<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_CHROMA_GAIN</constant></entry> <entry>integer</entry> <entry>Adjusts the Chroma gain control (for use when chroma AGC is disabled).</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), <constant>V4L2_COLORFX_SEPIA</constant> (2), <constant>V4L2_COLORFX_NEGATIVE</constant> (3), <constant>V4L2_COLORFX_EMBOSS</constant> (4), <constant>V4L2_COLORFX_SKETCH</constant> (5), <constant>V4L2_COLORFX_SKY_BLUE</constant> (6), <constant>V4L2_COLORFX_GRASS_GREEN</constant> (7), <constant>V4L2_COLORFX_SKIN_WHITEN</constant> (8) and <constant>V4L2_COLORFX_VIVID</constant> (9).</entry> </row> <row> <entry><constant>V4L2_CID_ROTATE</constant></entry> <entry>integer</entry> <entry>Rotates the image by specified angle. Common angles are 90, 270 and 180. Rotating the image to 90 and 270 will reverse the height and width of the display window. It is necessary to set the new height and width of the picture using the &VIDIOC-S-FMT; ioctl according to the rotation angle selected.</entry> </row> <row> <entry><constant>V4L2_CID_BG_COLOR</constant></entry> <entry>integer</entry> <entry>Sets the background color on the current output device. Background color needs to be specified in the RGB24 format. The supplied 32 bit value is interpreted as bits 0-7 Red color information, bits 8-15 Green color information, bits 16-23 Blue color information and bits 24-31 must be zero.</entry> </row> <row> <entry><constant>V4L2_CID_LASTP1</constant></entry> <entry></entry> <entry>End of the predefined control IDs (currently <constant>V4L2_CID_BG_COLOR</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_IRIS_ABSOLUTE</constant> </entry> <entry>integer</entry> </row><row><entry spanname="descr">This control sets the camera's aperture to the specified value. The unit is undefined. Larger values open the iris wider, smaller values close it.</entry> </row> <row><entry></entry></row> <row> <entry spanname="id"><constant>V4L2_CID_IRIS_RELATIVE</constant> </entry> <entry>integer</entry> </row><row><entry spanname="descr">This control modifies the camera's aperture by the specified amount. The unit is undefined. Positive values open the iris one step further, negative values close it one step further. This is a write-only control.</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: -->