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.
89 #. It is important to realize that due to the flexibility of controls it is
90 necessary to check whether the control you want to set actually is
91 supported in the driver and what the valid range of values is. So use
92 the :ref:`VIDIOC_QUERYCTRL` (or :ref:`VIDIOC_QUERY_EXT_CTRL
93 <VIDIOC_QUERYCTRL>`) and :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>`
96 #. It is possible that some of the menu indices in a control of
97 type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
98 will return an error). A good example is the list of supported MPEG
99 audio bitrates. Some drivers only support one or two bitrates, others
100 support a wider range.
102 All controls use machine endianness.
105 Enumerating Extended Controls
106 =============================
108 The recommended way to enumerate over the extended controls is by using
109 :ref:`VIDIOC_QUERYCTRL` in combination with the
110 ``V4L2_CTRL_FLAG_NEXT_CTRL`` flag:
115 struct v4l2_queryctrl qctrl;
117 qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
118 while (0 == ioctl (fd, VIDIOC_QUERYCTRL, &qctrl)) {
120 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
123 The initial control ID is set to 0 ORed with the
124 ``V4L2_CTRL_FLAG_NEXT_CTRL`` flag. The ``VIDIOC_QUERYCTRL`` ioctl will
125 return the first control with a higher ID than the specified one. When
126 no such controls are found an error is returned.
128 If you want to get all controls within a specific control class, then
129 you can set the initial ``qctrl.id`` value to the control class and add
130 an extra check to break out of the loop when a control of another
131 control class is found:
136 qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
137 while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &qctrl)) {
138 if (V4L2_CTRL_ID2CLASS(qctrl.id) != V4L2_CTRL_CLASS_MPEG)
141 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
144 The 32-bit ``qctrl.id`` value is subdivided into three bit ranges: the
145 top 4 bits are reserved for flags (e. g. ``V4L2_CTRL_FLAG_NEXT_CTRL``)
146 and are not actually part of the ID. The remaining 28 bits form the
147 control ID, of which the most significant 12 bits define the control
148 class and the least significant 16 bits identify the control within the
149 control class. It is guaranteed that these last 16 bits are always
150 non-zero for controls. The range of 0x1000 and up are reserved for
151 driver-specific controls. The macro ``V4L2_CTRL_ID2CLASS(id)`` returns
152 the control class ID based on a control ID.
154 If the driver does not support extended controls, then
155 ``VIDIOC_QUERYCTRL`` will fail when used in combination with
156 ``V4L2_CTRL_FLAG_NEXT_CTRL``. In that case the old method of enumerating
157 control should be used (see :ref:`enum_all_controls`). But if it is
158 supported, then it is guaranteed to enumerate over all controls,
159 including driver-private controls.
162 Creating Control Panels
163 =======================
165 It is possible to create control panels for a graphical user interface
166 where the user can select the various controls. Basically you will have
167 to iterate over all controls using the method described above. Each
168 control class starts with a control of type
169 ``V4L2_CTRL_TYPE_CTRL_CLASS``. ``VIDIOC_QUERYCTRL`` will return the name
170 of this control class which can be used as the title of a tab page
171 within a control panel.
173 The flags field of struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` also
174 contains hints on the behavior of the control. See the
175 :ref:`VIDIOC_QUERYCTRL` documentation for more
181 Codec Control Reference
182 =======================
184 Below all controls within the Codec control class are described. First
185 the generic controls, then controls specific for certain hardware.
187 .. note:: These controls are applicable to all codecs and not just MPEG. The
188 defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
189 were originally made for MPEG codecs and later extended to cover all
193 Generic Codec Controls
194 ----------------------
202 ``V4L2_CID_MPEG_CLASS (class)``
203 The Codec class descriptor. Calling
204 :ref:`VIDIOC_QUERYCTRL` for this control will
205 return a description of this control class. This description can be
206 used as the caption of a Tab page in a GUI, for example.
208 .. _v4l2-mpeg-stream-type:
210 ``V4L2_CID_MPEG_STREAM_TYPE (enum v4l2_mpeg_stream_type)``
211 The MPEG-1, -2 or -4 output stream type. One cannot assume anything
212 here. Each hardware MPEG encoder tends to support different subsets
213 of the available MPEG stream types. This control is specific to
214 multiplexed MPEG streams. The currently defined stream types are:
225 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_PS``
227 - MPEG-2 program stream
231 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_TS``
233 - MPEG-2 transport stream
237 - ``V4L2_MPEG_STREAM_TYPE_MPEG1_SS``
239 - MPEG-1 system stream
243 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_DVD``
245 - MPEG-2 DVD-compatible stream
249 - ``V4L2_MPEG_STREAM_TYPE_MPEG1_VCD``
251 - MPEG-1 VCD-compatible stream
255 - ``V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD``
257 - MPEG-2 SVCD-compatible stream
261 ``V4L2_CID_MPEG_STREAM_PID_PMT (integer)``
262 Program Map Table Packet ID for the MPEG transport stream (default
265 ``V4L2_CID_MPEG_STREAM_PID_AUDIO (integer)``
266 Audio Packet ID for the MPEG transport stream (default 256)
268 ``V4L2_CID_MPEG_STREAM_PID_VIDEO (integer)``
269 Video Packet ID for the MPEG transport stream (default 260)
271 ``V4L2_CID_MPEG_STREAM_PID_PCR (integer)``
272 Packet ID for the MPEG transport stream carrying PCR fields (default
275 ``V4L2_CID_MPEG_STREAM_PES_ID_AUDIO (integer)``
276 Audio ID for MPEG PES
278 ``V4L2_CID_MPEG_STREAM_PES_ID_VIDEO (integer)``
279 Video ID for MPEG PES
281 .. _v4l2-mpeg-stream-vbi-fmt:
283 ``V4L2_CID_MPEG_STREAM_VBI_FMT (enum v4l2_mpeg_stream_vbi_fmt)``
284 Some cards can embed VBI data (e. g. Closed Caption, Teletext) into
285 the MPEG stream. This control selects whether VBI data should be
286 embedded, and if so, what embedding method should be used. The list
287 of possible VBI formats depends on the driver. The currently defined
288 VBI format types are:
299 - ``V4L2_MPEG_STREAM_VBI_FMT_NONE``
301 - No VBI in the MPEG stream
305 - ``V4L2_MPEG_STREAM_VBI_FMT_IVTV``
307 - VBI in private packets, IVTV format (documented in the kernel
309 ``Documentation/video4linux/cx2341x/README.vbi``)
313 .. _v4l2-mpeg-audio-sampling-freq:
315 ``V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ (enum v4l2_mpeg_audio_sampling_freq)``
316 MPEG Audio sampling frequency. Possible values are:
327 - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100``
333 - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000``
339 - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000``
345 .. _v4l2-mpeg-audio-encoding:
347 ``V4L2_CID_MPEG_AUDIO_ENCODING (enum v4l2_mpeg_audio_encoding)``
348 MPEG Audio encoding. This control is specific to multiplexed MPEG
349 streams. Possible values are:
360 - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_1``
362 - MPEG-1/2 Layer I encoding
366 - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_2``
368 - MPEG-1/2 Layer II encoding
372 - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_3``
374 - MPEG-1/2 Layer III encoding
378 - ``V4L2_MPEG_AUDIO_ENCODING_AAC``
380 - MPEG-2/4 AAC (Advanced Audio Coding)
384 - ``V4L2_MPEG_AUDIO_ENCODING_AC3``
386 - AC-3 aka ATSC A/52 encoding
390 .. _v4l2-mpeg-audio-l1-bitrate:
392 ``V4L2_CID_MPEG_AUDIO_L1_BITRATE (enum v4l2_mpeg_audio_l1_bitrate)``
393 MPEG-1/2 Layer I bitrate. Possible values are:
404 - ``V4L2_MPEG_AUDIO_L1_BITRATE_32K``
410 - ``V4L2_MPEG_AUDIO_L1_BITRATE_64K``
416 - ``V4L2_MPEG_AUDIO_L1_BITRATE_96K``
422 - ``V4L2_MPEG_AUDIO_L1_BITRATE_128K``
428 - ``V4L2_MPEG_AUDIO_L1_BITRATE_160K``
434 - ``V4L2_MPEG_AUDIO_L1_BITRATE_192K``
440 - ``V4L2_MPEG_AUDIO_L1_BITRATE_224K``
446 - ``V4L2_MPEG_AUDIO_L1_BITRATE_256K``
452 - ``V4L2_MPEG_AUDIO_L1_BITRATE_288K``
458 - ``V4L2_MPEG_AUDIO_L1_BITRATE_320K``
464 - ``V4L2_MPEG_AUDIO_L1_BITRATE_352K``
470 - ``V4L2_MPEG_AUDIO_L1_BITRATE_384K``
476 - ``V4L2_MPEG_AUDIO_L1_BITRATE_416K``
482 - ``V4L2_MPEG_AUDIO_L1_BITRATE_448K``
488 .. _v4l2-mpeg-audio-l2-bitrate:
490 ``V4L2_CID_MPEG_AUDIO_L2_BITRATE (enum v4l2_mpeg_audio_l2_bitrate)``
491 MPEG-1/2 Layer II bitrate. Possible values are:
502 - ``V4L2_MPEG_AUDIO_L2_BITRATE_32K``
508 - ``V4L2_MPEG_AUDIO_L2_BITRATE_48K``
514 - ``V4L2_MPEG_AUDIO_L2_BITRATE_56K``
520 - ``V4L2_MPEG_AUDIO_L2_BITRATE_64K``
526 - ``V4L2_MPEG_AUDIO_L2_BITRATE_80K``
532 - ``V4L2_MPEG_AUDIO_L2_BITRATE_96K``
538 - ``V4L2_MPEG_AUDIO_L2_BITRATE_112K``
544 - ``V4L2_MPEG_AUDIO_L2_BITRATE_128K``
550 - ``V4L2_MPEG_AUDIO_L2_BITRATE_160K``
556 - ``V4L2_MPEG_AUDIO_L2_BITRATE_192K``
562 - ``V4L2_MPEG_AUDIO_L2_BITRATE_224K``
568 - ``V4L2_MPEG_AUDIO_L2_BITRATE_256K``
574 - ``V4L2_MPEG_AUDIO_L2_BITRATE_320K``
580 - ``V4L2_MPEG_AUDIO_L2_BITRATE_384K``
586 .. _v4l2-mpeg-audio-l3-bitrate:
588 ``V4L2_CID_MPEG_AUDIO_L3_BITRATE (enum v4l2_mpeg_audio_l3_bitrate)``
589 MPEG-1/2 Layer III bitrate. Possible values are:
600 - ``V4L2_MPEG_AUDIO_L3_BITRATE_32K``
606 - ``V4L2_MPEG_AUDIO_L3_BITRATE_40K``
612 - ``V4L2_MPEG_AUDIO_L3_BITRATE_48K``
618 - ``V4L2_MPEG_AUDIO_L3_BITRATE_56K``
624 - ``V4L2_MPEG_AUDIO_L3_BITRATE_64K``
630 - ``V4L2_MPEG_AUDIO_L3_BITRATE_80K``
636 - ``V4L2_MPEG_AUDIO_L3_BITRATE_96K``
642 - ``V4L2_MPEG_AUDIO_L3_BITRATE_112K``
648 - ``V4L2_MPEG_AUDIO_L3_BITRATE_128K``
654 - ``V4L2_MPEG_AUDIO_L3_BITRATE_160K``
660 - ``V4L2_MPEG_AUDIO_L3_BITRATE_192K``
666 - ``V4L2_MPEG_AUDIO_L3_BITRATE_224K``
672 - ``V4L2_MPEG_AUDIO_L3_BITRATE_256K``
678 - ``V4L2_MPEG_AUDIO_L3_BITRATE_320K``
684 ``V4L2_CID_MPEG_AUDIO_AAC_BITRATE (integer)``
685 AAC bitrate in bits per second.
687 .. _v4l2-mpeg-audio-ac3-bitrate:
689 ``V4L2_CID_MPEG_AUDIO_AC3_BITRATE (enum v4l2_mpeg_audio_ac3_bitrate)``
690 AC-3 bitrate. Possible values are:
701 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_32K``
707 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_40K``
713 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_48K``
719 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_56K``
725 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_64K``
731 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_80K``
737 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_96K``
743 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_112K``
749 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_128K``
755 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_160K``
761 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_192K``
767 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_224K``
773 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_256K``
779 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_320K``
785 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_384K``
791 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_448K``
797 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_512K``
803 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_576K``
809 - ``V4L2_MPEG_AUDIO_AC3_BITRATE_640K``
815 .. _v4l2-mpeg-audio-mode:
817 ``V4L2_CID_MPEG_AUDIO_MODE (enum v4l2_mpeg_audio_mode)``
818 MPEG Audio mode. Possible values are:
829 - ``V4L2_MPEG_AUDIO_MODE_STEREO``
835 - ``V4L2_MPEG_AUDIO_MODE_JOINT_STEREO``
841 - ``V4L2_MPEG_AUDIO_MODE_DUAL``
847 - ``V4L2_MPEG_AUDIO_MODE_MONO``
853 .. _v4l2-mpeg-audio-mode-extension:
855 ``V4L2_CID_MPEG_AUDIO_MODE_EXTENSION (enum v4l2_mpeg_audio_mode_extension)``
856 Joint Stereo audio mode extension. In Layer I and II they indicate
857 which subbands are in intensity stereo. All other subbands are coded
858 in stereo. Layer III is not (yet) supported. Possible values are:
869 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4``
871 - Subbands 4-31 in intensity stereo
875 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8``
877 - Subbands 8-31 in intensity stereo
881 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12``
883 - Subbands 12-31 in intensity stereo
887 - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16``
889 - Subbands 16-31 in intensity stereo
893 .. _v4l2-mpeg-audio-emphasis:
895 ``V4L2_CID_MPEG_AUDIO_EMPHASIS (enum v4l2_mpeg_audio_emphasis)``
896 Audio Emphasis. Possible values are:
907 - ``V4L2_MPEG_AUDIO_EMPHASIS_NONE``
913 - ``V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS``
915 - 50/15 microsecond emphasis
919 - ``V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17``
925 .. _v4l2-mpeg-audio-crc:
927 ``V4L2_CID_MPEG_AUDIO_CRC (enum v4l2_mpeg_audio_crc)``
928 CRC method. Possible values are:
939 - ``V4L2_MPEG_AUDIO_CRC_NONE``
945 - ``V4L2_MPEG_AUDIO_CRC_CRC16``
947 - 16 bit parity check
951 ``V4L2_CID_MPEG_AUDIO_MUTE (boolean)``
952 Mutes the audio when capturing. This is not done by muting audio
953 hardware, which can still produce a slight hiss, but in the encoder
954 itself, guaranteeing a fixed and reproducible audio bitstream. 0 =
957 .. _v4l2-mpeg-audio-dec-playback:
959 ``V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK (enum v4l2_mpeg_audio_dec_playback)``
960 Determines how monolingual audio should be played back. Possible
972 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO``
974 - Automatically determines the best playback mode.
978 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO``
984 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT``
986 - Left channel playback.
990 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT``
992 - Right channel playback.
996 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO``
1002 - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO``
1004 - Stereo playback with swapped left and right channels.
1008 .. _v4l2-mpeg-audio-dec-multilingual-playback:
1010 ``V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK (enum v4l2_mpeg_audio_dec_playback)``
1011 Determines how multilingual audio should be played back.
1013 .. _v4l2-mpeg-video-encoding:
1015 ``V4L2_CID_MPEG_VIDEO_ENCODING (enum v4l2_mpeg_video_encoding)``
1016 MPEG Video encoding method. This control is specific to multiplexed
1017 MPEG streams. Possible values are:
1028 - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_1``
1030 - MPEG-1 Video encoding
1034 - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_2``
1036 - MPEG-2 Video encoding
1040 - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC``
1042 - MPEG-4 AVC (H.264) Video encoding
1046 .. _v4l2-mpeg-video-aspect:
1048 ``V4L2_CID_MPEG_VIDEO_ASPECT (enum v4l2_mpeg_video_aspect)``
1049 Video aspect. Possible values are:
1060 - ``V4L2_MPEG_VIDEO_ASPECT_1x1``
1064 - ``V4L2_MPEG_VIDEO_ASPECT_4x3``
1068 - ``V4L2_MPEG_VIDEO_ASPECT_16x9``
1072 - ``V4L2_MPEG_VIDEO_ASPECT_221x100``
1076 ``V4L2_CID_MPEG_VIDEO_B_FRAMES (integer)``
1077 Number of B-Frames (default 2)
1079 ``V4L2_CID_MPEG_VIDEO_GOP_SIZE (integer)``
1080 GOP size (default 12)
1082 ``V4L2_CID_MPEG_VIDEO_GOP_CLOSURE (boolean)``
1083 GOP closure (default 1)
1085 ``V4L2_CID_MPEG_VIDEO_PULLDOWN (boolean)``
1086 Enable 3:2 pulldown (default 0)
1088 .. _v4l2-mpeg-video-bitrate-mode:
1090 ``V4L2_CID_MPEG_VIDEO_BITRATE_MODE (enum v4l2_mpeg_video_bitrate_mode)``
1091 Video bitrate mode. Possible values are:
1102 - ``V4L2_MPEG_VIDEO_BITRATE_MODE_VBR``
1108 - ``V4L2_MPEG_VIDEO_BITRATE_MODE_CBR``
1114 ``V4L2_CID_MPEG_VIDEO_BITRATE (integer)``
1115 Video bitrate in bits per second.
1117 ``V4L2_CID_MPEG_VIDEO_BITRATE_PEAK (integer)``
1118 Peak video bitrate in bits per second. Must be larger or equal to
1119 the average video bitrate. It is ignored if the video bitrate mode
1120 is set to constant bitrate.
1122 ``V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION (integer)``
1123 For every captured frame, skip this many subsequent frames (default
1126 ``V4L2_CID_MPEG_VIDEO_MUTE (boolean)``
1127 "Mutes" the video to a fixed color when capturing. This is useful
1128 for testing, to produce a fixed video bitstream. 0 = unmuted, 1 =
1131 ``V4L2_CID_MPEG_VIDEO_MUTE_YUV (integer)``
1132 Sets the "mute" color of the video. The supplied 32-bit integer is
1133 interpreted as follows (bit 0 = least significant bit):
1146 - V chrominance information
1152 - U chrominance information
1158 - Y luminance information
1168 .. _v4l2-mpeg-video-dec-pts:
1170 ``V4L2_CID_MPEG_VIDEO_DEC_PTS (integer64)``
1171 This read-only control returns the 33-bit video Presentation Time
1172 Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of the
1173 currently displayed frame. This is the same PTS as is used in
1174 :ref:`VIDIOC_DECODER_CMD`.
1176 .. _v4l2-mpeg-video-dec-frame:
1178 ``V4L2_CID_MPEG_VIDEO_DEC_FRAME (integer64)``
1179 This read-only control returns the frame counter of the frame that
1180 is currently displayed (decoded). This value is reset to 0 whenever
1181 the decoder is started.
1183 ``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
1184 If enabled the decoder expects to receive a single slice per buffer,
1185 otherwise the decoder expects a single frame in per buffer.
1186 Applicable to the decoder, all codecs.
1188 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_ENABLE (boolean)``
1189 Enable writing sample aspect ratio in the Video Usability
1190 Information. Applicable to the H264 encoder.
1192 .. _v4l2-mpeg-video-h264-vui-sar-idc:
1194 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_IDC (enum v4l2_mpeg_video_h264_vui_sar_idc)``
1195 VUI sample aspect ratio indicator for H.264 encoding. The value is
1196 defined in the table E-1 in the standard. Applicable to the H264
1208 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_UNSPECIFIED``
1214 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_1x1``
1220 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_12x11``
1226 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_10x11``
1232 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_16x11``
1238 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_40x33``
1244 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_24x11``
1250 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_20x11``
1256 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_32x11``
1262 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_80x33``
1268 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_18x11``
1274 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_15x11``
1280 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_64x33``
1286 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_160x99``
1292 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_4x3``
1298 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_3x2``
1304 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_2x1``
1310 - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_EXTENDED``
1316 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_WIDTH (integer)``
1317 Extended sample aspect ratio width for H.264 VUI encoding.
1318 Applicable to the H264 encoder.
1320 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_HEIGHT (integer)``
1321 Extended sample aspect ratio height for H.264 VUI encoding.
1322 Applicable to the H264 encoder.
1324 .. _v4l2-mpeg-video-h264-level:
1326 ``V4L2_CID_MPEG_VIDEO_H264_LEVEL (enum v4l2_mpeg_video_h264_level)``
1327 The level information for the H264 video elementary stream.
1328 Applicable to the H264 encoder. Possible values are:
1339 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_0``
1345 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1B``
1351 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_1``
1357 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_2``
1363 - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_3``
1369 - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_0``
1375 - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_1``
1381 - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_2``
1387 - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_0``
1393 - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_1``
1399 - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_2``
1405 - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_0``
1411 - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_1``
1417 - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_2``
1423 - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_0``
1429 - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_1``
1435 .. _v4l2-mpeg-video-mpeg4-level:
1437 ``V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL (enum v4l2_mpeg_video_mpeg4_level)``
1438 The level information for the MPEG4 elementary stream. Applicable to
1439 the MPEG4 encoder. Possible values are:
1450 - ``V4L2_MPEG_VIDEO_LEVEL_0``
1456 - ``V4L2_MPEG_VIDEO_LEVEL_0B``
1462 - ``V4L2_MPEG_VIDEO_LEVEL_1``
1468 - ``V4L2_MPEG_VIDEO_LEVEL_2``
1474 - ``V4L2_MPEG_VIDEO_LEVEL_3``
1480 - ``V4L2_MPEG_VIDEO_LEVEL_3B``
1486 - ``V4L2_MPEG_VIDEO_LEVEL_4``
1492 - ``V4L2_MPEG_VIDEO_LEVEL_5``
1498 .. _v4l2-mpeg-video-h264-profile:
1500 ``V4L2_CID_MPEG_VIDEO_H264_PROFILE (enum v4l2_mpeg_video_h264_profile)``
1501 The profile information for H264. Applicable to the H264 encoder.
1502 Possible values are:
1513 - ``V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE``
1519 - ``V4L2_MPEG_VIDEO_H264_PROFILE_CONSTRAINED_BASELINE``
1521 - Constrained Baseline profile
1525 - ``V4L2_MPEG_VIDEO_H264_PROFILE_MAIN``
1531 - ``V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED``
1537 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH``
1543 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10``
1549 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422``
1555 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE``
1557 - High 444 Predictive profile
1561 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10_INTRA``
1563 - High 10 Intra profile
1567 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422_INTRA``
1569 - High 422 Intra profile
1573 - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_INTRA``
1575 - High 444 Intra profile
1579 - ``V4L2_MPEG_VIDEO_H264_PROFILE_CAVLC_444_INTRA``
1581 - CAVLC 444 Intra profile
1585 - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE``
1587 - Scalable Baseline profile
1591 - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH``
1593 - Scalable High profile
1597 - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH_INTRA``
1599 - Scalable High Intra profile
1603 - ``V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH``
1605 - Stereo High profile
1609 - ``V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH``
1611 - Multiview High profile
1615 .. _v4l2-mpeg-video-mpeg4-profile:
1617 ``V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE (enum v4l2_mpeg_video_mpeg4_profile)``
1618 The profile information for MPEG4. Applicable to the MPEG4 encoder.
1619 Possible values are:
1630 - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE``
1636 - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_SIMPLE``
1638 - Advanced Simple profile
1642 - ``V4L2_MPEG_VIDEO_PROFILE_CORE``
1648 - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE_SCALABLE``
1650 - Simple Scalable profile
1654 - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_CODING_EFFICIENCY``
1660 ``V4L2_CID_MPEG_VIDEO_MAX_REF_PIC (integer)``
1661 The maximum number of reference pictures used for encoding.
1662 Applicable to the encoder.
1664 .. _v4l2-mpeg-video-multi-slice-mode:
1666 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE (enum v4l2_mpeg_video_multi_slice_mode)``
1667 Determines how the encoder should handle division of frame into
1668 slices. Applicable to the encoder. Possible values are:
1679 - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_SINGLE``
1681 - Single slice per frame.
1685 - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``
1687 - Multiple slices with set maximum number of macroblocks per slice.
1691 - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``
1693 - Multiple slice with set maximum size in bytes per slice.
1697 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB (integer)``
1698 The maximum number of macroblocks in a slice. Used when
1699 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1700 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``. Applicable to the
1703 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES (integer)``
1704 The maximum size of a slice in bytes. Used when
1705 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1706 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``. Applicable to the
1709 .. _v4l2-mpeg-video-h264-loop-filter-mode:
1711 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_MODE (enum v4l2_mpeg_video_h264_loop_filter_mode)``
1712 Loop filter mode for H264 encoder. Possible values are:
1723 - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_ENABLED``
1725 - Loop filter is enabled.
1729 - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED``
1731 - Loop filter is disabled.
1735 - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
1737 - Loop filter is disabled at the slice boundary.
1741 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)``
1742 Loop filter alpha coefficient, defined in the H264 standard.
1743 Applicable to the H264 encoder.
1745 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)``
1746 Loop filter beta coefficient, defined in the H264 standard.
1747 Applicable to the H264 encoder.
1749 .. _v4l2-mpeg-video-h264-entropy-mode:
1751 ``V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE (enum v4l2_mpeg_video_h264_entropy_mode)``
1752 Entropy coding mode for H264 - CABAC/CAVALC. Applicable to the H264
1753 encoder. Possible values are:
1764 - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CAVLC``
1766 - Use CAVLC entropy coding.
1770 - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CABAC``
1772 - Use CABAC entropy coding.
1776 ``V4L2_CID_MPEG_VIDEO_H264_8X8_TRANSFORM (boolean)``
1777 Enable 8X8 transform for H264. Applicable to the H264 encoder.
1779 ``V4L2_CID_MPEG_VIDEO_CYCLIC_INTRA_REFRESH_MB (integer)``
1780 Cyclic intra macroblock refresh. This is the number of continuous
1781 macroblocks refreshed every frame. Each frame a successive set of
1782 macroblocks is refreshed until the cycle completes and starts from
1783 the top of the frame. Applicable to H264, H263 and MPEG4 encoder.
1785 ``V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE (boolean)``
1786 Frame level rate control enable. If this control is disabled then
1787 the quantization parameter for each frame type is constant and set
1788 with appropriate controls (e.g.
1789 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP``). If frame rate control is
1790 enabled then quantization parameter is adjusted to meet the chosen
1791 bitrate. Minimum and maximum value for the quantization parameter
1792 can be set with appropriate controls (e.g.
1793 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP``). Applicable to encoders.
1795 ``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE (boolean)``
1796 Macroblock level rate control enable. Applicable to the MPEG4 and
1799 ``V4L2_CID_MPEG_VIDEO_MPEG4_QPEL (boolean)``
1800 Quarter pixel motion estimation for MPEG4. Applicable to the MPEG4
1803 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (integer)``
1804 Quantization parameter for an I frame for H263. Valid range: from 1
1807 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP (integer)``
1808 Minimum quantization parameter for H263. Valid range: from 1 to 31.
1810 ``V4L2_CID_MPEG_VIDEO_H263_MAX_QP (integer)``
1811 Maximum quantization parameter for H263. Valid range: from 1 to 31.
1813 ``V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (integer)``
1814 Quantization parameter for an P frame for H263. Valid range: from 1
1817 ``V4L2_CID_MPEG_VIDEO_H263_B_FRAME_QP (integer)``
1818 Quantization parameter for an B frame for H263. Valid range: from 1
1821 ``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_QP (integer)``
1822 Quantization parameter for an I frame for H264. Valid range: from 0
1825 ``V4L2_CID_MPEG_VIDEO_H264_MIN_QP (integer)``
1826 Minimum quantization parameter for H264. Valid range: from 0 to 51.
1828 ``V4L2_CID_MPEG_VIDEO_H264_MAX_QP (integer)``
1829 Maximum quantization parameter for H264. Valid range: from 0 to 51.
1831 ``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP (integer)``
1832 Quantization parameter for an P frame for H264. Valid range: from 0
1835 ``V4L2_CID_MPEG_VIDEO_H264_B_FRAME_QP (integer)``
1836 Quantization parameter for an B frame for H264. Valid range: from 0
1839 ``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
1840 Quantization parameter for an I frame for MPEG4. Valid range: from 1
1843 ``V4L2_CID_MPEG_VIDEO_MPEG4_MIN_QP (integer)``
1844 Minimum quantization parameter for MPEG4. Valid range: from 1 to 31.
1846 ``V4L2_CID_MPEG_VIDEO_MPEG4_MAX_QP (integer)``
1847 Maximum quantization parameter for MPEG4. Valid range: from 1 to 31.
1849 ``V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (integer)``
1850 Quantization parameter for an P frame for MPEG4. Valid range: from 1
1853 ``V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (integer)``
1854 Quantization parameter for an B frame for MPEG4. Valid range: from 1
1857 ``V4L2_CID_MPEG_VIDEO_VBV_SIZE (integer)``
1858 The Video Buffer Verifier size in kilobytes, it is used as a
1859 limitation of frame skip. The VBV is defined in the standard as a
1860 mean to verify that the produced stream will be successfully
1861 decoded. The standard describes it as "Part of a hypothetical
1862 decoder that is conceptually connected to the output of the encoder.
1863 Its purpose is to provide a constraint on the variability of the
1864 data rate that an encoder or editing process may produce.".
1865 Applicable to the MPEG1, MPEG2, MPEG4 encoders.
1867 .. _v4l2-mpeg-video-vbv-delay:
1869 ``V4L2_CID_MPEG_VIDEO_VBV_DELAY (integer)``
1870 Sets the initial delay in milliseconds for VBV buffer control.
1872 .. _v4l2-mpeg-video-hor-search-range:
1874 ``V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (integer)``
1875 Horizontal search range defines maximum horizontal search area in
1876 pixels to search and match for the present Macroblock (MB) in the
1877 reference picture. This V4L2 control macro is used to set horizontal
1878 search range for motion estimation module in video encoder.
1880 .. _v4l2-mpeg-video-vert-search-range:
1882 ``V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (integer)``
1883 Vertical search range defines maximum vertical search area in pixels
1884 to search and match for the present Macroblock (MB) in the reference
1885 picture. This V4L2 control macro is used to set vertical search
1886 range for motion estimation module in video encoder.
1888 .. _v4l2-mpeg-video-force-key-frame:
1890 ``V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (button)``
1891 Force a key frame for the next queued buffer. Applicable to
1892 encoders. This is a general, codec-agnostic keyframe control.
1894 ``V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE (integer)``
1895 The Coded Picture Buffer size in kilobytes, it is used as a
1896 limitation of frame skip. The CPB is defined in the H264 standard as
1897 a mean to verify that the produced stream will be successfully
1898 decoded. Applicable to the H264 encoder.
1900 ``V4L2_CID_MPEG_VIDEO_H264_I_PERIOD (integer)``
1901 Period between I-frames in the open GOP for H264. In case of an open
1902 GOP this is the period between two I-frames. The period between IDR
1903 (Instantaneous Decoding Refresh) frames is taken from the GOP_SIZE
1904 control. An IDR frame, which stands for Instantaneous Decoding
1905 Refresh is an I-frame after which no prior frames are referenced.
1906 This means that a stream can be restarted from an IDR frame without
1907 the need to store or decode any previous frames. Applicable to the
1910 .. _v4l2-mpeg-video-header-mode:
1912 ``V4L2_CID_MPEG_VIDEO_HEADER_MODE (enum v4l2_mpeg_video_header_mode)``
1913 Determines whether the header is returned as the first buffer or is
1914 it returned together with the first frame. Applicable to encoders.
1915 Possible values are:
1926 - ``V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE``
1928 - The stream header is returned separately in the first buffer.
1932 - ``V4L2_MPEG_VIDEO_HEADER_MODE_JOINED_WITH_1ST_FRAME``
1934 - The stream header is returned together with the first encoded
1939 ``V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (boolean)``
1940 Repeat the video sequence headers. Repeating these headers makes
1941 random access to the video stream easier. Applicable to the MPEG1, 2
1944 ``V4L2_CID_MPEG_VIDEO_DECODER_MPEG4_DEBLOCK_FILTER (boolean)``
1945 Enabled the deblocking post processing filter for MPEG4 decoder.
1946 Applicable to the MPEG4 decoder.
1948 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_RES (integer)``
1949 vop_time_increment_resolution value for MPEG4. Applicable to the
1952 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_INC (integer)``
1953 vop_time_increment value for MPEG4. Applicable to the MPEG4
1956 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FRAME_PACKING (boolean)``
1957 Enable generation of frame packing supplemental enhancement
1958 information in the encoded bitstream. The frame packing SEI message
1959 contains the arrangement of L and R planes for 3D viewing.
1960 Applicable to the H264 encoder.
1962 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_CURRENT_FRAME_0 (boolean)``
1963 Sets current frame as frame0 in frame packing SEI. Applicable to the
1966 .. _v4l2-mpeg-video-h264-sei-fp-arrangement-type:
1968 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE (enum v4l2_mpeg_video_h264_sei_fp_arrangement_type)``
1969 Frame packing arrangement type for H264 SEI. Applicable to the H264
1970 encoder. Possible values are:
1981 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_CHEKERBOARD``
1983 - Pixels are alternatively from L and R.
1987 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_COLUMN``
1989 - L and R are interlaced by column.
1993 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_ROW``
1995 - L and R are interlaced by row.
1999 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_SIDE_BY_SIDE``
2001 - L is on the left, R on the right.
2005 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TOP_BOTTOM``
2007 - L is on top, R on bottom.
2011 - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TEMPORAL``
2013 - One view per frame.
2017 ``V4L2_CID_MPEG_VIDEO_H264_FMO (boolean)``
2018 Enables flexible macroblock ordering in the encoded bitstream. It is
2019 a technique used for restructuring the ordering of macroblocks in
2020 pictures. Applicable to the H264 encoder.
2022 .. _v4l2-mpeg-video-h264-fmo-map-type:
2024 ``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE (enum v4l2_mpeg_video_h264_fmo_map_type)``
2025 When using FMO, the map type divides the image in different scan
2026 patterns of macroblocks. Applicable to the H264 encoder. Possible
2038 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_INTERLEAVED_SLICES``
2040 - Slices are interleaved one after other with macroblocks in run
2045 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_SCATTERED_SLICES``
2047 - Scatters the macroblocks based on a mathematical function known to
2048 both encoder and decoder.
2052 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_FOREGROUND_WITH_LEFT_OVER``
2054 - Macroblocks arranged in rectangular areas or regions of interest.
2058 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_BOX_OUT``
2060 - Slice groups grow in a cyclic way from centre to outwards.
2064 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_RASTER_SCAN``
2066 - Slice groups grow in raster scan pattern from left to right.
2070 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_WIPE_SCAN``
2072 - Slice groups grow in wipe scan pattern from top to bottom.
2076 - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_EXPLICIT``
2078 - User defined map type.
2082 ``V4L2_CID_MPEG_VIDEO_H264_FMO_SLICE_GROUP (integer)``
2083 Number of slice groups in FMO. Applicable to the H264 encoder.
2085 .. _v4l2-mpeg-video-h264-fmo-change-direction:
2087 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_DIRECTION (enum v4l2_mpeg_video_h264_fmo_change_dir)``
2088 Specifies a direction of the slice group change for raster and wipe
2089 maps. Applicable to the H264 encoder. Possible values are:
2100 - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_RIGHT``
2102 - Raster scan or wipe right.
2106 - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_LEFT``
2108 - Reverse raster scan or wipe left.
2112 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_RATE (integer)``
2113 Specifies the size of the first slice group for raster and wipe map.
2114 Applicable to the H264 encoder.
2116 ``V4L2_CID_MPEG_VIDEO_H264_FMO_RUN_LENGTH (integer)``
2117 Specifies the number of consecutive macroblocks for the interleaved
2118 map. Applicable to the H264 encoder.
2120 ``V4L2_CID_MPEG_VIDEO_H264_ASO (boolean)``
2121 Enables arbitrary slice ordering in encoded bitstream. Applicable to
2124 ``V4L2_CID_MPEG_VIDEO_H264_ASO_SLICE_ORDER (integer)``
2125 Specifies the slice order in ASO. Applicable to the H264 encoder.
2126 The supplied 32-bit integer is interpreted as follows (bit 0 = least
2146 - Slice position or order
2150 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING (boolean)``
2151 Enables H264 hierarchical coding. Applicable to the H264 encoder.
2153 .. _v4l2-mpeg-video-h264-hierarchical-coding-type:
2155 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_TYPE (enum v4l2_mpeg_video_h264_hierarchical_coding_type)``
2156 Specifies the hierarchical coding type. Applicable to the H264
2157 encoder. Possible values are:
2168 - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_B``
2170 - Hierarchical B coding.
2174 - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_P``
2176 - Hierarchical P coding.
2180 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (integer)``
2181 Specifies the number of hierarchical coding layers. Applicable to
2184 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (integer)``
2185 Specifies a user defined QP for each layer. Applicable to the H264
2186 encoder. The supplied 32-bit integer is interpreted as follows (bit
2187 0 = least significant bit):
2211 MFC 5.1 MPEG Controls
2212 ---------------------
2214 The following MPEG class controls deal with MPEG decoding and encoding
2215 settings that are specific to the Multi Format Codec 5.1 device present
2216 in the S5P family of SoCs by Samsung.
2219 .. _mfc51-control-id:
2224 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY_ENABLE (boolean)``
2225 If the display delay is enabled then the decoder is forced to return
2226 a CAPTURE buffer (decoded frame) after processing a certain number
2227 of OUTPUT buffers. The delay can be set through
2228 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY``. This
2229 feature can be used for example for generating thumbnails of videos.
2230 Applicable to the H264 decoder.
2232 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY (integer)``
2233 Display delay value for H264 decoder. The decoder is forced to
2234 return a decoded frame after the set 'display delay' number of
2235 frames. If this number is low it may result in frames returned out
2236 of dispaly order, in addition the hardware may still be using the
2237 returned buffer as a reference picture for subsequent frames.
2239 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P (integer)``
2240 The number of reference pictures used for encoding a P picture.
2241 Applicable to the H264 encoder.
2243 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING (boolean)``
2244 Padding enable in the encoder - use a color instead of repeating
2245 border pixels. Applicable to encoders.
2247 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING_YUV (integer)``
2248 Padding color in the encoder. Applicable to encoders. The supplied
2249 32-bit integer is interpreted as follows (bit 0 = least significant
2263 - V chrominance information
2269 - U chrominance information
2275 - Y luminance information
2285 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
2286 Reaction coefficient for MFC rate control. Applicable to encoders.
2290 #. Valid only when the frame level RC is enabled.
2292 #. For tight CBR, this field must be small (ex. 2 ~ 10). For
2293 VBR, this field must be large (ex. 100 ~ 1000).
2295 #. It is not recommended to use the greater number than
2296 FRAME_RATE * (10^9 / BIT_RATE).
2298 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
2299 Adaptive rate control for dark region. Valid only when H.264 and
2300 macroblock level RC is enabled
2301 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2304 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_SMOOTH (boolean)``
2305 Adaptive rate control for smooth region. Valid only when H.264 and
2306 macroblock level RC is enabled
2307 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2310 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC (boolean)``
2311 Adaptive rate control for static region. Valid only when H.264 and
2312 macroblock level RC is enabled
2313 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2316 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_ACTIVITY (boolean)``
2317 Adaptive rate control for activity region. Valid only when H.264 and
2318 macroblock level RC is enabled
2319 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
2322 .. _v4l2-mpeg-mfc51-video-frame-skip-mode:
2324 ``V4L2_CID_MPEG_MFC51_VIDEO_FRAME_SKIP_MODE (enum v4l2_mpeg_mfc51_video_frame_skip_mode)``
2325 Indicates in what conditions the encoder should skip frames. If
2326 encoding a frame would cause the encoded stream to be larger then a
2327 chosen data limit then the frame will be skipped. Possible values
2339 - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_DISABLED``
2341 - Frame skip mode is disabled.
2345 - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_LEVEL_LIMIT``
2347 - Frame skip mode enabled and buffer limit is set by the chosen
2348 level and is defined by the standard.
2352 - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_BUF_LIMIT``
2354 - Frame skip mode enabled and buffer limit is set by the VBV
2355 (MPEG1/2/4) or CPB (H264) buffer size control.
2359 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT (integer)``
2360 Enable rate-control with fixed target bit. If this setting is
2361 enabled, then the rate control logic of the encoder will calculate
2362 the average bitrate for a GOP and keep it below or equal the set
2363 bitrate target. Otherwise the rate control logic calculates the
2364 overall average bitrate for the stream and keeps it below or equal
2365 to the set bitrate. In the first case the average bitrate for the
2366 whole stream will be smaller then the set bitrate. This is caused
2367 because the average is calculated for smaller number of frames, on
2368 the other hand enabling this setting will ensure that the stream
2369 will meet tight bandwidth constraints. Applicable to encoders.
2371 .. _v4l2-mpeg-mfc51-video-force-frame-type:
2373 ``V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE (enum v4l2_mpeg_mfc51_video_force_frame_type)``
2374 Force a frame type for the next queued buffer. Applicable to
2375 encoders. Possible values are:
2386 - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_DISABLED``
2388 - Forcing a specific frame type disabled.
2392 - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_I_FRAME``
2398 - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_NOT_CODED``
2400 - Force a non-coded frame.
2405 CX2341x MPEG Controls
2406 ---------------------
2408 The following MPEG class controls deal with MPEG encoding settings that
2409 are specific to the Conexant CX23415 and CX23416 MPEG encoding chips.
2412 .. _cx2341x-control-id:
2417 .. _v4l2-mpeg-cx2341x-video-spatial-filter-mode:
2419 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE (enum v4l2_mpeg_cx2341x_video_spatial_filter_mode)``
2420 Sets the Spatial Filter mode (default ``MANUAL``). Possible values
2432 - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL``
2434 - Choose the filter manually
2438 - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO``
2440 - Choose the filter automatically
2444 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER (integer (0-15))``
2445 The setting for the Spatial Filter. 0 = off, 15 = maximum. (Default
2448 .. _luma-spatial-filter-type:
2450 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type)``
2451 Select the algorithm to use for the Luma Spatial Filter (default
2452 ``1D_HOR``). Possible values:
2463 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF``
2469 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR``
2471 - One-dimensional horizontal
2475 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT``
2477 - One-dimensional vertical
2481 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE``
2483 - Two-dimensional separable
2487 - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE``
2489 - Two-dimensional symmetrical non-separable
2493 .. _chroma-spatial-filter-type:
2495 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type)``
2496 Select the algorithm for the Chroma Spatial Filter (default
2497 ``1D_HOR``). Possible values are:
2508 - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF``
2514 - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR``
2516 - One-dimensional horizontal
2520 .. _v4l2-mpeg-cx2341x-video-temporal-filter-mode:
2522 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE (enum v4l2_mpeg_cx2341x_video_temporal_filter_mode)``
2523 Sets the Temporal Filter mode (default ``MANUAL``). Possible values
2535 - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL``
2537 - Choose the filter manually
2541 - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO``
2543 - Choose the filter automatically
2547 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER (integer (0-31))``
2548 The setting for the Temporal Filter. 0 = off, 31 = maximum. (Default
2549 is 8 for full-scale capturing and 0 for scaled capturing.)
2551 .. _v4l2-mpeg-cx2341x-video-median-filter-type:
2553 ``V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE (enum v4l2_mpeg_cx2341x_video_median_filter_type)``
2554 Median Filter Type (default ``OFF``). Possible values are:
2565 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF``
2571 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR``
2577 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT``
2583 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT``
2585 - Horizontal and vertical filter
2589 - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG``
2595 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
2596 Threshold above which the luminance median filter is enabled
2599 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP (integer (0-255))``
2600 Threshold below which the luminance median filter is enabled
2603 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
2604 Threshold above which the chroma median filter is enabled (default
2607 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP (integer (0-255))``
2608 Threshold below which the chroma median filter is enabled (default
2611 ``V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS (boolean)``
2612 The CX2341X MPEG encoder can insert one empty MPEG-2 PES packet into
2613 the stream between every four video frames. The packet size is 2048
2614 bytes, including the packet_start_code_prefix and stream_id
2615 fields. The stream_id is 0xBF (private stream 2). The payload
2616 consists of 0x00 bytes, to be filled in by the application. 0 = do
2617 not insert, 1 = insert packets.
2620 VPX Control Reference
2621 ---------------------
2623 The VPX controls include controls for encoding parameters of VPx video
2632 .. _v4l2-vpx-num-partitions:
2634 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS (enum v4l2_vp8_num_partitions)``
2635 The number of token partitions to use in VP8 encoder. Possible
2647 - ``V4L2_CID_MPEG_VIDEO_VPX_1_PARTITION``
2649 - 1 coefficient partition
2653 - ``V4L2_CID_MPEG_VIDEO_VPX_2_PARTITIONS``
2655 - 2 coefficient partitions
2659 - ``V4L2_CID_MPEG_VIDEO_VPX_4_PARTITIONS``
2661 - 4 coefficient partitions
2665 - ``V4L2_CID_MPEG_VIDEO_VPX_8_PARTITIONS``
2667 - 8 coefficient partitions
2671 ``V4L2_CID_MPEG_VIDEO_VPX_IMD_DISABLE_4X4 (boolean)``
2672 Setting this prevents intra 4x4 mode in the intra mode decision.
2674 .. _v4l2-vpx-num-ref-frames:
2676 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES (enum v4l2_vp8_num_ref_frames)``
2677 The number of reference pictures for encoding P frames. Possible
2689 - ``V4L2_CID_MPEG_VIDEO_VPX_1_REF_FRAME``
2691 - Last encoded frame will be searched
2695 - ``V4L2_CID_MPEG_VIDEO_VPX_2_REF_FRAME``
2697 - Two frames will be searched among the last encoded frame, the
2698 golden frame and the alternate reference (altref) frame. The
2699 encoder implementation will decide which two are chosen.
2703 - ``V4L2_CID_MPEG_VIDEO_VPX_3_REF_FRAME``
2705 - The last encoded frame, the golden frame and the altref frame will
2710 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_LEVEL (integer)``
2711 Indicates the loop filter level. The adjustment of the loop filter
2712 level is done via a delta value against a baseline loop filter
2715 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_SHARPNESS (integer)``
2716 This parameter affects the loop filter. Anything above zero weakens
2717 the deblocking effect on the loop filter.
2719 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD (integer)``
2720 Sets the refresh period for the golden frame. The period is defined
2721 in number of frames. For a value of 'n', every nth frame starting
2722 from the first key frame will be taken as a golden frame. For eg.
2723 for encoding sequence of 0, 1, 2, 3, 4, 5, 6, 7 where the golden
2724 frame refresh period is set as 4, the frames 0, 4, 8 etc will be
2725 taken as the golden frames as frame 0 is always a key frame.
2727 .. _v4l2-vpx-golden-frame-sel:
2729 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_SEL (enum v4l2_vp8_golden_frame_sel)``
2730 Selects the golden frame for encoding. Possible values are:
2741 - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_PREV``
2743 - Use the (n-2)th frame as a golden frame, current frame index being
2748 - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_REF_PERIOD``
2750 - Use the previous specific frame indicated by
2751 V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD as a
2756 ``V4L2_CID_MPEG_VIDEO_VPX_MIN_QP (integer)``
2757 Minimum quantization parameter for VP8.
2759 ``V4L2_CID_MPEG_VIDEO_VPX_MAX_QP (integer)``
2760 Maximum quantization parameter for VP8.
2762 ``V4L2_CID_MPEG_VIDEO_VPX_I_FRAME_QP (integer)``
2763 Quantization parameter for an I frame for VP8.
2765 ``V4L2_CID_MPEG_VIDEO_VPX_P_FRAME_QP (integer)``
2766 Quantization parameter for a P frame for VP8.
2768 ``V4L2_CID_MPEG_VIDEO_VPX_PROFILE (integer)``
2769 Select the desired profile for VPx encoder. Acceptable values are 0,
2770 1, 2 and 3 corresponding to encoder profiles 0, 1, 2 and 3.
2773 .. _camera-controls:
2775 Camera Control Reference
2776 ========================
2778 The Camera class includes controls for mechanical (or equivalent
2779 digital) features of a device such as controllable lenses or sensors.
2782 .. _camera-control-id:
2787 ``V4L2_CID_CAMERA_CLASS (class)``
2788 The Camera class descriptor. Calling
2789 :ref:`VIDIOC_QUERYCTRL` for this control will
2790 return a description of this control class.
2792 .. _v4l2-exposure-auto-type:
2794 ``V4L2_CID_EXPOSURE_AUTO (enum v4l2_exposure_auto_type)``
2795 Enables automatic adjustments of the exposure time and/or iris
2796 aperture. The effect of manual changes of the exposure time or iris
2797 aperture while these features are enabled is undefined, drivers
2798 should ignore such requests. Possible values are:
2809 - ``V4L2_EXPOSURE_AUTO``
2811 - Automatic exposure time, automatic iris aperture.
2815 - ``V4L2_EXPOSURE_MANUAL``
2817 - Manual exposure time, manual iris.
2821 - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
2823 - Manual exposure time, auto iris.
2827 - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
2829 - Auto exposure time, manual iris.
2833 ``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
2834 Determines the exposure time of the camera sensor. The exposure time
2835 is limited by the frame interval. Drivers should interpret the
2836 values as 100 µs units, where the value 1 stands for 1/10000th of a
2837 second, 10000 for 1 second and 100000 for 10 seconds.
2839 ``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
2840 When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
2841 ``APERTURE_PRIORITY``, this control determines if the device may
2842 dynamically vary the frame rate. By default this feature is disabled
2843 (0) and the frame rate must remain constant.
2845 ``V4L2_CID_EXPOSURE_BIAS (integer menu)``
2846 Determines the automatic exposure compensation, it is effective only
2847 when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
2848 ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
2849 terms of EV, drivers should interpret the values as 0.001 EV units,
2850 where the value 1000 stands for +1 EV.
2852 Increasing the exposure compensation value is equivalent to
2853 decreasing the exposure value (EV) and will increase the amount of
2854 light at the image sensor. The camera performs the exposure
2855 compensation by adjusting absolute exposure time and/or aperture.
2857 .. _v4l2-exposure-metering:
2859 ``V4L2_CID_EXPOSURE_METERING (enum v4l2_exposure_metering)``
2860 Determines how the camera measures the amount of light available for
2861 the frame exposure. Possible values are:
2872 - ``V4L2_EXPOSURE_METERING_AVERAGE``
2874 - Use the light information coming from the entire frame and average
2875 giving no weighting to any particular portion of the metered area.
2879 - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
2881 - Average the light information coming from the entire frame giving
2882 priority to the center of the metered area.
2886 - ``V4L2_EXPOSURE_METERING_SPOT``
2888 - Measure only very small area at the center of the frame.
2892 - ``V4L2_EXPOSURE_METERING_MATRIX``
2894 - A multi-zone metering. The light intensity is measured in several
2895 points of the frame and the results are combined. The algorithm of
2896 the zones selection and their significance in calculating the
2897 final value is device dependent.
2901 ``V4L2_CID_PAN_RELATIVE (integer)``
2902 This control turns the camera horizontally by the specified amount.
2903 The unit is undefined. A positive value moves the camera to the
2904 right (clockwise when viewed from above), a negative value to the
2905 left. A value of zero does not cause motion. This is a write-only
2908 ``V4L2_CID_TILT_RELATIVE (integer)``
2909 This control turns the camera vertically by the specified amount.
2910 The unit is undefined. A positive value moves the camera up, a
2911 negative value down. A value of zero does not cause motion. This is
2912 a write-only control.
2914 ``V4L2_CID_PAN_RESET (button)``
2915 When this control is set, the camera moves horizontally to the
2918 ``V4L2_CID_TILT_RESET (button)``
2919 When this control is set, the camera moves vertically to the default
2922 ``V4L2_CID_PAN_ABSOLUTE (integer)``
2923 This control turns the camera horizontally to the specified
2924 position. Positive values move the camera to the right (clockwise
2925 when viewed from above), negative values to the left. Drivers should
2926 interpret the values as arc seconds, with valid values between -180
2927 * 3600 and +180 * 3600 inclusive.
2929 ``V4L2_CID_TILT_ABSOLUTE (integer)``
2930 This control turns the camera vertically to the specified position.
2931 Positive values move the camera up, negative values down. Drivers
2932 should interpret the values as arc seconds, with valid values
2933 between -180 * 3600 and +180 * 3600 inclusive.
2935 ``V4L2_CID_FOCUS_ABSOLUTE (integer)``
2936 This control sets the focal point of the camera to the specified
2937 position. The unit is undefined. Positive values set the focus
2938 closer to the camera, negative values towards infinity.
2940 ``V4L2_CID_FOCUS_RELATIVE (integer)``
2941 This control moves the focal point of the camera by the specified
2942 amount. The unit is undefined. Positive values move the focus closer
2943 to the camera, negative values towards infinity. This is a
2946 ``V4L2_CID_FOCUS_AUTO (boolean)``
2947 Enables continuous automatic focus adjustments. The effect of manual
2948 focus adjustments while this feature is enabled is undefined,
2949 drivers should ignore such requests.
2951 ``V4L2_CID_AUTO_FOCUS_START (button)``
2952 Starts single auto focus process. The effect of setting this control
2953 when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
2954 drivers should ignore such requests.
2956 ``V4L2_CID_AUTO_FOCUS_STOP (button)``
2957 Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
2958 control. It is effective only when the continuous autofocus is
2959 disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
2962 .. _v4l2-auto-focus-status:
2964 ``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
2965 The automatic focus status. This is a read-only control.
2967 Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
2968 control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
2980 - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
2982 - Automatic focus is not active.
2986 - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
2988 - Automatic focusing is in progress.
2992 - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
2994 - Focus has been reached.
2998 - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
3000 - Automatic focus has failed, the driver will not transition from
3001 this state until another action is performed by an application.
3005 .. _v4l2-auto-focus-range:
3007 ``V4L2_CID_AUTO_FOCUS_RANGE (enum v4l2_auto_focus_range)``
3008 Determines auto focus distance range for which lens may be adjusted.
3019 - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
3021 - The camera automatically selects the focus range.
3025 - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
3027 - Normal distance range, limited for best automatic focus
3032 - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
3034 - Macro (close-up) auto focus. The camera will use its minimum
3035 possible distance for auto focus.
3039 - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
3041 - The lens is set to focus on an object at infinite distance.
3045 ``V4L2_CID_ZOOM_ABSOLUTE (integer)``
3046 Specify the objective lens focal length as an absolute value. The
3047 zoom unit is driver-specific and its value should be a positive
3050 ``V4L2_CID_ZOOM_RELATIVE (integer)``
3051 Specify the objective lens focal length relatively to the current
3052 value. Positive values move the zoom lens group towards the
3053 telephoto direction, negative values towards the wide-angle
3054 direction. The zoom unit is driver-specific. This is a write-only
3057 ``V4L2_CID_ZOOM_CONTINUOUS (integer)``
3058 Move the objective lens group at the specified speed until it
3059 reaches physical device limits or until an explicit request to stop
3060 the movement. A positive value moves the zoom lens group towards the
3061 telephoto direction. A value of zero stops the zoom lens group
3062 movement. A negative value moves the zoom lens group towards the
3063 wide-angle direction. The zoom speed unit is driver-specific.
3065 ``V4L2_CID_IRIS_ABSOLUTE (integer)``
3066 This control sets the camera's aperture to the specified value. The
3067 unit is undefined. Larger values open the iris wider, smaller values
3070 ``V4L2_CID_IRIS_RELATIVE (integer)``
3071 This control modifies the camera's aperture by the specified amount.
3072 The unit is undefined. Positive values open the iris one step
3073 further, negative values close it one step further. This is a
3076 ``V4L2_CID_PRIVACY (boolean)``
3077 Prevent video from being acquired by the camera. When this control
3078 is set to ``TRUE`` (1), no image can be captured by the camera.
3079 Common means to enforce privacy are mechanical obturation of the
3080 sensor and firmware image processing, but the device is not
3081 restricted to these methods. Devices that implement the privacy
3082 control must support read access and may support write access.
3084 ``V4L2_CID_BAND_STOP_FILTER (integer)``
3085 Switch the band-stop filter of a camera sensor on or off, or specify
3086 its strength. Such band-stop filters can be used, for example, to
3087 filter out the fluorescent light component.
3089 .. _v4l2-auto-n-preset-white-balance:
3091 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE (enum v4l2_auto_n_preset_white_balance)``
3092 Sets white balance to automatic, manual or a preset. The presets
3093 determine color temperature of the light as a hint to the camera for
3094 white balance adjustments resulting in most accurate color
3095 representation. The following white balance presets are listed in
3096 order of increasing color temperature.
3107 - ``V4L2_WHITE_BALANCE_MANUAL``
3109 - Manual white balance.
3113 - ``V4L2_WHITE_BALANCE_AUTO``
3115 - Automatic white balance adjustments.
3119 - ``V4L2_WHITE_BALANCE_INCANDESCENT``
3121 - White balance setting for incandescent (tungsten) lighting. It
3122 generally cools down the colors and corresponds approximately to
3123 2500...3500 K color temperature range.
3127 - ``V4L2_WHITE_BALANCE_FLUORESCENT``
3129 - White balance preset for fluorescent lighting. It corresponds
3130 approximately to 4000...5000 K color temperature.
3134 - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
3136 - With this setting the camera will compensate for fluorescent H
3141 - ``V4L2_WHITE_BALANCE_HORIZON``
3143 - White balance setting for horizon daylight. It corresponds
3144 approximately to 5000 K color temperature.
3148 - ``V4L2_WHITE_BALANCE_DAYLIGHT``
3150 - White balance preset for daylight (with clear sky). It corresponds
3151 approximately to 5000...6500 K color temperature.
3155 - ``V4L2_WHITE_BALANCE_FLASH``
3157 - With this setting the camera will compensate for the flash light.
3158 It slightly warms up the colors and corresponds roughly to
3159 5000...5500 K color temperature.
3163 - ``V4L2_WHITE_BALANCE_CLOUDY``
3165 - White balance preset for moderately overcast sky. This option
3166 corresponds approximately to 6500...8000 K color temperature
3171 - ``V4L2_WHITE_BALANCE_SHADE``
3173 - White balance preset for shade or heavily overcast sky. It
3174 corresponds approximately to 9000...10000 K color temperature.
3178 .. _v4l2-wide-dynamic-range:
3180 ``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
3181 Enables or disables the camera's wide dynamic range feature. This
3182 feature allows to obtain clear images in situations where intensity
3183 of the illumination varies significantly throughout the scene, i.e.
3184 there are simultaneously very dark and very bright areas. It is most
3185 commonly realized in cameras by combining two subsequent frames with
3186 different exposure times. [#f1]_
3188 .. _v4l2-image-stabilization:
3190 ``V4L2_CID_IMAGE_STABILIZATION (boolean)``
3191 Enables or disables image stabilization.
3193 ``V4L2_CID_ISO_SENSITIVITY (integer menu)``
3194 Determines ISO equivalent of an image sensor indicating the sensor's
3195 sensitivity to light. The numbers are expressed in arithmetic scale,
3196 as per :ref:`iso12232` standard, where doubling the sensor
3197 sensitivity is represented by doubling the numerical ISO value.
3198 Applications should interpret the values as standard ISO values
3199 multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
3200 Drivers will usually support only a subset of standard ISO values.
3201 The effect of setting this control while the
3202 ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
3203 than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
3204 should ignore such requests.
3206 .. _v4l2-iso-sensitivity-auto-type:
3208 ``V4L2_CID_ISO_SENSITIVITY_AUTO (enum v4l2_iso_sensitivity_type)``
3209 Enables or disables automatic ISO sensitivity adjustments.
3220 - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
3222 - Manual ISO sensitivity.
3226 - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
3228 - Automatic ISO sensitivity adjustments.
3232 .. _v4l2-scene-mode:
3234 ``V4L2_CID_SCENE_MODE (enum v4l2_scene_mode)``
3235 This control allows to select scene programs as the camera automatic
3236 modes optimized for common shooting scenes. Within these modes the
3237 camera determines best exposure, aperture, focusing, light metering,
3238 white balance and equivalent sensitivity. The controls of those
3239 parameters are influenced by the scene mode control. An exact
3240 behavior in each mode is subject to the camera specification.
3242 When the scene mode feature is not used, this control should be set
3243 to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
3244 controls are accessible. The following scene programs are defined:
3255 - ``V4L2_SCENE_MODE_NONE``
3257 - The scene mode feature is disabled.
3261 - ``V4L2_SCENE_MODE_BACKLIGHT``
3263 - Backlight. Compensates for dark shadows when light is coming from
3264 behind a subject, also by automatically turning on the flash.
3268 - ``V4L2_SCENE_MODE_BEACH_SNOW``
3270 - Beach and snow. This mode compensates for all-white or bright
3271 scenes, which tend to look gray and low contrast, when camera's
3272 automatic exposure is based on an average scene brightness. To
3273 compensate, this mode automatically slightly overexposes the
3274 frames. The white balance may also be adjusted to compensate for
3275 the fact that reflected snow looks bluish rather than white.
3279 - ``V4L2_SCENE_MODE_CANDLELIGHT``
3281 - Candle light. The camera generally raises the ISO sensitivity and
3282 lowers the shutter speed. This mode compensates for relatively
3283 close subject in the scene. The flash is disabled in order to
3284 preserve the ambiance of the light.
3288 - ``V4L2_SCENE_MODE_DAWN_DUSK``
3290 - Dawn and dusk. Preserves the colors seen in low natural light
3291 before dusk and after down. The camera may turn off the flash, and
3292 automatically focus at infinity. It will usually boost saturation
3293 and lower the shutter speed.
3297 - ``V4L2_SCENE_MODE_FALL_COLORS``
3299 - Fall colors. Increases saturation and adjusts white balance for
3300 color enhancement. Pictures of autumn leaves get saturated reds
3305 - ``V4L2_SCENE_MODE_FIREWORKS``
3307 - Fireworks. Long exposure times are used to capture the expanding
3308 burst of light from a firework. The camera may invoke image
3313 - ``V4L2_SCENE_MODE_LANDSCAPE``
3315 - Landscape. The camera may choose a small aperture to provide deep
3316 depth of field and long exposure duration to help capture detail
3317 in dim light conditions. The focus is fixed at infinity. Suitable
3318 for distant and wide scenery.
3322 - ``V4L2_SCENE_MODE_NIGHT``
3324 - Night, also known as Night Landscape. Designed for low light
3325 conditions, it preserves detail in the dark areas without blowing
3326 out bright objects. The camera generally sets itself to a
3327 medium-to-high ISO sensitivity, with a relatively long exposure
3328 time, and turns flash off. As such, there will be increased image
3329 noise and the possibility of blurred image.
3333 - ``V4L2_SCENE_MODE_PARTY_INDOOR``
3335 - Party and indoor. Designed to capture indoor scenes that are lit
3336 by indoor background lighting as well as the flash. The camera
3337 usually increases ISO sensitivity, and adjusts exposure for the
3338 low light conditions.
3342 - ``V4L2_SCENE_MODE_PORTRAIT``
3344 - Portrait. The camera adjusts the aperture so that the depth of
3345 field is reduced, which helps to isolate the subject against a
3346 smooth background. Most cameras recognize the presence of faces in
3347 the scene and focus on them. The color hue is adjusted to enhance
3348 skin tones. The intensity of the flash is often reduced.
3352 - ``V4L2_SCENE_MODE_SPORTS``
3354 - Sports. Significantly increases ISO and uses a fast shutter speed
3355 to freeze motion of rapidly-moving subjects. Increased image noise
3356 may be seen in this mode.
3360 - ``V4L2_SCENE_MODE_SUNSET``
3362 - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
3367 - ``V4L2_SCENE_MODE_TEXT``
3369 - Text. It applies extra contrast and sharpness, it is typically a
3370 black-and-white mode optimized for readability. Automatic focus
3371 may be switched to close-up mode and this setting may also involve
3372 some lens-distortion correction.
3376 ``V4L2_CID_3A_LOCK (bitmask)``
3377 This control locks or unlocks the automatic focus, exposure and
3378 white balance. The automatic adjustments can be paused independently
3379 by setting the corresponding lock bit to 1. The camera then retains
3380 the settings until the lock bit is cleared. The following lock bits
3383 When a given algorithm is not enabled, drivers should ignore
3384 requests to lock it and should return no error. An example might be
3385 an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
3386 ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
3387 value of this control may be changed by exposure, white balance or
3399 - ``V4L2_LOCK_EXPOSURE``
3401 - Automatic exposure adjustments lock.
3405 - ``V4L2_LOCK_WHITE_BALANCE``
3407 - Automatic white balance adjustments lock.
3411 - ``V4L2_LOCK_FOCUS``
3413 - Automatic focus lock.
3417 ``V4L2_CID_PAN_SPEED (integer)``
3418 This control turns the camera horizontally at the specific speed.
3419 The unit is undefined. A positive value moves the camera to the
3420 right (clockwise when viewed from above), a negative value to the
3421 left. A value of zero stops the motion if one is in progress and has
3422 no effect otherwise.
3424 ``V4L2_CID_TILT_SPEED (integer)``
3425 This control turns the camera vertically at the specified speed. The
3426 unit is undefined. A positive value moves the camera up, a negative
3427 value down. A value of zero stops the motion if one is in progress
3428 and has no effect otherwise.
3433 FM Transmitter Control Reference
3434 ================================
3436 The FM Transmitter (FM_TX) class includes controls for common features
3437 of FM transmissions capable devices. Currently this class includes
3438 parameters for audio compression, pilot tone generation, audio deviation
3439 limiter, RDS transmission and tuning power features.
3442 .. _fm-tx-control-id:
3447 ``V4L2_CID_FM_TX_CLASS (class)``
3448 The FM_TX class descriptor. Calling
3449 :ref:`VIDIOC_QUERYCTRL` for this control will
3450 return a description of this control class.
3452 ``V4L2_CID_RDS_TX_DEVIATION (integer)``
3453 Configures RDS signal frequency deviation level in Hz. The range and
3454 step are driver-specific.
3456 ``V4L2_CID_RDS_TX_PI (integer)``
3457 Sets the RDS Programme Identification field for transmission.
3459 ``V4L2_CID_RDS_TX_PTY (integer)``
3460 Sets the RDS Programme Type field for transmission. This encodes up
3461 to 31 pre-defined programme types.
3463 ``V4L2_CID_RDS_TX_PS_NAME (string)``
3464 Sets the Programme Service name (PS_NAME) for transmission. It is
3465 intended for static display on a receiver. It is the primary aid to
3466 listeners in programme service identification and selection. In
3467 Annex E of :ref:`iec62106`, the RDS specification, there is a full
3468 description of the correct character encoding for Programme Service
3469 name strings. Also from RDS specification, PS is usually a single
3470 eight character text. However, it is also possible to find receivers
3471 which can scroll strings sized as 8 x N characters. So, this control
3472 must be configured with steps of 8 characters. The result is it must
3473 always contain a string with size multiple of 8.
3475 ``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
3476 Sets the Radio Text info for transmission. It is a textual
3477 description of what is being broadcasted. RDS Radio Text can be
3478 applied when broadcaster wishes to transmit longer PS names,
3479 programme-related information or any other text. In these cases,
3480 RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``.
3481 The encoding for Radio Text strings is also fully described in Annex
3482 E of :ref:`iec62106`. The length of Radio Text strings depends on
3483 which RDS Block is being used to transmit it, either 32 (2A block)
3484 or 64 (2B block). However, it is also possible to find receivers
3485 which can scroll strings sized as 32 x N or 64 x N characters. So,
3486 this control must be configured with steps of 32 or 64 characters.
3487 The result is it must always contain a string with size multiple of
3490 ``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
3491 Sets the Mono/Stereo bit of the Decoder Identification code. If set,
3492 then the audio was recorded as stereo.
3494 ``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
3496 `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__
3497 bit of the Decoder Identification code. If set, then the audio was
3498 recorded using an artificial head.
3500 ``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
3501 Sets the Compressed bit of the Decoder Identification code. If set,
3502 then the audio is compressed.
3504 ``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
3505 Sets the Dynamic PTY bit of the Decoder Identification code. If set,
3506 then the PTY code is dynamically switched.
3508 ``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)``
3509 If set, then a traffic announcement is in progress.
3511 ``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
3512 If set, then the tuned programme carries traffic announcements.
3514 ``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
3515 If set, then this channel broadcasts music. If cleared, then it
3516 broadcasts speech. If the transmitter doesn't make this distinction,
3517 then it should be set.
3519 ``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
3520 If set, then transmit alternate frequencies.
3522 ``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
3523 The alternate frequencies in kHz units. The RDS standard allows for
3524 up to 25 frequencies to be defined. Drivers may support fewer
3525 frequencies so check the array size.
3527 ``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
3528 Enables or disables the audio deviation limiter feature. The limiter
3529 is useful when trying to maximize the audio volume, minimize
3530 receiver-generated distortion and prevent overmodulation.
3532 ``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
3533 Sets the audio deviation limiter feature release time. Unit is in
3534 useconds. Step and range are driver-specific.
3536 ``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
3537 Configures audio frequency deviation level in Hz. The range and step
3538 are driver-specific.
3540 ``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)``
3541 Enables or disables the audio compression feature. This feature
3542 amplifies signals below the threshold by a fixed gain and compresses
3543 audio signals above the threshold by the ratio of Threshold/(Gain +
3546 ``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
3547 Sets the gain for audio compression feature. It is a dB value. The
3548 range and step are driver-specific.
3550 ``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
3551 Sets the threshold level for audio compression freature. It is a dB
3552 value. The range and step are driver-specific.
3554 ``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
3555 Sets the attack time for audio compression feature. It is a useconds
3556 value. The range and step are driver-specific.
3558 ``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
3559 Sets the release time for audio compression feature. It is a
3560 useconds value. The range and step are driver-specific.
3562 ``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
3563 Enables or disables the pilot tone generation feature.
3565 ``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
3566 Configures pilot tone frequency deviation level. Unit is in Hz. The
3567 range and step are driver-specific.
3569 ``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
3570 Configures pilot tone frequency value. Unit is in Hz. The range and
3571 step are driver-specific.
3573 ``V4L2_CID_TUNE_PREEMPHASIS (enum v4l2_preemphasis)``
3574 Configures the pre-emphasis value for broadcasting. A pre-emphasis
3575 filter is applied to the broadcast to accentuate the high audio
3576 frequencies. Depending on the region, a time constant of either 50
3577 or 75 useconds is used. The enum v4l2_preemphasis defines possible
3578 values for pre-emphasis. Here they are:
3589 - ``V4L2_PREEMPHASIS_DISABLED``
3591 - No pre-emphasis is applied.
3595 - ``V4L2_PREEMPHASIS_50_uS``
3597 - A pre-emphasis of 50 uS is used.
3601 - ``V4L2_PREEMPHASIS_75_uS``
3603 - A pre-emphasis of 75 uS is used.
3607 ``V4L2_CID_TUNE_POWER_LEVEL (integer)``
3608 Sets the output power level for signal transmission. Unit is in
3609 dBuV. Range and step are driver-specific.
3611 ``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
3612 This selects the value of antenna tuning capacitor manually or
3613 automatically if set to zero. Unit, range and step are
3616 For more details about RDS specification, refer to :ref:`iec62106`
3617 document, from CENELEC.
3622 Flash Control Reference
3623 =======================
3625 The V4L2 flash controls are intended to provide generic access to flash
3626 controller devices. Flash controller devices are typically used in
3629 The interface can support both LED and xenon flash devices. As of
3630 writing this, there is no xenon flash driver using this interface.
3633 .. _flash-controls-use-cases:
3639 Unsynchronised LED flash (software strobe)
3640 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3642 Unsynchronised LED flash is controlled directly by the host as the
3643 sensor. The flash must be enabled by the host before the exposure of the
3644 image starts and disabled once it ends. The host is fully responsible
3645 for the timing of the flash.
3647 Example of such device: Nokia N900.
3650 Synchronised LED flash (hardware strobe)
3651 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3653 The synchronised LED flash is pre-programmed by the host (power and
3654 timeout) but controlled by the sensor through a strobe signal from the
3655 sensor to the flash.
3657 The sensor controls the flash duration and timing. This information
3658 typically must be made available to the sensor.
3664 LED flash may be used as torch in conjunction with another use case
3665 involving camera or individually.
3668 .. _flash-control-id:
3673 ``V4L2_CID_FLASH_CLASS (class)``
3674 The FLASH class descriptor.
3676 ``V4L2_CID_FLASH_LED_MODE (menu)``
3677 Defines the mode of the flash LED, the high-power white LED attached
3678 to the flash controller. Setting this control may not be possible in
3679 presence of some faults. See V4L2_CID_FLASH_FAULT.
3690 - ``V4L2_FLASH_LED_MODE_NONE``
3696 - ``V4L2_FLASH_LED_MODE_FLASH``
3702 - ``V4L2_FLASH_LED_MODE_TORCH``
3704 - Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.
3708 ``V4L2_CID_FLASH_STROBE_SOURCE (menu)``
3709 Defines the source of the flash LED strobe.
3720 - ``V4L2_FLASH_STROBE_SOURCE_SOFTWARE``
3722 - The flash strobe is triggered by using the
3723 V4L2_CID_FLASH_STROBE control.
3727 - ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``
3729 - The flash strobe is triggered by an external source. Typically
3730 this is a sensor, which makes it possible to synchronises the
3731 flash strobe start to exposure start.
3735 ``V4L2_CID_FLASH_STROBE (button)``
3736 Strobe flash. Valid when V4L2_CID_FLASH_LED_MODE is set to
3737 V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
3738 is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
3739 control may not be possible in presence of some faults. See
3740 V4L2_CID_FLASH_FAULT.
3742 ``V4L2_CID_FLASH_STROBE_STOP (button)``
3743 Stop flash strobe immediately.
3745 ``V4L2_CID_FLASH_STROBE_STATUS (boolean)``
3746 Strobe status: whether the flash is strobing at the moment or not.
3747 This is a read-only control.
3749 ``V4L2_CID_FLASH_TIMEOUT (integer)``
3750 Hardware timeout for flash. The flash strobe is stopped after this
3751 period of time has passed from the start of the strobe.
3753 ``V4L2_CID_FLASH_INTENSITY (integer)``
3754 Intensity of the flash strobe when the flash LED is in flash mode
3755 (V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps (mA)
3758 ``V4L2_CID_FLASH_TORCH_INTENSITY (integer)``
3759 Intensity of the flash LED in torch mode
3760 (V4L2_FLASH_LED_MODE_TORCH). The unit should be milliamps (mA)
3761 if possible. Setting this control may not be possible in presence of
3762 some faults. See V4L2_CID_FLASH_FAULT.
3764 ``V4L2_CID_FLASH_INDICATOR_INTENSITY (integer)``
3765 Intensity of the indicator LED. The indicator LED may be fully
3766 independent of the flash LED. The unit should be microamps (uA) if
3769 ``V4L2_CID_FLASH_FAULT (bitmask)``
3770 Faults related to the flash. The faults tell about specific problems
3771 in the flash chip itself or the LEDs attached to it. Faults may
3772 prevent further use of some of the flash controls. In particular,
3773 V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
3774 if the fault affects the flash LED. Exactly which faults have such
3775 an effect is chip dependent. Reading the faults resets the control
3776 and returns the chip to a usable state if possible.
3787 - ``V4L2_FLASH_FAULT_OVER_VOLTAGE``
3789 - Flash controller voltage to the flash LED has exceeded the limit
3790 specific to the flash controller.
3794 - ``V4L2_FLASH_FAULT_TIMEOUT``
3796 - The flash strobe was still on when the timeout set by the user ---
3797 V4L2_CID_FLASH_TIMEOUT control --- has expired. Not all flash
3798 controllers may set this in all such conditions.
3802 - ``V4L2_FLASH_FAULT_OVER_TEMPERATURE``
3804 - The flash controller has overheated.
3808 - ``V4L2_FLASH_FAULT_SHORT_CIRCUIT``
3810 - The short circuit protection of the flash controller has been
3815 - ``V4L2_FLASH_FAULT_OVER_CURRENT``
3817 - Current in the LED power supply has exceeded the limit specific to
3818 the flash controller.
3822 - ``V4L2_FLASH_FAULT_INDICATOR``
3824 - The flash controller has detected a short or open circuit
3825 condition on the indicator LED.
3829 - ``V4L2_FLASH_FAULT_UNDER_VOLTAGE``
3831 - Flash controller voltage to the flash LED has been below the
3832 minimum limit specific to the flash controller.
3836 - ``V4L2_FLASH_FAULT_INPUT_VOLTAGE``
3838 - The input voltage of the flash controller is below the limit under
3839 which strobing the flash at full current will not be possible.The
3840 condition persists until this flag is no longer set.
3844 - ``V4L2_FLASH_FAULT_LED_OVER_TEMPERATURE``
3846 - The temperature of the LED has exceeded its allowed upper limit.
3850 ``V4L2_CID_FLASH_CHARGE (boolean)``
3851 Enable or disable charging of the xenon flash capacitor.
3853 ``V4L2_CID_FLASH_READY (boolean)``
3854 Is the flash ready to strobe? Xenon flashes require their capacitors
3855 charged before strobing. LED flashes often require a cooldown period
3856 after strobe during which another strobe will not be possible. This
3857 is a read-only control.
3862 JPEG Control Reference
3863 ======================
3865 The JPEG class includes controls for common features of JPEG encoders
3866 and decoders. Currently it includes features for codecs implementing
3867 progressive baseline DCT compression process with Huffman entrophy
3871 .. _jpeg-control-id:
3876 ``V4L2_CID_JPEG_CLASS (class)``
3877 The JPEG class descriptor. Calling
3878 :ref:`VIDIOC_QUERYCTRL` for this control will
3879 return a description of this control class.
3881 ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)``
3882 The chroma subsampling factors describe how each component of an
3883 input image is sampled, in respect to maximum sample rate in each
3884 spatial dimension. See :ref:`itu-t81`, clause A.1.1. for more
3885 details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines
3886 how Cb and Cr components are downsampled after coverting an input
3887 image from RGB to Y'CbCr color space.
3898 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444``
3900 - No chroma subsampling, each pixel has Y, Cr and Cb values.
3904 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422``
3906 - Horizontally subsample Cr, Cb components by a factor of 2.
3910 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420``
3912 - Subsample Cr, Cb components horizontally and vertically by 2.
3916 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411``
3918 - Horizontally subsample Cr, Cb components by a factor of 4.
3922 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410``
3924 - Subsample Cr, Cb components horizontally by 4 and vertically by 2.
3928 - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY``
3930 - Use only luminance component.
3934 ``V4L2_CID_JPEG_RESTART_INTERVAL (integer)``
3935 The restart interval determines an interval of inserting RSTm
3936 markers (m = 0..7). The purpose of these markers is to additionally
3937 reinitialize the encoder process, in order to process blocks of an
3938 image independently. For the lossy compression processes the restart
3939 interval unit is MCU (Minimum Coded Unit) and its value is contained
3940 in DRI (Define Restart Interval) marker. If
3941 ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm
3942 markers will not be inserted.
3944 .. _jpeg-quality-control:
3946 ``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)``
3947 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control determines trade-off
3948 between image quality and size. It provides simpler method for
3949 applications to control image quality, without a need for direct
3950 reconfiguration of luminance and chrominance quantization tables. In
3951 cases where a driver uses quantization tables configured directly by
3952 an application, using interfaces defined elsewhere,
3953 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by
3956 The value range of this control is driver-specific. Only positive,
3957 non-zero values are meaningful. The recommended range is 1 - 100,
3958 where larger values correspond to better image quality.
3960 .. _jpeg-active-marker-control:
3962 ``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)``
3963 Specify which JPEG markers are included in compressed stream. This
3964 control is valid only for encoders.
3975 - ``V4L2_JPEG_ACTIVE_MARKER_APP0``
3977 - Application data segment APP\ :sub:`0`.
3981 - ``V4L2_JPEG_ACTIVE_MARKER_APP1``
3983 - Application data segment APP\ :sub:`1`.
3987 - ``V4L2_JPEG_ACTIVE_MARKER_COM``
3993 - ``V4L2_JPEG_ACTIVE_MARKER_DQT``
3995 - Quantization tables segment.
3999 - ``V4L2_JPEG_ACTIVE_MARKER_DHT``
4001 - Huffman tables segment.
4005 For more details about JPEG specification, refer to :ref:`itu-t81`,
4006 :ref:`jfif`, :ref:`w3c-jpeg-jfif`.
4009 .. _image-source-controls:
4011 Image Source Control Reference
4012 ==============================
4014 The Image Source control class is intended for low-level control of
4015 image source devices such as image sensors. The devices feature an
4016 analogue to digital converter and a bus transmitter to transmit the
4017 image data out of the device.
4020 .. _image-source-control-id:
4022 Image Source Control IDs
4023 ------------------------
4025 ``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
4026 The IMAGE_SOURCE class descriptor.
4028 ``V4L2_CID_VBLANK (integer)``
4029 Vertical blanking. The idle period after every frame during which no
4030 image data is produced. The unit of vertical blanking is a line.
4031 Every line has length of the image width plus horizontal blanking at
4032 the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
4035 ``V4L2_CID_HBLANK (integer)``
4036 Horizontal blanking. The idle period after every line of image data
4037 during which no image data is produced. The unit of horizontal
4040 ``V4L2_CID_ANALOGUE_GAIN (integer)``
4041 Analogue gain is gain affecting all colour components in the pixel
4042 matrix. The gain operation is performed in the analogue domain
4043 before A/D conversion.
4045 ``V4L2_CID_TEST_PATTERN_RED (integer)``
4046 Test pattern red colour component.
4048 ``V4L2_CID_TEST_PATTERN_GREENR (integer)``
4049 Test pattern green (next to red) colour component.
4051 ``V4L2_CID_TEST_PATTERN_BLUE (integer)``
4052 Test pattern blue colour component.
4054 ``V4L2_CID_TEST_PATTERN_GREENB (integer)``
4055 Test pattern green (next to blue) colour component.
4058 .. _image-process-controls:
4060 Image Process Control Reference
4061 ===============================
4063 The Image Process control class is intended for low-level control of
4064 image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
4065 controls in this class affect processing the image, and do not control
4069 .. _image-process-control-id:
4071 Image Process Control IDs
4072 -------------------------
4074 ``V4L2_CID_IMAGE_PROC_CLASS (class)``
4075 The IMAGE_PROC class descriptor.
4077 ``V4L2_CID_LINK_FREQ (integer menu)``
4078 Data bus frequency. Together with the media bus pixel code, bus type
4079 (clock cycles per sample), the data bus frequency defines the pixel
4080 rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
4081 elsewhere, if the device is not an image sensor). The frame rate can
4082 be calculated from the pixel clock, image width and height and
4083 horizontal and vertical blanking. While the pixel rate control may
4084 be defined elsewhere than in the subdev containing the pixel array,
4085 the frame rate cannot be obtained from that information. This is
4086 because only on the pixel array it can be assumed that the vertical
4087 and horizontal blanking information is exact: no other blanking is
4088 allowed in the pixel array. The selection of frame rate is performed
4089 by selecting the desired horizontal and vertical blanking. The unit
4090 of this control is Hz.
4092 ``V4L2_CID_PIXEL_RATE (64-bit integer)``
4093 Pixel rate in the source pads of the subdev. This control is
4094 read-only and its unit is pixels / second.
4096 ``V4L2_CID_TEST_PATTERN (menu)``
4097 Some capture/display/sensor devices have the capability to generate
4098 test pattern images. These hardware specific test patterns can be
4099 used to test if a device is working properly.
4104 Digital Video Control Reference
4105 ===============================
4107 The Digital Video control class is intended to control receivers and
4108 transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
4109 `DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__
4110 (Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort
4111 (:ref:`dp`). These controls are generally expected to be private to
4112 the receiver or transmitter subdevice that implements them, so they are
4113 only exposed on the ``/dev/v4l-subdev*`` device node.
4117 Note that these devices can have multiple input or output pads which are
4118 hooked up to e.g. HDMI connectors. Even though the subdevice will
4119 receive or transmit video from/to only one of those pads, the other pads
4120 can still be active when it comes to EDID (Extended Display
4121 Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
4122 Content Protection System, :ref:`hdcp`) processing, allowing the
4123 device to do the fairly slow EDID/HDCP handling in advance. This allows
4124 for quick switching between connectors.
4126 These pads appear in several of the controls in this section as
4127 bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad
4128 1, etc. The maximum value of the control is the set of valid pads.
4133 Digital Video Control IDs
4134 -------------------------
4136 ``V4L2_CID_DV_CLASS (class)``
4137 The Digital Video class descriptor.
4139 ``V4L2_CID_DV_TX_HOTPLUG (bitmask)``
4140 Many connectors have a hotplug pin which is high if EDID information
4141 is available from the source. This control shows the state of the
4142 hotplug pin as seen by the transmitter. Each bit corresponds to an
4143 output pad on the transmitter. If an output pad does not have an
4144 associated hotplug pin, then the bit for that pad will be 0. This
4145 read-only control is applicable to DVI-D, HDMI and DisplayPort
4148 ``V4L2_CID_DV_TX_RXSENSE (bitmask)``
4149 Rx Sense is the detection of pull-ups on the TMDS clock lines. This
4150 normally means that the sink has left/entered standby (i.e. the
4151 transmitter can sense that the receiver is ready to receive video).
4152 Each bit corresponds to an output pad on the transmitter. If an
4153 output pad does not have an associated Rx Sense, then the bit for
4154 that pad will be 0. This read-only control is applicable to DVI-D
4157 ``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)``
4158 When the transmitter sees the hotplug signal from the receiver it
4159 will attempt to read the EDID. If set, then the transmitter has read
4160 at least the first block (= 128 bytes). Each bit corresponds to an
4161 output pad on the transmitter. If an output pad does not support
4162 EDIDs, then the bit for that pad will be 0. This read-only control
4163 is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors.
4165 ``V4L2_CID_DV_TX_MODE (enum v4l2_dv_tx_mode)``
4166 HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI
4167 mode (video + audio + auxiliary data). This control selects which
4168 mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI.
4169 This control is applicable to HDMI connectors.
4171 ``V4L2_CID_DV_TX_RGB_RANGE (enum v4l2_dv_rgb_range)``
4172 Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO
4173 follows the RGB quantization range specified in the standard for the
4174 video interface (ie. :ref:`cea861` for HDMI).
4175 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
4176 standard to be compatible with sinks that have not implemented the
4177 standard correctly (unfortunately quite common for HDMI and DVI-D).
4178 Full range allows all possible values to be used whereas limited
4179 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
4180 the number of bits per component. This control is applicable to VGA,
4181 DVI-A/D, HDMI and DisplayPort connectors.
4183 ``V4L2_CID_DV_TX_IT_CONTENT_TYPE (enum v4l2_dv_it_content_type)``
4184 Configures the IT Content Type of the transmitted video. This
4185 information is sent over HDMI and DisplayPort connectors as part of
4186 the AVI InfoFrame. The term 'IT Content' is used for content that
4187 originates from a computer as opposed to content from a TV broadcast
4188 or an analog source. The enum v4l2_dv_it_content_type defines
4189 the possible content types:
4200 - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS``
4202 - Graphics content. Pixel data should be passed unfiltered and
4203 without analog reconstruction.
4207 - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO``
4209 - Photo content. The content is derived from digital still pictures.
4210 The content should be passed through with minimal scaling and
4211 picture enhancements.
4215 - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA``
4221 - ``V4L2_DV_IT_CONTENT_TYPE_GAME``
4223 - Game content. Audio and video latency should be minimized.
4227 - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC``
4229 - No IT Content information is available and the ITC bit in the AVI
4230 InfoFrame is set to 0.
4234 ``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)``
4235 Detects whether the receiver receives power from the source (e.g.
4236 HDMI carries 5V on one of the pins). This is often used to power an
4237 eeprom which contains EDID information, such that the source can
4238 read the EDID even if the sink is in standby/power off. Each bit
4239 corresponds to an input pad on the transmitter. If an input pad
4240 cannot detect whether power is present, then the bit for that pad
4241 will be 0. This read-only control is applicable to DVI-D, HDMI and
4242 DisplayPort connectors.
4244 ``V4L2_CID_DV_RX_RGB_RANGE (enum v4l2_dv_rgb_range)``
4245 Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO
4246 follows the RGB quantization range specified in the standard for the
4247 video interface (ie. :ref:`cea861` for HDMI).
4248 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
4249 standard to be compatible with sources that have not implemented the
4250 standard correctly (unfortunately quite common for HDMI and DVI-D).
4251 Full range allows all possible values to be used whereas limited
4252 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
4253 the number of bits per component. This control is applicable to VGA,
4254 DVI-A/D, HDMI and DisplayPort connectors.
4256 ``V4L2_CID_DV_RX_IT_CONTENT_TYPE (enum v4l2_dv_it_content_type)``
4257 Reads the IT Content Type of the received video. This information is
4258 sent over HDMI and DisplayPort connectors as part of the AVI
4259 InfoFrame. The term 'IT Content' is used for content that originates
4260 from a computer as opposed to content from a TV broadcast or an
4261 analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the
4262 available content types.
4267 FM Receiver Control Reference
4268 =============================
4270 The FM Receiver (FM_RX) class includes controls for common features of
4271 FM Reception capable devices.
4274 .. _fm-rx-control-id:
4279 ``V4L2_CID_FM_RX_CLASS (class)``
4280 The FM_RX class descriptor. Calling
4281 :ref:`VIDIOC_QUERYCTRL` for this control will
4282 return a description of this control class.
4284 ``V4L2_CID_RDS_RECEPTION (boolean)``
4285 Enables/disables RDS reception by the radio tuner
4287 ``V4L2_CID_RDS_RX_PTY (integer)``
4288 Gets RDS Programme Type field. This encodes up to 31 pre-defined
4291 ``V4L2_CID_RDS_RX_PS_NAME (string)``
4292 Gets the Programme Service name (PS_NAME). It is intended for
4293 static display on a receiver. It is the primary aid to listeners in
4294 programme service identification and selection. In Annex E of
4295 :ref:`iec62106`, the RDS specification, there is a full
4296 description of the correct character encoding for Programme Service
4297 name strings. Also from RDS specification, PS is usually a single
4298 eight character text. However, it is also possible to find receivers
4299 which can scroll strings sized as 8 x N characters. So, this control
4300 must be configured with steps of 8 characters. The result is it must
4301 always contain a string with size multiple of 8.
4303 ``V4L2_CID_RDS_RX_RADIO_TEXT (string)``
4304 Gets the Radio Text info. It is a textual description of what is
4305 being broadcasted. RDS Radio Text can be applied when broadcaster
4306 wishes to transmit longer PS names, programme-related information or
4307 any other text. In these cases, RadioText can be used in addition to
4308 ``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is
4309 also fully described in Annex E of :ref:`iec62106`. The length of
4310 Radio Text strings depends on which RDS Block is being used to
4311 transmit it, either 32 (2A block) or 64 (2B block). However, it is
4312 also possible to find receivers which can scroll strings sized as 32
4313 x N or 64 x N characters. So, this control must be configured with
4314 steps of 32 or 64 characters. The result is it must always contain a
4315 string with size multiple of 32 or 64.
4317 ``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)``
4318 If set, then a traffic announcement is in progress.
4320 ``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)``
4321 If set, then the tuned programme carries traffic announcements.
4323 ``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)``
4324 If set, then this channel broadcasts music. If cleared, then it
4325 broadcasts speech. If the transmitter doesn't make this distinction,
4326 then it will be set.
4328 ``V4L2_CID_TUNE_DEEMPHASIS (enum v4l2_deemphasis)``
4329 Configures the de-emphasis value for reception. A de-emphasis filter
4330 is applied to the broadcast to accentuate the high audio
4331 frequencies. Depending on the region, a time constant of either 50
4332 or 75 useconds is used. The enum v4l2_deemphasis defines possible
4333 values for de-emphasis. Here they are:
4344 - ``V4L2_DEEMPHASIS_DISABLED``
4346 - No de-emphasis is applied.
4350 - ``V4L2_DEEMPHASIS_50_uS``
4352 - A de-emphasis of 50 uS is used.
4356 - ``V4L2_DEEMPHASIS_75_uS``
4358 - A de-emphasis of 75 uS is used.
4363 .. _detect-controls:
4365 Detect Control Reference
4366 ========================
4368 The Detect class includes controls for common features of various motion
4369 or object detection capable devices.
4372 .. _detect-control-id:
4377 ``V4L2_CID_DETECT_CLASS (class)``
4378 The Detect class descriptor. Calling
4379 :ref:`VIDIOC_QUERYCTRL` for this control will
4380 return a description of this control class.
4382 ``V4L2_CID_DETECT_MD_MODE (menu)``
4383 Sets the motion detection mode.
4394 - ``V4L2_DETECT_MD_MODE_DISABLED``
4396 - Disable motion detection.
4400 - ``V4L2_DETECT_MD_MODE_GLOBAL``
4402 - Use a single motion detection threshold.
4406 - ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID``
4408 - The image is divided into a grid, each cell with its own motion
4409 detection threshold. These thresholds are set through the
4410 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID`` matrix control.
4414 - ``V4L2_DETECT_MD_MODE_REGION_GRID``
4416 - The image is divided into a grid, each cell with its own region
4417 value that specifies which per-region motion detection thresholds
4418 should be used. Each region has its own thresholds. How these
4419 per-region thresholds are set up is driver-specific. The region
4420 values for the grid are set through the
4421 ``V4L2_CID_DETECT_MD_REGION_GRID`` matrix control.
4425 ``V4L2_CID_DETECT_MD_GLOBAL_THRESHOLD (integer)``
4426 Sets the global motion detection threshold to be used with the
4427 ``V4L2_DETECT_MD_MODE_GLOBAL`` motion detection mode.
4429 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID (__u16 matrix)``
4430 Sets the motion detection thresholds for each cell in the grid. To
4431 be used with the ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID`` motion
4432 detection mode. Matrix element (0, 0) represents the cell at the
4433 top-left of the grid.
4435 ``V4L2_CID_DETECT_MD_REGION_GRID (__u8 matrix)``
4436 Sets the motion detection region value for each cell in the grid. To
4437 be used with the ``V4L2_DETECT_MD_MODE_REGION_GRID`` motion
4438 detection mode. Matrix element (0, 0) represents the cell at the
4439 top-left of the grid.
4442 .. _rf-tuner-controls:
4444 RF Tuner Control Reference
4445 ==========================
4447 The RF Tuner (RF_TUNER) class includes controls for common features of
4448 devices having RF tuner.
4450 In this context, RF tuner is radio receiver circuit between antenna and
4451 demodulator. It receives radio frequency (RF) from the antenna and
4452 converts that received signal to lower intermediate frequency (IF) or
4453 baseband frequency (BB). Tuners that could do baseband output are often
4454 called Zero-IF tuners. Older tuners were typically simple PLL tuners
4455 inside a metal box, whilst newer ones are highly integrated chips
4456 without a metal box "silicon tuners". These controls are mostly
4457 applicable for new feature rich silicon tuners, just because older
4458 tuners does not have much adjustable features.
4460 For more information about RF tuners see
4461 `Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
4462 and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
4466 .. _rf-tuner-control-id:
4468 RF_TUNER Control IDs
4469 --------------------
4471 ``V4L2_CID_RF_TUNER_CLASS (class)``
4472 The RF_TUNER class descriptor. Calling
4473 :ref:`VIDIOC_QUERYCTRL` for this control will
4474 return a description of this control class.
4476 ``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
4477 Enables/disables tuner radio channel bandwidth configuration. In
4478 automatic mode bandwidth configuration is performed by the driver.
4480 ``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
4481 Filter(s) on tuner signal path are used to filter signal according
4482 to receiving party needs. Driver configures filters to fulfill
4483 desired bandwidth requirement. Used when
4484 V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
4485 range and step are driver-specific.
4487 ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
4488 Enables/disables LNA automatic gain control (AGC)
4490 ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
4491 Enables/disables mixer automatic gain control (AGC)
4493 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
4494 Enables/disables IF automatic gain control (AGC)
4496 ``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
4497 The RF amplifier is the very first amplifier on the receiver signal
4498 path, just right after the antenna input. The difference between the
4499 LNA gain and the RF gain in this document is that the LNA gain is
4500 integrated in the tuner chip while the RF gain is a separate chip.
4501 There may be both RF and LNA gain controls in the same device. The
4502 range and step are driver-specific.
4504 ``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
4505 LNA (low noise amplifier) gain is first gain stage on the RF tuner
4506 signal path. It is located very close to tuner antenna input. Used
4507 when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
4508 ``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
4509 differs from the each others. The range and step are
4512 ``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
4513 Mixer gain is second gain stage on the RF tuner signal path. It is
4514 located inside mixer block, where RF signal is down-converted by the
4515 mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
4516 The range and step are driver-specific.
4518 ``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
4519 IF gain is last gain stage on the RF tuner signal path. It is
4520 located on output of RF tuner. It controls signal level of
4521 intermediate frequency output or baseband output. Used when
4522 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
4523 are driver-specific.
4525 ``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
4526 Is synthesizer PLL locked? RF tuner is receiving given frequency
4527 when that control is set. This is a read-only control.
4530 This control may be changed to a menu control in the future, if more
4531 options are required.
projects / cascardo / linux.git / blob