From 4484d72262532de4b0332a7ac331035e8f07297d Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Wed, 16 Sep 2009 11:02:15 -0300 Subject: v4l2-spec: Remove duplicated xml files From: Mauro Carvalho Chehab Instead of having its own version, use the one at kernel docs. Priority: normal Signed-off-by: Mauro Carvalho Chehab --- v4l2-spec/controls.sgml | 2049 ----------------------------------------------- 1 file changed, 2049 deletions(-) delete mode 100644 v4l2-spec/controls.sgml (limited to 'v4l2-spec/controls.sgml') diff --git a/v4l2-spec/controls.sgml b/v4l2-spec/controls.sgml deleted file mode 100644 index f492accb6..000000000 --- a/v4l2-spec/controls.sgml +++ /dev/null @@ -1,2049 +0,0 @@ -
- User Controls - - 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. - - All controls are accessed using an ID value. V4L2 defines -several IDs for specific purposes. Drivers can also implement their -own custom controls using V4L2_CID_PRIVATE_BASE -and higher values. The pre-defined control IDs have the prefix -V4L2_CID_, and are listed in . The ID is used when querying the attributes of -a control, and when getting or setting the current value. - - 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. - - 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 -custom ID can also change name and -type. - It will be more convenient for applications if drivers -make use of the V4L2_CTRL_FLAG_DISABLED flag, but -that was never required. - 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. - 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. - - - - Control IDs - - &cs-def; - - - ID - Type - Description - - - - - V4L2_CID_BASE - - First predefined ID, equal to -V4L2_CID_BRIGHTNESS. - - - V4L2_CID_USER_BASE - - Synonym of V4L2_CID_BASE. - - - V4L2_CID_BRIGHTNESS - integer - Picture brightness, or more precisely, the black -level. - - - V4L2_CID_CONTRAST - integer - Picture contrast or luma gain. - - - V4L2_CID_SATURATION - integer - Picture color saturation or chroma gain. - - - V4L2_CID_HUE - integer - Hue or color balance. - - - V4L2_CID_AUDIO_VOLUME - integer - Overall audio volume. Note some drivers also -provide an OSS or ALSA mixer interface. - - - V4L2_CID_AUDIO_BALANCE - integer - Audio stereo balance. Minimum corresponds to all -the way left, maximum to right. - - - V4L2_CID_AUDIO_BASS - integer - Audio bass adjustment. - - - V4L2_CID_AUDIO_TREBLE - integer - Audio treble adjustment. - - - V4L2_CID_AUDIO_MUTE - boolean - Mute audio, &ie; set the volume to zero, however -without affecting V4L2_CID_AUDIO_VOLUME. 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. - - - V4L2_CID_AUDIO_LOUDNESS - boolean - Loudness mode (bass boost). - - - V4L2_CID_BLACK_LEVEL - integer - Another name for brightness (not a synonym of -V4L2_CID_BRIGHTNESS). This control is deprecated -and should not be used in new drivers and applications. - - - V4L2_CID_AUTO_WHITE_BALANCE - boolean - Automatic white balance (cameras). - - - V4L2_CID_DO_WHITE_BALANCE - button - 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 -V4L2_CID_AUTO_WHITE_BALANCE, which, when -activated, keeps adjusting the white balance. - - - V4L2_CID_RED_BALANCE - integer - Red chroma balance. - - - V4L2_CID_BLUE_BALANCE - integer - Blue chroma balance. - - - V4L2_CID_GAMMA - integer - Gamma adjust. - - - V4L2_CID_WHITENESS - integer - Whiteness for grey-scale devices. This is a synonym -for V4L2_CID_GAMMA. This control is deprecated -and should not be used in new drivers and applications. - - - V4L2_CID_EXPOSURE - integer - Exposure (cameras). [Unit?] - - - V4L2_CID_AUTOGAIN - boolean - Automatic gain/exposure control. - - - V4L2_CID_GAIN - integer - Gain control. - - - V4L2_CID_HFLIP - boolean - Mirror the picture horizontally. - - - V4L2_CID_VFLIP - boolean - Mirror the picture vertically. - - - V4L2_CID_HCENTER_DEPRECATED (formerly V4L2_CID_HCENTER) - integer - Horizontal image centering. This control is -deprecated. New drivers and applications should use the Camera class controls -V4L2_CID_PAN_ABSOLUTE, -V4L2_CID_PAN_RELATIVE and -V4L2_CID_PAN_RESET instead. - - - V4L2_CID_VCENTER_DEPRECATED - (formerly V4L2_CID_VCENTER) - integer - Vertical image centering. Centering is intended to -physically adjust cameras. For image cropping see -, for clipping . This -control is deprecated. New drivers and applications should use the -Camera class controls -V4L2_CID_TILT_ABSOLUTE, -V4L2_CID_TILT_RELATIVE and -V4L2_CID_TILT_RESET instead. - - - V4L2_CID_POWER_LINE_FREQUENCY - enum - Enables a power line frequency filter to avoid -flicker. Possible values for enum v4l2_power_line_frequency are: -V4L2_CID_POWER_LINE_FREQUENCY_DISABLED (0), -V4L2_CID_POWER_LINE_FREQUENCY_50HZ (1) and -V4L2_CID_POWER_LINE_FREQUENCY_60HZ (2). - - - V4L2_CID_HUE_AUTO - boolean - Enables automatic hue control by the device. The -effect of setting V4L2_CID_HUE while automatic -hue control is enabled is undefined, drivers should ignore such -request. - - - V4L2_CID_WHITE_BALANCE_TEMPERATURE - integer - 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 Wikipedia. - - - V4L2_CID_SHARPNESS - integer - Adjusts the sharpness filters in a camera. The -minimum value disables the filters, higher values give a sharper -picture. - - - V4L2_CID_BACKLIGHT_COMPENSATION - integer - Adjusts the backlight compensation in a camera. The -minimum value disables backlight compensation. - - - V4L2_CID_CHROMA_AGC - boolean - Chroma automatic gain control. - - - V4L2_CID_COLOR_KILLER - boolean - Enable the color killer (&ie; force a black & white image in case of a weak video signal). - - - V4L2_CID_COLORFX - enum - Selects a color effect. Possible values for -enum v4l2_colorfx are: -V4L2_COLORFX_NONE (0), -V4L2_COLORFX_BW (1) and -V4L2_COLORFX_SEPIA (2). - - - V4L2_CID_LASTP1 - - End of the predefined control IDs (currently -V4L2_CID_COLORFX + 1). - - - V4L2_CID_PRIVATE_BASE - - ID of the first custom (driver specific) control. -Applications depending on particular custom controls should check the -driver name and version, see . - - - -
- - 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 VIDIOC_QUERYCTRL, -VIDIOC_G_CTRL and -VIDIOC_S_CTRL when the device has one or more -controls, VIDIOC_QUERYMENU when it has one or -more menu type controls. - - - Enumerating all controls - - -&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); - } -} - - - - - Changing controls - - -&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); - - -
- -
- Extended Controls - -
- Introduction - - 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. - - 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. - - 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. - - 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. -
- -
- The Extended Control API - - 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. - - 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 -V4L2_CTRL_CLASS_USER contains all user controls -(&ie; all controls that can also be set using the old -VIDIOC_S_CTRL ioctl). Control class -V4L2_CTRL_CLASS_MPEG contains all controls -relating to MPEG encoding, etc. - - All controls in the control array must belong to the -specified control class. An error is returned if this is not the -case. - - It is also possible to use an empty control array (count -== 0) to check whether the specified control class is -supported. - - The control array is a &v4l2-ext-control; array. The -v4l2_ext_control structure is very similar to -&v4l2-control;, except for the fact that it also allows for 64-bit -values and pointers to be passed. - - 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 V4L2_CTRL_TYPE_MENU -may not be supported (VIDIOC_QUERYMENU 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. -
- -
- Enumerating Extended Controls - - The recommended way to enumerate over the extended -controls is by using &VIDIOC-QUERYCTRL; in combination with the -V4L2_CTRL_FLAG_NEXT_CTRL flag: - - - -&v4l2-queryctrl; qctrl; - -qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL; -while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &qctrl)) { - /* ... */ - qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL; -} - - - - The initial control ID is set to 0 ORed with the -V4L2_CTRL_FLAG_NEXT_CTRL flag. The -VIDIOC_QUERYCTRL ioctl will return the first -control with a higher ID than the specified one. When no such controls -are found an error is returned. - - If you want to get all controls within a specific control -class, then you can set the initial -qctrl.id 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: - - - -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; - } - - - - The 32-bit qctrl.id value is -subdivided into three bit ranges: the top 4 bits are reserved for -flags (⪚ V4L2_CTRL_FLAG_NEXT_CTRL) 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 -V4L2_CTRL_ID2CLASS(id) returns the control class -ID based on a control ID. - - If the driver does not support extended controls, then -VIDIOC_QUERYCTRL will fail when used in -combination with V4L2_CTRL_FLAG_NEXT_CTRL. 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. -
- -
- Creating Control Panels - - 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 -V4L2_CTRL_TYPE_CTRL_CLASS. -VIDIOC_QUERYCTRL will return the name of this -control class which can be used as the title of a tab page within a -control panel. - - The flags field of &v4l2-queryctrl; also contains hints on -the behavior of the control. See the &VIDIOC-QUERYCTRL; documentation -for more details. -
- -
- MPEG Control Reference - - Below all controls within the MPEG control class are -described. First the generic controls, then controls specific for -certain hardware. - -
- Generic MPEG Controls - - - MPEG Control IDs - - - - - - - - - - ID - Type - Description - - - - - - V4L2_CID_MPEG_CLASS  - class - 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. - - - - V4L2_CID_MPEG_STREAM_TYPE  - enum v4l2_mpeg_stream_type - 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: - - - - - - V4L2_MPEG_STREAM_TYPE_MPEG2_PS  - MPEG-2 program stream - - - V4L2_MPEG_STREAM_TYPE_MPEG2_TS  - MPEG-2 transport stream - - - V4L2_MPEG_STREAM_TYPE_MPEG1_SS  - MPEG-1 system stream - - - V4L2_MPEG_STREAM_TYPE_MPEG2_DVD  - MPEG-2 DVD-compatible stream - - - V4L2_MPEG_STREAM_TYPE_MPEG1_VCD  - MPEG-1 VCD-compatible stream - - - V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD  - MPEG-2 SVCD-compatible stream - - - - - - - V4L2_CID_MPEG_STREAM_PID_PMT  - integer - Program Map Table -Packet ID for the MPEG transport stream (default 16) - - - - V4L2_CID_MPEG_STREAM_PID_AUDIO  - integer - Audio Packet ID for -the MPEG transport stream (default 256) - - - - V4L2_CID_MPEG_STREAM_PID_VIDEO  - integer - Video Packet ID for -the MPEG transport stream (default 260) - - - - V4L2_CID_MPEG_STREAM_PID_PCR  - integer - Packet ID for the -MPEG transport stream carrying PCR fields (default 259) - - - - V4L2_CID_MPEG_STREAM_PES_ID_AUDIO  - integer - Audio ID for MPEG -PES - - - - V4L2_CID_MPEG_STREAM_PES_ID_VIDEO  - integer - Video ID for MPEG -PES - - - - V4L2_CID_MPEG_STREAM_VBI_FMT  - enum v4l2_mpeg_stream_vbi_fmt - 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: - - - - - - V4L2_MPEG_STREAM_VBI_FMT_NONE  - No VBI in the MPEG stream - - - V4L2_MPEG_STREAM_VBI_FMT_IVTV  - VBI in private packets, IVTV format (documented -in the kernel sources in the file Documentation/video4linux/cx2341x/README.vbi) - - - - - - - V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ  - enum v4l2_mpeg_audio_sampling_freq - MPEG Audio sampling -frequency. Possible values are: - - - - - - V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100  - 44.1 kHz - - - V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000  - 48 kHz - - - V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000  - 32 kHz - - - - - - - V4L2_CID_MPEG_AUDIO_ENCODING  - enum v4l2_mpeg_audio_encoding - MPEG Audio encoding. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_ENCODING_LAYER_1  - MPEG-1/2 Layer I encoding - - - V4L2_MPEG_AUDIO_ENCODING_LAYER_2  - MPEG-1/2 Layer II encoding - - - V4L2_MPEG_AUDIO_ENCODING_LAYER_3  - MPEG-1/2 Layer III encoding - - - V4L2_MPEG_AUDIO_ENCODING_AAC  - MPEG-2/4 AAC (Advanced Audio Coding) - - - V4L2_MPEG_AUDIO_ENCODING_AC3  - AC-3 aka ATSC A/52 encoding - - - - - - - V4L2_CID_MPEG_AUDIO_L1_BITRATE  - enum v4l2_mpeg_audio_l1_bitrate - MPEG-1/2 Layer I bitrate. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_L1_BITRATE_32K  - 32 kbit/s - - V4L2_MPEG_AUDIO_L1_BITRATE_64K  - 64 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_96K  - 96 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_128K  - 128 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_160K  - 160 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_192K  - 192 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_224K  - 224 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_256K  - 256 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_288K  - 288 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_320K  - 320 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_352K  - 352 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_384K  - 384 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_416K  - 416 kbit/s - - - V4L2_MPEG_AUDIO_L1_BITRATE_448K  - 448 kbit/s - - - - - - - V4L2_CID_MPEG_AUDIO_L2_BITRATE  - enum v4l2_mpeg_audio_l2_bitrate - MPEG-1/2 Layer II bitrate. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_L2_BITRATE_32K  - 32 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_48K  - 48 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_56K  - 56 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_64K  - 64 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_80K  - 80 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_96K  - 96 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_112K  - 112 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_128K  - 128 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_160K  - 160 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_192K  - 192 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_224K  - 224 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_256K  - 256 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_320K  - 320 kbit/s - - - V4L2_MPEG_AUDIO_L2_BITRATE_384K  - 384 kbit/s - - - - - - - V4L2_CID_MPEG_AUDIO_L3_BITRATE  - enum v4l2_mpeg_audio_l3_bitrate - MPEG-1/2 Layer III bitrate. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_L3_BITRATE_32K  - 32 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_40K  - 40 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_48K  - 48 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_56K  - 56 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_64K  - 64 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_80K  - 80 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_96K  - 96 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_112K  - 112 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_128K  - 128 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_160K  - 160 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_192K  - 192 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_224K  - 224 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_256K  - 256 kbit/s - - - V4L2_MPEG_AUDIO_L3_BITRATE_320K  - 320 kbit/s - - - - - - - V4L2_CID_MPEG_AUDIO_AAC_BITRATE  - integer - AAC bitrate in bits per second. - - - - V4L2_CID_MPEG_AUDIO_AC3_BITRATE  - enum v4l2_mpeg_audio_ac3_bitrate - AC-3 bitrate. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_AC3_BITRATE_32K  - 32 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_40K  - 40 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_48K  - 48 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_56K  - 56 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_64K  - 64 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_80K  - 80 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_96K  - 96 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_112K  - 112 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_128K  - 128 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_160K  - 160 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_192K  - 192 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_224K  - 224 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_256K  - 256 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_320K  - 320 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_384K  - 384 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_448K  - 448 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_512K  - 512 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_576K  - 576 kbit/s - - - V4L2_MPEG_AUDIO_AC3_BITRATE_640K  - 640 kbit/s - - - - - - - V4L2_CID_MPEG_AUDIO_MODE  - enum v4l2_mpeg_audio_mode - MPEG Audio mode. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_MODE_STEREO  - Stereo - - - V4L2_MPEG_AUDIO_MODE_JOINT_STEREO  - Joint Stereo - - - V4L2_MPEG_AUDIO_MODE_DUAL  - Bilingual - - - V4L2_MPEG_AUDIO_MODE_MONO  - Mono - - - - - - - V4L2_CID_MPEG_AUDIO_MODE_EXTENSION  - enum v4l2_mpeg_audio_mode_extension - 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: - - - - - - V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4  - Subbands 4-31 in intensity stereo - - - V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8  - Subbands 8-31 in intensity stereo - - - V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12  - Subbands 12-31 in intensity stereo - - - V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16  - Subbands 16-31 in intensity stereo - - - - - - - V4L2_CID_MPEG_AUDIO_EMPHASIS  - enum v4l2_mpeg_audio_emphasis - Audio Emphasis. -Possible values are: - - - - - - V4L2_MPEG_AUDIO_EMPHASIS_NONE  - None - - - V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS  - 50/15 microsecond emphasis - - - V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17  - CCITT J.17 - - - - - - - V4L2_CID_MPEG_AUDIO_CRC  - enum v4l2_mpeg_audio_crc - CRC method. Possible -values are: - - - - - - V4L2_MPEG_AUDIO_CRC_NONE  - None - - - V4L2_MPEG_AUDIO_CRC_CRC16  - 16 bit parity check - - - - - - - V4L2_CID_MPEG_AUDIO_MUTE  - boolean - 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. - - - - V4L2_CID_MPEG_VIDEO_ENCODING  - enum v4l2_mpeg_video_encoding - MPEG Video encoding -method. Possible values are: - - - - - - V4L2_MPEG_VIDEO_ENCODING_MPEG_1  - MPEG-1 Video encoding - - - V4L2_MPEG_VIDEO_ENCODING_MPEG_2  - MPEG-2 Video encoding - - - V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC  - MPEG-4 AVC (H.264) Video encoding - - - - - - - V4L2_CID_MPEG_VIDEO_ASPECT  - enum v4l2_mpeg_video_aspect - Video aspect. -Possible values are: - - - - - - V4L2_MPEG_VIDEO_ASPECT_1x1  - - - V4L2_MPEG_VIDEO_ASPECT_4x3  - - - V4L2_MPEG_VIDEO_ASPECT_16x9  - - - V4L2_MPEG_VIDEO_ASPECT_221x100  - - - - - - - V4L2_CID_MPEG_VIDEO_B_FRAMES  - integer - Number of B-Frames -(default 2) - - - - V4L2_CID_MPEG_VIDEO_GOP_SIZE  - integer - GOP size (default -12) - - - - V4L2_CID_MPEG_VIDEO_GOP_CLOSURE  - boolean - GOP closure (default -1) - - - - V4L2_CID_MPEG_VIDEO_PULLDOWN  - boolean - Enable 3:2 pulldown -(default 0) - - - - V4L2_CID_MPEG_VIDEO_BITRATE_MODE  - enum v4l2_mpeg_video_bitrate_mode - Video bitrate mode. -Possible values are: - - - - - - V4L2_MPEG_VIDEO_BITRATE_MODE_VBR  - Variable bitrate - - - V4L2_MPEG_VIDEO_BITRATE_MODE_CBR  - Constant bitrate - - - - - - - V4L2_CID_MPEG_VIDEO_BITRATE  - integer - Video bitrate in bits -per second. - - - - V4L2_CID_MPEG_VIDEO_BITRATE_PEAK  - integer - 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. - - - - V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION  - integer - For every captured -frame, skip this many subsequent frames (default 0). - - - - V4L2_CID_MPEG_VIDEO_MUTE  - boolean - - "Mutes" the video to a -fixed color when capturing. This is useful for testing, to produce a -fixed video bitstream. 0 = unmuted, 1 = muted. - - - - V4L2_CID_MPEG_VIDEO_MUTE_YUV  - integer - Sets the "mute" color -of the video. The supplied 32-bit integer is interpreted as follows (bit -0 = least significant bit): - - - - - - Bit 0:7 - V chrominance information - - - Bit 8:15 - U chrominance information - - - Bit 16:23 - Y luminance information - - - Bit 24:31 - Must be zero. - - - - - - -
-
- -
- CX2341x MPEG Controls - - The following MPEG class controls deal with MPEG -encoding settings that are specific to the Conexant CX23415 and -CX23416 MPEG encoding chips. - - - CX2341x Control IDs - - - - - - - - - - ID - Type - Description - - - - - - V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE  - enum v4l2_mpeg_cx2341x_video_spatial_filter_mode - Sets the Spatial -Filter mode (default MANUAL). Possible values -are: - - - - - - V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL  - Choose the filter manually - - - V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO  - Choose the filter automatically - - - - - - - V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER  - integer (0-15) - The setting for the -Spatial Filter. 0 = off, 15 = maximum. (Default is 0.) - - - - V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE  - enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type - Select the algorithm -to use for the Luma Spatial Filter (default -1D_HOR). Possible values: - - - - - - V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF  - No filter - - - V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR  - One-dimensional horizontal - - - V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT  - One-dimensional vertical - - - V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE  - Two-dimensional separable - - - V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE  - Two-dimensional symmetrical -non-separable - - - - - - - V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE  - enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type - Select the algorithm -for the Chroma Spatial Filter (default 1D_HOR). -Possible values are: - - - - - - V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF  - No filter - - - V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR  - One-dimensional horizontal - - - - - - - V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE  - enum v4l2_mpeg_cx2341x_video_temporal_filter_mode - Sets the Temporal -Filter mode (default MANUAL). Possible values -are: - - - - - - V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL  - Choose the filter manually - - - V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO  - Choose the filter automatically - - - - - - - V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER  - integer (0-31) - The setting for the -Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale -capturing and 0 for scaled capturing.) - - - - V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE  - enum v4l2_mpeg_cx2341x_video_median_filter_type - Median Filter Type -(default OFF). Possible values are: - - - - - - V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF  - No filter - - - V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR  - Horizontal filter - - - V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT  - Vertical filter - - - V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT  - Horizontal and vertical filter - - - V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG  - Diagonal filter - - - - - - - V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM  - integer (0-255) - Threshold above which -the luminance median filter is enabled (default 0) - - - - V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP  - integer (0-255) - Threshold below which -the luminance median filter is enabled (default 255) - - - - V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM  - integer (0-255) - Threshold above which -the chroma median filter is enabled (default 0) - - - - V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP  - integer (0-255) - Threshold below which -the chroma median filter is enabled (default 255) - - - - V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS  - boolean - - 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. - - - -
-
-
- -
- Camera Control Reference - - The Camera class includes controls for mechanical (or -equivalent digital) features of a device such as controllable lenses -or sensors. - - - Camera Control IDs - - - - - - - - - - ID - Type - Description - - - - - - V4L2_CID_CAMERA_CLASS  - class - The Camera class -descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a -description of this control class. - - - - - V4L2_CID_EXPOSURE_AUTO  - enum v4l2_exposure_auto_type - 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: - - - - - - V4L2_EXPOSURE_AUTO  - Automatic exposure time, automatic iris -aperture. - - - V4L2_EXPOSURE_MANUAL  - Manual exposure time, manual iris. - - - V4L2_EXPOSURE_SHUTTER_PRIORITY  - Manual exposure time, auto iris. - - - V4L2_EXPOSURE_APERTURE_PRIORITY  - Auto exposure time, manual iris. - - - - - - - - V4L2_CID_EXPOSURE_ABSOLUTE  - integer - 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. - - - - - V4L2_CID_EXPOSURE_AUTO_PRIORITY  - boolean - When -V4L2_CID_EXPOSURE_AUTO is set to -AUTO or APERTURE_PRIORITY, -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. - - - - - V4L2_CID_PAN_RELATIVE  - integer - 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. - - - - - V4L2_CID_TILT_RELATIVE  - integer - 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. - - - - - V4L2_CID_PAN_RESET  - button - When this control is set, -the camera moves horizontally to the default position. - - - - - V4L2_CID_TILT_RESET  - button - When this control is set, -the camera moves vertically to the default position. - - - - - V4L2_CID_PAN_ABSOLUTE  - integer - 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. - - - - - V4L2_CID_TILT_ABSOLUTE  - integer - 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. - - - - - V4L2_CID_FOCUS_ABSOLUTE  - integer - 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. - - - - - V4L2_CID_FOCUS_RELATIVE  - integer - 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. - - - - - V4L2_CID_FOCUS_AUTO  - boolean - Enables automatic focus -adjustments. The effect of manual focus adjustments while this feature -is enabled is undefined, drivers should ignore such requests. - - - - - V4L2_CID_ZOOM_ABSOLUTE  - integer - Specify the objective lens -focal length as an absolute value. The zoom unit is driver-specific and its -value should be a positive integer. - - - - - V4L2_CID_ZOOM_RELATIVE  - integer - 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. - - - - - V4L2_CID_ZOOM_CONTINUOUS  - integer - 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. - - - - - V4L2_CID_PRIVACY  - boolean - Prevent video from being acquired -by the camera. When this control is set to TRUE (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. - - - - V4L2_CID_BAND_STOP_FILTER  - integer - 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. - - - - -
-
- -
- FM Transmitter Control Reference - - 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. - - - FM_TX Control IDs - - - - - - - - - - - ID - Type - Description - - - - - - V4L2_CID_FM_TX_CLASS  - class - The FM_TX class -descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a -description of this control class. - - - V4L2_CID_RDS_TX_DEVIATION  - integer - - Configures RDS signal frequency deviation level in Hz. -The range and step are driver-specific. - - - V4L2_CID_RDS_TX_PI  - integer - - Sets the RDS Programme Identification field -for transmission. - - - V4L2_CID_RDS_TX_PTY  - integer - - Sets the RDS Programme Type field for transmission. -This encodes up to 31 pre-defined programme types. - - - V4L2_CID_RDS_TX_PS_NAME  - string - - 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 , 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. - - - V4L2_CID_RDS_TX_RADIO_TEXT  - string - - 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 -V4L2_CID_RDS_TX_PS_NAME. The encoding for Radio Text strings is also fully described -in Annex E of . 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. - - - V4L2_CID_AUDIO_LIMITER_ENABLED  - boolean - - 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. - - - - V4L2_CID_AUDIO_LIMITER_RELEASE_TIME  - integer - - Sets the audio deviation limiter feature release time. -Unit is in useconds. Step and range are driver-specific. - - - V4L2_CID_AUDIO_LIMITER_DEVIATION  - integer - - Configures audio frequency deviation level in Hz. -The range and step are driver-specific. - - - V4L2_CID_AUDIO_COMPRESSION_ENABLED  - boolean - - 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). - - - V4L2_CID_AUDIO_COMPRESSION_GAIN  - integer - - Sets the gain for audio compression feature. It is -a dB value. The range and step are driver-specific. - - - V4L2_CID_AUDIO_COMPRESSION_THRESHOLD  - integer - - Sets the threshold level for audio compression freature. -It is a dB value. The range and step are driver-specific. - - - V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME  - integer - - Sets the attack time for audio compression feature. -It is a useconds value. The range and step are driver-specific. - - - V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME  - integer - - Sets the release time for audio compression feature. -It is a useconds value. The range and step are driver-specific. - - - V4L2_CID_PILOT_TONE_ENABLED  - boolean - - Enables or disables the pilot tone generation feature. - - - V4L2_CID_PILOT_TONE_DEVIATION  - integer - - Configures pilot tone frequency deviation level. Unit is -in Hz. The range and step are driver-specific. - - - V4L2_CID_PILOT_TONE_FREQUENCY  - integer - - Configures pilot tone frequency value. Unit is -in Hz. The range and step are driver-specific. - - - V4L2_CID_TUNE_PREEMPHASIS  - integer - - 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: - - - - - V4L2_PREEMPHASIS_DISABLED  - No pre-emphasis is applied. - - - V4L2_PREEMPHASIS_50_uS  - A pre-emphasis of 50 uS is used. - - - V4L2_PREEMPHASIS_75_uS  - A pre-emphasis of 75 uS is used. - - - - - - - V4L2_CID_TUNE_POWER_LEVEL  - integer - - Sets the output power level for signal transmission. -Unit is in dBuV. Range and step are driver-specific. - - - V4L2_CID_TUNE_ANTENNA_CAPACITOR  - integer - - This selects the value of antenna tuning capacitor -manually or automatically if set to zero. Unit, range and step are driver-specific. - - - - -
- -For more details about RDS specification, refer to - document, from CENELEC. -
-
- - -- cgit v1.2.3