1 .. -*- coding: utf-8; mode: rst -*-
13 The control mechanism as originally designed was meant to be used for
14 user settings (brightness, saturation, etc). However, it turned out to
15 be a very useful model for implementing more complicated driver APIs
16 where each driver implements only a subset of a larger API.
18 The MPEG encoding API was the driving force behind designing and
19 implementing this extended control mechanism: the MPEG standard is quite
20 large and the currently supported hardware MPEG encoders each only
21 implement a subset of this standard. Further more, many parameters
22 relating to how the video is encoded into an MPEG stream are specific to
23 the MPEG encoding chip since the MPEG standard only defines the format
24 of the resulting MPEG stream, not how the video is actually encoded into
27 Unfortunately, the original control API lacked some features needed for
28 these new uses and so it was extended into the (not terribly originally
29 named) extended control API.
31 Even though the MPEG encoding API was the first effort to use the
32 Extended Control API, nowadays there are also other classes of Extended
33 Controls, such as Camera Controls and FM Transmitter Controls. The
34 Extended Controls API as well as all Extended Controls classes are
35 described in the following text.
38 The Extended Control API
39 ========================
41 Three new ioctls are available:
42 :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
43 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and
44 :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. These ioctls act
45 on arrays of controls (as opposed to the
46 :ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
47 :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls that act on a single
48 control). This is needed since it is often required to atomically change
49 several controls at once.
51 Each of the new ioctls expects a pointer to a struct
52 :ref:`v4l2_ext_controls <v4l2-ext-controls>`. This structure
53 contains a pointer to the control array, a count of the number of
54 controls in that array and a control class. Control classes are used to
55 group similar controls into a single class. For example, control class
56 ``V4L2_CTRL_CLASS_USER`` contains all user controls (i. e. all controls
57 that can also be set using the old :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>`
58 ioctl). Control class ``V4L2_CTRL_CLASS_MPEG`` contains all controls
59 relating to MPEG encoding, etc.
61 All controls in the control array must belong to the specified control
62 class. An error is returned if this is not the case.
64 It is also possible to use an empty control array (``count`` == 0) to check
65 whether the specified control class is supported.
67 The control array is a struct
68 :ref:`v4l2_ext_control <v4l2-ext-control>` array. The
69 :ref:`struct v4l2_ext_control <v4l2-ext-control>` structure is very similar to
70 struct :ref:`v4l2_control <v4l2-control>`, except for the fact that
71 it also allows for 64-bit values and pointers to be passed.
73 Since the struct :ref:`v4l2_ext_control <v4l2-ext-control>` supports
74 pointers it is now also possible to have controls with compound types
75 such as N-dimensional arrays and/or structures. You need to specify the
76 ``V4L2_CTRL_FLAG_NEXT_COMPOUND`` when enumerating controls to actually
77 be able to see such compound controls. In other words, these controls
78 with compound types should only be used programmatically.
80 Since such compound controls need to expose more information about
81 themselves than is possible with
82 :ref:`VIDIOC_QUERYCTRL` the
83 :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>` ioctl was added. In
84 particular, this ioctl gives the dimensions of the N-dimensional array
85 if this control consists of more than one element.
87 It is important to realize that due to the flexibility of controls it is
88 necessary to check whether the control you want to set actually is
89 supported in the driver and what the valid range of values is. So use
90 the :ref:`VIDIOC_QUERYCTRL` (or
91 :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>`) and
92 :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>` ioctls to check this. Also
93 note that it is possible that some of the menu indices in a control of
94 type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
95 will return an error). A good example is the list of supported MPEG
96 audio bitrates. Some drivers only support one or two bitrates, others
97 support a wider range.
99 All controls use machine endianness.
102 Enumerating Extended Controls
103 =============================
105 The recommended way to enumerate over the extended controls is by using
106 :ref:`VIDIOC_QUERYCTRL` in combination with the
107 ``V4L2_CTRL_FLAG_NEXT_CTRL`` flag:
112 struct v4l2_queryctrl qctrl;
114 qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
115 while (0 == ioctl (fd, VIDIOC_QUERYCTRL, &qctrl)) {
117 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
120 The initial control ID is set to 0 ORed with the
121 ``V4L2_CTRL_FLAG_NEXT_CTRL`` flag. The ``VIDIOC_QUERYCTRL`` ioctl will
122 return the first control with a higher ID than the specified one. When
123 no such controls are found an error is returned.
125 If you want to get all controls within a specific control class, then
126 you can set the initial ``qctrl.id`` value to the control class and add
127 an extra check to break out of the loop when a control of another
128 control class is found:
133 qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
134 while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &qctrl)) {
135 if (V4L2_CTRL_ID2CLASS(qctrl.id) != V4L2_CTRL_CLASS_MPEG)
138 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
141 The 32-bit ``qctrl.id`` value is subdivided into three bit ranges: the
142 top 4 bits are reserved for flags (e. g. ``V4L2_CTRL_FLAG_NEXT_CTRL``)
143 and are not actually part of the ID. The remaining 28 bits form the
144 control ID, of which the most significant 12 bits define the control
145 class and the least significant 16 bits identify the control within the
146 control class. It is guaranteed that these last 16 bits are always
147 non-zero for controls. The range of 0x1000 and up are reserved for
148 driver-specific controls. The macro ``V4L2_CTRL_ID2CLASS(id)`` returns
149 the control class ID based on a control ID.
151 If the driver does not support extended controls, then
152 ``VIDIOC_QUERYCTRL`` will fail when used in combination with
153 ``V4L2_CTRL_FLAG_NEXT_CTRL``. In that case the old method of enumerating
154 control should be used (see :ref:`enum_all_controls`). But if it is
155 supported, then it is guaranteed to enumerate over all controls,
156 including driver-private controls.
159 Creating Control Panels
160 =======================
162 It is possible to create control panels for a graphical user interface
163 where the user can select the various controls. Basically you will have
164 to iterate over all controls using the method described above. Each
165 control class starts with a control of type
166 ``V4L2_CTRL_TYPE_CTRL_CLASS``. ``VIDIOC_QUERYCTRL`` will return the name
167 of this control class which can be used as the title of a tab page
168 within a control panel.
170 The flags field of struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` also
171 contains hints on the behavior of the control. See the
172 :ref:`VIDIOC_QUERYCTRL` documentation for more
178 Codec Control Reference
179 =======================
181 Below all controls within the Codec control class are described. First
182 the generic controls, then controls specific for certain hardware.
184 Note: These controls are applicable to all codecs and not just MPEG. The
185 defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
186 were originally made for MPEG codecs and later extended to cover all
190 Generic Codec Controls
191 ----------------------
199 ``V4L2_CID_MPEG_CLASS (class)``
200 The Codec class descriptor. Calling
201 :ref:`VIDIOC_QUERYCTRL` for this control will
202 return a description of this control class. This description can be
203 used as the caption of a Tab page in a GUI, for example.
205 .. _`v4l2-mpeg-stream-type`:
207 ``V4L2_CID_MPEG_STREAM_TYPE (enum v4l2_mpeg_stream_type)``
208 The MPEG-1, -2 or -4 output stream type. One cannot assume anything
209 here. Each hardware MPEG encoder tends to support different subsets
210 of the available MPEG stream types. This control is specific to
211 multiplexed MPEG streams. The currently defined stream types are:
222 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_PS``
224 - MPEG-2 program stream
228 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_TS``
230 - MPEG-2 transport stream
234 - ``V4L2_MPEG_STREAM_TYPE_MPEG1_SS``
236 - MPEG-1 system stream
240 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_DVD``
242 - MPEG-2 DVD-compatible stream
246 - ``V4L2_MPEG_STREAM_TYPE_MPEG1_VCD``
248 - MPEG-1 VCD-compatible stream
252 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD``
254 - MPEG-2 SVCD-compatible stream
258 ``V4L2_CID_MPEG_STREAM_PID_PMT (integer)``
259 Program Map Table Packet ID for the MPEG transport stream (default
262 ``V4L2_CID_MPEG_STREAM_PID_AUDIO (integer)``
263 Audio Packet ID for the MPEG transport stream (default 256)
265 ``V4L2_CID_MPEG_STREAM_PID_VIDEO (integer)``
266 Video Packet ID for the MPEG transport stream (default 260)
268 ``V4L2_CID_MPEG_STREAM_PID_PCR (integer)``
269 Packet ID for the MPEG transport stream carrying PCR fields (default
272 ``V4L2_CID_MPEG_STREAM_PES_ID_AUDIO (integer)``
273 Audio ID for MPEG PES
275 ``V4L2_CID_MPEG_STREAM_PES_ID_VIDEO (integer)``
276 Video ID for MPEG PES
278 .. _`v4l2-mpeg-stream-vbi-fmt`:
280 ``V4L2_CID_MPEG_STREAM_VBI_FMT (enum v4l2_mpeg_stream_vbi_fmt)``
281 Some cards can embed VBI data (e. g. Closed Caption, Teletext) into
282 the MPEG stream. This control selects whether VBI data should be
283 embedded, and if so, what embedding method should be used. The list
284 of possible VBI formats depends on the driver. The currently defined
285 VBI format types are:
296 - ``V4L2_MPEG_STREAM_VBI_FMT_NONE``
298 - No VBI in the MPEG stream
302 - ``V4L2_MPEG_STREAM_VBI_FMT_IVTV``
304 - VBI in private packets, IVTV format (documented in the kernel
306 ``Documentation/video4linux/cx2341x/README.vbi``)
310 .. _`v4l2-mpeg-audio-sampling-freq`:
312 ``V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ (enum v4l2_mpeg_audio_sampling_freq)``
313 MPEG Audio sampling frequency. Possible values are:
324 - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100``
330 - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000``
336 - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000``
342 .. _`v4l2-mpeg-audio-encoding`:
344 ``V4L2_CID_MPEG_AUDIO_ENCODING (enum v4l2_mpeg_audio_encoding)``
345 MPEG Audio encoding. This control is specific to multiplexed MPEG
346 streams. Possible values are:
357 - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_1``
359 - MPEG-1/2 Layer I encoding
363 - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_2``
365 - MPEG-1/2 Layer II encoding
369 - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_3``
371 - MPEG-1/2 Layer III encoding
375 - ``V4L2_MPEG_AUDIO_ENCODING_AAC``
377 - MPEG-2/4 AAC (Advanced Audio Coding)
381 - ``V4L2_MPEG_AUDIO_ENCODING_AC3``
383 - AC-3 aka ATSC A/52 encoding
387 .. _`v4l2-mpeg-audio-l1-bitrate`:
389 ``V4L2_CID_MPEG_AUDIO_L1_BITRATE (enum v4l2_mpeg_audio_l1_bitrate)``
390 MPEG-1/2 Layer I bitrate. Possible values are:
401 - ``V4L2_MPEG_AUDIO_L1_BITRATE_32K``
407 - ``V4L2_MPEG_AUDIO_L1_BITRATE_64K``
413 - ``V4L2_MPEG_AUDIO_L1_BITRATE_96K``
419 - ``V4L2_MPEG_AUDIO_L1_BITRATE_128K``
425 - ``V4L2_MPEG_AUDIO_L1_BITRATE_160K``
431 - ``V4L2_MPEG_AUDIO_L1_BITRATE_192K``
437 - ``V4L2_MPEG_AUDIO_L1_BITRATE_224K``
443 - ``V4L2_MPEG_AUDIO_L1_BITRATE_256K``
449 - ``V4L2_MPEG_AUDIO_L1_BITRATE_288K``
455 - ``V4L2_MPEG_AUDIO_L1_BITRATE_320K``
461 - ``V4L2_MPEG_AUDIO_L1_BITRATE_352K``
467 - ``V4L2_MPEG_AUDIO_L1_BITRATE_384K``
473 - ``V4L2_MPEG_AUDIO_L1_BITRATE_416K``
479 - ``V4L2_MPEG_AUDIO_L1_BITRATE_448K``
485 .. _`v4l2-mpeg-audio-l2-bitrate`:
487 ``V4L2_CID_MPEG_AUDIO_L2_BITRATE (enum v4l2_mpeg_audio_l2_bitrate)``
488 MPEG-1/2 Layer II bitrate. Possible values are:
499 - ``V4L2_MPEG_AUDIO_L2_BITRATE_32K``
505 - ``V4L2_MPEG_AUDIO_L2_BITRATE_48K``
511 - ``V4L2_MPEG_AUDIO_L2_BITRATE_56K``
517 - ``V4L2_MPEG_AUDIO_L2_BITRATE_64K``
523 - ``V4L2_MPEG_AUDIO_L2_BITRATE_80K``
529 - ``V4L2_MPEG_AUDIO_L2_BITRATE_96K``
535 - ``V4L2_MPEG_AUDIO_L2_BITRATE_112K``
541 - ``V4L2_MPEG_AUDIO_L2_BITRATE_128K``
547 - ``V4L2_MPEG_AUDIO_L2_BITRATE_160K``
553 - ``V4L2_MPEG_AUDIO_L2_BITRATE_192K``
559 - ``V4L2_MPEG_AUDIO_L2_BITRATE_224K``
565 - ``V4L2_MPEG_AUDIO_L2_BITRATE_256K``
571 - ``V4L2_MPEG_AUDIO_L2_BITRATE_320K``
577 - ``V4L2_MPEG_AUDIO_L2_BITRATE_384K``
583 .. _`v4l2-mpeg-audio-l3-bitrate`:
585 ``V4L2_CID_MPEG_AUDIO_L3_BITRATE (enum v4l2_mpeg_audio_l3_bitrate)``
586 MPEG-1/2 Layer III bitrate. Possible values are:
597 - ``V4L2_MPEG_AUDIO_L3_BITRATE_32K``
603 - ``V4L2_MPEG_AUDIO_L3_BITRATE_40K``
609 - ``V4L2_MPEG_AUDIO_L3_BITRATE_48K``
615 - ``V4L2_MPEG_AUDIO_L3_BITRATE_56K``
621 - ``V4L2_MPEG_AUDIO_L3_BITRATE_64K``
627 - ``V4L2_MPEG_AUDIO_L3_BITRATE_80K``
633 - ``V4L2_MPEG_AUDIO_L3_BITRATE_96K``
639 - ``V4L2_MPEG_AUDIO_L3_BITRATE_112K``
645 - ``V4L2_MPEG_AUDIO_L3_BITRATE_128K``
651 - ``V4L2_MPEG_AUDIO_L3_BITRATE_160K``
657 - ``V4L2_MPEG_AUDIO_L3_BITRATE_192K``
663 - ``V4L2_MPEG_AUDIO_L3_BITRATE_224K``
669 - ``V4L2_MPEG_AUDIO_L3_BITRATE_256K``
675 - ``V4L2_MPEG_AUDIO_L3_BITRATE_320K``
681 ``V4L2_CID_MPEG_AUDIO_AAC_BITRATE (integer)``
682 AAC bitrate in bits per second.
684 .. _`v4l2-mpeg-audio-ac3-bitrate`:
686 ``V4L2_CID_MPEG_AUDIO_AC3_BITRATE (enum v4l2_mpeg_audio_ac3_bitrate)``
687 AC-3 bitrate. Possible values are:
698 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_32K``
704 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_40K``
710 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_48K``
716 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_56K``
722 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_64K``
728 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_80K``
734 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_96K``
740 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_112K``
746 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_128K``
752 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_160K``
758 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_192K``
764 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_224K``
770 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_256K``
776 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_320K``
782 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_384K``
788 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_448K``
794 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_512K``
800 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_576K``
806 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_640K``
812 .. _`v4l2-mpeg-audio-mode`:
814 ``V4L2_CID_MPEG_AUDIO_MODE (enum v4l2_mpeg_audio_mode)``
815 MPEG Audio mode. Possible values are:
826 - ``V4L2_MPEG_AUDIO_MODE_STEREO``
832 - ``V4L2_MPEG_AUDIO_MODE_JOINT_STEREO``
838 - ``V4L2_MPEG_AUDIO_MODE_DUAL``
844 - ``V4L2_MPEG_AUDIO_MODE_MONO``
850 .. _`v4l2-mpeg-audio-mode-extension`:
852 ``V4L2_CID_MPEG_AUDIO_MODE_EXTENSION (enum v4l2_mpeg_audio_mode_extension)``
853 Joint Stereo audio mode extension. In Layer I and II they indicate
854 which subbands are in intensity stereo. All other subbands are coded
855 in stereo. Layer III is not (yet) supported. Possible values are:
866 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4``
868 - Subbands 4-31 in intensity stereo
872 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8``
874 - Subbands 8-31 in intensity stereo
878 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12``
880 - Subbands 12-31 in intensity stereo
884 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16``
886 - Subbands 16-31 in intensity stereo
890 .. _`v4l2-mpeg-audio-emphasis`:
892 ``V4L2_CID_MPEG_AUDIO_EMPHASIS (enum v4l2_mpeg_audio_emphasis)``
893 Audio Emphasis. Possible values are:
904 - ``V4L2_MPEG_AUDIO_EMPHASIS_NONE``
910 - ``V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS``
912 - 50/15 microsecond emphasis
916 - ``V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17``
922 .. _`v4l2-mpeg-audio-crc`:
924 ``V4L2_CID_MPEG_AUDIO_CRC (enum v4l2_mpeg_audio_crc)``
925 CRC method. Possible values are:
936 - ``V4L2_MPEG_AUDIO_CRC_NONE``
942 - ``V4L2_MPEG_AUDIO_CRC_CRC16``
944 - 16 bit parity check
948 ``V4L2_CID_MPEG_AUDIO_MUTE (boolean)``
949 Mutes the audio when capturing. This is not done by muting audio
950 hardware, which can still produce a slight hiss, but in the encoder
951 itself, guaranteeing a fixed and reproducible audio bitstream. 0 =
954 .. _`v4l2-mpeg-audio-dec-playback`:
956 ``V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK (enum v4l2_mpeg_audio_dec_playback)``
957 Determines how monolingual audio should be played back. Possible
969 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO``
971 - Automatically determines the best playback mode.
975 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO``
981 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT``
983 - Left channel playback.
987 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT``
989 - Right channel playback.
993 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO``
999 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO``
1001 - Stereo playback with swapped left and right channels.
1005 .. _`v4l2-mpeg-audio-dec-multilingual-playback`:
1007 ``V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK (enum v4l2_mpeg_audio_dec_playback)``
1008 Determines how multilingual audio should be played back.
1010 .. _`v4l2-mpeg-video-encoding`:
1012 ``V4L2_CID_MPEG_VIDEO_ENCODING (enum v4l2_mpeg_video_encoding)``
1013 MPEG Video encoding method. This control is specific to multiplexed
1014 MPEG streams. Possible values are:
1025 - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_1``
1027 - MPEG-1 Video encoding
1031 - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_2``
1033 - MPEG-2 Video encoding
1037 - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC``
1039 - MPEG-4 AVC (H.264) Video encoding
1043 .. _`v4l2-mpeg-video-aspect`:
1045 ``V4L2_CID_MPEG_VIDEO_ASPECT (enum v4l2_mpeg_video_aspect)``
1046 Video aspect. Possible values are:
1057 - ``V4L2_MPEG_VIDEO_ASPECT_1x1``
1061 - ``V4L2_MPEG_VIDEO_ASPECT_4x3``
1065 - ``V4L2_MPEG_VIDEO_ASPECT_16x9``
1069 - ``V4L2_MPEG_VIDEO_ASPECT_221x100``
1073 ``V4L2_CID_MPEG_VIDEO_B_FRAMES (integer)``
1074 Number of B-Frames (default 2)
1076 ``V4L2_CID_MPEG_VIDEO_GOP_SIZE (integer)``
1077 GOP size (default 12)
1079 ``V4L2_CID_MPEG_VIDEO_GOP_CLOSURE (boolean)``
1080 GOP closure (default 1)
1082 ``V4L2_CID_MPEG_VIDEO_PULLDOWN (boolean)``
1083 Enable 3:2 pulldown (default 0)
1085 .. _`v4l2-mpeg-video-bitrate-mode`:
1087 ``V4L2_CID_MPEG_VIDEO_BITRATE_MODE (enum v4l2_mpeg_video_bitrate_mode)``
1088 Video bitrate mode. Possible values are:
1099 - ``V4L2_MPEG_VIDEO_BITRATE_MODE_VBR``
1105 - ``V4L2_MPEG_VIDEO_BITRATE_MODE_CBR``
1111 ``V4L2_CID_MPEG_VIDEO_BITRATE (integer)``
1112 Video bitrate in bits per second.
1114 ``V4L2_CID_MPEG_VIDEO_BITRATE_PEAK (integer)``
1115 Peak video bitrate in bits per second. Must be larger or equal to
1116 the average video bitrate. It is ignored if the video bitrate mode
1117 is set to constant bitrate.
1119 ``V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION (integer)``
1120 For every captured frame, skip this many subsequent frames (default
1123 ``V4L2_CID_MPEG_VIDEO_MUTE (boolean)``
1124 "Mutes" the video to a fixed color when capturing. This is useful
1125 for testing, to produce a fixed video bitstream. 0 = unmuted, 1 =
1128 ``V4L2_CID_MPEG_VIDEO_MUTE_YUV (integer)``
1129 Sets the "mute" color of the video. The supplied 32-bit integer is
1130 interpreted as follows (bit 0 = least significant bit):
1143 - V chrominance information
1149 - U chrominance information
1155 - Y luminance information
1165 .. _`v4l2-mpeg-video-dec-pts`:
1167 ``V4L2_CID_MPEG_VIDEO_DEC_PTS (integer64)``
1168 This read-only control returns the 33-bit video Presentation Time
1169 Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of the
1170 currently displayed frame. This is the same PTS as is used in
1171 :ref:`VIDIOC_DECODER_CMD`.
1173 .. _`v4l2-mpeg-video-dec-frame`:
1175 ``V4L2_CID_MPEG_VIDEO_DEC_FRAME (integer64)``
1176 This read-only control returns the frame counter of the frame that
1177 is currently displayed (decoded). This value is reset to 0 whenever
1178 the decoder is started.
1180 ``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
1181 If enabled the decoder expects to receive a single slice per buffer,
1182 otherwise the decoder expects a single frame in per buffer.
1183 Applicable to the decoder, all codecs.
1185 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_ENABLE (boolean)``
1186 Enable writing sample aspect ratio in the Video Usability
1187 Information. Applicable to the H264 encoder.
1189 .. _`v4l2-mpeg-video-h264-vui-sar-idc`:
1191 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_IDC (enum v4l2_mpeg_video_h264_vui_sar_idc)``
1192 VUI sample aspect ratio indicator for H.264 encoding. The value is
1193 defined in the table E-1 in the standard. Applicable to the H264
1205 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_UNSPECIFIED``
1211 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_1x1``
1217 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_12x11``
1223 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_10x11``
1229 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_16x11``
1235 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_40x33``
1241 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_24x11``
1247 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_20x11``
1253 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_32x11``
1259 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_80x33``
1265 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_18x11``
1271 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_15x11``
1277 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_64x33``
1283 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_160x99``
1289 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_4x3``
1295 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_3x2``
1301 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_2x1``
1307 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_EXTENDED``
1313 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_WIDTH (integer)``
1314 Extended sample aspect ratio width for H.264 VUI encoding.
1315 Applicable to the H264 encoder.
1317 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_HEIGHT (integer)``
1318 Extended sample aspect ratio height for H.264 VUI encoding.
1319 Applicable to the H264 encoder.
1321 .. _`v4l2-mpeg-video-h264-level`:
1323 ``V4L2_CID_MPEG_VIDEO_H264_LEVEL (enum v4l2_mpeg_video_h264_level)``
1324 The level information for the H264 video elementary stream.
1325 Applicable to the H264 encoder. Possible values are:
1336 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_0``
1342 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1B``
1348 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_1``
1354 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_2``
1360 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_3``
1366 - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_0``
1372 - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_1``
1378 - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_2``
1384 - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_0``
1390 - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_1``
1396 - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_2``
1402 - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_0``
1408 - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_1``
1414 - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_2``
1420 - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_0``
1426 - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_1``
1432 .. _`v4l2-mpeg-video-mpeg4-level`:
1434 ``V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL (enum v4l2_mpeg_video_mpeg4_level)``
1435 The level information for the MPEG4 elementary stream. Applicable to
1436 the MPEG4 encoder. Possible values are:
1447 - ``V4L2_MPEG_VIDEO_LEVEL_0``
1453 - ``V4L2_MPEG_VIDEO_LEVEL_0B``
1459 - ``V4L2_MPEG_VIDEO_LEVEL_1``
1465 - ``V4L2_MPEG_VIDEO_LEVEL_2``
1471 - ``V4L2_MPEG_VIDEO_LEVEL_3``
1477 - ``V4L2_MPEG_VIDEO_LEVEL_3B``
1483 - ``V4L2_MPEG_VIDEO_LEVEL_4``
1489 - ``V4L2_MPEG_VIDEO_LEVEL_5``
1495 .. _`v4l2-mpeg-video-h264-profile`:
1497 ``V4L2_CID_MPEG_VIDEO_H264_PROFILE (enum v4l2_mpeg_video_h264_profile)``
1498 The profile information for H264. Applicable to the H264 encoder.
1499 Possible values are:
1510 - ``V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE``
1516 - ``V4L2_MPEG_VIDEO_H264_PROFILE_CONSTRAINED_BASELINE``
1518 - Constrained Baseline profile
1522 - ``V4L2_MPEG_VIDEO_H264_PROFILE_MAIN``
1528 - ``V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED``
1534 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH``
1540 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10``
1546 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422``
1552 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE``
1554 - High 444 Predictive profile
1558 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10_INTRA``
1560 - High 10 Intra profile
1564 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422_INTRA``
1566 - High 422 Intra profile
1570 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_INTRA``
1572 - High 444 Intra profile
1576 - ``V4L2_MPEG_VIDEO_H264_PROFILE_CAVLC_444_INTRA``
1578 - CAVLC 444 Intra profile
1582 - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE``
1584 - Scalable Baseline profile
1588 - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH``
1590 - Scalable High profile
1594 - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH_INTRA``
1596 - Scalable High Intra profile
1600 - ``V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH``
1602 - Stereo High profile
1606 - ``V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH``
1608 - Multiview High profile
1612 .. _`v4l2-mpeg-video-mpeg4-profile`:
1614 ``V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE (enum v4l2_mpeg_video_mpeg4_profile)``
1615 The profile information for MPEG4. Applicable to the MPEG4 encoder.
1616 Possible values are:
1627 - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE``
1633 - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_SIMPLE``
1635 - Advanced Simple profile
1639 - ``V4L2_MPEG_VIDEO_PROFILE_CORE``
1645 - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE_SCALABLE``
1647 - Simple Scalable profile
1651 - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_CODING_EFFICIENCY``
1657 ``V4L2_CID_MPEG_VIDEO_MAX_REF_PIC (integer)``
1658 The maximum number of reference pictures used for encoding.
1659 Applicable to the encoder.
1661 .. _`v4l2-mpeg-video-multi-slice-mode`:
1663 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE (enum v4l2_mpeg_video_multi_slice_mode)``
1664 Determines how the encoder should handle division of frame into
1665 slices. Applicable to the encoder. Possible values are:
1676 - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_SINGLE``
1678 - Single slice per frame.
1682 - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``
1684 - Multiple slices with set maximum number of macroblocks per slice.
1688 - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``
1690 - Multiple slice with set maximum size in bytes per slice.
1694 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB (integer)``
1695 The maximum number of macroblocks in a slice. Used when
1696 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1697 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``. Applicable to the
1700 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES (integer)``
1701 The maximum size of a slice in bytes. Used when
1702 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1703 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``. Applicable to the
1706 .. _`v4l2-mpeg-video-h264-loop-filter-mode`:
1708 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_MODE (enum v4l2_mpeg_video_h264_loop_filter_mode)``
1709 Loop filter mode for H264 encoder. Possible values are:
1720 - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_ENABLED``
1722 - Loop filter is enabled.
1726 - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED``
1728 - Loop filter is disabled.
1732 - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
1734 - Loop filter is disabled at the slice boundary.
1738 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)``
1739 Loop filter alpha coefficient, defined in the H264 standard.
1740 Applicable to the H264 encoder.
1742 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)``
1743 Loop filter beta coefficient, defined in the H264 standard.
1744 Applicable to the H264 encoder.
1746 .. _`v4l2-mpeg-video-h264-entropy-mode`:
1748 ``V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE (enum v4l2_mpeg_video_h264_entropy_mode)``
1749 Entropy coding mode for H264 - CABAC/CAVALC. Applicable to the H264
1750 encoder. Possible values are:
1761 - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CAVLC``
1763 - Use CAVLC entropy coding.
1767 - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CABAC``
1769 - Use CABAC entropy coding.
1773 ``V4L2_CID_MPEG_VIDEO_H264_8X8_TRANSFORM (boolean)``
1774 Enable 8X8 transform for H264. Applicable to the H264 encoder.
1776 ``V4L2_CID_MPEG_VIDEO_CYCLIC_INTRA_REFRESH_MB (integer)``
1777 Cyclic intra macroblock refresh. This is the number of continuous
1778 macroblocks refreshed every frame. Each frame a successive set of
1779 macroblocks is refreshed until the cycle completes and starts from
1780 the top of the frame. Applicable to H264, H263 and MPEG4 encoder.
1782 ``V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE (boolean)``
1783 Frame level rate control enable. If this control is disabled then
1784 the quantization parameter for each frame type is constant and set
1785 with appropriate controls (e.g.
1786 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP``). If frame rate control is
1787 enabled then quantization parameter is adjusted to meet the chosen
1788 bitrate. Minimum and maximum value for the quantization parameter
1789 can be set with appropriate controls (e.g.
1790 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP``). Applicable to encoders.
1792 ``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE (boolean)``
1793 Macroblock level rate control enable. Applicable to the MPEG4 and
1796 ``V4L2_CID_MPEG_VIDEO_MPEG4_QPEL (boolean)``
1797 Quarter pixel motion estimation for MPEG4. Applicable to the MPEG4
1800 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (integer)``
1801 Quantization parameter for an I frame for H263. Valid range: from 1
1804 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP (integer)``
1805 Minimum quantization parameter for H263. Valid range: from 1 to 31.
1807 ``V4L2_CID_MPEG_VIDEO_H263_MAX_QP (integer)``
1808 Maximum quantization parameter for H263. Valid range: from 1 to 31.
1810 ``V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (integer)``
1811 Quantization parameter for an P frame for H263. Valid range: from 1
1814 ``V4L2_CID_MPEG_VIDEO_H263_B_FRAME_QP (integer)``
1815 Quantization parameter for an B frame for H263. Valid range: from 1
1818 ``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_QP (integer)``
1819 Quantization parameter for an I frame for H264. Valid range: from 0
1822 ``V4L2_CID_MPEG_VIDEO_H264_MIN_QP (integer)``
1823 Minimum quantization parameter for H264. Valid range: from 0 to 51.
1825 ``V4L2_CID_MPEG_VIDEO_H264_MAX_QP (integer)``
1826 Maximum quantization parameter for H264. Valid range: from 0 to 51.
1828 ``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP (integer)``
1829 Quantization parameter for an P frame for H264. Valid range: from 0
1832 ``V4L2_CID_MPEG_VIDEO_H264_B_FRAME_QP (integer)``
1833 Quantization parameter for an B frame for H264. Valid range: from 0
1836 ``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
1837 Quantization parameter for an I frame for MPEG4. Valid range: from 1
1840 ``V4L2_CID_MPEG_VIDEO_MPEG4_MIN_QP (integer)``
1841 Minimum quantization parameter for MPEG4. Valid range: from 1 to 31.
1843 ``V4L2_CID_MPEG_VIDEO_MPEG4_MAX_QP (integer)``
1844 Maximum quantization parameter for MPEG4. Valid range: from 1 to 31.
1846 ``V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (integer)``
1847 Quantization parameter for an P frame for MPEG4. Valid range: from 1
1850 ``V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (integer)``
1851 Quantization parameter for an B frame for MPEG4. Valid range: from 1
1854 ``V4L2_CID_MPEG_VIDEO_VBV_SIZE (integer)``
1855 The Video Buffer Verifier size in kilobytes, it is used as a
1856 limitation of frame skip. The VBV is defined in the standard as a
1857 mean to verify that the produced stream will be successfully
1858 decoded. The standard describes it as "Part of a hypothetical
1859 decoder that is conceptually connected to the output of the encoder.
1860 Its purpose is to provide a constraint on the variability of the
1861 data rate that an encoder or editing process may produce.".
1862 Applicable to the MPEG1, MPEG2, MPEG4 encoders.
1864 .. _`v4l2-mpeg-video-vbv-delay`:
1866 ``V4L2_CID_MPEG_VIDEO_VBV_DELAY (integer)``
1867 Sets the initial delay in milliseconds for VBV buffer control.
1869 .. _`v4l2-mpeg-video-hor-search-range`:
1871 ``V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (integer)``
1872 Horizontal search range defines maximum horizontal search area in
1873 pixels to search and match for the present Macroblock (MB) in the
1874 reference picture. This V4L2 control macro is used to set horizontal
1875 search range for motion estimation module in video encoder.
1877 .. _`v4l2-mpeg-video-vert-search-range`:
1879 ``V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (integer)``
1880 Vertical search range defines maximum vertical search area in pixels
1881 to search and match for the present Macroblock (MB) in the reference
1882 picture. This V4L2 control macro is used to set vertical search
1883 range for motion estimation module in video encoder.
1885 .. _`v4l2-mpeg-video-force-key-frame`:
1887 ``V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (button)``
1888 Force a key frame for the next queued buffer. Applicable to
1889 encoders. This is a general, codec-agnostic keyframe control.
1891 ``V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE (integer)``
1892 The Coded Picture Buffer size in kilobytes, it is used as a
1893 limitation of frame skip. The CPB is defined in the H264 standard as
1894 a mean to verify that the produced stream will be successfully
1895 decoded. Applicable to the H264 encoder.
1897 ``V4L2_CID_MPEG_VIDEO_H264_I_PERIOD (integer)``
1898 Period between I-frames in the open GOP for H264. In case of an open
1899 GOP this is the period between two I-frames. The period between IDR
1900 (Instantaneous Decoding Refresh) frames is taken from the GOP_SIZE
1901 control. An IDR frame, which stands for Instantaneous Decoding
1902 Refresh is an I-frame after which no prior frames are referenced.
1903 This means that a stream can be restarted from an IDR frame without
1904 the need to store or decode any previous frames. Applicable to the
1907 .. _`v4l2-mpeg-video-header-mode`:
1909 ``V4L2_CID_MPEG_VIDEO_HEADER_MODE (enum v4l2_mpeg_video_header_mode)``
1910 Determines whether the header is returned as the first buffer or is
1911 it returned together with the first frame. Applicable to encoders.
1912 Possible values are:
1923 - ``V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE``
1925 - The stream header is returned separately in the first buffer.
1929 - ``V4L2_MPEG_VIDEO_HEADER_MODE_JOINED_WITH_1ST_FRAME``
1931 - The stream header is returned together with the first encoded
1936 ``V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (boolean)``
1937 Repeat the video sequence headers. Repeating these headers makes
1938 random access to the video stream easier. Applicable to the MPEG1, 2
1941 ``V4L2_CID_MPEG_VIDEO_DECODER_MPEG4_DEBLOCK_FILTER (boolean)``
1942 Enabled the deblocking post processing filter for MPEG4 decoder.
1943 Applicable to the MPEG4 decoder.
1945 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_RES (integer)``
1946 vop_time_increment_resolution value for MPEG4. Applicable to the
1949 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_INC (integer)``
1950 vop_time_increment value for MPEG4. Applicable to the MPEG4
1953 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FRAME_PACKING (boolean)``
1954 Enable generation of frame packing supplemental enhancement
1955 information in the encoded bitstream. The frame packing SEI message
1956 contains the arrangement of L and R planes for 3D viewing.
1957 Applicable to the H264 encoder.
1959 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_CURRENT_FRAME_0 (boolean)``
1960 Sets current frame as frame0 in frame packing SEI. Applicable to the
1963 .. _`v4l2-mpeg-video-h264-sei-fp-arrangement-type`:
1965 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE (enum v4l2_mpeg_video_h264_sei_fp_arrangement_type)``
1966 Frame packing arrangement type for H264 SEI. Applicable to the H264
1967 encoder. Possible values are:
1978 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_CHEKERBOARD``
1980 - Pixels are alternatively from L and R.
1984 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_COLUMN``
1986 - L and R are interlaced by column.
1990 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_ROW``
1992 - L and R are interlaced by row.
1996 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_SIDE_BY_SIDE``
1998 - L is on the left, R on the right.
2002 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TOP_BOTTOM``
2004 - L is on top, R on bottom.
2008 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TEMPORAL``
2010 - One view per frame.
2014 ``V4L2_CID_MPEG_VIDEO_H264_FMO (boolean)``
2015 Enables flexible macroblock ordering in the encoded bitstream. It is
2016 a technique used for restructuring the ordering of macroblocks in
2017 pictures. Applicable to the H264 encoder.
2019 .. _`v4l2-mpeg-video-h264-fmo-map-type`:
2021 ``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE (enum v4l2_mpeg_video_h264_fmo_map_type)``
2022 When using FMO, the map type divides the image in different scan
2023 patterns of macroblocks. Applicable to the H264 encoder. Possible
2035 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_INTERLEAVED_SLICES``
2037 - Slices are interleaved one after other with macroblocks in run
2042 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_SCATTERED_SLICES``
2044 - Scatters the macroblocks based on a mathematical function known to
2045 both encoder and decoder.
2049 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_FOREGROUND_WITH_LEFT_OVER``
2051 - Macroblocks arranged in rectangular areas or regions of interest.
2055 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_BOX_OUT``
2057 - Slice groups grow in a cyclic way from centre to outwards.
2061 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_RASTER_SCAN``
2063 - Slice groups grow in raster scan pattern from left to right.
2067 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_WIPE_SCAN``
2069 - Slice groups grow in wipe scan pattern from top to bottom.
2073 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_EXPLICIT``
2075 - User defined map type.
2079 ``V4L2_CID_MPEG_VIDEO_H264_FMO_SLICE_GROUP (integer)``
2080 Number of slice groups in FMO. Applicable to the H264 encoder.
2082 .. _`v4l2-mpeg-video-h264-fmo-change-direction`:
2084 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_DIRECTION (enum v4l2_mpeg_video_h264_fmo_change_dir)``
2085 Specifies a direction of the slice group change for raster and wipe
2086 maps. Applicable to the H264 encoder. Possible values are:
2097 - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_RIGHT``
2099 - Raster scan or wipe right.
2103 - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_LEFT``
2105 - Reverse raster scan or wipe left.
2109 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_RATE (integer)``
2110 Specifies the size of the first slice group for raster and wipe map.
2111 Applicable to the H264 encoder.
2113 ``V4L2_CID_MPEG_VIDEO_H264_FMO_RUN_LENGTH (integer)``
2114 Specifies the number of consecutive macroblocks for the interleaved
2115 map. Applicable to the H264 encoder.
2117 ``V4L2_CID_MPEG_VIDEO_H264_ASO (boolean)``
2118 Enables arbitrary slice ordering in encoded bitstream. Applicable to
2121 ``V4L2_CID_MPEG_VIDEO_H264_ASO_SLICE_ORDER (integer)``
2122 Specifies the slice order in ASO. Applicable to the H264 encoder.
2123 The supplied 32-bit integer is interpreted as follows (bit 0 = least
2143 - Slice position or order
2147 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING (boolean)``
2148 Enables H264 hierarchical coding. Applicable to the H264 encoder.
2150 .. _`v4l2-mpeg-video-h264-hierarchical-coding-type`:
2152 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_TYPE (enum v4l2_mpeg_video_h264_hierarchical_coding_type)``
2153 Specifies the hierarchical coding type. Applicable to the H264
2154 encoder. Possible values are:
2165 - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_B``
2167 - Hierarchical B coding.
2171 - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_P``
2173 - Hierarchical P coding.
2177 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (integer)``
2178 Specifies the number of hierarchical coding layers. Applicable to
2181 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (integer)``
2182 Specifies a user defined QP for each layer. Applicable to the H264
2183 encoder. The supplied 32-bit integer is interpreted as follows (bit
2184 0 = least significant bit):
2208 MFC 5.1 MPEG Controls
2209 ---------------------
2211 The following MPEG class controls deal with MPEG decoding and encoding
2212 settings that are specific to the Multi Format Codec 5.1 device present
2213 in the S5P family of SoCs by Samsung.
2216 .. _mfc51-control-id:
2221 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY_ENABLE (boolean)``
2222 If the display delay is enabled then the decoder is forced to return
2223 a CAPTURE buffer (decoded frame) after processing a certain number
2224 of OUTPUT buffers. The delay can be set through
2225 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY``. This
2226 feature can be used for example for generating thumbnails of videos.
2227 Applicable to the H264 decoder.
2229 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY (integer)``
2230 Display delay value for H264 decoder. The decoder is forced to
2231 return a decoded frame after the set 'display delay' number of
2232 frames. If this number is low it may result in frames returned out
2233 of dispaly order, in addition the hardware may still be using the
2234 returned buffer as a reference picture for subsequent frames.
2236 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P (integer)``
2237 The number of reference pictures used for encoding a P picture.
2238 Applicable to the H264 encoder.
2240 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING (boolean)``
2241 Padding enable in the encoder - use a color instead of repeating
2242 border pixels. Applicable to encoders.
2244 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING_YUV (integer)``
2245 Padding color in the encoder. Applicable to encoders. The supplied
2246 32-bit integer is interpreted as follows (bit 0 = least significant
2260 - V chrominance information
2266 - U chrominance information
2272 - Y luminance information
2282 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
2283 Reaction coefficient for MFC rate control. Applicable to encoders.
2285 Note 1: Valid only when the frame level RC is enabled.
2287 Note 2: For tight CBR, this field must be small (ex. 2 ~ 10). For
2288 VBR, this field must be large (ex. 100 ~ 1000).
2290 Note 3: It is not recommended to use the greater number than
2291 FRAME_RATE * (10^9 / BIT_RATE).
2293 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
2294 Adaptive rate control for dark region. Valid only when H.264 and
2295 macroblock level RC is enabled
2296 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2299 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_SMOOTH (boolean)``
2300 Adaptive rate control for smooth region. Valid only when H.264 and
2301 macroblock level RC is enabled
2302 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2305 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC (boolean)``
2306 Adaptive rate control for static region. Valid only when H.264 and
2307 macroblock level RC is enabled
2308 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2311 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_ACTIVITY (boolean)``
2312 Adaptive rate control for activity region. Valid only when H.264 and
2313 macroblock level RC is enabled
2314 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2317 .. _`v4l2-mpeg-mfc51-video-frame-skip-mode`:
2319 ``V4L2_CID_MPEG_MFC51_VIDEO_FRAME_SKIP_MODE (enum v4l2_mpeg_mfc51_video_frame_skip_mode)``
2320 Indicates in what conditions the encoder should skip frames. If
2321 encoding a frame would cause the encoded stream to be larger then a
2322 chosen data limit then the frame will be skipped. Possible values
2334 - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_DISABLED``
2336 - Frame skip mode is disabled.
2340 - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_LEVEL_LIMIT``
2342 - Frame skip mode enabled and buffer limit is set by the chosen
2343 level and is defined by the standard.
2347 - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_BUF_LIMIT``
2349 - Frame skip mode enabled and buffer limit is set by the VBV
2350 (MPEG1/2/4) or CPB (H264) buffer size control.
2354 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT (integer)``
2355 Enable rate-control with fixed target bit. If this setting is
2356 enabled, then the rate control logic of the encoder will calculate
2357 the average bitrate for a GOP and keep it below or equal the set
2358 bitrate target. Otherwise the rate control logic calculates the
2359 overall average bitrate for the stream and keeps it below or equal
2360 to the set bitrate. In the first case the average bitrate for the
2361 whole stream will be smaller then the set bitrate. This is caused
2362 because the average is calculated for smaller number of frames, on
2363 the other hand enabling this setting will ensure that the stream
2364 will meet tight bandwidth constraints. Applicable to encoders.
2366 .. _`v4l2-mpeg-mfc51-video-force-frame-type`:
2368 ``V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE (enum v4l2_mpeg_mfc51_video_force_frame_type)``
2369 Force a frame type for the next queued buffer. Applicable to
2370 encoders. Possible values are:
2381 - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_DISABLED``
2383 - Forcing a specific frame type disabled.
2387 - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_I_FRAME``
2393 - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_NOT_CODED``
2395 - Force a non-coded frame.
2400 CX2341x MPEG Controls
2401 ---------------------
2403 The following MPEG class controls deal with MPEG encoding settings that
2404 are specific to the Conexant CX23415 and CX23416 MPEG encoding chips.
2407 .. _cx2341x-control-id:
2412 .. _`v4l2-mpeg-cx2341x-video-spatial-filter-mode`:
2414 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE (enum v4l2_mpeg_cx2341x_video_spatial_filter_mode)``
2415 Sets the Spatial Filter mode (default ``MANUAL``). Possible values
2427 - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL``
2429 - Choose the filter manually
2433 - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO``
2435 - Choose the filter automatically
2439 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER (integer (0-15))``
2440 The setting for the Spatial Filter. 0 = off, 15 = maximum. (Default
2443 .. _`luma-spatial-filter-type`:
2445 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type)``
2446 Select the algorithm to use for the Luma Spatial Filter (default
2447 ``1D_HOR``). Possible values:
2458 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF``
2464 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR``
2466 - One-dimensional horizontal
2470 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT``
2472 - One-dimensional vertical
2476 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE``
2478 - Two-dimensional separable
2482 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE``
2484 - Two-dimensional symmetrical non-separable
2488 .. _`chroma-spatial-filter-type`:
2490 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type)``
2491 Select the algorithm for the Chroma Spatial Filter (default
2492 ``1D_HOR``). Possible values are:
2503 - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF``
2509 - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR``
2511 - One-dimensional horizontal
2515 .. _`v4l2-mpeg-cx2341x-video-temporal-filter-mode`:
2517 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE (enum v4l2_mpeg_cx2341x_video_temporal_filter_mode)``
2518 Sets the Temporal Filter mode (default ``MANUAL``). Possible values
2530 - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL``
2532 - Choose the filter manually
2536 - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO``
2538 - Choose the filter automatically
2542 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER (integer (0-31))``
2543 The setting for the Temporal Filter. 0 = off, 31 = maximum. (Default
2544 is 8 for full-scale capturing and 0 for scaled capturing.)
2546 .. _`v4l2-mpeg-cx2341x-video-median-filter-type`:
2548 ``V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_median_filter_type)``
2549 Median Filter Type (default ``OFF``). Possible values are:
2560 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF``
2566 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR``
2572 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT``
2578 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT``
2580 - Horizontal and vertical filter
2584 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG``
2590 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
2591 Threshold above which the luminance median filter is enabled
2594 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP (integer (0-255))``
2595 Threshold below which the luminance median filter is enabled
2598 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
2599 Threshold above which the chroma median filter is enabled (default
2602 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP (integer (0-255))``
2603 Threshold below which the chroma median filter is enabled (default
2606 ``V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS (boolean)``
2607 The CX2341X MPEG encoder can insert one empty MPEG-2 PES packet into
2608 the stream between every four video frames. The packet size is 2048
2609 bytes, including the packet_start_code_prefix and stream_id
2610 fields. The stream_id is 0xBF (private stream 2). The payload
2611 consists of 0x00 bytes, to be filled in by the application. 0 = do
2612 not insert, 1 = insert packets.
2615 VPX Control Reference
2616 ---------------------
2618 The VPX controls include controls for encoding parameters of VPx video
2627 .. _`v4l2-vpx-num-partitions`:
2629 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS (enum v4l2_vp8_num_partitions)``
2630 The number of token partitions to use in VP8 encoder. Possible
2642 - ``V4L2_CID_MPEG_VIDEO_VPX_1_PARTITION``
2644 - 1 coefficient partition
2648 - ``V4L2_CID_MPEG_VIDEO_VPX_2_PARTITIONS``
2650 - 2 coefficient partitions
2654 - ``V4L2_CID_MPEG_VIDEO_VPX_4_PARTITIONS``
2656 - 4 coefficient partitions
2660 - ``V4L2_CID_MPEG_VIDEO_VPX_8_PARTITIONS``
2662 - 8 coefficient partitions
2666 ``V4L2_CID_MPEG_VIDEO_VPX_IMD_DISABLE_4X4 (boolean)``
2667 Setting this prevents intra 4x4 mode in the intra mode decision.
2669 .. _`v4l2-vpx-num-ref-frames`:
2671 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES (enum v4l2_vp8_num_ref_frames)``
2672 The number of reference pictures for encoding P frames. Possible
2684 - ``V4L2_CID_MPEG_VIDEO_VPX_1_REF_FRAME``
2686 - Last encoded frame will be searched
2690 - ``V4L2_CID_MPEG_VIDEO_VPX_2_REF_FRAME``
2692 - Two frames will be searched among the last encoded frame, the
2693 golden frame and the alternate reference (altref) frame. The
2694 encoder implementation will decide which two are chosen.
2698 - ``V4L2_CID_MPEG_VIDEO_VPX_3_REF_FRAME``
2700 - The last encoded frame, the golden frame and the altref frame will
2705 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_LEVEL (integer)``
2706 Indicates the loop filter level. The adjustment of the loop filter
2707 level is done via a delta value against a baseline loop filter
2710 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_SHARPNESS (integer)``
2711 This parameter affects the loop filter. Anything above zero weakens
2712 the deblocking effect on the loop filter.
2714 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD (integer)``
2715 Sets the refresh period for the golden frame. The period is defined
2716 in number of frames. For a value of 'n', every nth frame starting
2717 from the first key frame will be taken as a golden frame. For eg.
2718 for encoding sequence of 0, 1, 2, 3, 4, 5, 6, 7 where the golden
2719 frame refresh period is set as 4, the frames 0, 4, 8 etc will be
2720 taken as the golden frames as frame 0 is always a key frame.
2722 .. _`v4l2-vpx-golden-frame-sel`:
2724 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_SEL (enum v4l2_vp8_golden_frame_sel)``
2725 Selects the golden frame for encoding. Possible values are:
2736 - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_PREV``
2738 - Use the (n-2)th frame as a golden frame, current frame index being
2743 - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_REF_PERIOD``
2745 - Use the previous specific frame indicated by
2746 V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD as a
2751 ``V4L2_CID_MPEG_VIDEO_VPX_MIN_QP (integer)``
2752 Minimum quantization parameter for VP8.
2754 ``V4L2_CID_MPEG_VIDEO_VPX_MAX_QP (integer)``
2755 Maximum quantization parameter for VP8.
2757 ``V4L2_CID_MPEG_VIDEO_VPX_I_FRAME_QP (integer)``
2758 Quantization parameter for an I frame for VP8.
2760 ``V4L2_CID_MPEG_VIDEO_VPX_P_FRAME_QP (integer)``
2761 Quantization parameter for a P frame for VP8.
2763 ``V4L2_CID_MPEG_VIDEO_VPX_PROFILE (integer)``
2764 Select the desired profile for VPx encoder. Acceptable values are 0,
2765 1, 2 and 3 corresponding to encoder profiles 0, 1, 2 and 3.
2768 .. _camera-controls:
2770 Camera Control Reference
2771 ========================
2773 The Camera class includes controls for mechanical (or equivalent
2774 digital) features of a device such as controllable lenses or sensors.
2777 .. _camera-control-id:
2782 ``V4L2_CID_CAMERA_CLASS (class)``
2783 The Camera class descriptor. Calling
2784 :ref:`VIDIOC_QUERYCTRL` for this control will
2785 return a description of this control class.
2787 .. _`v4l2-exposure-auto-type`:
2789 ``V4L2_CID_EXPOSURE_AUTO (enum v4l2_exposure_auto_type)``
2790 Enables automatic adjustments of the exposure time and/or iris
2791 aperture. The effect of manual changes of the exposure time or iris
2792 aperture while these features are enabled is undefined, drivers
2793 should ignore such requests. Possible values are:
2804 - ``V4L2_EXPOSURE_AUTO``
2806 - Automatic exposure time, automatic iris aperture.
2810 - ``V4L2_EXPOSURE_MANUAL``
2812 - Manual exposure time, manual iris.
2816 - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
2818 - Manual exposure time, auto iris.
2822 - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
2824 - Auto exposure time, manual iris.
2828 ``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
2829 Determines the exposure time of the camera sensor. The exposure time
2830 is limited by the frame interval. Drivers should interpret the
2831 values as 100 µs units, where the value 1 stands for 1/10000th of a
2832 second, 10000 for 1 second and 100000 for 10 seconds.
2834 ``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
2835 When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
2836 ``APERTURE_PRIORITY``, this control determines if the device may
2837 dynamically vary the frame rate. By default this feature is disabled
2838 (0) and the frame rate must remain constant.
2840 ``V4L2_CID_EXPOSURE_BIAS (integer menu)``
2841 Determines the automatic exposure compensation, it is effective only
2842 when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
2843 ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
2844 terms of EV, drivers should interpret the values as 0.001 EV units,
2845 where the value 1000 stands for +1 EV.
2847 Increasing the exposure compensation value is equivalent to
2848 decreasing the exposure value (EV) and will increase the amount of
2849 light at the image sensor. The camera performs the exposure
2850 compensation by adjusting absolute exposure time and/or aperture.
2852 .. _`v4l2-exposure-metering`:
2854 ``V4L2_CID_EXPOSURE_METERING (enum v4l2_exposure_metering)``
2855 Determines how the camera measures the amount of light available for
2856 the frame exposure. Possible values are:
2867 - ``V4L2_EXPOSURE_METERING_AVERAGE``
2869 - Use the light information coming from the entire frame and average
2870 giving no weighting to any particular portion of the metered area.
2874 - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
2876 - Average the light information coming from the entire frame giving
2877 priority to the center of the metered area.
2881 - ``V4L2_EXPOSURE_METERING_SPOT``
2883 - Measure only very small area at the center of the frame.
2887 - ``V4L2_EXPOSURE_METERING_MATRIX``
2889 - A multi-zone metering. The light intensity is measured in several
2890 points of the frame and the results are combined. The algorithm of
2891 the zones selection and their significance in calculating the
2892 final value is device dependent.
2896 ``V4L2_CID_PAN_RELATIVE (integer)``
2897 This control turns the camera horizontally by the specified amount.
2898 The unit is undefined. A positive value moves the camera to the
2899 right (clockwise when viewed from above), a negative value to the
2900 left. A value of zero does not cause motion. This is a write-only
2903 ``V4L2_CID_TILT_RELATIVE (integer)``
2904 This control turns the camera vertically by the specified amount.
2905 The unit is undefined. A positive value moves the camera up, a
2906 negative value down. A value of zero does not cause motion. This is
2907 a write-only control.
2909 ``V4L2_CID_PAN_RESET (button)``
2910 When this control is set, the camera moves horizontally to the
2913 ``V4L2_CID_TILT_RESET (button)``
2914 When this control is set, the camera moves vertically to the default
2917 ``V4L2_CID_PAN_ABSOLUTE (integer)``
2918 This control turns the camera horizontally to the specified
2919 position. Positive values move the camera to the right (clockwise
2920 when viewed from above), negative values to the left. Drivers should
2921 interpret the values as arc seconds, with valid values between -180
2922 * 3600 and +180 * 3600 inclusive.
2924 ``V4L2_CID_TILT_ABSOLUTE (integer)``
2925 This control turns the camera vertically to the specified position.
2926 Positive values move the camera up, negative values down. Drivers
2927 should interpret the values as arc seconds, with valid values
2928 between -180 * 3600 and +180 * 3600 inclusive.
2930 ``V4L2_CID_FOCUS_ABSOLUTE (integer)``
2931 This control sets the focal point of the camera to the specified
2932 position. The unit is undefined. Positive values set the focus
2933 closer to the camera, negative values towards infinity.
2935 ``V4L2_CID_FOCUS_RELATIVE (integer)``
2936 This control moves the focal point of the camera by the specified
2937 amount. The unit is undefined. Positive values move the focus closer
2938 to the camera, negative values towards infinity. This is a
2941 ``V4L2_CID_FOCUS_AUTO (boolean)``
2942 Enables continuous automatic focus adjustments. The effect of manual
2943 focus adjustments while this feature is enabled is undefined,
2944 drivers should ignore such requests.
2946 ``V4L2_CID_AUTO_FOCUS_START (button)``
2947 Starts single auto focus process. The effect of setting this control
2948 when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
2949 drivers should ignore such requests.
2951 ``V4L2_CID_AUTO_FOCUS_STOP (button)``
2952 Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
2953 control. It is effective only when the continuous autofocus is
2954 disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
2957 .. _`v4l2-auto-focus-status`:
2959 ``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
2960 The automatic focus status. This is a read-only control.
2962 Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
2963 control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
2975 - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
2977 - Automatic focus is not active.
2981 - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
2983 - Automatic focusing is in progress.
2987 - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
2989 - Focus has been reached.
2993 - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
2995 - Automatic focus has failed, the driver will not transition from
2996 this state until another action is performed by an application.
3000 .. _`v4l2-auto-focus-range`:
3002 ``V4L2_CID_AUTO_FOCUS_RANGE (enum v4l2_auto_focus_range)``
3003 Determines auto focus distance range for which lens may be adjusted.
3014 - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
3016 - The camera automatically selects the focus range.
3020 - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
3022 - Normal distance range, limited for best automatic focus
3027 - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
3029 - Macro (close-up) auto focus. The camera will use its minimum
3030 possible distance for auto focus.
3034 - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
3036 - The lens is set to focus on an object at infinite distance.
3040 ``V4L2_CID_ZOOM_ABSOLUTE (integer)``
3041 Specify the objective lens focal length as an absolute value. The
3042 zoom unit is driver-specific and its value should be a positive
3045 ``V4L2_CID_ZOOM_RELATIVE (integer)``
3046 Specify the objective lens focal length relatively to the current
3047 value. Positive values move the zoom lens group towards the
3048 telephoto direction, negative values towards the wide-angle
3049 direction. The zoom unit is driver-specific. This is a write-only
3052 ``V4L2_CID_ZOOM_CONTINUOUS (integer)``
3053 Move the objective lens group at the specified speed until it
3054 reaches physical device limits or until an explicit request to stop
3055 the movement. A positive value moves the zoom lens group towards the
3056 telephoto direction. A value of zero stops the zoom lens group
3057 movement. A negative value moves the zoom lens group towards the
3058 wide-angle direction. The zoom speed unit is driver-specific.
3060 ``V4L2_CID_IRIS_ABSOLUTE (integer)``
3061 This control sets the camera's aperture to the specified value. The
3062 unit is undefined. Larger values open the iris wider, smaller values
3065 ``V4L2_CID_IRIS_RELATIVE (integer)``
3066 This control modifies the camera's aperture by the specified amount.
3067 The unit is undefined. Positive values open the iris one step
3068 further, negative values close it one step further. This is a
3071 ``V4L2_CID_PRIVACY (boolean)``
3072 Prevent video from being acquired by the camera. When this control
3073 is set to ``TRUE`` (1), no image can be captured by the camera.
3074 Common means to enforce privacy are mechanical obturation of the
3075 sensor and firmware image processing, but the device is not
3076 restricted to these methods. Devices that implement the privacy
3077 control must support read access and may support write access.
3079 ``V4L2_CID_BAND_STOP_FILTER (integer)``
3080 Switch the band-stop filter of a camera sensor on or off, or specify
3081 its strength. Such band-stop filters can be used, for example, to
3082 filter out the fluorescent light component.
3084 .. _`v4l2-auto-n-preset-white-balance`:
3086 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE (enum v4l2_auto_n_preset_white_balance)``
3087 Sets white balance to automatic, manual or a preset. The presets
3088 determine color temperature of the light as a hint to the camera for
3089 white balance adjustments resulting in most accurate color
3090 representation. The following white balance presets are listed in
3091 order of increasing color temperature.
3102 - ``V4L2_WHITE_BALANCE_MANUAL``
3104 - Manual white balance.
3108 - ``V4L2_WHITE_BALANCE_AUTO``
3110 - Automatic white balance adjustments.
3114 - ``V4L2_WHITE_BALANCE_INCANDESCENT``
3116 - White balance setting for incandescent (tungsten) lighting. It
3117 generally cools down the colors and corresponds approximately to
3118 2500...3500 K color temperature range.
3122 - ``V4L2_WHITE_BALANCE_FLUORESCENT``
3124 - White balance preset for fluorescent lighting. It corresponds
3125 approximately to 4000...5000 K color temperature.
3129 - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
3131 - With this setting the camera will compensate for fluorescent H
3136 - ``V4L2_WHITE_BALANCE_HORIZON``
3138 - White balance setting for horizon daylight. It corresponds
3139 approximately to 5000 K color temperature.
3143 - ``V4L2_WHITE_BALANCE_DAYLIGHT``
3145 - White balance preset for daylight (with clear sky). It corresponds
3146 approximately to 5000...6500 K color temperature.
3150 - ``V4L2_WHITE_BALANCE_FLASH``
3152 - With this setting the camera will compensate for the flash light.
3153 It slightly warms up the colors and corresponds roughly to
3154 5000...5500 K color temperature.
3158 - ``V4L2_WHITE_BALANCE_CLOUDY``
3160 - White balance preset for moderately overcast sky. This option
3161 corresponds approximately to 6500...8000 K color temperature
3166 - ``V4L2_WHITE_BALANCE_SHADE``
3168 - White balance preset for shade or heavily overcast sky. It
3169 corresponds approximately to 9000...10000 K color temperature.
3173 .. _`v4l2-wide-dynamic-range`:
3175 ``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
3176 Enables or disables the camera's wide dynamic range feature. This
3177 feature allows to obtain clear images in situations where intensity
3178 of the illumination varies significantly throughout the scene, i.e.
3179 there are simultaneously very dark and very bright areas. It is most
3180 commonly realized in cameras by combining two subsequent frames with
3181 different exposure times. [1]_
3183 .. _`v4l2-image-stabilization`:
3185 ``V4L2_CID_IMAGE_STABILIZATION (boolean)``
3186 Enables or disables image stabilization.
3188 ``V4L2_CID_ISO_SENSITIVITY (integer menu)``
3189 Determines ISO equivalent of an image sensor indicating the sensor's
3190 sensitivity to light. The numbers are expressed in arithmetic scale,
3191 as per :ref:`iso12232` standard, where doubling the sensor
3192 sensitivity is represented by doubling the numerical ISO value.
3193 Applications should interpret the values as standard ISO values
3194 multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
3195 Drivers will usually support only a subset of standard ISO values.
3196 The effect of setting this control while the
3197 ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
3198 than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
3199 should ignore such requests.
3201 .. _`v4l2-iso-sensitivity-auto-type`:
3203 ``V4L2_CID_ISO_SENSITIVITY_AUTO (enum v4l2_iso_sensitivity_type)``
3204 Enables or disables automatic ISO sensitivity adjustments.
3215 - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
3217 - Manual ISO sensitivity.
3221 - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
3223 - Automatic ISO sensitivity adjustments.
3227 .. _`v4l2-scene-mode`:
3229 ``V4L2_CID_SCENE_MODE (enum v4l2_scene_mode)``
3230 This control allows to select scene programs as the camera automatic
3231 modes optimized for common shooting scenes. Within these modes the
3232 camera determines best exposure, aperture, focusing, light metering,
3233 white balance and equivalent sensitivity. The controls of those
3234 parameters are influenced by the scene mode control. An exact
3235 behavior in each mode is subject to the camera specification.
3237 When the scene mode feature is not used, this control should be set
3238 to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
3239 controls are accessible. The following scene programs are defined:
3250 - ``V4L2_SCENE_MODE_NONE``
3252 - The scene mode feature is disabled.
3256 - ``V4L2_SCENE_MODE_BACKLIGHT``
3258 - Backlight. Compensates for dark shadows when light is coming from
3259 behind a subject, also by automatically turning on the flash.
3263 - ``V4L2_SCENE_MODE_BEACH_SNOW``
3265 - Beach and snow. This mode compensates for all-white or bright
3266 scenes, which tend to look gray and low contrast, when camera's
3267 automatic exposure is based on an average scene brightness. To
3268 compensate, this mode automatically slightly overexposes the
3269 frames. The white balance may also be adjusted to compensate for
3270 the fact that reflected snow looks bluish rather than white.
3274 - ``V4L2_SCENE_MODE_CANDLELIGHT``
3276 - Candle light. The camera generally raises the ISO sensitivity and
3277 lowers the shutter speed. This mode compensates for relatively
3278 close subject in the scene. The flash is disabled in order to
3279 preserve the ambiance of the light.
3283 - ``V4L2_SCENE_MODE_DAWN_DUSK``
3285 - Dawn and dusk. Preserves the colors seen in low natural light
3286 before dusk and after down. The camera may turn off the flash, and
3287 automatically focus at infinity. It will usually boost saturation
3288 and lower the shutter speed.
3292 - ``V4L2_SCENE_MODE_FALL_COLORS``
3294 - Fall colors. Increases saturation and adjusts white balance for
3295 color enhancement. Pictures of autumn leaves get saturated reds
3300 - ``V4L2_SCENE_MODE_FIREWORKS``
3302 - Fireworks. Long exposure times are used to capture the expanding
3303 burst of light from a firework. The camera may invoke image
3308 - ``V4L2_SCENE_MODE_LANDSCAPE``
3310 - Landscape. The camera may choose a small aperture to provide deep
3311 depth of field and long exposure duration to help capture detail
3312 in dim light conditions. The focus is fixed at infinity. Suitable
3313 for distant and wide scenery.
3317 - ``V4L2_SCENE_MODE_NIGHT``
3319 - Night, also known as Night Landscape. Designed for low light
3320 conditions, it preserves detail in the dark areas without blowing
3321 out bright objects. The camera generally sets itself to a
3322 medium-to-high ISO sensitivity, with a relatively long exposure
3323 time, and turns flash off. As such, there will be increased image
3324 noise and the possibility of blurred image.
3328 - ``V4L2_SCENE_MODE_PARTY_INDOOR``
3330 - Party and indoor. Designed to capture indoor scenes that are lit
3331 by indoor background lighting as well as the flash. The camera
3332 usually increases ISO sensitivity, and adjusts exposure for the
3333 low light conditions.
3337 - ``V4L2_SCENE_MODE_PORTRAIT``
3339 - Portrait. The camera adjusts the aperture so that the depth of
3340 field is reduced, which helps to isolate the subject against a
3341 smooth background. Most cameras recognize the presence of faces in
3342 the scene and focus on them. The color hue is adjusted to enhance
3343 skin tones. The intensity of the flash is often reduced.
3347 - ``V4L2_SCENE_MODE_SPORTS``
3349 - Sports. Significantly increases ISO and uses a fast shutter speed
3350 to freeze motion of rapidly-moving subjects. Increased image noise
3351 may be seen in this mode.
3355 - ``V4L2_SCENE_MODE_SUNSET``
3357 - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
3362 - ``V4L2_SCENE_MODE_TEXT``
3364 - Text. It applies extra contrast and sharpness, it is typically a
3365 black-and-white mode optimized for readability. Automatic focus
3366 may be switched to close-up mode and this setting may also involve
3367 some lens-distortion correction.
3371 ``V4L2_CID_3A_LOCK (bitmask)``
3372 This control locks or unlocks the automatic focus, exposure and
3373 white balance. The automatic adjustments can be paused independently
3374 by setting the corresponding lock bit to 1. The camera then retains
3375 the settings until the lock bit is cleared. The following lock bits
3378 When a given algorithm is not enabled, drivers should ignore
3379 requests to lock it and should return no error. An example might be
3380 an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
3381 ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
3382 value of this control may be changed by exposure, white balance or
3394 - ``V4L2_LOCK_EXPOSURE``
3396 - Automatic exposure adjustments lock.
3400 - ``V4L2_LOCK_WHITE_BALANCE``
3402 - Automatic white balance adjustments lock.
3406 - ``V4L2_LOCK_FOCUS``
3408 - Automatic focus lock.
3412 ``V4L2_CID_PAN_SPEED (integer)``
3413 This control turns the camera horizontally at the specific speed.
3414 The unit is undefined. A positive value moves the camera to the
3415 right (clockwise when viewed from above), a negative value to the
3416 left. A value of zero stops the motion if one is in progress and has
3417 no effect otherwise.
3419 ``V4L2_CID_TILT_SPEED (integer)``
3420 This control turns the camera vertically at the specified speed. The
3421 unit is undefined. A positive value moves the camera up, a negative
3422 value down. A value of zero stops the motion if one is in progress
3423 and has no effect otherwise.
3428 FM Transmitter Control Reference
3429 ================================
3431 The FM Transmitter (FM_TX) class includes controls for common features
3432 of FM transmissions capable devices. Currently this class includes
3433 parameters for audio compression, pilot tone generation, audio deviation
3434 limiter, RDS transmission and tuning power features.
3437 .. _fm-tx-control-id:
3442 ``V4L2_CID_FM_TX_CLASS (class)``
3443 The FM_TX class descriptor. Calling
3444 :ref:`VIDIOC_QUERYCTRL` for this control will
3445 return a description of this control class.
3447 ``V4L2_CID_RDS_TX_DEVIATION (integer)``
3448 Configures RDS signal frequency deviation level in Hz. The range and
3449 step are driver-specific.
3451 ``V4L2_CID_RDS_TX_PI (integer)``
3452 Sets the RDS Programme Identification field for transmission.
3454 ``V4L2_CID_RDS_TX_PTY (integer)``
3455 Sets the RDS Programme Type field for transmission. This encodes up
3456 to 31 pre-defined programme types.
3458 ``V4L2_CID_RDS_TX_PS_NAME (string)``
3459 Sets the Programme Service name (PS_NAME) for transmission. It is
3460 intended for static display on a receiver. It is the primary aid to
3461 listeners in programme service identification and selection. In
3462 Annex E of :ref:`iec62106`, the RDS specification, there is a full
3463 description of the correct character encoding for Programme Service
3464 name strings. Also from RDS specification, PS is usually a single
3465 eight character text. However, it is also possible to find receivers
3466 which can scroll strings sized as 8 x N characters. So, this control
3467 must be configured with steps of 8 characters. The result is it must
3468 always contain a string with size multiple of 8.
3470 ``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
3471 Sets the Radio Text info for transmission. It is a textual
3472 description of what is being broadcasted. RDS Radio Text can be
3473 applied when broadcaster wishes to transmit longer PS names,
3474 programme-related information or any other text. In these cases,
3475 RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``.
3476 The encoding for Radio Text strings is also fully described in Annex
3477 E of :ref:`iec62106`. The length of Radio Text strings depends on
3478 which RDS Block is being used to transmit it, either 32 (2A block)
3479 or 64 (2B block). However, it is also possible to find receivers
3480 which can scroll strings sized as 32 x N or 64 x N characters. So,
3481 this control must be configured with steps of 32 or 64 characters.
3482 The result is it must always contain a string with size multiple of
3485 ``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
3486 Sets the Mono/Stereo bit of the Decoder Identification code. If set,
3487 then the audio was recorded as stereo.
3489 ``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
3491 `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__
3492 bit of the Decoder Identification code. If set, then the audio was
3493 recorded using an artificial head.
3495 ``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
3496 Sets the Compressed bit of the Decoder Identification code. If set,
3497 then the audio is compressed.
3499 ``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
3500 Sets the Dynamic PTY bit of the Decoder Identification code. If set,
3501 then the PTY code is dynamically switched.
3503 ``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)``
3504 If set, then a traffic announcement is in progress.
3506 ``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
3507 If set, then the tuned programme carries traffic announcements.
3509 ``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
3510 If set, then this channel broadcasts music. If cleared, then it
3511 broadcasts speech. If the transmitter doesn't make this distinction,
3512 then it should be set.
3514 ``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
3515 If set, then transmit alternate frequencies.
3517 ``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
3518 The alternate frequencies in kHz units. The RDS standard allows for
3519 up to 25 frequencies to be defined. Drivers may support fewer
3520 frequencies so check the array size.
3522 ``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
3523 Enables or disables the audio deviation limiter feature. The limiter
3524 is useful when trying to maximize the audio volume, minimize
3525 receiver-generated distortion and prevent overmodulation.
3527 ``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
3528 Sets the audio deviation limiter feature release time. Unit is in
3529 useconds. Step and range are driver-specific.
3531 ``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
3532 Configures audio frequency deviation level in Hz. The range and step
3533 are driver-specific.
3535 ``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)``
3536 Enables or disables the audio compression feature. This feature
3537 amplifies signals below the threshold by a fixed gain and compresses
3538 audio signals above the threshold by the ratio of Threshold/(Gain +
3541 ``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
3542 Sets the gain for audio compression feature. It is a dB value. The
3543 range and step are driver-specific.
3545 ``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
3546 Sets the threshold level for audio compression freature. It is a dB
3547 value. The range and step are driver-specific.
3549 ``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
3550 Sets the attack time for audio compression feature. It is a useconds
3551 value. The range and step are driver-specific.
3553 ``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
3554 Sets the release time for audio compression feature. It is a
3555 useconds value. The range and step are driver-specific.
3557 ``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
3558 Enables or disables the pilot tone generation feature.
3560 ``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
3561 Configures pilot tone frequency deviation level. Unit is in Hz. The
3562 range and step are driver-specific.
3564 ``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
3565 Configures pilot tone frequency value. Unit is in Hz. The range and
3566 step are driver-specific.
3568 ``V4L2_CID_TUNE_PREEMPHASIS (enum v4l2_preemphasis)``
3569 Configures the pre-emphasis value for broadcasting. A pre-emphasis
3570 filter is applied to the broadcast to accentuate the high audio
3571 frequencies. Depending on the region, a time constant of either 50
3572 or 75 useconds is used. The enum v4l2_preemphasis defines possible
3573 values for pre-emphasis. Here they are:
3584 - ``V4L2_PREEMPHASIS_DISABLED``
3586 - No pre-emphasis is applied.
3590 - ``V4L2_PREEMPHASIS_50_uS``
3592 - A pre-emphasis of 50 uS is used.
3596 - ``V4L2_PREEMPHASIS_75_uS``
3598 - A pre-emphasis of 75 uS is used.
3602 ``V4L2_CID_TUNE_POWER_LEVEL (integer)``
3603 Sets the output power level for signal transmission. Unit is in
3604 dBuV. Range and step are driver-specific.
3606 ``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
3607 This selects the value of antenna tuning capacitor manually or
3608 automatically if set to zero. Unit, range and step are
3611 For more details about RDS specification, refer to :ref:`iec62106`
3612 document, from CENELEC.
3617 Flash Control Reference
3618 =======================
3620 The V4L2 flash controls are intended to provide generic access to flash
3621 controller devices. Flash controller devices are typically used in
3624 The interface can support both LED and xenon flash devices. As of
3625 writing this, there is no xenon flash driver using this interface.
3628 .. _flash-controls-use-cases:
3634 Unsynchronised LED flash (software strobe)
3635 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3637 Unsynchronised LED flash is controlled directly by the host as the
3638 sensor. The flash must be enabled by the host before the exposure of the
3639 image starts and disabled once it ends. The host is fully responsible
3640 for the timing of the flash.
3642 Example of such device: Nokia N900.
3645 Synchronised LED flash (hardware strobe)
3646 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3648 The synchronised LED flash is pre-programmed by the host (power and
3649 timeout) but controlled by the sensor through a strobe signal from the
3650 sensor to the flash.
3652 The sensor controls the flash duration and timing. This information
3653 typically must be made available to the sensor.
3659 LED flash may be used as torch in conjunction with another use case
3660 involving camera or individually.
3663 .. _flash-control-id:
3668 ``V4L2_CID_FLASH_CLASS (class)``
3669 The FLASH class descriptor.
3671 ``V4L2_CID_FLASH_LED_MODE (menu)``
3672 Defines the mode of the flash LED, the high-power white LED attached
3673 to the flash controller. Setting this control may not be possible in
3674 presence of some faults. See V4L2_CID_FLASH_FAULT.
3685 - ``V4L2_FLASH_LED_MODE_NONE``
3691 - ``V4L2_FLASH_LED_MODE_FLASH``
3697 - ``V4L2_FLASH_LED_MODE_TORCH``
3699 - Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.
3703 ``V4L2_CID_FLASH_STROBE_SOURCE (menu)``
3704 Defines the source of the flash LED strobe.
3715 - ``V4L2_FLASH_STROBE_SOURCE_SOFTWARE``
3717 - The flash strobe is triggered by using the
3718 V4L2_CID_FLASH_STROBE control.
3722 - ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``
3724 - The flash strobe is triggered by an external source. Typically
3725 this is a sensor, which makes it possible to synchronises the
3726 flash strobe start to exposure start.
3730 ``V4L2_CID_FLASH_STROBE (button)``
3731 Strobe flash. Valid when V4L2_CID_FLASH_LED_MODE is set to
3732 V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
3733 is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
3734 control may not be possible in presence of some faults. See
3735 V4L2_CID_FLASH_FAULT.
3737 ``V4L2_CID_FLASH_STROBE_STOP (button)``
3738 Stop flash strobe immediately.
3740 ``V4L2_CID_FLASH_STROBE_STATUS (boolean)``
3741 Strobe status: whether the flash is strobing at the moment or not.
3742 This is a read-only control.
3744 ``V4L2_CID_FLASH_TIMEOUT (integer)``
3745 Hardware timeout for flash. The flash strobe is stopped after this
3746 period of time has passed from the start of the strobe.
3748 ``V4L2_CID_FLASH_INTENSITY (integer)``
3749 Intensity of the flash strobe when the flash LED is in flash mode
3750 (V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps (mA)
3753 ``V4L2_CID_FLASH_TORCH_INTENSITY (integer)``
3754 Intensity of the flash LED in torch mode
3755 (V4L2_FLASH_LED_MODE_TORCH). The unit should be milliamps (mA)
3756 if possible. Setting this control may not be possible in presence of
3757 some faults. See V4L2_CID_FLASH_FAULT.
3759 ``V4L2_CID_FLASH_INDICATOR_INTENSITY (integer)``
3760 Intensity of the indicator LED. The indicator LED may be fully
3761 independent of the flash LED. The unit should be microamps (uA) if
3764 ``V4L2_CID_FLASH_FAULT (bitmask)``
3765 Faults related to the flash. The faults tell about specific problems
3766 in the flash chip itself or the LEDs attached to it. Faults may
3767 prevent further use of some of the flash controls. In particular,
3768 V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
3769 if the fault affects the flash LED. Exactly which faults have such
3770 an effect is chip dependent. Reading the faults resets the control
3771 and returns the chip to a usable state if possible.
3782 - ``V4L2_FLASH_FAULT_OVER_VOLTAGE``
3784 - Flash controller voltage to the flash LED has exceeded the limit
3785 specific to the flash controller.
3789 - ``V4L2_FLASH_FAULT_TIMEOUT``
3791 - The flash strobe was still on when the timeout set by the user ---
3792 V4L2_CID_FLASH_TIMEOUT control --- has expired. Not all flash
3793 controllers may set this in all such conditions.
3797 - ``V4L2_FLASH_FAULT_OVER_TEMPERATURE``
3799 - The flash controller has overheated.
3803 - ``V4L2_FLASH_FAULT_SHORT_CIRCUIT``
3805 - The short circuit protection of the flash controller has been
3810 - ``V4L2_FLASH_FAULT_OVER_CURRENT``
3812 - Current in the LED power supply has exceeded the limit specific to
3813 the flash controller.
3817 - ``V4L2_FLASH_FAULT_INDICATOR``
3819 - The flash controller has detected a short or open circuit
3820 condition on the indicator LED.
3824 - ``V4L2_FLASH_FAULT_UNDER_VOLTAGE``
3826 - Flash controller voltage to the flash LED has been below the
3827 minimum limit specific to the flash controller.
3831 - ``V4L2_FLASH_FAULT_INPUT_VOLTAGE``
3833 - The input voltage of the flash controller is below the limit under
3834 which strobing the flash at full current will not be possible.The
3835 condition persists until this flag is no longer set.
3839 - ``V4L2_FLASH_FAULT_LED_OVER_TEMPERATURE``
3841 - The temperature of the LED has exceeded its allowed upper limit.
3845 ``V4L2_CID_FLASH_CHARGE (boolean)``
3846 Enable or disable charging of the xenon flash capacitor.
3848 ``V4L2_CID_FLASH_READY (boolean)``
3849 Is the flash ready to strobe? Xenon flashes require their capacitors
3850 charged before strobing. LED flashes often require a cooldown period
3851 after strobe during which another strobe will not be possible. This
3852 is a read-only control.
3857 JPEG Control Reference
3858 ======================
3860 The JPEG class includes controls for common features of JPEG encoders
3861 and decoders. Currently it includes features for codecs implementing
3862 progressive baseline DCT compression process with Huffman entrophy
3866 .. _jpeg-control-id:
3871 ``V4L2_CID_JPEG_CLASS (class)``
3872 The JPEG class descriptor. Calling
3873 :ref:`VIDIOC_QUERYCTRL` for this control will
3874 return a description of this control class.
3876 ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)``
3877 The chroma subsampling factors describe how each component of an
3878 input image is sampled, in respect to maximum sample rate in each
3879 spatial dimension. See :ref:`itu-t81`, clause A.1.1. for more
3880 details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines
3881 how Cb and Cr components are downsampled after coverting an input
3882 image from RGB to Y'CbCr color space.
3893 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444``
3895 - No chroma subsampling, each pixel has Y, Cr and Cb values.
3899 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422``
3901 - Horizontally subsample Cr, Cb components by a factor of 2.
3905 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420``
3907 - Subsample Cr, Cb components horizontally and vertically by 2.
3911 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411``
3913 - Horizontally subsample Cr, Cb components by a factor of 4.
3917 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410``
3919 - Subsample Cr, Cb components horizontally by 4 and vertically by 2.
3923 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY``
3925 - Use only luminance component.
3929 ``V4L2_CID_JPEG_RESTART_INTERVAL (integer)``
3930 The restart interval determines an interval of inserting RSTm
3931 markers (m = 0..7). The purpose of these markers is to additionally
3932 reinitialize the encoder process, in order to process blocks of an
3933 image independently. For the lossy compression processes the restart
3934 interval unit is MCU (Minimum Coded Unit) and its value is contained
3935 in DRI (Define Restart Interval) marker. If
3936 ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm
3937 markers will not be inserted.
3939 .. _`jpeg-quality-control`:
3941 ``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)``
3942 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control determines trade-off
3943 between image quality and size. It provides simpler method for
3944 applications to control image quality, without a need for direct
3945 reconfiguration of luminance and chrominance quantization tables. In
3946 cases where a driver uses quantization tables configured directly by
3947 an application, using interfaces defined elsewhere,
3948 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by
3951 The value range of this control is driver-specific. Only positive,
3952 non-zero values are meaningful. The recommended range is 1 - 100,
3953 where larger values correspond to better image quality.
3955 .. _`jpeg-active-marker-control`:
3957 ``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)``
3958 Specify which JPEG markers are included in compressed stream. This
3959 control is valid only for encoders.
3970 - ``V4L2_JPEG_ACTIVE_MARKER_APP0``
3972 - Application data segment APP\ :sub:`0`.
3976 - ``V4L2_JPEG_ACTIVE_MARKER_APP1``
3978 - Application data segment APP\ :sub:`1`.
3982 - ``V4L2_JPEG_ACTIVE_MARKER_COM``
3988 - ``V4L2_JPEG_ACTIVE_MARKER_DQT``
3990 - Quantization tables segment.
3994 - ``V4L2_JPEG_ACTIVE_MARKER_DHT``
3996 - Huffman tables segment.
4000 For more details about JPEG specification, refer to :ref:`itu-t81`,
4001 :ref:`jfif`, :ref:`w3c-jpeg-jfif`.
4004 .. _image-source-controls:
4006 Image Source Control Reference
4007 ==============================
4009 The Image Source control class is intended for low-level control of
4010 image source devices such as image sensors. The devices feature an
4011 analogue to digital converter and a bus transmitter to transmit the
4012 image data out of the device.
4015 .. _image-source-control-id:
4017 Image Source Control IDs
4018 ------------------------
4020 ``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
4021 The IMAGE_SOURCE class descriptor.
4023 ``V4L2_CID_VBLANK (integer)``
4024 Vertical blanking. The idle period after every frame during which no
4025 image data is produced. The unit of vertical blanking is a line.
4026 Every line has length of the image width plus horizontal blanking at
4027 the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
4030 ``V4L2_CID_HBLANK (integer)``
4031 Horizontal blanking. The idle period after every line of image data
4032 during which no image data is produced. The unit of horizontal
4035 ``V4L2_CID_ANALOGUE_GAIN (integer)``
4036 Analogue gain is gain affecting all colour components in the pixel
4037 matrix. The gain operation is performed in the analogue domain
4038 before A/D conversion.
4040 ``V4L2_CID_TEST_PATTERN_RED (integer)``
4041 Test pattern red colour component.
4043 ``V4L2_CID_TEST_PATTERN_GREENR (integer)``
4044 Test pattern green (next to red) colour component.
4046 ``V4L2_CID_TEST_PATTERN_BLUE (integer)``
4047 Test pattern blue colour component.
4049 ``V4L2_CID_TEST_PATTERN_GREENB (integer)``
4050 Test pattern green (next to blue) colour component.
4053 .. _image-process-controls:
4055 Image Process Control Reference
4056 ===============================
4058 The Image Process control class is intended for low-level control of
4059 image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
4060 controls in this class affect processing the image, and do not control
4064 .. _image-process-control-id:
4066 Image Process Control IDs
4067 -------------------------
4069 ``V4L2_CID_IMAGE_PROC_CLASS (class)``
4070 The IMAGE_PROC class descriptor.
4072 ``V4L2_CID_LINK_FREQ (integer menu)``
4073 Data bus frequency. Together with the media bus pixel code, bus type
4074 (clock cycles per sample), the data bus frequency defines the pixel
4075 rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
4076 elsewhere, if the device is not an image sensor). The frame rate can
4077 be calculated from the pixel clock, image width and height and
4078 horizontal and vertical blanking. While the pixel rate control may
4079 be defined elsewhere than in the subdev containing the pixel array,
4080 the frame rate cannot be obtained from that information. This is
4081 because only on the pixel array it can be assumed that the vertical
4082 and horizontal blanking information is exact: no other blanking is
4083 allowed in the pixel array. The selection of frame rate is performed
4084 by selecting the desired horizontal and vertical blanking. The unit
4085 of this control is Hz.
4087 ``V4L2_CID_PIXEL_RATE (64-bit integer)``
4088 Pixel rate in the source pads of the subdev. This control is
4089 read-only and its unit is pixels / second.
4091 ``V4L2_CID_TEST_PATTERN (menu)``
4092 Some capture/display/sensor devices have the capability to generate
4093 test pattern images. These hardware specific test patterns can be
4094 used to test if a device is working properly.
4099 Digital Video Control Reference
4100 ===============================
4102 The Digital Video control class is intended to control receivers and
4103 transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
4104 `DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__
4105 (Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort
4106 (:ref:`dp`). These controls are generally expected to be private to
4107 the receiver or transmitter subdevice that implements them, so they are
4108 only exposed on the ``/dev/v4l-subdev*`` device node.
4110 Note that these devices can have multiple input or output pads which are
4111 hooked up to e.g. HDMI connectors. Even though the subdevice will
4112 receive or transmit video from/to only one of those pads, the other pads
4113 can still be active when it comes to EDID (Extended Display
4114 Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
4115 Content Protection System, :ref:`hdcp`) processing, allowing the
4116 device to do the fairly slow EDID/HDCP handling in advance. This allows
4117 for quick switching between connectors.
4119 These pads appear in several of the controls in this section as
4120 bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad
4121 1, etc. The maximum value of the control is the set of valid pads.
4126 Digital Video Control IDs
4127 -------------------------
4129 ``V4L2_CID_DV_CLASS (class)``
4130 The Digital Video class descriptor.
4132 ``V4L2_CID_DV_TX_HOTPLUG (bitmask)``
4133 Many connectors have a hotplug pin which is high if EDID information
4134 is available from the source. This control shows the state of the
4135 hotplug pin as seen by the transmitter. Each bit corresponds to an
4136 output pad on the transmitter. If an output pad does not have an
4137 associated hotplug pin, then the bit for that pad will be 0. This
4138 read-only control is applicable to DVI-D, HDMI and DisplayPort
4141 ``V4L2_CID_DV_TX_RXSENSE (bitmask)``
4142 Rx Sense is the detection of pull-ups on the TMDS clock lines. This
4143 normally means that the sink has left/entered standby (i.e. the
4144 transmitter can sense that the receiver is ready to receive video).
4145 Each bit corresponds to an output pad on the transmitter. If an
4146 output pad does not have an associated Rx Sense, then the bit for
4147 that pad will be 0. This read-only control is applicable to DVI-D
4150 ``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)``
4151 When the transmitter sees the hotplug signal from the receiver it
4152 will attempt to read the EDID. If set, then the transmitter has read
4153 at least the first block (= 128 bytes). Each bit corresponds to an
4154 output pad on the transmitter. If an output pad does not support
4155 EDIDs, then the bit for that pad will be 0. This read-only control
4156 is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors.
4158 ``V4L2_CID_DV_TX_MODE (enum v4l2_dv_tx_mode)``
4159 HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI
4160 mode (video + audio + auxiliary data). This control selects which
4161 mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI.
4162 This control is applicable to HDMI connectors.
4164 ``V4L2_CID_DV_TX_RGB_RANGE (enum v4l2_dv_rgb_range)``
4165 Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO
4166 follows the RGB quantization range specified in the standard for the
4167 video interface (ie. :ref:`cea861` for HDMI).
4168 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
4169 standard to be compatible with sinks that have not implemented the
4170 standard correctly (unfortunately quite common for HDMI and DVI-D).
4171 Full range allows all possible values to be used whereas limited
4172 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
4173 the number of bits per component. This control is applicable to VGA,
4174 DVI-A/D, HDMI and DisplayPort connectors.
4176 ``V4L2_CID_DV_TX_IT_CONTENT_TYPE (enum v4l2_dv_it_content_type)``
4177 Configures the IT Content Type of the transmitted video. This
4178 information is sent over HDMI and DisplayPort connectors as part of
4179 the AVI InfoFrame. The term 'IT Content' is used for content that
4180 originates from a computer as opposed to content from a TV broadcast
4181 or an analog source. The enum v4l2_dv_it_content_type defines
4182 the possible content types:
4193 - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS``
4195 - Graphics content. Pixel data should be passed unfiltered and
4196 without analog reconstruction.
4200 - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO``
4202 - Photo content. The content is derived from digital still pictures.
4203 The content should be passed through with minimal scaling and
4204 picture enhancements.
4208 - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA``
4214 - ``V4L2_DV_IT_CONTENT_TYPE_GAME``
4216 - Game content. Audio and video latency should be minimized.
4220 - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC``
4222 - No IT Content information is available and the ITC bit in the AVI
4223 InfoFrame is set to 0.
4227 ``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)``
4228 Detects whether the receiver receives power from the source (e.g.
4229 HDMI carries 5V on one of the pins). This is often used to power an
4230 eeprom which contains EDID information, such that the source can
4231 read the EDID even if the sink is in standby/power off. Each bit
4232 corresponds to an input pad on the transmitter. If an input pad
4233 cannot detect whether power is present, then the bit for that pad
4234 will be 0. This read-only control is applicable to DVI-D, HDMI and
4235 DisplayPort connectors.
4237 ``V4L2_CID_DV_RX_RGB_RANGE (enum v4l2_dv_rgb_range)``
4238 Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO
4239 follows the RGB quantization range specified in the standard for the
4240 video interface (ie. :ref:`cea861` for HDMI).
4241 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
4242 standard to be compatible with sources that have not implemented the
4243 standard correctly (unfortunately quite common for HDMI and DVI-D).
4244 Full range allows all possible values to be used whereas limited
4245 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
4246 the number of bits per component. This control is applicable to VGA,
4247 DVI-A/D, HDMI and DisplayPort connectors.
4249 ``V4L2_CID_DV_RX_IT_CONTENT_TYPE (enum v4l2_dv_it_content_type)``
4250 Reads the IT Content Type of the received video. This information is
4251 sent over HDMI and DisplayPort connectors as part of the AVI
4252 InfoFrame. The term 'IT Content' is used for content that originates
4253 from a computer as opposed to content from a TV broadcast or an
4254 analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the
4255 available content types.
4260 FM Receiver Control Reference
4261 =============================
4263 The FM Receiver (FM_RX) class includes controls for common features of
4264 FM Reception capable devices.
4267 .. _fm-rx-control-id:
4272 ``V4L2_CID_FM_RX_CLASS (class)``
4273 The FM_RX class descriptor. Calling
4274 :ref:`VIDIOC_QUERYCTRL` for this control will
4275 return a description of this control class.
4277 ``V4L2_CID_RDS_RECEPTION (boolean)``
4278 Enables/disables RDS reception by the radio tuner
4280 ``V4L2_CID_RDS_RX_PTY (integer)``
4281 Gets RDS Programme Type field. This encodes up to 31 pre-defined
4284 ``V4L2_CID_RDS_RX_PS_NAME (string)``
4285 Gets the Programme Service name (PS_NAME). It is intended for
4286 static display on a receiver. It is the primary aid to listeners in
4287 programme service identification and selection. In Annex E of
4288 :ref:`iec62106`, the RDS specification, there is a full
4289 description of the correct character encoding for Programme Service
4290 name strings. Also from RDS specification, PS is usually a single
4291 eight character text. However, it is also possible to find receivers
4292 which can scroll strings sized as 8 x N characters. So, this control
4293 must be configured with steps of 8 characters. The result is it must
4294 always contain a string with size multiple of 8.
4296 ``V4L2_CID_RDS_RX_RADIO_TEXT (string)``
4297 Gets the Radio Text info. It is a textual description of what is
4298 being broadcasted. RDS Radio Text can be applied when broadcaster
4299 wishes to transmit longer PS names, programme-related information or
4300 any other text. In these cases, RadioText can be used in addition to
4301 ``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is
4302 also fully described in Annex E of :ref:`iec62106`. The length of
4303 Radio Text strings depends on which RDS Block is being used to
4304 transmit it, either 32 (2A block) or 64 (2B block). However, it is
4305 also possible to find receivers which can scroll strings sized as 32
4306 x N or 64 x N characters. So, this control must be configured with
4307 steps of 32 or 64 characters. The result is it must always contain a
4308 string with size multiple of 32 or 64.
4310 ``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)``
4311 If set, then a traffic announcement is in progress.
4313 ``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)``
4314 If set, then the tuned programme carries traffic announcements.
4316 ``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)``
4317 If set, then this channel broadcasts music. If cleared, then it
4318 broadcasts speech. If the transmitter doesn't make this distinction,
4319 then it will be set.
4321 ``V4L2_CID_TUNE_DEEMPHASIS (enum v4l2_deemphasis)``
4322 Configures the de-emphasis value for reception. A de-emphasis filter
4323 is applied to the broadcast to accentuate the high audio
4324 frequencies. Depending on the region, a time constant of either 50
4325 or 75 useconds is used. The enum v4l2_deemphasis defines possible
4326 values for de-emphasis. Here they are:
4337 - ``V4L2_DEEMPHASIS_DISABLED``
4339 - No de-emphasis is applied.
4343 - ``V4L2_DEEMPHASIS_50_uS``
4345 - A de-emphasis of 50 uS is used.
4349 - ``V4L2_DEEMPHASIS_75_uS``
4351 - A de-emphasis of 75 uS is used.
4356 .. _detect-controls:
4358 Detect Control Reference
4359 ========================
4361 The Detect class includes controls for common features of various motion
4362 or object detection capable devices.
4365 .. _detect-control-id:
4370 ``V4L2_CID_DETECT_CLASS (class)``
4371 The Detect class descriptor. Calling
4372 :ref:`VIDIOC_QUERYCTRL` for this control will
4373 return a description of this control class.
4375 ``V4L2_CID_DETECT_MD_MODE (menu)``
4376 Sets the motion detection mode.
4387 - ``V4L2_DETECT_MD_MODE_DISABLED``
4389 - Disable motion detection.
4393 - ``V4L2_DETECT_MD_MODE_GLOBAL``
4395 - Use a single motion detection threshold.
4399 - ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID``
4401 - The image is divided into a grid, each cell with its own motion
4402 detection threshold. These thresholds are set through the
4403 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID`` matrix control.
4407 - ``V4L2_DETECT_MD_MODE_REGION_GRID``
4409 - The image is divided into a grid, each cell with its own region
4410 value that specifies which per-region motion detection thresholds
4411 should be used. Each region has its own thresholds. How these
4412 per-region thresholds are set up is driver-specific. The region
4413 values for the grid are set through the
4414 ``V4L2_CID_DETECT_MD_REGION_GRID`` matrix control.
4418 ``V4L2_CID_DETECT_MD_GLOBAL_THRESHOLD (integer)``
4419 Sets the global motion detection threshold to be used with the
4420 ``V4L2_DETECT_MD_MODE_GLOBAL`` motion detection mode.
4422 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID (__u16 matrix)``
4423 Sets the motion detection thresholds for each cell in the grid. To
4424 be used with the ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID`` motion
4425 detection mode. Matrix element (0, 0) represents the cell at the
4426 top-left of the grid.
4428 ``V4L2_CID_DETECT_MD_REGION_GRID (__u8 matrix)``
4429 Sets the motion detection region value for each cell in the grid. To
4430 be used with the ``V4L2_DETECT_MD_MODE_REGION_GRID`` motion
4431 detection mode. Matrix element (0, 0) represents the cell at the
4432 top-left of the grid.
4435 .. _rf-tuner-controls:
4437 RF Tuner Control Reference
4438 ==========================
4440 The RF Tuner (RF_TUNER) class includes controls for common features of
4441 devices having RF tuner.
4443 In this context, RF tuner is radio receiver circuit between antenna and
4444 demodulator. It receives radio frequency (RF) from the antenna and
4445 converts that received signal to lower intermediate frequency (IF) or
4446 baseband frequency (BB). Tuners that could do baseband output are often
4447 called Zero-IF tuners. Older tuners were typically simple PLL tuners
4448 inside a metal box, whilst newer ones are highly integrated chips
4449 without a metal box "silicon tuners". These controls are mostly
4450 applicable for new feature rich silicon tuners, just because older
4451 tuners does not have much adjustable features.
4453 For more information about RF tuners see
4454 `Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
4455 and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
4459 .. _rf-tuner-control-id:
4461 RF_TUNER Control IDs
4462 --------------------
4464 ``V4L2_CID_RF_TUNER_CLASS (class)``
4465 The RF_TUNER class descriptor. Calling
4466 :ref:`VIDIOC_QUERYCTRL` for this control will
4467 return a description of this control class.
4469 ``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
4470 Enables/disables tuner radio channel bandwidth configuration. In
4471 automatic mode bandwidth configuration is performed by the driver.
4473 ``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
4474 Filter(s) on tuner signal path are used to filter signal according
4475 to receiving party needs. Driver configures filters to fulfill
4476 desired bandwidth requirement. Used when
4477 V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
4478 range and step are driver-specific.
4480 ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
4481 Enables/disables LNA automatic gain control (AGC)
4483 ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
4484 Enables/disables mixer automatic gain control (AGC)
4486 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
4487 Enables/disables IF automatic gain control (AGC)
4489 ``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
4490 The RF amplifier is the very first amplifier on the receiver signal
4491 path, just right after the antenna input. The difference between the
4492 LNA gain and the RF gain in this document is that the LNA gain is
4493 integrated in the tuner chip while the RF gain is a separate chip.
4494 There may be both RF and LNA gain controls in the same device. The
4495 range and step are driver-specific.
4497 ``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
4498 LNA (low noise amplifier) gain is first gain stage on the RF tuner
4499 signal path. It is located very close to tuner antenna input. Used
4500 when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
4501 ``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
4502 differs from the each others. The range and step are
4505 ``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
4506 Mixer gain is second gain stage on the RF tuner signal path. It is
4507 located inside mixer block, where RF signal is down-converted by the
4508 mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
4509 The range and step are driver-specific.
4511 ``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
4512 IF gain is last gain stage on the RF tuner signal path. It is
4513 located on output of RF tuner. It controls signal level of
4514 intermediate frequency output or baseband output. Used when
4515 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
4516 are driver-specific.
4518 ``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
4519 Is synthesizer PLL locked? RF tuner is receiving given frequency
4520 when that control is set. This is a read-only control.
4523 This control may be changed to a menu control in the future, if more
4524 options are required.
projects / deliverable / linux.git / blob