| <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_ILLUMINATORS_1</constant> |
| <constant>V4L2_CID_ILLUMINATORS_2</constant></entry> |
| <entry>boolean</entry> |
| <entry>Switch on or off the illuminator 1 or 2 of the device |
| (usually a microscope).</entry> |
| </row> |
| <row> |
| <entry><constant>V4L2_CID_LASTP1</constant></entry> |
| <entry></entry> |
| <entry>End of the predefined control IDs (currently |
| <constant>V4L2_CID_ILLUMINATORS_2</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); |
| } |
| } |
| } |
| |
| 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> |
| |
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