diff options
Diffstat (limited to 'v4l2-spec/controls.sgml')
| -rw-r--r-- | v4l2-spec/controls.sgml | 270 |
1 files changed, 246 insertions, 24 deletions
diff --git a/v4l2-spec/controls.sgml b/v4l2-spec/controls.sgml index 477a97077..f492accb6 100644 --- a/v4l2-spec/controls.sgml +++ b/v4l2-spec/controls.sgml @@ -15,7 +15,7 @@ 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 +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 @@ -215,7 +215,7 @@ linkend="camera-controls">Camera class controls</link> <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 +<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>, @@ -291,7 +291,7 @@ minimum value disables backlight compensation.</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> +driver name and version, see <xref linkend="querycap" />.</entry> </row> </tbody> </tgroup> @@ -458,6 +458,12 @@ 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> @@ -492,8 +498,7 @@ 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 (although the latter is not yet used -anywhere).</para> +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 @@ -541,7 +546,7 @@ 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)) { +while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &qctrl)) { if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG) break; /* ... */ @@ -600,12 +605,12 @@ certain hardware.</para> <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"> + <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> @@ -1381,12 +1386,12 @@ 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"> + <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> @@ -1600,12 +1605,12 @@ 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"> + <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> @@ -1811,11 +1816,228 @@ 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> <!-- |