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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _extended-controls:
+
+*****************
+Extended Controls
+*****************
+
+
+Introduction
+============
+
+The control mechanism as originally designed was meant to be used for
+user settings (brightness, saturation, etc). However, it turned out to
+be a very useful model for implementing more complicated driver APIs
+where each driver implements only a subset of a larger API.
+
+The MPEG encoding API was the driving force behind designing and
+implementing this extended control mechanism: the MPEG standard is quite
+large and the currently supported hardware MPEG encoders each only
+implement a subset of this standard. Further more, many parameters
+relating to how the video is encoded into an MPEG stream are specific to
+the MPEG encoding chip since the MPEG standard only defines the format
+of the resulting MPEG stream, not how the video is actually encoded into
+that format.
+
+Unfortunately, the original control API lacked some features needed for
+these new uses and so it was extended into the (not terribly originally
+named) extended control API.
+
+Even though the MPEG encoding API was the first effort to use the
+Extended Control API, nowadays there are also other classes of Extended
+Controls, such as Camera Controls and FM Transmitter Controls. The
+Extended Controls API as well as all Extended Controls classes are
+described in the following text.
+
+
+The Extended Control API
+========================
+
+Three new ioctls are available:
+:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
+:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and
+:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. These ioctls act
+on arrays of controls (as opposed to the
+:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
+:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls that act on a single
+control). This is needed since it is often required to atomically change
+several controls at once.
+
+Each of the new ioctls expects a pointer to a struct
+:ref:`v4l2_ext_controls <v4l2-ext-controls>`. This structure
+contains a pointer to the control array, a count of the number of
+controls in that array and a control class. Control classes are used to
+group similar controls into a single class. For example, control class
+``V4L2_CTRL_CLASS_USER`` contains all user controls (i. e. all controls
+that can also be set using the old :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>`
+ioctl). Control class ``V4L2_CTRL_CLASS_MPEG`` contains all controls
+relating to MPEG encoding, etc.
+
+All controls in the control array must belong to the specified control
+class. An error is returned if this is not the case.
+
+It is also possible to use an empty control array (``count`` == 0) to check
+whether the specified control class is supported.
+
+The control array is a struct
+:ref:`v4l2_ext_control <v4l2-ext-control>` array. The
+:ref:`struct v4l2_ext_control <v4l2-ext-control>` structure is very similar to
+struct :ref:`v4l2_control <v4l2-control>`, except for the fact that
+it also allows for 64-bit values and pointers to be passed.
+
+Since the struct :ref:`v4l2_ext_control <v4l2-ext-control>` supports
+pointers it is now also possible to have controls with compound types
+such as N-dimensional arrays and/or structures. You need to specify the
+``V4L2_CTRL_FLAG_NEXT_COMPOUND`` when enumerating controls to actually
+be able to see such compound controls. In other words, these controls
+with compound types should only be used programmatically.
+
+Since such compound controls need to expose more information about
+themselves than is possible with
+:ref:`VIDIOC_QUERYCTRL` the
+:ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>` ioctl was added. In
+particular, this ioctl gives the dimensions of the N-dimensional array
+if this control consists of more than one element.
+
+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 :ref:`VIDIOC_QUERYCTRL` (or
+:ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>`) and
+:ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>` ioctls to check this. Also
+note that it is possible that some of the menu indices in a control of
+type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
+will return an error). A good example is the list of supported MPEG
+audio bitrates. Some drivers only support one or two bitrates, others
+support a wider range.
+
+All controls use machine endianness.
+
+
+Enumerating Extended Controls
+=============================
+
+The recommended way to enumerate over the extended controls is by using
+:ref:`VIDIOC_QUERYCTRL` in combination with the
+``V4L2_CTRL_FLAG_NEXT_CTRL`` flag:
+
+
+.. code-block:: c
+
+ struct v4l2_queryctrl qctrl;
+
+ qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
+ while (0 == ioctl (fd, VIDIOC_QUERYCTRL, &qctrl)) {
+ /* ... */
+ qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
+ }
+
+The initial control ID is set to 0 ORed with the
+``V4L2_CTRL_FLAG_NEXT_CTRL`` flag. The ``VIDIOC_QUERYCTRL`` ioctl will
+return the first control with a higher ID than the specified one. When
+no such controls are found an error is returned.
+
+If you want to get all controls within a specific control class, then
+you can set the initial ``qctrl.id`` value to the control class and add
+an extra check to break out of the loop when a control of another
+control class is found:
+
+
+.. code-block:: c
+
+ qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
+ while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &qctrl)) {
+ if (V4L2_CTRL_ID2CLASS(qctrl.id) != V4L2_CTRL_CLASS_MPEG)
+ break;
+ /* ... */
+ qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
+ }
+
+The 32-bit ``qctrl.id`` value is subdivided into three bit ranges: the
+top 4 bits are reserved for flags (e. g. ``V4L2_CTRL_FLAG_NEXT_CTRL``)
+and are not actually part of the ID. The remaining 28 bits form the
+control ID, of which the most significant 12 bits define the control
+class and the least significant 16 bits identify the control within the
+control class. It is guaranteed that these last 16 bits are always
+non-zero for controls. The range of 0x1000 and up are reserved for
+driver-specific controls. The macro ``V4L2_CTRL_ID2CLASS(id)`` returns
+the control class ID based on a control ID.
+
+If the driver does not support extended controls, then
+``VIDIOC_QUERYCTRL`` will fail when used in combination with
+``V4L2_CTRL_FLAG_NEXT_CTRL``. In that case the old method of enumerating
+control should be used (see :ref:`enum_all_controls`). But if it is
+supported, then it is guaranteed to enumerate over all controls,
+including driver-private controls.
+
+
+Creating Control Panels
+=======================
+
+It is possible to create control panels for a graphical user interface
+where the user can select the various controls. Basically you will have
+to iterate over all controls using the method described above. Each
+control class starts with a control of type
+``V4L2_CTRL_TYPE_CTRL_CLASS``. ``VIDIOC_QUERYCTRL`` will return the name
+of this control class which can be used as the title of a tab page
+within a control panel.
+
+The flags field of struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` also
+contains hints on the behavior of the control. See the
+:ref:`VIDIOC_QUERYCTRL` documentation for more
+details.
+
+
+.. _mpeg-controls:
+
+Codec Control Reference
+=======================
+
+Below all controls within the Codec control class are described. First
+the generic controls, then controls specific for certain hardware.
+
+Note: These controls are applicable to all codecs and not just MPEG. The
+defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
+were originally made for MPEG codecs and later extended to cover all
+encoding formats.
+
+
+Generic Codec Controls
+----------------------
+
+
+.. _mpeg-control-id:
+
+Codec Control IDs
+^^^^^^^^^^^^^^^^^
+
+``V4L2_CID_MPEG_CLASS (class)``
+ The Codec class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class. This description can be
+ used as the caption of a Tab page in a GUI, for example.
+
+.. _v4l2-mpeg-stream-type:
+
+``V4L2_CID_MPEG_STREAM_TYPE (enum v4l2_mpeg_stream_type)``
+ The MPEG-1, -2 or -4 output stream type. One cannot assume anything
+ here. Each hardware MPEG encoder tends to support different subsets
+ of the available MPEG stream types. This control is specific to
+ multiplexed MPEG streams. The currently defined stream types are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_STREAM_TYPE_MPEG2_PS``
+
+ - MPEG-2 program stream
+
+ - .. row 2
+
+ - ``V4L2_MPEG_STREAM_TYPE_MPEG2_TS``
+
+ - MPEG-2 transport stream
+
+ - .. row 3
+
+ - ``V4L2_MPEG_STREAM_TYPE_MPEG1_SS``
+
+ - MPEG-1 system stream
+
+ - .. row 4
+
+ - ``V4L2_MPEG_STREAM_TYPE_MPEG2_DVD``
+
+ - MPEG-2 DVD-compatible stream
+
+ - .. row 5
+
+ - ``V4L2_MPEG_STREAM_TYPE_MPEG1_VCD``
+
+ - MPEG-1 VCD-compatible stream
+
+ - .. row 6
+
+ - ``V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD``
+
+ - MPEG-2 SVCD-compatible stream
+
+
+
+``V4L2_CID_MPEG_STREAM_PID_PMT (integer)``
+ Program Map Table Packet ID for the MPEG transport stream (default
+ 16)
+
+``V4L2_CID_MPEG_STREAM_PID_AUDIO (integer)``
+ Audio Packet ID for the MPEG transport stream (default 256)
+
+``V4L2_CID_MPEG_STREAM_PID_VIDEO (integer)``
+ Video Packet ID for the MPEG transport stream (default 260)
+
+``V4L2_CID_MPEG_STREAM_PID_PCR (integer)``
+ Packet ID for the MPEG transport stream carrying PCR fields (default
+ 259)
+
+``V4L2_CID_MPEG_STREAM_PES_ID_AUDIO (integer)``
+ Audio ID for MPEG PES
+
+``V4L2_CID_MPEG_STREAM_PES_ID_VIDEO (integer)``
+ Video ID for MPEG PES
+
+.. _v4l2-mpeg-stream-vbi-fmt:
+
+``V4L2_CID_MPEG_STREAM_VBI_FMT (enum v4l2_mpeg_stream_vbi_fmt)``
+ Some cards can embed VBI data (e. g. 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:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_STREAM_VBI_FMT_NONE``
+
+ - No VBI in the MPEG stream
+
+ - .. row 2
+
+ - ``V4L2_MPEG_STREAM_VBI_FMT_IVTV``
+
+ - VBI in private packets, IVTV format (documented in the kernel
+ sources in the file
+ ``Documentation/video4linux/cx2341x/README.vbi``)
+
+
+
+.. _v4l2-mpeg-audio-sampling-freq:
+
+``V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ (enum v4l2_mpeg_audio_sampling_freq)``
+ MPEG Audio sampling frequency. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100``
+
+ - 44.1 kHz
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000``
+
+ - 48 kHz
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000``
+
+ - 32 kHz
+
+
+
+.. _v4l2-mpeg-audio-encoding:
+
+``V4L2_CID_MPEG_AUDIO_ENCODING (enum v4l2_mpeg_audio_encoding)``
+ MPEG Audio encoding. This control is specific to multiplexed MPEG
+ streams. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_1``
+
+ - MPEG-1/2 Layer I encoding
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_2``
+
+ - MPEG-1/2 Layer II encoding
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_3``
+
+ - MPEG-1/2 Layer III encoding
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_ENCODING_AAC``
+
+ - MPEG-2/4 AAC (Advanced Audio Coding)
+
+ - .. row 5
+
+ - ``V4L2_MPEG_AUDIO_ENCODING_AC3``
+
+ - AC-3 aka ATSC A/52 encoding
+
+
+
+.. _v4l2-mpeg-audio-l1-bitrate:
+
+``V4L2_CID_MPEG_AUDIO_L1_BITRATE (enum v4l2_mpeg_audio_l1_bitrate)``
+ MPEG-1/2 Layer I bitrate. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_32K``
+
+ - 32 kbit/s
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_64K``
+
+ - 64 kbit/s
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_96K``
+
+ - 96 kbit/s
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_128K``
+
+ - 128 kbit/s
+
+ - .. row 5
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_160K``
+
+ - 160 kbit/s
+
+ - .. row 6
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_192K``
+
+ - 192 kbit/s
+
+ - .. row 7
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_224K``
+
+ - 224 kbit/s
+
+ - .. row 8
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_256K``
+
+ - 256 kbit/s
+
+ - .. row 9
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_288K``
+
+ - 288 kbit/s
+
+ - .. row 10
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_320K``
+
+ - 320 kbit/s
+
+ - .. row 11
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_352K``
+
+ - 352 kbit/s
+
+ - .. row 12
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_384K``
+
+ - 384 kbit/s
+
+ - .. row 13
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_416K``
+
+ - 416 kbit/s
+
+ - .. row 14
+
+ - ``V4L2_MPEG_AUDIO_L1_BITRATE_448K``
+
+ - 448 kbit/s
+
+
+
+.. _v4l2-mpeg-audio-l2-bitrate:
+
+``V4L2_CID_MPEG_AUDIO_L2_BITRATE (enum v4l2_mpeg_audio_l2_bitrate)``
+ MPEG-1/2 Layer II bitrate. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_32K``
+
+ - 32 kbit/s
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_48K``
+
+ - 48 kbit/s
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_56K``
+
+ - 56 kbit/s
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_64K``
+
+ - 64 kbit/s
+
+ - .. row 5
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_80K``
+
+ - 80 kbit/s
+
+ - .. row 6
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_96K``
+
+ - 96 kbit/s
+
+ - .. row 7
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_112K``
+
+ - 112 kbit/s
+
+ - .. row 8
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_128K``
+
+ - 128 kbit/s
+
+ - .. row 9
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_160K``
+
+ - 160 kbit/s
+
+ - .. row 10
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_192K``
+
+ - 192 kbit/s
+
+ - .. row 11
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_224K``
+
+ - 224 kbit/s
+
+ - .. row 12
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_256K``
+
+ - 256 kbit/s
+
+ - .. row 13
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_320K``
+
+ - 320 kbit/s
+
+ - .. row 14
+
+ - ``V4L2_MPEG_AUDIO_L2_BITRATE_384K``
+
+ - 384 kbit/s
+
+
+
+.. _v4l2-mpeg-audio-l3-bitrate:
+
+``V4L2_CID_MPEG_AUDIO_L3_BITRATE (enum v4l2_mpeg_audio_l3_bitrate)``
+ MPEG-1/2 Layer III bitrate. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_32K``
+
+ - 32 kbit/s
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_40K``
+
+ - 40 kbit/s
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_48K``
+
+ - 48 kbit/s
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_56K``
+
+ - 56 kbit/s
+
+ - .. row 5
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_64K``
+
+ - 64 kbit/s
+
+ - .. row 6
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_80K``
+
+ - 80 kbit/s
+
+ - .. row 7
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_96K``
+
+ - 96 kbit/s
+
+ - .. row 8
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_112K``
+
+ - 112 kbit/s
+
+ - .. row 9
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_128K``
+
+ - 128 kbit/s
+
+ - .. row 10
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_160K``
+
+ - 160 kbit/s
+
+ - .. row 11
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_192K``
+
+ - 192 kbit/s
+
+ - .. row 12
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_224K``
+
+ - 224 kbit/s
+
+ - .. row 13
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_256K``
+
+ - 256 kbit/s
+
+ - .. row 14
+
+ - ``V4L2_MPEG_AUDIO_L3_BITRATE_320K``
+
+ - 320 kbit/s
+
+
+
+``V4L2_CID_MPEG_AUDIO_AAC_BITRATE (integer)``
+ AAC bitrate in bits per second.
+
+.. _v4l2-mpeg-audio-ac3-bitrate:
+
+``V4L2_CID_MPEG_AUDIO_AC3_BITRATE (enum v4l2_mpeg_audio_ac3_bitrate)``
+ AC-3 bitrate. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_32K``
+
+ - 32 kbit/s
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_40K``
+
+ - 40 kbit/s
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_48K``
+
+ - 48 kbit/s
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_56K``
+
+ - 56 kbit/s
+
+ - .. row 5
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_64K``
+
+ - 64 kbit/s
+
+ - .. row 6
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_80K``
+
+ - 80 kbit/s
+
+ - .. row 7
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_96K``
+
+ - 96 kbit/s
+
+ - .. row 8
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_112K``
+
+ - 112 kbit/s
+
+ - .. row 9
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_128K``
+
+ - 128 kbit/s
+
+ - .. row 10
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_160K``
+
+ - 160 kbit/s
+
+ - .. row 11
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_192K``
+
+ - 192 kbit/s
+
+ - .. row 12
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_224K``
+
+ - 224 kbit/s
+
+ - .. row 13
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_256K``
+
+ - 256 kbit/s
+
+ - .. row 14
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_320K``
+
+ - 320 kbit/s
+
+ - .. row 15
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_384K``
+
+ - 384 kbit/s
+
+ - .. row 16
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_448K``
+
+ - 448 kbit/s
+
+ - .. row 17
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_512K``
+
+ - 512 kbit/s
+
+ - .. row 18
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_576K``
+
+ - 576 kbit/s
+
+ - .. row 19
+
+ - ``V4L2_MPEG_AUDIO_AC3_BITRATE_640K``
+
+ - 640 kbit/s
+
+
+
+.. _v4l2-mpeg-audio-mode:
+
+``V4L2_CID_MPEG_AUDIO_MODE (enum v4l2_mpeg_audio_mode)``
+ MPEG Audio mode. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_MODE_STEREO``
+
+ - Stereo
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_MODE_JOINT_STEREO``
+
+ - Joint Stereo
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_MODE_DUAL``
+
+ - Bilingual
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_MODE_MONO``
+
+ - Mono
+
+
+
+.. _v4l2-mpeg-audio-mode-extension:
+
+``V4L2_CID_MPEG_AUDIO_MODE_EXTENSION (enum v4l2_mpeg_audio_mode_extension)``
+ Joint Stereo audio mode extension. In Layer I and II they indicate
+ which subbands are in intensity stereo. All other subbands are coded
+ in stereo. Layer III is not (yet) supported. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4``
+
+ - Subbands 4-31 in intensity stereo
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8``
+
+ - Subbands 8-31 in intensity stereo
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12``
+
+ - Subbands 12-31 in intensity stereo
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16``
+
+ - Subbands 16-31 in intensity stereo
+
+
+
+.. _v4l2-mpeg-audio-emphasis:
+
+``V4L2_CID_MPEG_AUDIO_EMPHASIS (enum v4l2_mpeg_audio_emphasis)``
+ Audio Emphasis. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_EMPHASIS_NONE``
+
+ - None
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS``
+
+ - 50/15 microsecond emphasis
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17``
+
+ - CCITT J.17
+
+
+
+.. _v4l2-mpeg-audio-crc:
+
+``V4L2_CID_MPEG_AUDIO_CRC (enum v4l2_mpeg_audio_crc)``
+ CRC method. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_CRC_NONE``
+
+ - None
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_CRC_CRC16``
+
+ - 16 bit parity check
+
+
+
+``V4L2_CID_MPEG_AUDIO_MUTE (boolean)``
+ Mutes the audio when capturing. This is not done by muting audio
+ hardware, which can still produce a slight hiss, but in the encoder
+ itself, guaranteeing a fixed and reproducible audio bitstream. 0 =
+ unmuted, 1 = muted.
+
+.. _v4l2-mpeg-audio-dec-playback:
+
+``V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK (enum v4l2_mpeg_audio_dec_playback)``
+ Determines how monolingual audio should be played back. Possible
+ values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO``
+
+ - Automatically determines the best playback mode.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO``
+
+ - Stereo playback.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT``
+
+ - Left channel playback.
+
+ - .. row 4
+
+ - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT``
+
+ - Right channel playback.
+
+ - .. row 5
+
+ - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO``
+
+ - Mono playback.
+
+ - .. row 6
+
+ - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO``
+
+ - Stereo playback with swapped left and right channels.
+
+
+
+.. _v4l2-mpeg-audio-dec-multilingual-playback:
+
+``V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK (enum v4l2_mpeg_audio_dec_playback)``
+ Determines how multilingual audio should be played back.
+
+.. _v4l2-mpeg-video-encoding:
+
+``V4L2_CID_MPEG_VIDEO_ENCODING (enum v4l2_mpeg_video_encoding)``
+ MPEG Video encoding method. This control is specific to multiplexed
+ MPEG streams. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_1``
+
+ - MPEG-1 Video encoding
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_2``
+
+ - MPEG-2 Video encoding
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC``
+
+ - MPEG-4 AVC (H.264) Video encoding
+
+
+
+.. _v4l2-mpeg-video-aspect:
+
+``V4L2_CID_MPEG_VIDEO_ASPECT (enum v4l2_mpeg_video_aspect)``
+ Video aspect. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_ASPECT_1x1``
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_ASPECT_4x3``
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_ASPECT_16x9``
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_ASPECT_221x100``
+
+
+
+``V4L2_CID_MPEG_VIDEO_B_FRAMES (integer)``
+ Number of B-Frames (default 2)
+
+``V4L2_CID_MPEG_VIDEO_GOP_SIZE (integer)``
+ GOP size (default 12)
+
+``V4L2_CID_MPEG_VIDEO_GOP_CLOSURE (boolean)``
+ GOP closure (default 1)
+
+``V4L2_CID_MPEG_VIDEO_PULLDOWN (boolean)``
+ Enable 3:2 pulldown (default 0)
+
+.. _v4l2-mpeg-video-bitrate-mode:
+
+``V4L2_CID_MPEG_VIDEO_BITRATE_MODE (enum v4l2_mpeg_video_bitrate_mode)``
+ Video bitrate mode. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_BITRATE_MODE_VBR``
+
+ - Variable bitrate
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_BITRATE_MODE_CBR``
+
+ - Constant bitrate
+
+
+
+``V4L2_CID_MPEG_VIDEO_BITRATE (integer)``
+ Video bitrate in bits per second.
+
+``V4L2_CID_MPEG_VIDEO_BITRATE_PEAK (integer)``
+ Peak video bitrate in bits per second. Must be larger or equal to
+ the average video bitrate. It is ignored if the video bitrate mode
+ is set to constant bitrate.
+
+``V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION (integer)``
+ For every captured frame, skip this many subsequent frames (default
+ 0).
+
+``V4L2_CID_MPEG_VIDEO_MUTE (boolean)``
+ "Mutes" the video to a fixed color when capturing. This is useful
+ for testing, to produce a fixed video bitstream. 0 = unmuted, 1 =
+ muted.
+
+``V4L2_CID_MPEG_VIDEO_MUTE_YUV (integer)``
+ Sets the "mute" color of the video. The supplied 32-bit integer is
+ interpreted as follows (bit 0 = least significant bit):
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Bit 0:7
+
+ - V chrominance information
+
+ - .. row 2
+
+ - Bit 8:15
+
+ - U chrominance information
+
+ - .. row 3
+
+ - Bit 16:23
+
+ - Y luminance information
+
+ - .. row 4
+
+ - Bit 24:31
+
+ - Must be zero.
+
+
+
+.. _v4l2-mpeg-video-dec-pts:
+
+``V4L2_CID_MPEG_VIDEO_DEC_PTS (integer64)``
+ This read-only control returns the 33-bit video Presentation Time
+ Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of the
+ currently displayed frame. This is the same PTS as is used in
+ :ref:`VIDIOC_DECODER_CMD`.
+
+.. _v4l2-mpeg-video-dec-frame:
+
+``V4L2_CID_MPEG_VIDEO_DEC_FRAME (integer64)``
+ This read-only control returns the frame counter of the frame that
+ is currently displayed (decoded). This value is reset to 0 whenever
+ the decoder is started.
+
+``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
+ If enabled the decoder expects to receive a single slice per buffer,
+ otherwise the decoder expects a single frame in per buffer.
+ Applicable to the decoder, all codecs.
+
+``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_ENABLE (boolean)``
+ Enable writing sample aspect ratio in the Video Usability
+ Information. Applicable to the H264 encoder.
+
+.. _v4l2-mpeg-video-h264-vui-sar-idc:
+
+``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_IDC (enum v4l2_mpeg_video_h264_vui_sar_idc)``
+ VUI sample aspect ratio indicator for H.264 encoding. The value is
+ defined in the table E-1 in the standard. Applicable to the H264
+ encoder.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_UNSPECIFIED``
+
+ - Unspecified
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_1x1``
+
+ - 1x1
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_12x11``
+
+ - 12x11
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_10x11``
+
+ - 10x11
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_16x11``
+
+ - 16x11
+
+ - .. row 6
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_40x33``
+
+ - 40x33
+
+ - .. row 7
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_24x11``
+
+ - 24x11
+
+ - .. row 8
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_20x11``
+
+ - 20x11
+
+ - .. row 9
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_32x11``
+
+ - 32x11
+
+ - .. row 10
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_80x33``
+
+ - 80x33
+
+ - .. row 11
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_18x11``
+
+ - 18x11
+
+ - .. row 12
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_15x11``
+
+ - 15x11
+
+ - .. row 13
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_64x33``
+
+ - 64x33
+
+ - .. row 14
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_160x99``
+
+ - 160x99
+
+ - .. row 15
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_4x3``
+
+ - 4x3
+
+ - .. row 16
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_3x2``
+
+ - 3x2
+
+ - .. row 17
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_2x1``
+
+ - 2x1
+
+ - .. row 18
+
+ - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_EXTENDED``
+
+ - Extended SAR
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_WIDTH (integer)``
+ Extended sample aspect ratio width for H.264 VUI encoding.
+ Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_HEIGHT (integer)``
+ Extended sample aspect ratio height for H.264 VUI encoding.
+ Applicable to the H264 encoder.
+
+.. _v4l2-mpeg-video-h264-level:
+
+``V4L2_CID_MPEG_VIDEO_H264_LEVEL (enum v4l2_mpeg_video_h264_level)``
+ The level information for the H264 video elementary stream.
+ Applicable to the H264 encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_0``
+
+ - Level 1.0
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_1B``
+
+ - Level 1B
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_1``
+
+ - Level 1.1
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_2``
+
+ - Level 1.2
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_3``
+
+ - Level 1.3
+
+ - .. row 6
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_0``
+
+ - Level 2.0
+
+ - .. row 7
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_1``
+
+ - Level 2.1
+
+ - .. row 8
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_2``
+
+ - Level 2.2
+
+ - .. row 9
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_0``
+
+ - Level 3.0
+
+ - .. row 10
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_1``
+
+ - Level 3.1
+
+ - .. row 11
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_2``
+
+ - Level 3.2
+
+ - .. row 12
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_0``
+
+ - Level 4.0
+
+ - .. row 13
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_1``
+
+ - Level 4.1
+
+ - .. row 14
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_2``
+
+ - Level 4.2
+
+ - .. row 15
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_0``
+
+ - Level 5.0
+
+ - .. row 16
+
+ - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_1``
+
+ - Level 5.1
+
+
+
+.. _v4l2-mpeg-video-mpeg4-level:
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL (enum v4l2_mpeg_video_mpeg4_level)``
+ The level information for the MPEG4 elementary stream. Applicable to
+ the MPEG4 encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_0``
+
+ - Level 0
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_0B``
+
+ - Level 0b
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_1``
+
+ - Level 1
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_2``
+
+ - Level 2
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_3``
+
+ - Level 3
+
+ - .. row 6
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_3B``
+
+ - Level 3b
+
+ - .. row 7
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_4``
+
+ - Level 4
+
+ - .. row 8
+
+ - ``V4L2_MPEG_VIDEO_LEVEL_5``
+
+ - Level 5
+
+
+
+.. _v4l2-mpeg-video-h264-profile:
+
+``V4L2_CID_MPEG_VIDEO_H264_PROFILE (enum v4l2_mpeg_video_h264_profile)``
+ The profile information for H264. Applicable to the H264 encoder.
+ Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE``
+
+ - Baseline profile
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_CONSTRAINED_BASELINE``
+
+ - Constrained Baseline profile
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_MAIN``
+
+ - Main profile
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED``
+
+ - Extended profile
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH``
+
+ - High profile
+
+ - .. row 6
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10``
+
+ - High 10 profile
+
+ - .. row 7
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422``
+
+ - High 422 profile
+
+ - .. row 8
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE``
+
+ - High 444 Predictive profile
+
+ - .. row 9
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10_INTRA``
+
+ - High 10 Intra profile
+
+ - .. row 10
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422_INTRA``
+
+ - High 422 Intra profile
+
+ - .. row 11
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_INTRA``
+
+ - High 444 Intra profile
+
+ - .. row 12
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_CAVLC_444_INTRA``
+
+ - CAVLC 444 Intra profile
+
+ - .. row 13
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE``
+
+ - Scalable Baseline profile
+
+ - .. row 14
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH``
+
+ - Scalable High profile
+
+ - .. row 15
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH_INTRA``
+
+ - Scalable High Intra profile
+
+ - .. row 16
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH``
+
+ - Stereo High profile
+
+ - .. row 17
+
+ - ``V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH``
+
+ - Multiview High profile
+
+
+
+.. _v4l2-mpeg-video-mpeg4-profile:
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE (enum v4l2_mpeg_video_mpeg4_profile)``
+ The profile information for MPEG4. Applicable to the MPEG4 encoder.
+ Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE``
+
+ - Simple profile
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_SIMPLE``
+
+ - Advanced Simple profile
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_PROFILE_CORE``
+
+ - Core profile
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE_SCALABLE``
+
+ - Simple Scalable profile
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_CODING_EFFICIENCY``
+
+ -
+
+
+
+``V4L2_CID_MPEG_VIDEO_MAX_REF_PIC (integer)``
+ The maximum number of reference pictures used for encoding.
+ Applicable to the encoder.
+
+.. _v4l2-mpeg-video-multi-slice-mode:
+
+``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE (enum v4l2_mpeg_video_multi_slice_mode)``
+ Determines how the encoder should handle division of frame into
+ slices. Applicable to the encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_SINGLE``
+
+ - Single slice per frame.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``
+
+ - Multiple slices with set maximum number of macroblocks per slice.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``
+
+ - Multiple slice with set maximum size in bytes per slice.
+
+
+
+``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB (integer)``
+ The maximum number of macroblocks in a slice. Used when
+ ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
+ ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``. Applicable to the
+ encoder.
+
+``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES (integer)``
+ The maximum size of a slice in bytes. Used when
+ ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
+ ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``. Applicable to the
+ encoder.
+
+.. _v4l2-mpeg-video-h264-loop-filter-mode:
+
+``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_MODE (enum v4l2_mpeg_video_h264_loop_filter_mode)``
+ Loop filter mode for H264 encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_ENABLED``
+
+ - Loop filter is enabled.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED``
+
+ - Loop filter is disabled.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
+
+ - Loop filter is disabled at the slice boundary.
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)``
+ Loop filter alpha coefficient, defined in the H264 standard.
+ Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)``
+ Loop filter beta coefficient, defined in the H264 standard.
+ Applicable to the H264 encoder.
+
+.. _v4l2-mpeg-video-h264-entropy-mode:
+
+``V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE (enum v4l2_mpeg_video_h264_entropy_mode)``
+ Entropy coding mode for H264 - CABAC/CAVALC. Applicable to the H264
+ encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CAVLC``
+
+ - Use CAVLC entropy coding.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CABAC``
+
+ - Use CABAC entropy coding.
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_8X8_TRANSFORM (boolean)``
+ Enable 8X8 transform for H264. Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_CYCLIC_INTRA_REFRESH_MB (integer)``
+ Cyclic intra macroblock refresh. This is the number of continuous
+ macroblocks refreshed every frame. Each frame a successive set of
+ macroblocks is refreshed until the cycle completes and starts from
+ the top of the frame. Applicable to H264, H263 and MPEG4 encoder.
+
+``V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE (boolean)``
+ Frame level rate control enable. If this control is disabled then
+ the quantization parameter for each frame type is constant and set
+ with appropriate controls (e.g.
+ ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP``). If frame rate control is
+ enabled then quantization parameter is adjusted to meet the chosen
+ bitrate. Minimum and maximum value for the quantization parameter
+ can be set with appropriate controls (e.g.
+ ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP``). Applicable to encoders.
+
+``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE (boolean)``
+ Macroblock level rate control enable. Applicable to the MPEG4 and
+ H264 encoders.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_QPEL (boolean)``
+ Quarter pixel motion estimation for MPEG4. Applicable to the MPEG4
+ encoder.
+
+``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (integer)``
+ Quantization parameter for an I frame for H263. Valid range: from 1
+ to 31.
+
+``V4L2_CID_MPEG_VIDEO_H263_MIN_QP (integer)``
+ Minimum quantization parameter for H263. Valid range: from 1 to 31.
+
+``V4L2_CID_MPEG_VIDEO_H263_MAX_QP (integer)``
+ Maximum quantization parameter for H263. Valid range: from 1 to 31.
+
+``V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (integer)``
+ Quantization parameter for an P frame for H263. Valid range: from 1
+ to 31.
+
+``V4L2_CID_MPEG_VIDEO_H263_B_FRAME_QP (integer)``
+ Quantization parameter for an B frame for H263. Valid range: from 1
+ to 31.
+
+``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_QP (integer)``
+ Quantization parameter for an I frame for H264. Valid range: from 0
+ to 51.
+
+``V4L2_CID_MPEG_VIDEO_H264_MIN_QP (integer)``
+ Minimum quantization parameter for H264. Valid range: from 0 to 51.
+
+``V4L2_CID_MPEG_VIDEO_H264_MAX_QP (integer)``
+ Maximum quantization parameter for H264. Valid range: from 0 to 51.
+
+``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP (integer)``
+ Quantization parameter for an P frame for H264. Valid range: from 0
+ to 51.
+
+``V4L2_CID_MPEG_VIDEO_H264_B_FRAME_QP (integer)``
+ Quantization parameter for an B frame for H264. Valid range: from 0
+ to 51.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
+ Quantization parameter for an I frame for MPEG4. Valid range: from 1
+ to 31.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_MIN_QP (integer)``
+ Minimum quantization parameter for MPEG4. Valid range: from 1 to 31.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_MAX_QP (integer)``
+ Maximum quantization parameter for MPEG4. Valid range: from 1 to 31.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (integer)``
+ Quantization parameter for an P frame for MPEG4. Valid range: from 1
+ to 31.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (integer)``
+ Quantization parameter for an B frame for MPEG4. Valid range: from 1
+ to 31.
+
+``V4L2_CID_MPEG_VIDEO_VBV_SIZE (integer)``
+ The Video Buffer Verifier size in kilobytes, it is used as a
+ limitation of frame skip. The VBV is defined in the standard as a
+ mean to verify that the produced stream will be successfully
+ decoded. The standard describes it as "Part of a hypothetical
+ decoder that is conceptually connected to the output of the encoder.
+ Its purpose is to provide a constraint on the variability of the
+ data rate that an encoder or editing process may produce.".
+ Applicable to the MPEG1, MPEG2, MPEG4 encoders.
+
+.. _v4l2-mpeg-video-vbv-delay:
+
+``V4L2_CID_MPEG_VIDEO_VBV_DELAY (integer)``
+ Sets the initial delay in milliseconds for VBV buffer control.
+
+.. _v4l2-mpeg-video-hor-search-range:
+
+``V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (integer)``
+ Horizontal search range defines maximum horizontal search area in
+ pixels to search and match for the present Macroblock (MB) in the
+ reference picture. This V4L2 control macro is used to set horizontal
+ search range for motion estimation module in video encoder.
+
+.. _v4l2-mpeg-video-vert-search-range:
+
+``V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (integer)``
+ Vertical search range defines maximum vertical search area in pixels
+ to search and match for the present Macroblock (MB) in the reference
+ picture. This V4L2 control macro is used to set vertical search
+ range for motion estimation module in video encoder.
+
+.. _v4l2-mpeg-video-force-key-frame:
+
+``V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (button)``
+ Force a key frame for the next queued buffer. Applicable to
+ encoders. This is a general, codec-agnostic keyframe control.
+
+``V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE (integer)``
+ The Coded Picture Buffer size in kilobytes, it is used as a
+ limitation of frame skip. The CPB is defined in the H264 standard as
+ a mean to verify that the produced stream will be successfully
+ decoded. Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_I_PERIOD (integer)``
+ Period between I-frames in the open GOP for H264. In case of an open
+ GOP this is the period between two I-frames. The period between IDR
+ (Instantaneous Decoding Refresh) frames is taken from the GOP_SIZE
+ control. An IDR frame, which stands for Instantaneous Decoding
+ Refresh is an I-frame after which no prior frames are referenced.
+ This means that a stream can be restarted from an IDR frame without
+ the need to store or decode any previous frames. Applicable to the
+ H264 encoder.
+
+.. _v4l2-mpeg-video-header-mode:
+
+``V4L2_CID_MPEG_VIDEO_HEADER_MODE (enum v4l2_mpeg_video_header_mode)``
+ Determines whether the header is returned as the first buffer or is
+ it returned together with the first frame. Applicable to encoders.
+ Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE``
+
+ - The stream header is returned separately in the first buffer.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_HEADER_MODE_JOINED_WITH_1ST_FRAME``
+
+ - The stream header is returned together with the first encoded
+ frame.
+
+
+
+``V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (boolean)``
+ Repeat the video sequence headers. Repeating these headers makes
+ random access to the video stream easier. Applicable to the MPEG1, 2
+ and 4 encoder.
+
+``V4L2_CID_MPEG_VIDEO_DECODER_MPEG4_DEBLOCK_FILTER (boolean)``
+ Enabled the deblocking post processing filter for MPEG4 decoder.
+ Applicable to the MPEG4 decoder.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_RES (integer)``
+ vop_time_increment_resolution value for MPEG4. Applicable to the
+ MPEG4 encoder.
+
+``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_INC (integer)``
+ vop_time_increment value for MPEG4. Applicable to the MPEG4
+ encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_SEI_FRAME_PACKING (boolean)``
+ Enable generation of frame packing supplemental enhancement
+ information in the encoded bitstream. The frame packing SEI message
+ contains the arrangement of L and R planes for 3D viewing.
+ Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_CURRENT_FRAME_0 (boolean)``
+ Sets current frame as frame0 in frame packing SEI. Applicable to the
+ H264 encoder.
+
+.. _v4l2-mpeg-video-h264-sei-fp-arrangement-type:
+
+``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE (enum v4l2_mpeg_video_h264_sei_fp_arrangement_type)``
+ Frame packing arrangement type for H264 SEI. Applicable to the H264
+ encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_CHEKERBOARD``
+
+ - Pixels are alternatively from L and R.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_COLUMN``
+
+ - L and R are interlaced by column.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_ROW``
+
+ - L and R are interlaced by row.
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_SIDE_BY_SIDE``
+
+ - L is on the left, R on the right.
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TOP_BOTTOM``
+
+ - L is on top, R on bottom.
+
+ - .. row 6
+
+ - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TEMPORAL``
+
+ - One view per frame.
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_FMO (boolean)``
+ Enables flexible macroblock ordering in the encoded bitstream. It is
+ a technique used for restructuring the ordering of macroblocks in
+ pictures. Applicable to the H264 encoder.
+
+.. _v4l2-mpeg-video-h264-fmo-map-type:
+
+``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE (enum v4l2_mpeg_video_h264_fmo_map_type)``
+ When using FMO, the map type divides the image in different scan
+ patterns of macroblocks. Applicable to the H264 encoder. Possible
+ values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_INTERLEAVED_SLICES``
+
+ - Slices are interleaved one after other with macroblocks in run
+ length order.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_SCATTERED_SLICES``
+
+ - Scatters the macroblocks based on a mathematical function known to
+ both encoder and decoder.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_FOREGROUND_WITH_LEFT_OVER``
+
+ - Macroblocks arranged in rectangular areas or regions of interest.
+
+ - .. row 4
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_BOX_OUT``
+
+ - Slice groups grow in a cyclic way from centre to outwards.
+
+ - .. row 5
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_RASTER_SCAN``
+
+ - Slice groups grow in raster scan pattern from left to right.
+
+ - .. row 6
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_WIPE_SCAN``
+
+ - Slice groups grow in wipe scan pattern from top to bottom.
+
+ - .. row 7
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_EXPLICIT``
+
+ - User defined map type.
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_FMO_SLICE_GROUP (integer)``
+ Number of slice groups in FMO. Applicable to the H264 encoder.
+
+.. _v4l2-mpeg-video-h264-fmo-change-direction:
+
+``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_DIRECTION (enum v4l2_mpeg_video_h264_fmo_change_dir)``
+ Specifies a direction of the slice group change for raster and wipe
+ maps. Applicable to the H264 encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_RIGHT``
+
+ - Raster scan or wipe right.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_LEFT``
+
+ - Reverse raster scan or wipe left.
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_RATE (integer)``
+ Specifies the size of the first slice group for raster and wipe map.
+ Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_FMO_RUN_LENGTH (integer)``
+ Specifies the number of consecutive macroblocks for the interleaved
+ map. Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_ASO (boolean)``
+ Enables arbitrary slice ordering in encoded bitstream. Applicable to
+ the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_ASO_SLICE_ORDER (integer)``
+ Specifies the slice order in ASO. Applicable to the H264 encoder.
+ The supplied 32-bit integer is interpreted as follows (bit 0 = least
+ significant bit):
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Bit 0:15
+
+ - Slice ID
+
+ - .. row 2
+
+ - Bit 16:32
+
+ - Slice position or order
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING (boolean)``
+ Enables H264 hierarchical coding. Applicable to the H264 encoder.
+
+.. _v4l2-mpeg-video-h264-hierarchical-coding-type:
+
+``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_TYPE (enum v4l2_mpeg_video_h264_hierarchical_coding_type)``
+ Specifies the hierarchical coding type. Applicable to the H264
+ encoder. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_B``
+
+ - Hierarchical B coding.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_P``
+
+ - Hierarchical P coding.
+
+
+
+``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (integer)``
+ Specifies the number of hierarchical coding layers. Applicable to
+ the H264 encoder.
+
+``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (integer)``
+ Specifies a user defined QP for each layer. Applicable to the H264
+ encoder. The supplied 32-bit integer is interpreted as follows (bit
+ 0 = least significant bit):
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Bit 0:15
+
+ - QP value
+
+ - .. row 2
+
+ - Bit 16:32
+
+ - Layer number
+
+
+
+
+MFC 5.1 MPEG Controls
+---------------------
+
+The following MPEG class controls deal with MPEG decoding and encoding
+settings that are specific to the Multi Format Codec 5.1 device present
+in the S5P family of SoCs by Samsung.
+
+
+.. _mfc51-control-id:
+
+MFC 5.1 Control IDs
+^^^^^^^^^^^^^^^^^^^
+
+``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY_ENABLE (boolean)``
+ If the display delay is enabled then the decoder is forced to return
+ a CAPTURE buffer (decoded frame) after processing a certain number
+ of OUTPUT buffers. The delay can be set through
+ ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY``. This
+ feature can be used for example for generating thumbnails of videos.
+ Applicable to the H264 decoder.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY (integer)``
+ Display delay value for H264 decoder. The decoder is forced to
+ return a decoded frame after the set 'display delay' number of
+ frames. If this number is low it may result in frames returned out
+ of dispaly order, in addition the hardware may still be using the
+ returned buffer as a reference picture for subsequent frames.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P (integer)``
+ The number of reference pictures used for encoding a P picture.
+ Applicable to the H264 encoder.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_PADDING (boolean)``
+ Padding enable in the encoder - use a color instead of repeating
+ border pixels. Applicable to encoders.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_PADDING_YUV (integer)``
+ Padding color in the encoder. Applicable to encoders. The supplied
+ 32-bit integer is interpreted as follows (bit 0 = least significant
+ bit):
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - Bit 0:7
+
+ - V chrominance information
+
+ - .. row 2
+
+ - Bit 8:15
+
+ - U chrominance information
+
+ - .. row 3
+
+ - Bit 16:23
+
+ - Y luminance information
+
+ - .. row 4
+
+ - Bit 24:31
+
+ - Must be zero.
+
+
+
+``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
+ Reaction coefficient for MFC rate control. Applicable to encoders.
+
+ Note 1: Valid only when the frame level RC is enabled.
+
+ Note 2: For tight CBR, this field must be small (ex. 2 ~ 10). For
+ VBR, this field must be large (ex. 100 ~ 1000).
+
+ Note 3: It is not recommended to use the greater number than
+ FRAME_RATE * (10^9 / BIT_RATE).
+
+``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
+ Adaptive rate control for dark region. Valid only when H.264 and
+ macroblock level RC is enabled
+ (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
+ encoder.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_SMOOTH (boolean)``
+ Adaptive rate control for smooth region. Valid only when H.264 and
+ macroblock level RC is enabled
+ (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
+ encoder.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC (boolean)``
+ Adaptive rate control for static region. Valid only when H.264 and
+ macroblock level RC is enabled
+ (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
+ encoder.
+
+``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_ACTIVITY (boolean)``
+ Adaptive rate control for activity region. Valid only when H.264 and
+ macroblock level RC is enabled
+ (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
+ encoder.
+
+.. _v4l2-mpeg-mfc51-video-frame-skip-mode:
+
+``V4L2_CID_MPEG_MFC51_VIDEO_FRAME_SKIP_MODE (enum v4l2_mpeg_mfc51_video_frame_skip_mode)``
+ Indicates in what conditions the encoder should skip frames. If
+ encoding a frame would cause the encoded stream to be larger then a
+ chosen data limit then the frame will be skipped. Possible values
+ are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_DISABLED``
+
+ - Frame skip mode is disabled.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_LEVEL_LIMIT``
+
+ - Frame skip mode enabled and buffer limit is set by the chosen
+ level and is defined by the standard.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_BUF_LIMIT``
+
+ - Frame skip mode enabled and buffer limit is set by the VBV
+ (MPEG1/2/4) or CPB (H264) buffer size control.
+
+
+
+``V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT (integer)``
+ Enable rate-control with fixed target bit. If this setting is
+ enabled, then the rate control logic of the encoder will calculate
+ the average bitrate for a GOP and keep it below or equal the set
+ bitrate target. Otherwise the rate control logic calculates the
+ overall average bitrate for the stream and keeps it below or equal
+ to the set bitrate. In the first case the average bitrate for the
+ whole stream will be smaller then the set bitrate. This is caused
+ because the average is calculated for smaller number of frames, on
+ the other hand enabling this setting will ensure that the stream
+ will meet tight bandwidth constraints. Applicable to encoders.
+
+.. _v4l2-mpeg-mfc51-video-force-frame-type:
+
+``V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE (enum v4l2_mpeg_mfc51_video_force_frame_type)``
+ Force a frame type for the next queued buffer. Applicable to
+ encoders. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_DISABLED``
+
+ - Forcing a specific frame type disabled.
+
+ - .. row 2
+
+ - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_I_FRAME``
+
+ - Force an I-frame.
+
+ - .. row 3
+
+ - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_NOT_CODED``
+
+ - Force a non-coded frame.
+
+
+
+
+CX2341x MPEG Controls
+---------------------
+
+The following MPEG class controls deal with MPEG encoding settings that
+are specific to the Conexant CX23415 and CX23416 MPEG encoding chips.
+
+
+.. _cx2341x-control-id:
+
+CX2341x Control IDs
+^^^^^^^^^^^^^^^^^^^
+
+.. _v4l2-mpeg-cx2341x-video-spatial-filter-mode:
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE (enum v4l2_mpeg_cx2341x_video_spatial_filter_mode)``
+ Sets the Spatial Filter mode (default ``MANUAL``). Possible values
+ are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL``
+
+ - Choose the filter manually
+
+ - .. row 2
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO``
+
+ - Choose the filter automatically
+
+
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER (integer (0-15))``
+ The setting for the Spatial Filter. 0 = off, 15 = maximum. (Default
+ is 0.)
+
+.. _luma-spatial-filter-type:
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type)``
+ Select the algorithm to use for the Luma Spatial Filter (default
+ ``1D_HOR``). Possible values:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF``
+
+ - No filter
+
+ - .. row 2
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR``
+
+ - One-dimensional horizontal
+
+ - .. row 3
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT``
+
+ - One-dimensional vertical
+
+ - .. row 4
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE``
+
+ - Two-dimensional separable
+
+ - .. row 5
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE``
+
+ - Two-dimensional symmetrical non-separable
+
+
+
+.. _chroma-spatial-filter-type:
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type)``
+ Select the algorithm for the Chroma Spatial Filter (default
+ ``1D_HOR``). Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF``
+
+ - No filter
+
+ - .. row 2
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR``
+
+ - One-dimensional horizontal
+
+
+
+.. _v4l2-mpeg-cx2341x-video-temporal-filter-mode:
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE (enum v4l2_mpeg_cx2341x_video_temporal_filter_mode)``
+ Sets the Temporal Filter mode (default ``MANUAL``). Possible values
+ are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL``
+
+ - Choose the filter manually
+
+ - .. row 2
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO``
+
+ - Choose the filter automatically
+
+
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER (integer (0-31))``
+ The setting for the Temporal Filter. 0 = off, 31 = maximum. (Default
+ is 8 for full-scale capturing and 0 for scaled capturing.)
+
+.. _v4l2-mpeg-cx2341x-video-median-filter-type:
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_median_filter_type)``
+ Median Filter Type (default ``OFF``). Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF``
+
+ - No filter
+
+ - .. row 2
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR``
+
+ - Horizontal filter
+
+ - .. row 3
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT``
+
+ - Vertical filter
+
+ - .. row 4
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT``
+
+ - Horizontal and vertical filter
+
+ - .. row 5
+
+ - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG``
+
+ - Diagonal filter
+
+
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
+ Threshold above which the luminance median filter is enabled
+ (default 0)
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP (integer (0-255))``
+ Threshold below which the luminance median filter is enabled
+ (default 255)
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
+ Threshold above which the chroma median filter is enabled (default
+ 0)
+
+``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP (integer (0-255))``
+ Threshold below which the chroma median filter is enabled (default
+ 255)
+
+``V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS (boolean)``
+ The CX2341X MPEG encoder can insert one empty MPEG-2 PES packet into
+ the stream between every four video frames. The packet size is 2048
+ bytes, including the packet_start_code_prefix and stream_id
+ fields. The stream_id is 0xBF (private stream 2). The payload
+ consists of 0x00 bytes, to be filled in by the application. 0 = do
+ not insert, 1 = insert packets.
+
+
+VPX Control Reference
+---------------------
+
+The VPX controls include controls for encoding parameters of VPx video
+codec.
+
+
+.. _vpx-control-id:
+
+VPX Control IDs
+^^^^^^^^^^^^^^^
+
+.. _v4l2-vpx-num-partitions:
+
+``V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS (enum v4l2_vp8_num_partitions)``
+ The number of token partitions to use in VP8 encoder. Possible
+ values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_1_PARTITION``
+
+ - 1 coefficient partition
+
+ - .. row 2
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_2_PARTITIONS``
+
+ - 2 coefficient partitions
+
+ - .. row 3
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_4_PARTITIONS``
+
+ - 4 coefficient partitions
+
+ - .. row 4
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_8_PARTITIONS``
+
+ - 8 coefficient partitions
+
+
+
+``V4L2_CID_MPEG_VIDEO_VPX_IMD_DISABLE_4X4 (boolean)``
+ Setting this prevents intra 4x4 mode in the intra mode decision.
+
+.. _v4l2-vpx-num-ref-frames:
+
+``V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES (enum v4l2_vp8_num_ref_frames)``
+ The number of reference pictures for encoding P frames. Possible
+ values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_1_REF_FRAME``
+
+ - Last encoded frame will be searched
+
+ - .. row 2
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_2_REF_FRAME``
+
+ - Two frames will be searched among the last encoded frame, the
+ golden frame and the alternate reference (altref) frame. The
+ encoder implementation will decide which two are chosen.
+
+ - .. row 3
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_3_REF_FRAME``
+
+ - The last encoded frame, the golden frame and the altref frame will
+ be searched.
+
+
+
+``V4L2_CID_MPEG_VIDEO_VPX_FILTER_LEVEL (integer)``
+ Indicates the loop filter level. The adjustment of the loop filter
+ level is done via a delta value against a baseline loop filter
+ value.
+
+``V4L2_CID_MPEG_VIDEO_VPX_FILTER_SHARPNESS (integer)``
+ This parameter affects the loop filter. Anything above zero weakens
+ the deblocking effect on the loop filter.
+
+``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD (integer)``
+ Sets the refresh period for the golden frame. The period is defined
+ in number of frames. For a value of 'n', every nth frame starting
+ from the first key frame will be taken as a golden frame. For eg.
+ for encoding sequence of 0, 1, 2, 3, 4, 5, 6, 7 where the golden
+ frame refresh period is set as 4, the frames 0, 4, 8 etc will be
+ taken as the golden frames as frame 0 is always a key frame.
+
+.. _v4l2-vpx-golden-frame-sel:
+
+``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_SEL (enum v4l2_vp8_golden_frame_sel)``
+ Selects the golden frame for encoding. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_PREV``
+
+ - Use the (n-2)th frame as a golden frame, current frame index being
+ 'n'.
+
+ - .. row 2
+
+ - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_REF_PERIOD``
+
+ - Use the previous specific frame indicated by
+ V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD as a
+ golden frame.
+
+
+
+``V4L2_CID_MPEG_VIDEO_VPX_MIN_QP (integer)``
+ Minimum quantization parameter for VP8.
+
+``V4L2_CID_MPEG_VIDEO_VPX_MAX_QP (integer)``
+ Maximum quantization parameter for VP8.
+
+``V4L2_CID_MPEG_VIDEO_VPX_I_FRAME_QP (integer)``
+ Quantization parameter for an I frame for VP8.
+
+``V4L2_CID_MPEG_VIDEO_VPX_P_FRAME_QP (integer)``
+ Quantization parameter for a P frame for VP8.
+
+``V4L2_CID_MPEG_VIDEO_VPX_PROFILE (integer)``
+ Select the desired profile for VPx encoder. Acceptable values are 0,
+ 1, 2 and 3 corresponding to encoder profiles 0, 1, 2 and 3.
+
+
+.. _camera-controls:
+
+Camera Control Reference
+========================
+
+The Camera class includes controls for mechanical (or equivalent
+digital) features of a device such as controllable lenses or sensors.
+
+
+.. _camera-control-id:
+
+Camera Control IDs
+------------------
+
+``V4L2_CID_CAMERA_CLASS (class)``
+ The Camera class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class.
+
+.. _v4l2-exposure-auto-type:
+
+``V4L2_CID_EXPOSURE_AUTO (enum v4l2_exposure_auto_type)``
+ Enables automatic adjustments of the exposure time and/or iris
+ aperture. The effect of manual changes of the exposure time or iris
+ aperture while these features are enabled is undefined, drivers
+ should ignore such requests. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_EXPOSURE_AUTO``
+
+ - Automatic exposure time, automatic iris aperture.
+
+ - .. row 2
+
+ - ``V4L2_EXPOSURE_MANUAL``
+
+ - Manual exposure time, manual iris.
+
+ - .. row 3
+
+ - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
+
+ - Manual exposure time, auto iris.
+
+ - .. row 4
+
+ - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
+
+ - Auto exposure time, manual iris.
+
+
+
+``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
+ Determines the exposure time of the camera sensor. The exposure time
+ is limited by the frame interval. Drivers should interpret the
+ values as 100 µs units, where the value 1 stands for 1/10000th of a
+ second, 10000 for 1 second and 100000 for 10 seconds.
+
+``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
+ When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
+ ``APERTURE_PRIORITY``, this control determines if the device may
+ dynamically vary the frame rate. By default this feature is disabled
+ (0) and the frame rate must remain constant.
+
+``V4L2_CID_EXPOSURE_BIAS (integer menu)``
+ Determines the automatic exposure compensation, it is effective only
+ when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
+ ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
+ terms of EV, drivers should interpret the values as 0.001 EV units,
+ where the value 1000 stands for +1 EV.
+
+ Increasing the exposure compensation value is equivalent to
+ decreasing the exposure value (EV) and will increase the amount of
+ light at the image sensor. The camera performs the exposure
+ compensation by adjusting absolute exposure time and/or aperture.
+
+.. _v4l2-exposure-metering:
+
+``V4L2_CID_EXPOSURE_METERING (enum v4l2_exposure_metering)``
+ Determines how the camera measures the amount of light available for
+ the frame exposure. Possible values are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_EXPOSURE_METERING_AVERAGE``
+
+ - Use the light information coming from the entire frame and average
+ giving no weighting to any particular portion of the metered area.
+
+ - .. row 2
+
+ - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
+
+ - Average the light information coming from the entire frame giving
+ priority to the center of the metered area.
+
+ - .. row 3
+
+ - ``V4L2_EXPOSURE_METERING_SPOT``
+
+ - Measure only very small area at the center of the frame.
+
+ - .. row 4
+
+ - ``V4L2_EXPOSURE_METERING_MATRIX``
+
+ - A multi-zone metering. The light intensity is measured in several
+ points of the frame and the results are combined. The algorithm of
+ the zones selection and their significance in calculating the
+ final value is device dependent.
+
+
+
+``V4L2_CID_PAN_RELATIVE (integer)``
+ This control turns the camera horizontally by the specified amount.
+ The unit is undefined. A positive value moves the camera to the
+ right (clockwise when viewed from above), a negative value to the
+ left. A value of zero does not cause motion. This is a write-only
+ control.
+
+``V4L2_CID_TILT_RELATIVE (integer)``
+ This control turns the camera vertically by the specified amount.
+ The unit is undefined. A positive value moves the camera up, a
+ negative value down. A value of zero does not cause motion. This is
+ a write-only control.
+
+``V4L2_CID_PAN_RESET (button)``
+ When this control is set, the camera moves horizontally to the
+ default position.
+
+``V4L2_CID_TILT_RESET (button)``
+ When this control is set, the camera moves vertically to the default
+ position.
+
+``V4L2_CID_PAN_ABSOLUTE (integer)``
+ This control turns the camera horizontally to the specified
+ position. Positive values move the camera to the right (clockwise
+ when viewed from above), negative values to the left. Drivers should
+ interpret the values as arc seconds, with valid values between -180
+ * 3600 and +180 * 3600 inclusive.
+
+``V4L2_CID_TILT_ABSOLUTE (integer)``
+ This control turns the camera vertically to the specified position.
+ Positive values move the camera up, negative values down. Drivers
+ should interpret the values as arc seconds, with valid values
+ between -180 * 3600 and +180 * 3600 inclusive.
+
+``V4L2_CID_FOCUS_ABSOLUTE (integer)``
+ This control sets the focal point of the camera to the specified
+ position. The unit is undefined. Positive values set the focus
+ closer to the camera, negative values towards infinity.
+
+``V4L2_CID_FOCUS_RELATIVE (integer)``
+ This control moves the focal point of the camera by the specified
+ amount. The unit is undefined. Positive values move the focus closer
+ to the camera, negative values towards infinity. This is a
+ write-only control.
+
+``V4L2_CID_FOCUS_AUTO (boolean)``
+ Enables continuous automatic focus adjustments. The effect of manual
+ focus adjustments while this feature is enabled is undefined,
+ drivers should ignore such requests.
+
+``V4L2_CID_AUTO_FOCUS_START (button)``
+ Starts single auto focus process. The effect of setting this control
+ when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
+ drivers should ignore such requests.
+
+``V4L2_CID_AUTO_FOCUS_STOP (button)``
+ Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
+ control. It is effective only when the continuous autofocus is
+ disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
+ ``FALSE`` (0).
+
+.. _v4l2-auto-focus-status:
+
+``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
+ The automatic focus status. This is a read-only control.
+
+ Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
+ control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
+ control value.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
+
+ - Automatic focus is not active.
+
+ - .. row 2
+
+ - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
+
+ - Automatic focusing is in progress.
+
+ - .. row 3
+
+ - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
+
+ - Focus has been reached.
+
+ - .. row 4
+
+ - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
+
+ - Automatic focus has failed, the driver will not transition from
+ this state until another action is performed by an application.
+
+
+
+.. _v4l2-auto-focus-range:
+
+``V4L2_CID_AUTO_FOCUS_RANGE (enum v4l2_auto_focus_range)``
+ Determines auto focus distance range for which lens may be adjusted.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
+
+ - The camera automatically selects the focus range.
+
+ - .. row 2
+
+ - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
+
+ - Normal distance range, limited for best automatic focus
+ performance.
+
+ - .. row 3
+
+ - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
+
+ - Macro (close-up) auto focus. The camera will use its minimum
+ possible distance for auto focus.
+
+ - .. row 4
+
+ - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
+
+ - The lens is set to focus on an object at infinite distance.
+
+
+
+``V4L2_CID_ZOOM_ABSOLUTE (integer)``
+ Specify the objective lens focal length as an absolute value. The
+ zoom unit is driver-specific and its value should be a positive
+ integer.
+
+``V4L2_CID_ZOOM_RELATIVE (integer)``
+ Specify the objective lens focal length relatively to the current
+ value. Positive values move the zoom lens group towards the
+ telephoto direction, negative values towards the wide-angle
+ direction. The zoom unit is driver-specific. This is a write-only
+ control.
+
+``V4L2_CID_ZOOM_CONTINUOUS (integer)``
+ Move the objective lens group at the specified speed until it
+ reaches physical device limits or until an explicit request to stop
+ the movement. A positive value moves the zoom lens group towards the
+ telephoto direction. A value of zero stops the zoom lens group
+ movement. A negative value moves the zoom lens group towards the
+ wide-angle direction. The zoom speed unit is driver-specific.
+
+``V4L2_CID_IRIS_ABSOLUTE (integer)``
+ 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.
+
+``V4L2_CID_IRIS_RELATIVE (integer)``
+ 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.
+
+``V4L2_CID_PRIVACY (boolean)``
+ Prevent video from being acquired by the camera. When this control
+ is set to ``TRUE`` (1), no image can be captured by the camera.
+ Common means to enforce privacy are mechanical obturation of the
+ sensor and firmware image processing, but the device is not
+ restricted to these methods. Devices that implement the privacy
+ control must support read access and may support write access.
+
+``V4L2_CID_BAND_STOP_FILTER (integer)``
+ Switch the band-stop filter of a camera sensor on or off, or specify
+ its strength. Such band-stop filters can be used, for example, to
+ filter out the fluorescent light component.
+
+.. _v4l2-auto-n-preset-white-balance:
+
+``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE (enum v4l2_auto_n_preset_white_balance)``
+ Sets white balance to automatic, manual or a preset. The presets
+ determine color temperature of the light as a hint to the camera for
+ white balance adjustments resulting in most accurate color
+ representation. The following white balance presets are listed in
+ order of increasing color temperature.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_WHITE_BALANCE_MANUAL``
+
+ - Manual white balance.
+
+ - .. row 2
+
+ - ``V4L2_WHITE_BALANCE_AUTO``
+
+ - Automatic white balance adjustments.
+
+ - .. row 3
+
+ - ``V4L2_WHITE_BALANCE_INCANDESCENT``
+
+ - White balance setting for incandescent (tungsten) lighting. It
+ generally cools down the colors and corresponds approximately to
+ 2500...3500 K color temperature range.
+
+ - .. row 4
+
+ - ``V4L2_WHITE_BALANCE_FLUORESCENT``
+
+ - White balance preset for fluorescent lighting. It corresponds
+ approximately to 4000...5000 K color temperature.
+
+ - .. row 5
+
+ - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
+
+ - With this setting the camera will compensate for fluorescent H
+ lighting.
+
+ - .. row 6
+
+ - ``V4L2_WHITE_BALANCE_HORIZON``
+
+ - White balance setting for horizon daylight. It corresponds
+ approximately to 5000 K color temperature.
+
+ - .. row 7
+
+ - ``V4L2_WHITE_BALANCE_DAYLIGHT``
+
+ - White balance preset for daylight (with clear sky). It corresponds
+ approximately to 5000...6500 K color temperature.
+
+ - .. row 8
+
+ - ``V4L2_WHITE_BALANCE_FLASH``
+
+ - With this setting the camera will compensate for the flash light.
+ It slightly warms up the colors and corresponds roughly to
+ 5000...5500 K color temperature.
+
+ - .. row 9
+
+ - ``V4L2_WHITE_BALANCE_CLOUDY``
+
+ - White balance preset for moderately overcast sky. This option
+ corresponds approximately to 6500...8000 K color temperature
+ range.
+
+ - .. row 10
+
+ - ``V4L2_WHITE_BALANCE_SHADE``
+
+ - White balance preset for shade or heavily overcast sky. It
+ corresponds approximately to 9000...10000 K color temperature.
+
+
+
+.. _v4l2-wide-dynamic-range:
+
+``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
+ Enables or disables the camera's wide dynamic range feature. This
+ feature allows to obtain clear images in situations where intensity
+ of the illumination varies significantly throughout the scene, i.e.
+ there are simultaneously very dark and very bright areas. It is most
+ commonly realized in cameras by combining two subsequent frames with
+ different exposure times. [1]_
+
+.. _v4l2-image-stabilization:
+
+``V4L2_CID_IMAGE_STABILIZATION (boolean)``
+ Enables or disables image stabilization.
+
+``V4L2_CID_ISO_SENSITIVITY (integer menu)``
+ Determines ISO equivalent of an image sensor indicating the sensor's
+ sensitivity to light. The numbers are expressed in arithmetic scale,
+ as per :ref:`iso12232` standard, where doubling the sensor
+ sensitivity is represented by doubling the numerical ISO value.
+ Applications should interpret the values as standard ISO values
+ multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
+ Drivers will usually support only a subset of standard ISO values.
+ The effect of setting this control while the
+ ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
+ than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
+ should ignore such requests.
+
+.. _v4l2-iso-sensitivity-auto-type:
+
+``V4L2_CID_ISO_SENSITIVITY_AUTO (enum v4l2_iso_sensitivity_type)``
+ Enables or disables automatic ISO sensitivity adjustments.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
+
+ - Manual ISO sensitivity.
+
+ - .. row 2
+
+ - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
+
+ - Automatic ISO sensitivity adjustments.
+
+
+
+.. _v4l2-scene-mode:
+
+``V4L2_CID_SCENE_MODE (enum v4l2_scene_mode)``
+ This control allows to select scene programs as the camera automatic
+ modes optimized for common shooting scenes. Within these modes the
+ camera determines best exposure, aperture, focusing, light metering,
+ white balance and equivalent sensitivity. The controls of those
+ parameters are influenced by the scene mode control. An exact
+ behavior in each mode is subject to the camera specification.
+
+ When the scene mode feature is not used, this control should be set
+ to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
+ controls are accessible. The following scene programs are defined:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_SCENE_MODE_NONE``
+
+ - The scene mode feature is disabled.
+
+ - .. row 2
+
+ - ``V4L2_SCENE_MODE_BACKLIGHT``
+
+ - Backlight. Compensates for dark shadows when light is coming from
+ behind a subject, also by automatically turning on the flash.
+
+ - .. row 3
+
+ - ``V4L2_SCENE_MODE_BEACH_SNOW``
+
+ - Beach and snow. This mode compensates for all-white or bright
+ scenes, which tend to look gray and low contrast, when camera's
+ automatic exposure is based on an average scene brightness. To
+ compensate, this mode automatically slightly overexposes the
+ frames. The white balance may also be adjusted to compensate for
+ the fact that reflected snow looks bluish rather than white.
+
+ - .. row 4
+
+ - ``V4L2_SCENE_MODE_CANDLELIGHT``
+
+ - Candle light. The camera generally raises the ISO sensitivity and
+ lowers the shutter speed. This mode compensates for relatively
+ close subject in the scene. The flash is disabled in order to
+ preserve the ambiance of the light.
+
+ - .. row 5
+
+ - ``V4L2_SCENE_MODE_DAWN_DUSK``
+
+ - Dawn and dusk. Preserves the colors seen in low natural light
+ before dusk and after down. The camera may turn off the flash, and
+ automatically focus at infinity. It will usually boost saturation
+ and lower the shutter speed.
+
+ - .. row 6
+
+ - ``V4L2_SCENE_MODE_FALL_COLORS``
+
+ - Fall colors. Increases saturation and adjusts white balance for
+ color enhancement. Pictures of autumn leaves get saturated reds
+ and yellows.
+
+ - .. row 7
+
+ - ``V4L2_SCENE_MODE_FIREWORKS``
+
+ - Fireworks. Long exposure times are used to capture the expanding
+ burst of light from a firework. The camera may invoke image
+ stabilization.
+
+ - .. row 8
+
+ - ``V4L2_SCENE_MODE_LANDSCAPE``
+
+ - Landscape. The camera may choose a small aperture to provide deep
+ depth of field and long exposure duration to help capture detail
+ in dim light conditions. The focus is fixed at infinity. Suitable
+ for distant and wide scenery.
+
+ - .. row 9
+
+ - ``V4L2_SCENE_MODE_NIGHT``
+
+ - Night, also known as Night Landscape. Designed for low light
+ conditions, it preserves detail in the dark areas without blowing
+ out bright objects. The camera generally sets itself to a
+ medium-to-high ISO sensitivity, with a relatively long exposure
+ time, and turns flash off. As such, there will be increased image
+ noise and the possibility of blurred image.
+
+ - .. row 10
+
+ - ``V4L2_SCENE_MODE_PARTY_INDOOR``
+
+ - Party and indoor. Designed to capture indoor scenes that are lit
+ by indoor background lighting as well as the flash. The camera
+ usually increases ISO sensitivity, and adjusts exposure for the
+ low light conditions.
+
+ - .. row 11
+
+ - ``V4L2_SCENE_MODE_PORTRAIT``
+
+ - Portrait. The camera adjusts the aperture so that the depth of
+ field is reduced, which helps to isolate the subject against a
+ smooth background. Most cameras recognize the presence of faces in
+ the scene and focus on them. The color hue is adjusted to enhance
+ skin tones. The intensity of the flash is often reduced.
+
+ - .. row 12
+
+ - ``V4L2_SCENE_MODE_SPORTS``
+
+ - Sports. Significantly increases ISO and uses a fast shutter speed
+ to freeze motion of rapidly-moving subjects. Increased image noise
+ may be seen in this mode.
+
+ - .. row 13
+
+ - ``V4L2_SCENE_MODE_SUNSET``
+
+ - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
+ up the saturation.
+
+ - .. row 14
+
+ - ``V4L2_SCENE_MODE_TEXT``
+
+ - Text. It applies extra contrast and sharpness, it is typically a
+ black-and-white mode optimized for readability. Automatic focus
+ may be switched to close-up mode and this setting may also involve
+ some lens-distortion correction.
+
+
+
+``V4L2_CID_3A_LOCK (bitmask)``
+ This control locks or unlocks the automatic focus, exposure and
+ white balance. The automatic adjustments can be paused independently
+ by setting the corresponding lock bit to 1. The camera then retains
+ the settings until the lock bit is cleared. The following lock bits
+ are defined:
+
+ When a given algorithm is not enabled, drivers should ignore
+ requests to lock it and should return no error. An example might be
+ an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
+ ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
+ value of this control may be changed by exposure, white balance or
+ focus controls.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_LOCK_EXPOSURE``
+
+ - Automatic exposure adjustments lock.
+
+ - .. row 2
+
+ - ``V4L2_LOCK_WHITE_BALANCE``
+
+ - Automatic white balance adjustments lock.
+
+ - .. row 3
+
+ - ``V4L2_LOCK_FOCUS``
+
+ - Automatic focus lock.
+
+
+
+``V4L2_CID_PAN_SPEED (integer)``
+ This control turns the camera horizontally at the specific speed.
+ 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 stops the motion if one is in progress and has
+ no effect otherwise.
+
+``V4L2_CID_TILT_SPEED (integer)``
+ This control turns the camera vertically at the specified speed. The
+ unit is undefined. A positive value moves the camera up, a negative
+ value down. A value of zero stops the motion if one is in progress
+ and has no effect otherwise.
+
+
+.. _fm-tx-controls:
+
+FM Transmitter Control Reference
+================================
+
+The FM Transmitter (FM_TX) class includes controls for common features
+of FM transmissions capable devices. Currently this class includes
+parameters for audio compression, pilot tone generation, audio deviation
+limiter, RDS transmission and tuning power features.
+
+
+.. _fm-tx-control-id:
+
+FM_TX Control IDs
+-----------------
+
+``V4L2_CID_FM_TX_CLASS (class)``
+ The FM_TX class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class.
+
+``V4L2_CID_RDS_TX_DEVIATION (integer)``
+ Configures RDS signal frequency deviation level in Hz. The range and
+ step are driver-specific.
+
+``V4L2_CID_RDS_TX_PI (integer)``
+ Sets the RDS Programme Identification field for transmission.
+
+``V4L2_CID_RDS_TX_PTY (integer)``
+ Sets the RDS Programme Type field for transmission. This encodes up
+ to 31 pre-defined programme types.
+
+``V4L2_CID_RDS_TX_PS_NAME (string)``
+ Sets the Programme Service name (PS_NAME) for transmission. It is
+ intended for static display on a receiver. It is the primary aid to
+ listeners in programme service identification and selection. In
+ Annex E of :ref:`iec62106`, the RDS specification, there is a full
+ description of the correct character encoding for Programme Service
+ name strings. Also from RDS specification, PS is usually a single
+ eight character text. However, it is also possible to find receivers
+ which can scroll strings sized as 8 x N characters. So, this control
+ must be configured with steps of 8 characters. The result is it must
+ always contain a string with size multiple of 8.
+
+``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
+ Sets the Radio Text info for transmission. It is a textual
+ description of what is being broadcasted. RDS Radio Text can be
+ applied when broadcaster wishes to transmit longer PS names,
+ programme-related information or any other text. In these cases,
+ RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``.
+ The encoding for Radio Text strings is also fully described in Annex
+ E of :ref:`iec62106`. The length of Radio Text strings depends on
+ which RDS Block is being used to transmit it, either 32 (2A block)
+ or 64 (2B block). However, it is also possible to find receivers
+ which can scroll strings sized as 32 x N or 64 x N characters. So,
+ this control must be configured with steps of 32 or 64 characters.
+ The result is it must always contain a string with size multiple of
+ 32 or 64.
+
+``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
+ Sets the Mono/Stereo bit of the Decoder Identification code. If set,
+ then the audio was recorded as stereo.
+
+``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
+ Sets the
+ `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__
+ bit of the Decoder Identification code. If set, then the audio was
+ recorded using an artificial head.
+
+``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
+ Sets the Compressed bit of the Decoder Identification code. If set,
+ then the audio is compressed.
+
+``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
+ Sets the Dynamic PTY bit of the Decoder Identification code. If set,
+ then the PTY code is dynamically switched.
+
+``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)``
+ If set, then a traffic announcement is in progress.
+
+``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
+ If set, then the tuned programme carries traffic announcements.
+
+``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
+ If set, then this channel broadcasts music. If cleared, then it
+ broadcasts speech. If the transmitter doesn't make this distinction,
+ then it should be set.
+
+``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
+ If set, then transmit alternate frequencies.
+
+``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
+ The alternate frequencies in kHz units. The RDS standard allows for
+ up to 25 frequencies to be defined. Drivers may support fewer
+ frequencies so check the array size.
+
+``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
+ Enables or disables the audio deviation limiter feature. The limiter
+ is useful when trying to maximize the audio volume, minimize
+ receiver-generated distortion and prevent overmodulation.
+
+``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
+ Sets the audio deviation limiter feature release time. Unit is in
+ useconds. Step and range are driver-specific.
+
+``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
+ Configures audio frequency deviation level in Hz. The range and step
+ are driver-specific.
+
+``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)``
+ Enables or disables the audio compression feature. This feature
+ amplifies signals below the threshold by a fixed gain and compresses
+ audio signals above the threshold by the ratio of Threshold/(Gain +
+ Threshold).
+
+``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
+ Sets the gain for audio compression feature. It is a dB value. The
+ range and step are driver-specific.
+
+``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
+ Sets the threshold level for audio compression freature. It is a dB
+ value. The range and step are driver-specific.
+
+``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
+ Sets the attack time for audio compression feature. It is a useconds
+ value. The range and step are driver-specific.
+
+``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
+ Sets the release time for audio compression feature. It is a
+ useconds value. The range and step are driver-specific.
+
+``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
+ Enables or disables the pilot tone generation feature.
+
+``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
+ Configures pilot tone frequency deviation level. Unit is in Hz. The
+ range and step are driver-specific.
+
+``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
+ Configures pilot tone frequency value. Unit is in Hz. The range and
+ step are driver-specific.
+
+``V4L2_CID_TUNE_PREEMPHASIS (enum v4l2_preemphasis)``
+ 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:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_PREEMPHASIS_DISABLED``
+
+ - No pre-emphasis is applied.
+
+ - .. row 2
+
+ - ``V4L2_PREEMPHASIS_50_uS``
+
+ - A pre-emphasis of 50 uS is used.
+
+ - .. row 3
+
+ - ``V4L2_PREEMPHASIS_75_uS``
+
+ - A pre-emphasis of 75 uS is used.
+
+
+
+``V4L2_CID_TUNE_POWER_LEVEL (integer)``
+ Sets the output power level for signal transmission. Unit is in
+ dBuV. Range and step are driver-specific.
+
+``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
+ This selects the value of antenna tuning capacitor manually or
+ automatically if set to zero. Unit, range and step are
+ driver-specific.
+
+For more details about RDS specification, refer to :ref:`iec62106`
+document, from CENELEC.
+
+
+.. _flash-controls:
+
+Flash Control Reference
+=======================
+
+The V4L2 flash controls are intended to provide generic access to flash
+controller devices. Flash controller devices are typically used in
+digital cameras.
+
+The interface can support both LED and xenon flash devices. As of
+writing this, there is no xenon flash driver using this interface.
+
+
+.. _flash-controls-use-cases:
+
+Supported use cases
+-------------------
+
+
+Unsynchronised LED flash (software strobe)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Unsynchronised LED flash is controlled directly by the host as the
+sensor. The flash must be enabled by the host before the exposure of the
+image starts and disabled once it ends. The host is fully responsible
+for the timing of the flash.
+
+Example of such device: Nokia N900.
+
+
+Synchronised LED flash (hardware strobe)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The synchronised LED flash is pre-programmed by the host (power and
+timeout) but controlled by the sensor through a strobe signal from the
+sensor to the flash.
+
+The sensor controls the flash duration and timing. This information
+typically must be made available to the sensor.
+
+
+LED flash as torch
+^^^^^^^^^^^^^^^^^^
+
+LED flash may be used as torch in conjunction with another use case
+involving camera or individually.
+
+
+.. _flash-control-id:
+
+Flash Control IDs
+"""""""""""""""""
+
+``V4L2_CID_FLASH_CLASS (class)``
+ The FLASH class descriptor.
+
+``V4L2_CID_FLASH_LED_MODE (menu)``
+ Defines the mode of the flash LED, the high-power white LED attached
+ to the flash controller. Setting this control may not be possible in
+ presence of some faults. See V4L2_CID_FLASH_FAULT.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_FLASH_LED_MODE_NONE``
+
+ - Off.
+
+ - .. row 2
+
+ - ``V4L2_FLASH_LED_MODE_FLASH``
+
+ - Flash mode.
+
+ - .. row 3
+
+ - ``V4L2_FLASH_LED_MODE_TORCH``
+
+ - Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.
+
+
+
+``V4L2_CID_FLASH_STROBE_SOURCE (menu)``
+ Defines the source of the flash LED strobe.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_FLASH_STROBE_SOURCE_SOFTWARE``
+
+ - The flash strobe is triggered by using the
+ V4L2_CID_FLASH_STROBE control.
+
+ - .. row 2
+
+ - ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``
+
+ - The flash strobe is triggered by an external source. Typically
+ this is a sensor, which makes it possible to synchronises the
+ flash strobe start to exposure start.
+
+
+
+``V4L2_CID_FLASH_STROBE (button)``
+ Strobe flash. Valid when V4L2_CID_FLASH_LED_MODE is set to
+ V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
+ is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
+ control may not be possible in presence of some faults. See
+ V4L2_CID_FLASH_FAULT.
+
+``V4L2_CID_FLASH_STROBE_STOP (button)``
+ Stop flash strobe immediately.
+
+``V4L2_CID_FLASH_STROBE_STATUS (boolean)``
+ Strobe status: whether the flash is strobing at the moment or not.
+ This is a read-only control.
+
+``V4L2_CID_FLASH_TIMEOUT (integer)``
+ Hardware timeout for flash. The flash strobe is stopped after this
+ period of time has passed from the start of the strobe.
+
+``V4L2_CID_FLASH_INTENSITY (integer)``
+ Intensity of the flash strobe when the flash LED is in flash mode
+ (V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps (mA)
+ if possible.
+
+``V4L2_CID_FLASH_TORCH_INTENSITY (integer)``
+ Intensity of the flash LED in torch mode
+ (V4L2_FLASH_LED_MODE_TORCH). The unit should be milliamps (mA)
+ if possible. Setting this control may not be possible in presence of
+ some faults. See V4L2_CID_FLASH_FAULT.
+
+``V4L2_CID_FLASH_INDICATOR_INTENSITY (integer)``
+ Intensity of the indicator LED. The indicator LED may be fully
+ independent of the flash LED. The unit should be microamps (uA) if
+ possible.
+
+``V4L2_CID_FLASH_FAULT (bitmask)``
+ Faults related to the flash. The faults tell about specific problems
+ in the flash chip itself or the LEDs attached to it. Faults may
+ prevent further use of some of the flash controls. In particular,
+ V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
+ if the fault affects the flash LED. Exactly which faults have such
+ an effect is chip dependent. Reading the faults resets the control
+ and returns the chip to a usable state if possible.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_FLASH_FAULT_OVER_VOLTAGE``
+
+ - Flash controller voltage to the flash LED has exceeded the limit
+ specific to the flash controller.
+
+ - .. row 2
+
+ - ``V4L2_FLASH_FAULT_TIMEOUT``
+
+ - The flash strobe was still on when the timeout set by the user ---
+ V4L2_CID_FLASH_TIMEOUT control --- has expired. Not all flash
+ controllers may set this in all such conditions.
+
+ - .. row 3
+
+ - ``V4L2_FLASH_FAULT_OVER_TEMPERATURE``
+
+ - The flash controller has overheated.
+
+ - .. row 4
+
+ - ``V4L2_FLASH_FAULT_SHORT_CIRCUIT``
+
+ - The short circuit protection of the flash controller has been
+ triggered.
+
+ - .. row 5
+
+ - ``V4L2_FLASH_FAULT_OVER_CURRENT``
+
+ - Current in the LED power supply has exceeded the limit specific to
+ the flash controller.
+
+ - .. row 6
+
+ - ``V4L2_FLASH_FAULT_INDICATOR``
+
+ - The flash controller has detected a short or open circuit
+ condition on the indicator LED.
+
+ - .. row 7
+
+ - ``V4L2_FLASH_FAULT_UNDER_VOLTAGE``
+
+ - Flash controller voltage to the flash LED has been below the
+ minimum limit specific to the flash controller.
+
+ - .. row 8
+
+ - ``V4L2_FLASH_FAULT_INPUT_VOLTAGE``
+
+ - The input voltage of the flash controller is below the limit under
+ which strobing the flash at full current will not be possible.The
+ condition persists until this flag is no longer set.
+
+ - .. row 9
+
+ - ``V4L2_FLASH_FAULT_LED_OVER_TEMPERATURE``
+
+ - The temperature of the LED has exceeded its allowed upper limit.
+
+
+
+``V4L2_CID_FLASH_CHARGE (boolean)``
+ Enable or disable charging of the xenon flash capacitor.
+
+``V4L2_CID_FLASH_READY (boolean)``
+ Is the flash ready to strobe? Xenon flashes require their capacitors
+ charged before strobing. LED flashes often require a cooldown period
+ after strobe during which another strobe will not be possible. This
+ is a read-only control.
+
+
+.. _jpeg-controls:
+
+JPEG Control Reference
+======================
+
+The JPEG class includes controls for common features of JPEG encoders
+and decoders. Currently it includes features for codecs implementing
+progressive baseline DCT compression process with Huffman entrophy
+coding.
+
+
+.. _jpeg-control-id:
+
+JPEG Control IDs
+----------------
+
+``V4L2_CID_JPEG_CLASS (class)``
+ The JPEG class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class.
+
+``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)``
+ The chroma subsampling factors describe how each component of an
+ input image is sampled, in respect to maximum sample rate in each
+ spatial dimension. See :ref:`itu-t81`, clause A.1.1. for more
+ details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines
+ how Cb and Cr components are downsampled after coverting an input
+ image from RGB to Y'CbCr color space.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444``
+
+ - No chroma subsampling, each pixel has Y, Cr and Cb values.
+
+ - .. row 2
+
+ - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422``
+
+ - Horizontally subsample Cr, Cb components by a factor of 2.
+
+ - .. row 3
+
+ - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420``
+
+ - Subsample Cr, Cb components horizontally and vertically by 2.
+
+ - .. row 4
+
+ - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411``
+
+ - Horizontally subsample Cr, Cb components by a factor of 4.
+
+ - .. row 5
+
+ - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410``
+
+ - Subsample Cr, Cb components horizontally by 4 and vertically by 2.
+
+ - .. row 6
+
+ - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY``
+
+ - Use only luminance component.
+
+
+
+``V4L2_CID_JPEG_RESTART_INTERVAL (integer)``
+ The restart interval determines an interval of inserting RSTm
+ markers (m = 0..7). The purpose of these markers is to additionally
+ reinitialize the encoder process, in order to process blocks of an
+ image independently. For the lossy compression processes the restart
+ interval unit is MCU (Minimum Coded Unit) and its value is contained
+ in DRI (Define Restart Interval) marker. If
+ ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm
+ markers will not be inserted.
+
+.. _jpeg-quality-control:
+
+``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)``
+ ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control determines trade-off
+ between image quality and size. It provides simpler method for
+ applications to control image quality, without a need for direct
+ reconfiguration of luminance and chrominance quantization tables. In
+ cases where a driver uses quantization tables configured directly by
+ an application, using interfaces defined elsewhere,
+ ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by
+ driver to 0.
+
+ The value range of this control is driver-specific. Only positive,
+ non-zero values are meaningful. The recommended range is 1 - 100,
+ where larger values correspond to better image quality.
+
+.. _jpeg-active-marker-control:
+
+``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)``
+ Specify which JPEG markers are included in compressed stream. This
+ control is valid only for encoders.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_JPEG_ACTIVE_MARKER_APP0``
+
+ - Application data segment APP\ :sub:`0`.
+
+ - .. row 2
+
+ - ``V4L2_JPEG_ACTIVE_MARKER_APP1``
+
+ - Application data segment APP\ :sub:`1`.
+
+ - .. row 3
+
+ - ``V4L2_JPEG_ACTIVE_MARKER_COM``
+
+ - Comment segment.
+
+ - .. row 4
+
+ - ``V4L2_JPEG_ACTIVE_MARKER_DQT``
+
+ - Quantization tables segment.
+
+ - .. row 5
+
+ - ``V4L2_JPEG_ACTIVE_MARKER_DHT``
+
+ - Huffman tables segment.
+
+
+
+For more details about JPEG specification, refer to :ref:`itu-t81`,
+:ref:`jfif`, :ref:`w3c-jpeg-jfif`.
+
+
+.. _image-source-controls:
+
+Image Source Control Reference
+==============================
+
+The Image Source control class is intended for low-level control of
+image source devices such as image sensors. The devices feature an
+analogue to digital converter and a bus transmitter to transmit the
+image data out of the device.
+
+
+.. _image-source-control-id:
+
+Image Source Control IDs
+------------------------
+
+``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
+ The IMAGE_SOURCE class descriptor.
+
+``V4L2_CID_VBLANK (integer)``
+ Vertical blanking. The idle period after every frame during which no
+ image data is produced. The unit of vertical blanking is a line.
+ Every line has length of the image width plus horizontal blanking at
+ the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
+ same sub-device.
+
+``V4L2_CID_HBLANK (integer)``
+ Horizontal blanking. The idle period after every line of image data
+ during which no image data is produced. The unit of horizontal
+ blanking is pixels.
+
+``V4L2_CID_ANALOGUE_GAIN (integer)``
+ Analogue gain is gain affecting all colour components in the pixel
+ matrix. The gain operation is performed in the analogue domain
+ before A/D conversion.
+
+``V4L2_CID_TEST_PATTERN_RED (integer)``
+ Test pattern red colour component.
+
+``V4L2_CID_TEST_PATTERN_GREENR (integer)``
+ Test pattern green (next to red) colour component.
+
+``V4L2_CID_TEST_PATTERN_BLUE (integer)``
+ Test pattern blue colour component.
+
+``V4L2_CID_TEST_PATTERN_GREENB (integer)``
+ Test pattern green (next to blue) colour component.
+
+
+.. _image-process-controls:
+
+Image Process Control Reference
+===============================
+
+The Image Process control class is intended for low-level control of
+image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
+controls in this class affect processing the image, and do not control
+capturing of it.
+
+
+.. _image-process-control-id:
+
+Image Process Control IDs
+-------------------------
+
+``V4L2_CID_IMAGE_PROC_CLASS (class)``
+ The IMAGE_PROC class descriptor.
+
+``V4L2_CID_LINK_FREQ (integer menu)``
+ Data bus frequency. Together with the media bus pixel code, bus type
+ (clock cycles per sample), the data bus frequency defines the pixel
+ rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
+ elsewhere, if the device is not an image sensor). The frame rate can
+ be calculated from the pixel clock, image width and height and
+ horizontal and vertical blanking. While the pixel rate control may
+ be defined elsewhere than in the subdev containing the pixel array,
+ the frame rate cannot be obtained from that information. This is
+ because only on the pixel array it can be assumed that the vertical
+ and horizontal blanking information is exact: no other blanking is
+ allowed in the pixel array. The selection of frame rate is performed
+ by selecting the desired horizontal and vertical blanking. The unit
+ of this control is Hz.
+
+``V4L2_CID_PIXEL_RATE (64-bit integer)``
+ Pixel rate in the source pads of the subdev. This control is
+ read-only and its unit is pixels / second.
+
+``V4L2_CID_TEST_PATTERN (menu)``
+ Some capture/display/sensor devices have the capability to generate
+ test pattern images. These hardware specific test patterns can be
+ used to test if a device is working properly.
+
+
+.. _dv-controls:
+
+Digital Video Control Reference
+===============================
+
+The Digital Video control class is intended to control receivers and
+transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
+`DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__
+(Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort
+(:ref:`dp`). These controls are generally expected to be private to
+the receiver or transmitter subdevice that implements them, so they are
+only exposed on the ``/dev/v4l-subdev*`` device node.
+
+Note that these devices can have multiple input or output pads which are
+hooked up to e.g. HDMI connectors. Even though the subdevice will
+receive or transmit video from/to only one of those pads, the other pads
+can still be active when it comes to EDID (Extended Display
+Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
+Content Protection System, :ref:`hdcp`) processing, allowing the
+device to do the fairly slow EDID/HDCP handling in advance. This allows
+for quick switching between connectors.
+
+These pads appear in several of the controls in this section as
+bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad
+1, etc. The maximum value of the control is the set of valid pads.
+
+
+.. _dv-control-id:
+
+Digital Video Control IDs
+-------------------------
+
+``V4L2_CID_DV_CLASS (class)``
+ The Digital Video class descriptor.
+
+``V4L2_CID_DV_TX_HOTPLUG (bitmask)``
+ Many connectors have a hotplug pin which is high if EDID information
+ is available from the source. This control shows the state of the
+ hotplug pin as seen by the transmitter. Each bit corresponds to an
+ output pad on the transmitter. If an output pad does not have an
+ associated hotplug pin, then the bit for that pad will be 0. This
+ read-only control is applicable to DVI-D, HDMI and DisplayPort
+ connectors.
+
+``V4L2_CID_DV_TX_RXSENSE (bitmask)``
+ Rx Sense is the detection of pull-ups on the TMDS clock lines. This
+ normally means that the sink has left/entered standby (i.e. the
+ transmitter can sense that the receiver is ready to receive video).
+ Each bit corresponds to an output pad on the transmitter. If an
+ output pad does not have an associated Rx Sense, then the bit for
+ that pad will be 0. This read-only control is applicable to DVI-D
+ and HDMI devices.
+
+``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)``
+ When the transmitter sees the hotplug signal from the receiver it
+ will attempt to read the EDID. If set, then the transmitter has read
+ at least the first block (= 128 bytes). Each bit corresponds to an
+ output pad on the transmitter. If an output pad does not support
+ EDIDs, then the bit for that pad will be 0. This read-only control
+ is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors.
+
+``V4L2_CID_DV_TX_MODE (enum v4l2_dv_tx_mode)``
+ HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI
+ mode (video + audio + auxiliary data). This control selects which
+ mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI.
+ This control is applicable to HDMI connectors.
+
+``V4L2_CID_DV_TX_RGB_RANGE (enum v4l2_dv_rgb_range)``
+ Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO
+ follows the RGB quantization range specified in the standard for the
+ video interface (ie. :ref:`cea861` for HDMI).
+ V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
+ standard to be compatible with sinks that have not implemented the
+ standard correctly (unfortunately quite common for HDMI and DVI-D).
+ Full range allows all possible values to be used whereas limited
+ range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
+ the number of bits per component. This control is applicable to VGA,
+ DVI-A/D, HDMI and DisplayPort connectors.
+
+``V4L2_CID_DV_TX_IT_CONTENT_TYPE (enum v4l2_dv_it_content_type)``
+ Configures the IT Content Type of the transmitted video. This
+ information is sent over HDMI and DisplayPort connectors as part of
+ the AVI InfoFrame. The term 'IT Content' is used for content that
+ originates from a computer as opposed to content from a TV broadcast
+ or an analog source. The enum v4l2_dv_it_content_type defines
+ the possible content types:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS``
+
+ - Graphics content. Pixel data should be passed unfiltered and
+ without analog reconstruction.
+
+ - .. row 2
+
+ - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO``
+
+ - Photo content. The content is derived from digital still pictures.
+ The content should be passed through with minimal scaling and
+ picture enhancements.
+
+ - .. row 3
+
+ - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA``
+
+ - Cinema content.
+
+ - .. row 4
+
+ - ``V4L2_DV_IT_CONTENT_TYPE_GAME``
+
+ - Game content. Audio and video latency should be minimized.
+
+ - .. row 5
+
+ - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC``
+
+ - No IT Content information is available and the ITC bit in the AVI
+ InfoFrame is set to 0.
+
+
+
+``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)``
+ Detects whether the receiver receives power from the source (e.g.
+ HDMI carries 5V on one of the pins). This is often used to power an
+ eeprom which contains EDID information, such that the source can
+ read the EDID even if the sink is in standby/power off. Each bit
+ corresponds to an input pad on the transmitter. If an input pad
+ cannot detect whether power is present, then the bit for that pad
+ will be 0. This read-only control is applicable to DVI-D, HDMI and
+ DisplayPort connectors.
+
+``V4L2_CID_DV_RX_RGB_RANGE (enum v4l2_dv_rgb_range)``
+ Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO
+ follows the RGB quantization range specified in the standard for the
+ video interface (ie. :ref:`cea861` for HDMI).
+ V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
+ standard to be compatible with sources that have not implemented the
+ standard correctly (unfortunately quite common for HDMI and DVI-D).
+ Full range allows all possible values to be used whereas limited
+ range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
+ the number of bits per component. This control is applicable to VGA,
+ DVI-A/D, HDMI and DisplayPort connectors.
+
+``V4L2_CID_DV_RX_IT_CONTENT_TYPE (enum v4l2_dv_it_content_type)``
+ Reads the IT Content Type of the received video. This information is
+ sent over HDMI and DisplayPort connectors as part of the AVI
+ InfoFrame. The term 'IT Content' is used for content that originates
+ from a computer as opposed to content from a TV broadcast or an
+ analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the
+ available content types.
+
+
+.. _fm-rx-controls:
+
+FM Receiver Control Reference
+=============================
+
+The FM Receiver (FM_RX) class includes controls for common features of
+FM Reception capable devices.
+
+
+.. _fm-rx-control-id:
+
+FM_RX Control IDs
+-----------------
+
+``V4L2_CID_FM_RX_CLASS (class)``
+ The FM_RX class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class.
+
+``V4L2_CID_RDS_RECEPTION (boolean)``
+ Enables/disables RDS reception by the radio tuner
+
+``V4L2_CID_RDS_RX_PTY (integer)``
+ Gets RDS Programme Type field. This encodes up to 31 pre-defined
+ programme types.
+
+``V4L2_CID_RDS_RX_PS_NAME (string)``
+ Gets the Programme Service name (PS_NAME). 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
+ :ref:`iec62106`, the RDS specification, there is a full
+ description of the correct character encoding for Programme Service
+ name strings. Also from RDS specification, PS is usually a single
+ eight character text. However, it is also possible to find receivers
+ which can scroll strings sized as 8 x N characters. So, this control
+ must be configured with steps of 8 characters. The result is it must
+ always contain a string with size multiple of 8.
+
+``V4L2_CID_RDS_RX_RADIO_TEXT (string)``
+ Gets the Radio Text info. 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 can be used in addition to
+ ``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is
+ also fully described in Annex E of :ref:`iec62106`. The length of
+ Radio Text strings depends on which RDS Block is being used to
+ transmit it, either 32 (2A block) or 64 (2B block). However, it is
+ also possible to find receivers which can scroll strings sized as 32
+ x N or 64 x N characters. So, this control must be configured with
+ steps of 32 or 64 characters. The result is it must always contain a
+ string with size multiple of 32 or 64.
+
+``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)``
+ If set, then a traffic announcement is in progress.
+
+``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)``
+ If set, then the tuned programme carries traffic announcements.
+
+``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)``
+ If set, then this channel broadcasts music. If cleared, then it
+ broadcasts speech. If the transmitter doesn't make this distinction,
+ then it will be set.
+
+``V4L2_CID_TUNE_DEEMPHASIS (enum v4l2_deemphasis)``
+ Configures the de-emphasis value for reception. A de-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_deemphasis defines possible
+ values for de-emphasis. Here they are:
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_DEEMPHASIS_DISABLED``
+
+ - No de-emphasis is applied.
+
+ - .. row 2
+
+ - ``V4L2_DEEMPHASIS_50_uS``
+
+ - A de-emphasis of 50 uS is used.
+
+ - .. row 3
+
+ - ``V4L2_DEEMPHASIS_75_uS``
+
+ - A de-emphasis of 75 uS is used.
+
+
+
+
+.. _detect-controls:
+
+Detect Control Reference
+========================
+
+The Detect class includes controls for common features of various motion
+or object detection capable devices.
+
+
+.. _detect-control-id:
+
+Detect Control IDs
+------------------
+
+``V4L2_CID_DETECT_CLASS (class)``
+ The Detect class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class.
+
+``V4L2_CID_DETECT_MD_MODE (menu)``
+ Sets the motion detection mode.
+
+
+
+.. flat-table::
+ :header-rows: 0
+ :stub-columns: 0
+
+
+ - .. row 1
+
+ - ``V4L2_DETECT_MD_MODE_DISABLED``
+
+ - Disable motion detection.
+
+ - .. row 2
+
+ - ``V4L2_DETECT_MD_MODE_GLOBAL``
+
+ - Use a single motion detection threshold.
+
+ - .. row 3
+
+ - ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID``
+
+ - The image is divided into a grid, each cell with its own motion
+ detection threshold. These thresholds are set through the
+ ``V4L2_CID_DETECT_MD_THRESHOLD_GRID`` matrix control.
+
+ - .. row 4
+
+ - ``V4L2_DETECT_MD_MODE_REGION_GRID``
+
+ - The image is divided into a grid, each cell with its own region
+ value that specifies which per-region motion detection thresholds
+ should be used. Each region has its own thresholds. How these
+ per-region thresholds are set up is driver-specific. The region
+ values for the grid are set through the
+ ``V4L2_CID_DETECT_MD_REGION_GRID`` matrix control.
+
+
+
+``V4L2_CID_DETECT_MD_GLOBAL_THRESHOLD (integer)``
+ Sets the global motion detection threshold to be used with the
+ ``V4L2_DETECT_MD_MODE_GLOBAL`` motion detection mode.
+
+``V4L2_CID_DETECT_MD_THRESHOLD_GRID (__u16 matrix)``
+ Sets the motion detection thresholds for each cell in the grid. To
+ be used with the ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID`` motion
+ detection mode. Matrix element (0, 0) represents the cell at the
+ top-left of the grid.
+
+``V4L2_CID_DETECT_MD_REGION_GRID (__u8 matrix)``
+ Sets the motion detection region value for each cell in the grid. To
+ be used with the ``V4L2_DETECT_MD_MODE_REGION_GRID`` motion
+ detection mode. Matrix element (0, 0) represents the cell at the
+ top-left of the grid.
+
+
+.. _rf-tuner-controls:
+
+RF Tuner Control Reference
+==========================
+
+The RF Tuner (RF_TUNER) class includes controls for common features of
+devices having RF tuner.
+
+In this context, RF tuner is radio receiver circuit between antenna and
+demodulator. It receives radio frequency (RF) from the antenna and
+converts that received signal to lower intermediate frequency (IF) or
+baseband frequency (BB). Tuners that could do baseband output are often
+called Zero-IF tuners. Older tuners were typically simple PLL tuners
+inside a metal box, whilst newer ones are highly integrated chips
+without a metal box "silicon tuners". These controls are mostly
+applicable for new feature rich silicon tuners, just because older
+tuners does not have much adjustable features.
+
+For more information about RF tuners see
+`Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
+and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
+from Wikipedia.
+
+
+.. _rf-tuner-control-id:
+
+RF_TUNER Control IDs
+--------------------
+
+``V4L2_CID_RF_TUNER_CLASS (class)``
+ The RF_TUNER class descriptor. Calling
+ :ref:`VIDIOC_QUERYCTRL` for this control will
+ return a description of this control class.
+
+``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
+ Enables/disables tuner radio channel bandwidth configuration. In
+ automatic mode bandwidth configuration is performed by the driver.
+
+``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
+ Filter(s) on tuner signal path are used to filter signal according
+ to receiving party needs. Driver configures filters to fulfill
+ desired bandwidth requirement. Used when
+ V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
+ range and step are driver-specific.
+
+``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
+ Enables/disables LNA automatic gain control (AGC)
+
+``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
+ Enables/disables mixer automatic gain control (AGC)
+
+``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
+ Enables/disables IF automatic gain control (AGC)
+
+``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
+ The RF amplifier is the very first amplifier on the receiver signal
+ path, just right after the antenna input. The difference between the
+ LNA gain and the RF gain in this document is that the LNA gain is
+ integrated in the tuner chip while the RF gain is a separate chip.
+ There may be both RF and LNA gain controls in the same device. The
+ range and step are driver-specific.
+
+``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
+ LNA (low noise amplifier) gain is first gain stage on the RF tuner
+ signal path. It is located very close to tuner antenna input. Used
+ when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
+ ``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
+ differs from the each others. The range and step are
+ driver-specific.
+
+``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
+ Mixer gain is second gain stage on the RF tuner signal path. It is
+ located inside mixer block, where RF signal is down-converted by the
+ mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
+ The range and step are driver-specific.
+
+``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
+ IF gain is last gain stage on the RF tuner signal path. It is
+ located on output of RF tuner. It controls signal level of
+ intermediate frequency output or baseband output. Used when
+ ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
+ are driver-specific.
+
+``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
+ Is synthesizer PLL locked? RF tuner is receiving given frequency
+ when that control is set. This is a read-only control.
+
+.. [1]
+ This control may be changed to a menu control in the future, if more
+ options are required.
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-28 22:06:48 +0300