this field to +<constant>V4L2_MEMORY_MMAP</constant> or +<constant>V4L2_MEMORY_USERPTR</constant>.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry>A place holder for future extensions and custom +(driver defined) buffer types <constant>V4L2_BUF_TYPE_PRIVATE</constant> and +higher.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The driver supports multiple opens and I/O is already +in progress, or reallocation of buffers was attempted although one or +more are still mapped.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The buffer type (<structfield>type</structfield> field) or the +requested I/O method (<structfield>memory</structfield>) is not +supported.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-s-hw-freq-seek.xml b/linux/Documentation/DocBook/v4l/vidioc-s-hw-freq-seek.xml new file mode 100644 index 000000000..14b3ec7ed --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-s-hw-freq-seek.xml @@ -0,0 +1,129 @@ +<refentry id="vidioc-s-hw-freq-seek"> + <refmeta> + <refentrytitle>ioctl VIDIOC_S_HW_FREQ_SEEK</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_S_HW_FREQ_SEEK</refname> + <refpurpose>Perform a hardware frequency seek</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_hw_freq_seek +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_S_HW_FREQ_SEEK</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>Start a hardware frequency seek from the current frequency. +To do this applications initialize the <structfield>tuner</structfield>, +<structfield>type</structfield>, <structfield>seek_upward</structfield> and +<structfield>wrap_around</structfield> fields, and zero out the +<structfield>reserved</structfield> array of a &v4l2-hw-freq-seek; and +call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> ioctl with a pointer +to this structure.</para> + + <para>This ioctl is supported if the <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability is set.</para> + + <table pgwide="1" frame="none" id="v4l2-hw-freq-seek"> + <title>struct <structname>v4l2_hw_freq_seek</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>tuner</structfield></entry> + <entry>The tuner index number. This is the +same value as in the &v4l2-input; <structfield>tuner</structfield> +field and the &v4l2-tuner; <structfield>index</structfield> field.</entry> + </row> + <row> + <entry>&v4l2-tuner-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>The tuner type. This is the same value as in the +&v4l2-tuner; <structfield>type</structfield> field.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>seek_upward</structfield></entry> + <entry>If non-zero, seek upward from the current frequency, else seek downward.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>wrap_around</structfield></entry> + <entry>If non-zero, wrap around when at the end of the frequency range, else stop seeking.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[8]</entry> + <entry>Reserved for future extensions. Drivers and + applications must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <structfield>tuner</structfield> index is out of +bounds or the value in the <structfield>type</structfield> field is +wrong.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EAGAIN</errorcode></term> + <listitem> + <para>The ioctl timed-out. Try again.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> diff --git a/linux/Documentation/DocBook/v4l/vidioc-streamon.xml b/linux/Documentation/DocBook/v4l/vidioc-streamon.xml new file mode 100644 index 000000000..e42bff1f2 --- /dev/null +++ b/linux/Documentation/DocBook/v4l/vidioc-streamon.xml @@ -0,0 +1,106 @@ +<refentry id="vidioc-streamon"> + <refmeta> + <refentrytitle>ioctl VIDIOC_STREAMON, VIDIOC_STREAMOFF</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_STREAMON</refname> + <refname>VIDIOC_STREAMOFF</refname> + <refpurpose>Start or stop streaming I/O</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const int *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_STREAMON, VIDIOC_STREAMOFF</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>The <constant>VIDIOC_STREAMON</constant> and +<constant>VIDIOC_STREAMOFF</constant> ioctl start and stop the capture +or output process during streaming (<link linkend="mmap">memory +mapping</link> or <link linkend="userp">user pointer</link>) I/O.</para> + + <para>Specifically the capture hardware is disabled and no input +buffers are filled (if there are any empty buffers in the incoming +queue) until <constant>VIDIOC_STREAMON</constant> has been called. +Accordingly the output hardware is disabled, no video signal is +produced until <constant>VIDIOC_STREAMON</constant> has been called. +The ioctl will succeed only when at least one output buffer is in the +incoming queue.</para> + + <para>The <constant>VIDIOC_STREAMOFF</constant> ioctl, apart of +aborting or finishing any DMA in progress, unlocks any user pointer +buffers locked in physical memory, and it removes all buffers from the +incoming and outgoing queues. That means all images captured but not +dequeued yet will be lost, likewise all images enqueued for output but +not transmitted yet. I/O returns to the same state as after calling +&VIDIOC-REQBUFS; and can be restarted accordingly.</para> + + <para>Both ioctls take a pointer to an integer, the desired buffer or +stream type. This is the same as &v4l2-requestbuffers; +<structfield>type</structfield>.</para> + + <para>Note applications can be preempted for unknown periods right +before or after the <constant>VIDIOC_STREAMON</constant> or +<constant>VIDIOC_STREAMOFF</constant> calls, there is no notion of +starting or stopping "now". Buffer timestamps can be used to +synchronize with other events.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>Streaming I/O is not supported, the buffer +<structfield>type</structfield> is not supported, or no buffers have +been allocated (memory mapping) or enqueued (output) yet.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> |
