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 :c:type:`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 :c:type:`v4l2_ext_control` array. The
69 struct :c:type:`v4l2_ext_control` is very similar to
70 struct :c:type:`v4l2_control`, except for the fact that
71 it also allows for 64-bit values and pointers to be passed.
73 Since the struct :c:type:`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.
189 These controls are applicable to all codecs and not just MPEG. The
190 defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
191 were originally made for MPEG codecs and later extended to cover all
195 Generic Codec Controls
196 ----------------------
204 ``V4L2_CID_MPEG_CLASS (class)``
205 The Codec class descriptor. Calling
206 :ref:`VIDIOC_QUERYCTRL` for this control will
207 return a description of this control class. This description can be
208 used as the caption of a Tab page in a GUI, for example.
210 .. _v4l2-mpeg-stream-type:
212 ``V4L2_CID_MPEG_STREAM_TYPE``
215 enum v4l2_mpeg_stream_type -
216 The MPEG-1, -2 or -4 output stream type. One cannot assume anything
217 here. Each hardware MPEG encoder tends to support different subsets
218 of the available MPEG stream types. This control is specific to
219 multiplexed MPEG streams. The currently defined stream types are:
227 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_PS``
228 - MPEG-2 program stream
229 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_TS``
230 - MPEG-2 transport stream
231 * - ``V4L2_MPEG_STREAM_TYPE_MPEG1_SS``
232 - MPEG-1 system stream
233 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_DVD``
234 - MPEG-2 DVD-compatible stream
235 * - ``V4L2_MPEG_STREAM_TYPE_MPEG1_VCD``
236 - MPEG-1 VCD-compatible stream
237 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD``
238 - MPEG-2 SVCD-compatible stream
242 ``V4L2_CID_MPEG_STREAM_PID_PMT (integer)``
243 Program Map Table Packet ID for the MPEG transport stream (default
246 ``V4L2_CID_MPEG_STREAM_PID_AUDIO (integer)``
247 Audio Packet ID for the MPEG transport stream (default 256)
249 ``V4L2_CID_MPEG_STREAM_PID_VIDEO (integer)``
250 Video Packet ID for the MPEG transport stream (default 260)
252 ``V4L2_CID_MPEG_STREAM_PID_PCR (integer)``
253 Packet ID for the MPEG transport stream carrying PCR fields (default
256 ``V4L2_CID_MPEG_STREAM_PES_ID_AUDIO (integer)``
257 Audio ID for MPEG PES
259 ``V4L2_CID_MPEG_STREAM_PES_ID_VIDEO (integer)``
260 Video ID for MPEG PES
262 .. _v4l2-mpeg-stream-vbi-fmt:
264 ``V4L2_CID_MPEG_STREAM_VBI_FMT``
267 enum v4l2_mpeg_stream_vbi_fmt -
268 Some cards can embed VBI data (e. g. Closed Caption, Teletext) into
269 the MPEG stream. This control selects whether VBI data should be
270 embedded, and if so, what embedding method should be used. The list
271 of possible VBI formats depends on the driver. The currently defined
272 VBI format types are:
276 .. tabularcolumns:: |p{6 cm}|p{11.5cm}|
282 * - ``V4L2_MPEG_STREAM_VBI_FMT_NONE``
283 - No VBI in the MPEG stream
284 * - ``V4L2_MPEG_STREAM_VBI_FMT_IVTV``
285 - VBI in private packets, IVTV format (documented in the kernel
287 ``Documentation/media/v4l-drivers/cx2341x.rst``)
291 .. _v4l2-mpeg-audio-sampling-freq:
293 ``V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ``
296 enum v4l2_mpeg_audio_sampling_freq -
297 MPEG Audio sampling frequency. Possible values are:
305 * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100``
307 * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000``
309 * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000``
314 .. _v4l2-mpeg-audio-encoding:
316 ``V4L2_CID_MPEG_AUDIO_ENCODING``
319 enum v4l2_mpeg_audio_encoding -
320 MPEG Audio encoding. This control is specific to multiplexed MPEG
321 streams. Possible values are:
329 * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_1``
330 - MPEG-1/2 Layer I encoding
331 * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_2``
332 - MPEG-1/2 Layer II encoding
333 * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_3``
334 - MPEG-1/2 Layer III encoding
335 * - ``V4L2_MPEG_AUDIO_ENCODING_AAC``
336 - MPEG-2/4 AAC (Advanced Audio Coding)
337 * - ``V4L2_MPEG_AUDIO_ENCODING_AC3``
338 - AC-3 aka ATSC A/52 encoding
342 .. _v4l2-mpeg-audio-l1-bitrate:
344 ``V4L2_CID_MPEG_AUDIO_L1_BITRATE``
347 enum v4l2_mpeg_audio_l1_bitrate -
348 MPEG-1/2 Layer I bitrate. Possible values are:
356 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_32K``
358 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_64K``
360 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_96K``
362 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_128K``
364 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_160K``
366 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_192K``
368 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_224K``
370 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_256K``
372 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_288K``
374 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_320K``
376 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_352K``
378 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_384K``
380 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_416K``
382 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_448K``
387 .. _v4l2-mpeg-audio-l2-bitrate:
389 ``V4L2_CID_MPEG_AUDIO_L2_BITRATE``
392 enum v4l2_mpeg_audio_l2_bitrate -
393 MPEG-1/2 Layer II bitrate. Possible values are:
401 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_32K``
403 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_48K``
405 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_56K``
407 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_64K``
409 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_80K``
411 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_96K``
413 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_112K``
415 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_128K``
417 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_160K``
419 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_192K``
421 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_224K``
423 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_256K``
425 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_320K``
427 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_384K``
432 .. _v4l2-mpeg-audio-l3-bitrate:
434 ``V4L2_CID_MPEG_AUDIO_L3_BITRATE``
437 enum v4l2_mpeg_audio_l3_bitrate -
438 MPEG-1/2 Layer III bitrate. Possible values are:
446 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_32K``
448 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_40K``
450 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_48K``
452 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_56K``
454 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_64K``
456 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_80K``
458 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_96K``
460 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_112K``
462 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_128K``
464 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_160K``
466 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_192K``
468 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_224K``
470 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_256K``
472 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_320K``
477 ``V4L2_CID_MPEG_AUDIO_AAC_BITRATE (integer)``
478 AAC bitrate in bits per second.
480 .. _v4l2-mpeg-audio-ac3-bitrate:
482 ``V4L2_CID_MPEG_AUDIO_AC3_BITRATE``
485 enum v4l2_mpeg_audio_ac3_bitrate -
486 AC-3 bitrate. Possible values are:
494 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_32K``
496 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_40K``
498 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_48K``
500 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_56K``
502 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_64K``
504 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_80K``
506 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_96K``
508 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_112K``
510 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_128K``
512 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_160K``
514 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_192K``
516 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_224K``
518 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_256K``
520 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_320K``
522 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_384K``
524 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_448K``
526 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_512K``
528 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_576K``
530 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_640K``
535 .. _v4l2-mpeg-audio-mode:
537 ``V4L2_CID_MPEG_AUDIO_MODE``
540 enum v4l2_mpeg_audio_mode -
541 MPEG Audio mode. Possible values are:
549 * - ``V4L2_MPEG_AUDIO_MODE_STEREO``
551 * - ``V4L2_MPEG_AUDIO_MODE_JOINT_STEREO``
553 * - ``V4L2_MPEG_AUDIO_MODE_DUAL``
555 * - ``V4L2_MPEG_AUDIO_MODE_MONO``
560 .. _v4l2-mpeg-audio-mode-extension:
562 ``V4L2_CID_MPEG_AUDIO_MODE_EXTENSION``
565 enum v4l2_mpeg_audio_mode_extension -
566 Joint Stereo audio mode extension. In Layer I and II they indicate
567 which subbands are in intensity stereo. All other subbands are coded
568 in stereo. Layer III is not (yet) supported. Possible values are:
576 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4``
577 - Subbands 4-31 in intensity stereo
578 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8``
579 - Subbands 8-31 in intensity stereo
580 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12``
581 - Subbands 12-31 in intensity stereo
582 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16``
583 - Subbands 16-31 in intensity stereo
587 .. _v4l2-mpeg-audio-emphasis:
589 ``V4L2_CID_MPEG_AUDIO_EMPHASIS``
592 enum v4l2_mpeg_audio_emphasis -
593 Audio Emphasis. Possible values are:
601 * - ``V4L2_MPEG_AUDIO_EMPHASIS_NONE``
603 * - ``V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS``
604 - 50/15 microsecond emphasis
605 * - ``V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17``
610 .. _v4l2-mpeg-audio-crc:
612 ``V4L2_CID_MPEG_AUDIO_CRC``
615 enum v4l2_mpeg_audio_crc -
616 CRC method. Possible values are:
624 * - ``V4L2_MPEG_AUDIO_CRC_NONE``
626 * - ``V4L2_MPEG_AUDIO_CRC_CRC16``
627 - 16 bit parity check
631 ``V4L2_CID_MPEG_AUDIO_MUTE (boolean)``
632 Mutes the audio when capturing. This is not done by muting audio
633 hardware, which can still produce a slight hiss, but in the encoder
634 itself, guaranteeing a fixed and reproducible audio bitstream. 0 =
637 .. _v4l2-mpeg-audio-dec-playback:
639 ``V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK``
642 enum v4l2_mpeg_audio_dec_playback -
643 Determines how monolingual audio should be played back. Possible
648 .. tabularcolumns:: |p{9.0cm}|p{8.5cm}|
654 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO``
655 - Automatically determines the best playback mode.
656 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO``
658 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT``
659 - Left channel playback.
660 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT``
661 - Right channel playback.
662 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO``
664 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO``
665 - Stereo playback with swapped left and right channels.
669 .. _v4l2-mpeg-audio-dec-multilingual-playback:
671 ``V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK``
674 enum v4l2_mpeg_audio_dec_playback -
675 Determines how multilingual audio should be played back.
677 .. _v4l2-mpeg-video-encoding:
679 ``V4L2_CID_MPEG_VIDEO_ENCODING``
682 enum v4l2_mpeg_video_encoding -
683 MPEG Video encoding method. This control is specific to multiplexed
684 MPEG streams. Possible values are:
692 * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_1``
693 - MPEG-1 Video encoding
694 * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_2``
695 - MPEG-2 Video encoding
696 * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC``
697 - MPEG-4 AVC (H.264) Video encoding
701 .. _v4l2-mpeg-video-aspect:
703 ``V4L2_CID_MPEG_VIDEO_ASPECT``
706 enum v4l2_mpeg_video_aspect -
707 Video aspect. Possible values are:
715 * - ``V4L2_MPEG_VIDEO_ASPECT_1x1``
716 * - ``V4L2_MPEG_VIDEO_ASPECT_4x3``
717 * - ``V4L2_MPEG_VIDEO_ASPECT_16x9``
718 * - ``V4L2_MPEG_VIDEO_ASPECT_221x100``
722 ``V4L2_CID_MPEG_VIDEO_B_FRAMES (integer)``
723 Number of B-Frames (default 2)
725 ``V4L2_CID_MPEG_VIDEO_GOP_SIZE (integer)``
726 GOP size (default 12)
728 ``V4L2_CID_MPEG_VIDEO_GOP_CLOSURE (boolean)``
729 GOP closure (default 1)
731 ``V4L2_CID_MPEG_VIDEO_PULLDOWN (boolean)``
732 Enable 3:2 pulldown (default 0)
734 .. _v4l2-mpeg-video-bitrate-mode:
736 ``V4L2_CID_MPEG_VIDEO_BITRATE_MODE``
739 enum v4l2_mpeg_video_bitrate_mode -
740 Video bitrate mode. Possible values are:
748 * - ``V4L2_MPEG_VIDEO_BITRATE_MODE_VBR``
750 * - ``V4L2_MPEG_VIDEO_BITRATE_MODE_CBR``
755 ``V4L2_CID_MPEG_VIDEO_BITRATE (integer)``
756 Video bitrate in bits per second.
758 ``V4L2_CID_MPEG_VIDEO_BITRATE_PEAK (integer)``
759 Peak video bitrate in bits per second. Must be larger or equal to
760 the average video bitrate. It is ignored if the video bitrate mode
761 is set to constant bitrate.
763 ``V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION (integer)``
764 For every captured frame, skip this many subsequent frames (default
767 ``V4L2_CID_MPEG_VIDEO_MUTE (boolean)``
768 "Mutes" the video to a fixed color when capturing. This is useful
769 for testing, to produce a fixed video bitstream. 0 = unmuted, 1 =
772 ``V4L2_CID_MPEG_VIDEO_MUTE_YUV (integer)``
773 Sets the "mute" color of the video. The supplied 32-bit integer is
774 interpreted as follows (bit 0 = least significant bit):
783 - V chrominance information
785 - U chrominance information
787 - Y luminance information
793 .. _v4l2-mpeg-video-dec-pts:
795 ``V4L2_CID_MPEG_VIDEO_DEC_PTS (integer64)``
796 This read-only control returns the 33-bit video Presentation Time
797 Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of the
798 currently displayed frame. This is the same PTS as is used in
799 :ref:`VIDIOC_DECODER_CMD`.
801 .. _v4l2-mpeg-video-dec-frame:
803 ``V4L2_CID_MPEG_VIDEO_DEC_FRAME (integer64)``
804 This read-only control returns the frame counter of the frame that
805 is currently displayed (decoded). This value is reset to 0 whenever
806 the decoder is started.
808 ``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
809 If enabled the decoder expects to receive a single slice per buffer,
810 otherwise the decoder expects a single frame in per buffer.
811 Applicable to the decoder, all codecs.
813 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_ENABLE (boolean)``
814 Enable writing sample aspect ratio in the Video Usability
815 Information. Applicable to the H264 encoder.
817 .. _v4l2-mpeg-video-h264-vui-sar-idc:
819 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_IDC``
822 enum v4l2_mpeg_video_h264_vui_sar_idc -
823 VUI sample aspect ratio indicator for H.264 encoding. The value is
824 defined in the table E-1 in the standard. Applicable to the H264
833 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_UNSPECIFIED``
835 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_1x1``
837 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_12x11``
839 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_10x11``
841 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_16x11``
843 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_40x33``
845 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_24x11``
847 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_20x11``
849 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_32x11``
851 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_80x33``
853 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_18x11``
855 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_15x11``
857 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_64x33``
859 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_160x99``
861 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_4x3``
863 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_3x2``
865 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_2x1``
867 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_EXTENDED``
872 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_WIDTH (integer)``
873 Extended sample aspect ratio width for H.264 VUI encoding.
874 Applicable to the H264 encoder.
876 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_HEIGHT (integer)``
877 Extended sample aspect ratio height for H.264 VUI encoding.
878 Applicable to the H264 encoder.
880 .. _v4l2-mpeg-video-h264-level:
882 ``V4L2_CID_MPEG_VIDEO_H264_LEVEL``
885 enum v4l2_mpeg_video_h264_level -
886 The level information for the H264 video elementary stream.
887 Applicable to the H264 encoder. Possible values are:
895 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_0``
897 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1B``
899 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_1``
901 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_2``
903 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_3``
905 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_0``
907 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_1``
909 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_2``
911 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_0``
913 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_1``
915 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_2``
917 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_0``
919 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_1``
921 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_2``
923 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_0``
925 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_1``
930 .. _v4l2-mpeg-video-mpeg4-level:
932 ``V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL``
935 enum v4l2_mpeg_video_mpeg4_level -
936 The level information for the MPEG4 elementary stream. Applicable to
937 the MPEG4 encoder. Possible values are:
945 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_0``
947 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_0B``
949 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_1``
951 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_2``
953 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_3``
955 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_3B``
957 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_4``
959 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_5``
964 .. _v4l2-mpeg-video-h264-profile:
966 ``V4L2_CID_MPEG_VIDEO_H264_PROFILE``
969 enum v4l2_mpeg_video_h264_profile -
970 The profile information for H264. Applicable to the H264 encoder.
979 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE``
981 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_CONSTRAINED_BASELINE``
982 - Constrained Baseline profile
983 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_MAIN``
985 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED``
987 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH``
989 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10``
991 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422``
993 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE``
994 - High 444 Predictive profile
995 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10_INTRA``
996 - High 10 Intra profile
997 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422_INTRA``
998 - High 422 Intra profile
999 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_INTRA``
1000 - High 444 Intra profile
1001 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_CAVLC_444_INTRA``
1002 - CAVLC 444 Intra profile
1003 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE``
1004 - Scalable Baseline profile
1005 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH``
1006 - Scalable High profile
1007 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH_INTRA``
1008 - Scalable High Intra profile
1009 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH``
1010 - Stereo High profile
1011 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH``
1012 - Multiview High profile
1016 .. _v4l2-mpeg-video-mpeg4-profile:
1018 ``V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE``
1021 enum v4l2_mpeg_video_mpeg4_profile -
1022 The profile information for MPEG4. Applicable to the MPEG4 encoder.
1023 Possible values are:
1031 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_SIMPLE``
1033 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_ADVANCED_SIMPLE``
1034 - Advanced Simple profile
1035 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_CORE``
1037 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_SIMPLE_SCALABLE``
1038 - Simple Scalable profile
1039 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_ADVANCED_CODING_EFFICIENCY``
1044 ``V4L2_CID_MPEG_VIDEO_MAX_REF_PIC (integer)``
1045 The maximum number of reference pictures used for encoding.
1046 Applicable to the encoder.
1048 .. _v4l2-mpeg-video-multi-slice-mode:
1050 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE``
1053 enum v4l2_mpeg_video_multi_slice_mode -
1054 Determines how the encoder should handle division of frame into
1055 slices. Applicable to the encoder. Possible values are:
1059 .. tabularcolumns:: |p{8.7cm}|p{8.8cm}|
1065 * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_SINGLE``
1066 - Single slice per frame.
1067 * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``
1068 - Multiple slices with set maximum number of macroblocks per slice.
1069 * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``
1070 - Multiple slice with set maximum size in bytes per slice.
1074 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB (integer)``
1075 The maximum number of macroblocks in a slice. Used when
1076 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1077 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``. Applicable to the
1080 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES (integer)``
1081 The maximum size of a slice in bytes. Used when
1082 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1083 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``. Applicable to the
1086 .. _v4l2-mpeg-video-h264-loop-filter-mode:
1088 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_MODE``
1091 enum v4l2_mpeg_video_h264_loop_filter_mode -
1092 Loop filter mode for H264 encoder. Possible values are:
1096 .. tabularcolumns:: |p{14.0cm}|p{3.5cm}|
1102 * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_ENABLED``
1103 - Loop filter is enabled.
1104 * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED``
1105 - Loop filter is disabled.
1106 * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
1107 - Loop filter is disabled at the slice boundary.
1111 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)``
1112 Loop filter alpha coefficient, defined in the H264 standard.
1113 Applicable to the H264 encoder.
1115 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)``
1116 Loop filter beta coefficient, defined in the H264 standard.
1117 Applicable to the H264 encoder.
1119 .. _v4l2-mpeg-video-h264-entropy-mode:
1121 ``V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE``
1124 enum v4l2_mpeg_video_h264_entropy_mode -
1125 Entropy coding mode for H264 - CABAC/CAVALC. Applicable to the H264
1126 encoder. Possible values are:
1134 * - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CAVLC``
1135 - Use CAVLC entropy coding.
1136 * - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CABAC``
1137 - Use CABAC entropy coding.
1141 ``V4L2_CID_MPEG_VIDEO_H264_8X8_TRANSFORM (boolean)``
1142 Enable 8X8 transform for H264. Applicable to the H264 encoder.
1144 ``V4L2_CID_MPEG_VIDEO_CYCLIC_INTRA_REFRESH_MB (integer)``
1145 Cyclic intra macroblock refresh. This is the number of continuous
1146 macroblocks refreshed every frame. Each frame a successive set of
1147 macroblocks is refreshed until the cycle completes and starts from
1148 the top of the frame. Applicable to H264, H263 and MPEG4 encoder.
1150 ``V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE (boolean)``
1151 Frame level rate control enable. If this control is disabled then
1152 the quantization parameter for each frame type is constant and set
1153 with appropriate controls (e.g.
1154 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP``). If frame rate control is
1155 enabled then quantization parameter is adjusted to meet the chosen
1156 bitrate. Minimum and maximum value for the quantization parameter
1157 can be set with appropriate controls (e.g.
1158 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP``). Applicable to encoders.
1160 ``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE (boolean)``
1161 Macroblock level rate control enable. Applicable to the MPEG4 and
1164 ``V4L2_CID_MPEG_VIDEO_MPEG4_QPEL (boolean)``
1165 Quarter pixel motion estimation for MPEG4. Applicable to the MPEG4
1168 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (integer)``
1169 Quantization parameter for an I frame for H263. Valid range: from 1
1172 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP (integer)``
1173 Minimum quantization parameter for H263. Valid range: from 1 to 31.
1175 ``V4L2_CID_MPEG_VIDEO_H263_MAX_QP (integer)``
1176 Maximum quantization parameter for H263. Valid range: from 1 to 31.
1178 ``V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (integer)``
1179 Quantization parameter for an P frame for H263. Valid range: from 1
1182 ``V4L2_CID_MPEG_VIDEO_H263_B_FRAME_QP (integer)``
1183 Quantization parameter for an B frame for H263. Valid range: from 1
1186 ``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_QP (integer)``
1187 Quantization parameter for an I frame for H264. Valid range: from 0
1190 ``V4L2_CID_MPEG_VIDEO_H264_MIN_QP (integer)``
1191 Minimum quantization parameter for H264. Valid range: from 0 to 51.
1193 ``V4L2_CID_MPEG_VIDEO_H264_MAX_QP (integer)``
1194 Maximum quantization parameter for H264. Valid range: from 0 to 51.
1196 ``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP (integer)``
1197 Quantization parameter for an P frame for H264. Valid range: from 0
1200 ``V4L2_CID_MPEG_VIDEO_H264_B_FRAME_QP (integer)``
1201 Quantization parameter for an B frame for H264. Valid range: from 0
1204 ``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
1205 Quantization parameter for an I frame for MPEG4. Valid range: from 1
1208 ``V4L2_CID_MPEG_VIDEO_MPEG4_MIN_QP (integer)``
1209 Minimum quantization parameter for MPEG4. Valid range: from 1 to 31.
1211 ``V4L2_CID_MPEG_VIDEO_MPEG4_MAX_QP (integer)``
1212 Maximum quantization parameter for MPEG4. Valid range: from 1 to 31.
1214 ``V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (integer)``
1215 Quantization parameter for an P frame for MPEG4. Valid range: from 1
1218 ``V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (integer)``
1219 Quantization parameter for an B frame for MPEG4. Valid range: from 1
1222 ``V4L2_CID_MPEG_VIDEO_VBV_SIZE (integer)``
1223 The Video Buffer Verifier size in kilobytes, it is used as a
1224 limitation of frame skip. The VBV is defined in the standard as a
1225 mean to verify that the produced stream will be successfully
1226 decoded. The standard describes it as "Part of a hypothetical
1227 decoder that is conceptually connected to the output of the encoder.
1228 Its purpose is to provide a constraint on the variability of the
1229 data rate that an encoder or editing process may produce.".
1230 Applicable to the MPEG1, MPEG2, MPEG4 encoders.
1232 .. _v4l2-mpeg-video-vbv-delay:
1234 ``V4L2_CID_MPEG_VIDEO_VBV_DELAY (integer)``
1235 Sets the initial delay in milliseconds for VBV buffer control.
1237 .. _v4l2-mpeg-video-hor-search-range:
1239 ``V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (integer)``
1240 Horizontal search range defines maximum horizontal search area in
1241 pixels to search and match for the present Macroblock (MB) in the
1242 reference picture. This V4L2 control macro is used to set horizontal
1243 search range for motion estimation module in video encoder.
1245 .. _v4l2-mpeg-video-vert-search-range:
1247 ``V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (integer)``
1248 Vertical search range defines maximum vertical search area in pixels
1249 to search and match for the present Macroblock (MB) in the reference
1250 picture. This V4L2 control macro is used to set vertical search
1251 range for motion estimation module in video encoder.
1253 .. _v4l2-mpeg-video-force-key-frame:
1255 ``V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (button)``
1256 Force a key frame for the next queued buffer. Applicable to
1257 encoders. This is a general, codec-agnostic keyframe control.
1259 ``V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE (integer)``
1260 The Coded Picture Buffer size in kilobytes, it is used as a
1261 limitation of frame skip. The CPB is defined in the H264 standard as
1262 a mean to verify that the produced stream will be successfully
1263 decoded. Applicable to the H264 encoder.
1265 ``V4L2_CID_MPEG_VIDEO_H264_I_PERIOD (integer)``
1266 Period between I-frames in the open GOP for H264. In case of an open
1267 GOP this is the period between two I-frames. The period between IDR
1268 (Instantaneous Decoding Refresh) frames is taken from the GOP_SIZE
1269 control. An IDR frame, which stands for Instantaneous Decoding
1270 Refresh is an I-frame after which no prior frames are referenced.
1271 This means that a stream can be restarted from an IDR frame without
1272 the need to store or decode any previous frames. Applicable to the
1275 .. _v4l2-mpeg-video-header-mode:
1277 ``V4L2_CID_MPEG_VIDEO_HEADER_MODE``
1280 enum v4l2_mpeg_video_header_mode -
1281 Determines whether the header is returned as the first buffer or is
1282 it returned together with the first frame. Applicable to encoders.
1283 Possible values are:
1287 .. tabularcolumns:: |p{10.3cm}|p{7.2cm}|
1293 * - ``V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE``
1294 - The stream header is returned separately in the first buffer.
1295 * - ``V4L2_MPEG_VIDEO_HEADER_MODE_JOINED_WITH_1ST_FRAME``
1296 - The stream header is returned together with the first encoded
1301 ``V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (boolean)``
1302 Repeat the video sequence headers. Repeating these headers makes
1303 random access to the video stream easier. Applicable to the MPEG1, 2
1306 ``V4L2_CID_MPEG_VIDEO_DECODER_MPEG4_DEBLOCK_FILTER (boolean)``
1307 Enabled the deblocking post processing filter for MPEG4 decoder.
1308 Applicable to the MPEG4 decoder.
1310 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_RES (integer)``
1311 vop_time_increment_resolution value for MPEG4. Applicable to the
1314 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_INC (integer)``
1315 vop_time_increment value for MPEG4. Applicable to the MPEG4
1318 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FRAME_PACKING (boolean)``
1319 Enable generation of frame packing supplemental enhancement
1320 information in the encoded bitstream. The frame packing SEI message
1321 contains the arrangement of L and R planes for 3D viewing.
1322 Applicable to the H264 encoder.
1324 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_CURRENT_FRAME_0 (boolean)``
1325 Sets current frame as frame0 in frame packing SEI. Applicable to the
1328 .. _v4l2-mpeg-video-h264-sei-fp-arrangement-type:
1330 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE``
1333 enum v4l2_mpeg_video_h264_sei_fp_arrangement_type -
1334 Frame packing arrangement type for H264 SEI. Applicable to the H264
1335 encoder. Possible values are:
1337 .. tabularcolumns:: |p{12cm}|p{5.5cm}|
1343 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_CHEKERBOARD``
1344 - Pixels are alternatively from L and R.
1345 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_COLUMN``
1346 - L and R are interlaced by column.
1347 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_ROW``
1348 - L and R are interlaced by row.
1349 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_SIDE_BY_SIDE``
1350 - L is on the left, R on the right.
1351 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TOP_BOTTOM``
1352 - L is on top, R on bottom.
1353 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TEMPORAL``
1354 - One view per frame.
1358 ``V4L2_CID_MPEG_VIDEO_H264_FMO (boolean)``
1359 Enables flexible macroblock ordering in the encoded bitstream. It is
1360 a technique used for restructuring the ordering of macroblocks in
1361 pictures. Applicable to the H264 encoder.
1363 .. _v4l2-mpeg-video-h264-fmo-map-type:
1365 ``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE``
1368 enum v4l2_mpeg_video_h264_fmo_map_type -
1369 When using FMO, the map type divides the image in different scan
1370 patterns of macroblocks. Applicable to the H264 encoder. Possible
1373 .. tabularcolumns:: |p{12.5cm}|p{5.0cm}|
1379 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_INTERLEAVED_SLICES``
1380 - Slices are interleaved one after other with macroblocks in run
1382 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_SCATTERED_SLICES``
1383 - Scatters the macroblocks based on a mathematical function known to
1384 both encoder and decoder.
1385 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_FOREGROUND_WITH_LEFT_OVER``
1386 - Macroblocks arranged in rectangular areas or regions of interest.
1387 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_BOX_OUT``
1388 - Slice groups grow in a cyclic way from centre to outwards.
1389 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_RASTER_SCAN``
1390 - Slice groups grow in raster scan pattern from left to right.
1391 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_WIPE_SCAN``
1392 - Slice groups grow in wipe scan pattern from top to bottom.
1393 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_EXPLICIT``
1394 - User defined map type.
1398 ``V4L2_CID_MPEG_VIDEO_H264_FMO_SLICE_GROUP (integer)``
1399 Number of slice groups in FMO. Applicable to the H264 encoder.
1401 .. _v4l2-mpeg-video-h264-fmo-change-direction:
1403 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_DIRECTION``
1406 enum v4l2_mpeg_video_h264_fmo_change_dir -
1407 Specifies a direction of the slice group change for raster and wipe
1408 maps. Applicable to the H264 encoder. Possible values are:
1416 * - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_RIGHT``
1417 - Raster scan or wipe right.
1418 * - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_LEFT``
1419 - Reverse raster scan or wipe left.
1423 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_RATE (integer)``
1424 Specifies the size of the first slice group for raster and wipe map.
1425 Applicable to the H264 encoder.
1427 ``V4L2_CID_MPEG_VIDEO_H264_FMO_RUN_LENGTH (integer)``
1428 Specifies the number of consecutive macroblocks for the interleaved
1429 map. Applicable to the H264 encoder.
1431 ``V4L2_CID_MPEG_VIDEO_H264_ASO (boolean)``
1432 Enables arbitrary slice ordering in encoded bitstream. Applicable to
1435 ``V4L2_CID_MPEG_VIDEO_H264_ASO_SLICE_ORDER (integer)``
1436 Specifies the slice order in ASO. Applicable to the H264 encoder.
1437 The supplied 32-bit integer is interpreted as follows (bit 0 = least
1449 - Slice position or order
1453 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING (boolean)``
1454 Enables H264 hierarchical coding. Applicable to the H264 encoder.
1456 .. _v4l2-mpeg-video-h264-hierarchical-coding-type:
1458 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_TYPE``
1461 enum v4l2_mpeg_video_h264_hierarchical_coding_type -
1462 Specifies the hierarchical coding type. Applicable to the H264
1463 encoder. Possible values are:
1471 * - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_B``
1472 - Hierarchical B coding.
1473 * - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_P``
1474 - Hierarchical P coding.
1478 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (integer)``
1479 Specifies the number of hierarchical coding layers. Applicable to
1482 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (integer)``
1483 Specifies a user defined QP for each layer. Applicable to the H264
1484 encoder. The supplied 32-bit integer is interpreted as follows (bit
1485 0 = least significant bit):
1500 .. _v4l2-mpeg-mpeg2:
1502 ``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS (struct)``
1503 Specifies the slice parameters (as extracted from the bitstream) for the
1504 associated MPEG-2 slice data. This includes the necessary parameters for
1505 configuring a stateless hardware decoding pipeline for MPEG-2.
1506 The bitstream parameters are defined according to :ref:`mpeg2part2`.
1508 .. c:type:: v4l2_ctrl_mpeg2_slice_params
1510 .. cssclass:: longtable
1512 .. flat-table:: struct v4l2_ctrl_mpeg2_slice_params
1519 - Size (in bits) of the current slice data.
1521 - ``data_bit_offset``
1522 - Offset (in bits) to the video data in the current slice data.
1523 * - struct :c:type:`v4l2_mpeg2_sequence`
1525 - Structure with MPEG-2 sequence metadata, merging relevant fields from
1526 the sequence header and sequence extension parts of the bitstream.
1527 * - struct :c:type:`v4l2_mpeg2_picture`
1529 - Structure with MPEG-2 picture metadata, merging relevant fields from
1530 the picture header and picture coding extension parts of the bitstream.
1532 - ``quantiser_scale_code``
1533 - Code used to determine the quantization scale to use for the IDCT.
1535 - ``backward_ref_index``
1536 - Index for the V4L2 buffer to use as backward reference, used with
1537 B-coded and P-coded frames.
1539 - ``forward_ref_index``
1540 - Index for the V4L2 buffer to use as forward reference, used with
1543 .. c:type:: v4l2_mpeg2_sequence
1545 .. cssclass:: longtable
1547 .. flat-table:: struct v4l2_mpeg2_sequence
1553 - ``horizontal_size``
1554 - The width of the displayable part of the frame's luminance component.
1557 - The height of the displayable part of the frame's luminance component.
1559 - ``vbv_buffer_size``
1560 - Used to calculate the required size of the video buffering verifier,
1561 defined (in bits) as: 16 * 1024 * vbv_buffer_size.
1563 - ``profile_and_level_indication``
1564 - The current profile and level indication as extracted from the
1567 - ``progressive_sequence``
1568 - Indication that all the frames for the sequence are progressive instead
1572 - The chrominance sub-sampling format (1: 4:2:0, 2: 4:2:2, 3: 4:4:4).
1574 .. c:type:: v4l2_mpeg2_picture
1576 .. cssclass:: longtable
1578 .. flat-table:: struct v4l2_mpeg2_picture
1584 - ``picture_coding_type``
1585 - Picture coding type for the frame covered by the current slice
1586 (V4L2_MPEG2_PICTURE_CODING_TYPE_I, V4L2_MPEG2_PICTURE_CODING_TYPE_P or
1587 V4L2_MPEG2_PICTURE_CODING_TYPE_B).
1590 - Motion vector codes.
1592 - ``intra_dc_precision``
1593 - Precision of Discrete Cosine transform (0: 8 bits precision,
1594 1: 9 bits precision, 2: 10 bits precision, 3: 11 bits precision).
1596 - ``picture_structure``
1597 - Picture structure (1: interlaced top field, 2: interlaced bottom field,
1598 3: progressive frame).
1600 - ``top_field_first``
1601 - If set to 1 and interlaced stream, top field is output first.
1603 - ``frame_pred_frame_dct``
1604 - If set to 1, only frame-DCT and frame prediction are used.
1606 - ``concealment_motion_vectors``
1607 - If set to 1, motion vectors are coded for intra macroblocks.
1610 - This flag affects the inverse quantization process.
1612 - ``intra_vlc_format``
1613 - This flag affects the decoding of transform coefficient data.
1615 - ``alternate_scan``
1616 - This flag affects the decoding of transform coefficient data.
1618 - ``repeat_first_field``
1619 - This flag affects the decoding process of progressive frames.
1621 - ``progressive_frame``
1622 - Indicates whether the current frame is progressive.
1624 ``V4L2_CID_MPEG_VIDEO_MPEG2_QUANTIZATION (struct)``
1625 Specifies quantization matrices (as extracted from the bitstream) for the
1626 associated MPEG-2 slice data.
1628 .. c:type:: v4l2_ctrl_mpeg2_quantization
1630 .. cssclass:: longtable
1632 .. flat-table:: struct v4l2_ctrl_mpeg2_quantization
1638 - ``load_intra_quantiser_matrix``
1639 - One bit to indicate whether to load the ``intra_quantiser_matrix`` data.
1641 - ``load_non_intra_quantiser_matrix``
1642 - One bit to indicate whether to load the ``non_intra_quantiser_matrix``
1645 - ``load_chroma_intra_quantiser_matrix``
1646 - One bit to indicate whether to load the
1647 ``chroma_intra_quantiser_matrix`` data, only relevant for non-4:2:0 YUV
1650 - ``load_chroma_non_intra_quantiser_matrix``
1651 - One bit to indicate whether to load the
1652 ``chroma_non_intra_quantiser_matrix`` data, only relevant for non-4:2:0
1655 - ``intra_quantiser_matrix[64]``
1656 - The quantization matrix coefficients for intra-coded frames, in zigzag
1657 scanning order. It is relevant for both luma and chroma components,
1658 although it can be superseded by the chroma-specific matrix for
1659 non-4:2:0 YUV formats.
1661 - ``non_intra_quantiser_matrix[64]``
1662 - The quantization matrix coefficients for non-intra-coded frames, in
1663 zigzag scanning order. It is relevant for both luma and chroma
1664 components, although it can be superseded by the chroma-specific matrix
1665 for non-4:2:0 YUV formats.
1667 - ``chroma_intra_quantiser_matrix[64]``
1668 - The quantization matrix coefficients for the chominance component of
1669 intra-coded frames, in zigzag scanning order. Only relevant for
1670 non-4:2:0 YUV formats.
1672 - ``chroma_non_intra_quantiser_matrix[64]``
1673 - The quantization matrix coefficients for the chrominance component of
1674 non-intra-coded frames, in zigzag scanning order. Only relevant for
1675 non-4:2:0 YUV formats.
1677 MFC 5.1 MPEG Controls
1678 ---------------------
1680 The following MPEG class controls deal with MPEG decoding and encoding
1681 settings that are specific to the Multi Format Codec 5.1 device present
1682 in the S5P family of SoCs by Samsung.
1685 .. _mfc51-control-id:
1690 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY_ENABLE (boolean)``
1691 If the display delay is enabled then the decoder is forced to return
1692 a CAPTURE buffer (decoded frame) after processing a certain number
1693 of OUTPUT buffers. The delay can be set through
1694 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY``. This
1695 feature can be used for example for generating thumbnails of videos.
1696 Applicable to the H264 decoder.
1698 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY (integer)``
1699 Display delay value for H264 decoder. The decoder is forced to
1700 return a decoded frame after the set 'display delay' number of
1701 frames. If this number is low it may result in frames returned out
1702 of dispaly order, in addition the hardware may still be using the
1703 returned buffer as a reference picture for subsequent frames.
1705 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P (integer)``
1706 The number of reference pictures used for encoding a P picture.
1707 Applicable to the H264 encoder.
1709 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING (boolean)``
1710 Padding enable in the encoder - use a color instead of repeating
1711 border pixels. Applicable to encoders.
1713 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING_YUV (integer)``
1714 Padding color in the encoder. Applicable to encoders. The supplied
1715 32-bit integer is interpreted as follows (bit 0 = least significant
1725 - V chrominance information
1727 - U chrominance information
1729 - Y luminance information
1735 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
1736 Reaction coefficient for MFC rate control. Applicable to encoders.
1740 #. Valid only when the frame level RC is enabled.
1742 #. For tight CBR, this field must be small (ex. 2 ~ 10). For
1743 VBR, this field must be large (ex. 100 ~ 1000).
1745 #. It is not recommended to use the greater number than
1746 FRAME_RATE * (10^9 / BIT_RATE).
1748 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
1749 Adaptive rate control for dark region. Valid only when H.264 and
1750 macroblock level RC is enabled
1751 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1754 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_SMOOTH (boolean)``
1755 Adaptive rate control for smooth region. Valid only when H.264 and
1756 macroblock level RC is enabled
1757 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1760 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC (boolean)``
1761 Adaptive rate control for static region. Valid only when H.264 and
1762 macroblock level RC is enabled
1763 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1766 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_ACTIVITY (boolean)``
1767 Adaptive rate control for activity region. Valid only when H.264 and
1768 macroblock level RC is enabled
1769 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1772 .. _v4l2-mpeg-mfc51-video-frame-skip-mode:
1774 ``V4L2_CID_MPEG_MFC51_VIDEO_FRAME_SKIP_MODE``
1777 enum v4l2_mpeg_mfc51_video_frame_skip_mode -
1778 Indicates in what conditions the encoder should skip frames. If
1779 encoding a frame would cause the encoded stream to be larger then a
1780 chosen data limit then the frame will be skipped. Possible values
1784 .. tabularcolumns:: |p{9.0cm}|p{8.5cm}|
1790 * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_DISABLED``
1791 - Frame skip mode is disabled.
1792 * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_LEVEL_LIMIT``
1793 - Frame skip mode enabled and buffer limit is set by the chosen
1794 level and is defined by the standard.
1795 * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_BUF_LIMIT``
1796 - Frame skip mode enabled and buffer limit is set by the VBV
1797 (MPEG1/2/4) or CPB (H264) buffer size control.
1801 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT (integer)``
1802 Enable rate-control with fixed target bit. If this setting is
1803 enabled, then the rate control logic of the encoder will calculate
1804 the average bitrate for a GOP and keep it below or equal the set
1805 bitrate target. Otherwise the rate control logic calculates the
1806 overall average bitrate for the stream and keeps it below or equal
1807 to the set bitrate. In the first case the average bitrate for the
1808 whole stream will be smaller then the set bitrate. This is caused
1809 because the average is calculated for smaller number of frames, on
1810 the other hand enabling this setting will ensure that the stream
1811 will meet tight bandwidth constraints. Applicable to encoders.
1813 .. _v4l2-mpeg-mfc51-video-force-frame-type:
1815 ``V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE``
1818 enum v4l2_mpeg_mfc51_video_force_frame_type -
1819 Force a frame type for the next queued buffer. Applicable to
1820 encoders. Possible values are:
1828 * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_DISABLED``
1829 - Forcing a specific frame type disabled.
1830 * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_I_FRAME``
1832 * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_NOT_CODED``
1833 - Force a non-coded frame.
1838 CX2341x MPEG Controls
1839 ---------------------
1841 The following MPEG class controls deal with MPEG encoding settings that
1842 are specific to the Conexant CX23415 and CX23416 MPEG encoding chips.
1845 .. _cx2341x-control-id:
1850 .. _v4l2-mpeg-cx2341x-video-spatial-filter-mode:
1852 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE``
1855 enum v4l2_mpeg_cx2341x_video_spatial_filter_mode -
1856 Sets the Spatial Filter mode (default ``MANUAL``). Possible values
1865 * - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL``
1866 - Choose the filter manually
1867 * - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO``
1868 - Choose the filter automatically
1872 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER (integer (0-15))``
1873 The setting for the Spatial Filter. 0 = off, 15 = maximum. (Default
1876 .. _luma-spatial-filter-type:
1878 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE``
1881 enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type -
1882 Select the algorithm to use for the Luma Spatial Filter (default
1883 ``1D_HOR``). Possible values:
1887 .. tabularcolumns:: |p{14.5cm}|p{3.0cm}|
1893 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF``
1895 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR``
1896 - One-dimensional horizontal
1897 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT``
1898 - One-dimensional vertical
1899 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE``
1900 - Two-dimensional separable
1901 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE``
1902 - Two-dimensional symmetrical non-separable
1906 .. _chroma-spatial-filter-type:
1908 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE``
1911 enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type -
1912 Select the algorithm for the Chroma Spatial Filter (default
1913 ``1D_HOR``). Possible values are:
1921 * - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF``
1923 * - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR``
1924 - One-dimensional horizontal
1928 .. _v4l2-mpeg-cx2341x-video-temporal-filter-mode:
1930 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE``
1933 enum v4l2_mpeg_cx2341x_video_temporal_filter_mode -
1934 Sets the Temporal Filter mode (default ``MANUAL``). Possible values
1943 * - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL``
1944 - Choose the filter manually
1945 * - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO``
1946 - Choose the filter automatically
1950 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER (integer (0-31))``
1951 The setting for the Temporal Filter. 0 = off, 31 = maximum. (Default
1952 is 8 for full-scale capturing and 0 for scaled capturing.)
1954 .. _v4l2-mpeg-cx2341x-video-median-filter-type:
1956 ``V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE``
1959 enum v4l2_mpeg_cx2341x_video_median_filter_type -
1960 Median Filter Type (default ``OFF``). Possible values are:
1968 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF``
1970 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR``
1972 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT``
1974 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT``
1975 - Horizontal and vertical filter
1976 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG``
1981 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
1982 Threshold above which the luminance median filter is enabled
1985 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP (integer (0-255))``
1986 Threshold below which the luminance median filter is enabled
1989 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
1990 Threshold above which the chroma median filter is enabled (default
1993 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP (integer (0-255))``
1994 Threshold below which the chroma median filter is enabled (default
1997 ``V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS (boolean)``
1998 The CX2341X MPEG encoder can insert one empty MPEG-2 PES packet into
1999 the stream between every four video frames. The packet size is 2048
2000 bytes, including the packet_start_code_prefix and stream_id
2001 fields. The stream_id is 0xBF (private stream 2). The payload
2002 consists of 0x00 bytes, to be filled in by the application. 0 = do
2003 not insert, 1 = insert packets.
2006 VPX Control Reference
2007 ---------------------
2009 The VPX controls include controls for encoding parameters of VPx video
2018 .. _v4l2-vpx-num-partitions:
2020 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS``
2023 enum v4l2_vp8_num_partitions -
2024 The number of token partitions to use in VP8 encoder. Possible
2033 * - ``V4L2_CID_MPEG_VIDEO_VPX_1_PARTITION``
2034 - 1 coefficient partition
2035 * - ``V4L2_CID_MPEG_VIDEO_VPX_2_PARTITIONS``
2036 - 2 coefficient partitions
2037 * - ``V4L2_CID_MPEG_VIDEO_VPX_4_PARTITIONS``
2038 - 4 coefficient partitions
2039 * - ``V4L2_CID_MPEG_VIDEO_VPX_8_PARTITIONS``
2040 - 8 coefficient partitions
2044 ``V4L2_CID_MPEG_VIDEO_VPX_IMD_DISABLE_4X4 (boolean)``
2045 Setting this prevents intra 4x4 mode in the intra mode decision.
2047 .. _v4l2-vpx-num-ref-frames:
2049 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES``
2052 enum v4l2_vp8_num_ref_frames -
2053 The number of reference pictures for encoding P frames. Possible
2056 .. tabularcolumns:: |p{7.9cm}|p{9.6cm}|
2062 * - ``V4L2_CID_MPEG_VIDEO_VPX_1_REF_FRAME``
2063 - Last encoded frame will be searched
2064 * - ``V4L2_CID_MPEG_VIDEO_VPX_2_REF_FRAME``
2065 - Two frames will be searched among the last encoded frame, the
2066 golden frame and the alternate reference (altref) frame. The
2067 encoder implementation will decide which two are chosen.
2068 * - ``V4L2_CID_MPEG_VIDEO_VPX_3_REF_FRAME``
2069 - The last encoded frame, the golden frame and the altref frame will
2074 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_LEVEL (integer)``
2075 Indicates the loop filter level. The adjustment of the loop filter
2076 level is done via a delta value against a baseline loop filter
2079 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_SHARPNESS (integer)``
2080 This parameter affects the loop filter. Anything above zero weakens
2081 the deblocking effect on the loop filter.
2083 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD (integer)``
2084 Sets the refresh period for the golden frame. The period is defined
2085 in number of frames. For a value of 'n', every nth frame starting
2086 from the first key frame will be taken as a golden frame. For eg.
2087 for encoding sequence of 0, 1, 2, 3, 4, 5, 6, 7 where the golden
2088 frame refresh period is set as 4, the frames 0, 4, 8 etc will be
2089 taken as the golden frames as frame 0 is always a key frame.
2091 .. _v4l2-vpx-golden-frame-sel:
2093 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_SEL``
2096 enum v4l2_vp8_golden_frame_sel -
2097 Selects the golden frame for encoding. Possible values are:
2103 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2109 * - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_PREV``
2110 - Use the (n-2)th frame as a golden frame, current frame index being
2112 * - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_REF_PERIOD``
2113 - Use the previous specific frame indicated by
2114 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD`` as a
2122 ``V4L2_CID_MPEG_VIDEO_VPX_MIN_QP (integer)``
2123 Minimum quantization parameter for VP8.
2125 ``V4L2_CID_MPEG_VIDEO_VPX_MAX_QP (integer)``
2126 Maximum quantization parameter for VP8.
2128 ``V4L2_CID_MPEG_VIDEO_VPX_I_FRAME_QP (integer)``
2129 Quantization parameter for an I frame for VP8.
2131 ``V4L2_CID_MPEG_VIDEO_VPX_P_FRAME_QP (integer)``
2132 Quantization parameter for a P frame for VP8.
2134 .. _v4l2-mpeg-video-vp8-profile:
2136 ``V4L2_CID_MPEG_VIDEO_VP8_PROFILE``
2139 enum v4l2_mpeg_video_vp8_profile -
2140 This control allows selecting the profile for VP8 encoder.
2141 This is also used to enumerate supported profiles by VP8 encoder or decoder.
2142 Possible values are:
2148 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_0``
2150 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_1``
2152 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_2``
2154 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_3``
2157 .. _v4l2-mpeg-video-vp9-profile:
2159 ``V4L2_CID_MPEG_VIDEO_VP9_PROFILE``
2162 enum v4l2_mpeg_video_vp9_profile -
2163 This control allows selecting the profile for VP9 encoder.
2164 This is also used to enumerate supported profiles by VP9 encoder or decoder.
2165 Possible values are:
2171 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_0``
2173 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_1``
2175 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_2``
2177 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_3``
2181 High Efficiency Video Coding (HEVC/H.265) Control Reference
2182 -----------------------------------------------------------
2184 The HEVC/H.265 controls include controls for encoding parameters of HEVC/H.265
2188 .. _hevc-control-id:
2190 HEVC/H.265 Control IDs
2191 ^^^^^^^^^^^^^^^^^^^^^^
2193 ``V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP (integer)``
2194 Minimum quantization parameter for HEVC.
2195 Valid range: from 0 to 51.
2197 ``V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP (integer)``
2198 Maximum quantization parameter for HEVC.
2199 Valid range: from 0 to 51.
2201 ``V4L2_CID_MPEG_VIDEO_HEVC_I_FRAME_QP (integer)``
2202 Quantization parameter for an I frame for HEVC.
2203 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2204 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2206 ``V4L2_CID_MPEG_VIDEO_HEVC_P_FRAME_QP (integer)``
2207 Quantization parameter for a P frame for HEVC.
2208 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2209 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2211 ``V4L2_CID_MPEG_VIDEO_HEVC_B_FRAME_QP (integer)``
2212 Quantization parameter for a B frame for HEVC.
2213 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2214 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2216 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_QP (boolean)``
2217 HIERARCHICAL_QP allows the host to specify the quantization parameter
2218 values for each temporal layer through HIERARCHICAL_QP_LAYER. This is
2219 valid only if HIERARCHICAL_CODING_LAYER is greater than 1. Setting the
2220 control value to 1 enables setting of the QP values for the layers.
2222 .. _v4l2-hevc-hier-coding-type:
2224 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_TYPE``
2227 enum v4l2_mpeg_video_hevc_hier_coding_type -
2228 Selects the hierarchical coding type for encoding. Possible values are:
2234 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2240 * - ``V4L2_MPEG_VIDEO_HEVC_HIERARCHICAL_CODING_B``
2241 - Use the B frame for hierarchical coding.
2242 * - ``V4L2_MPEG_VIDEO_HEVC_HIERARCHICAL_CODING_P``
2243 - Use the P frame for hierarchical coding.
2250 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_LAYER (integer)``
2251 Selects the hierarchical coding layer. In normal encoding
2252 (non-hierarchial coding), it should be zero. Possible values are [0, 6].
2253 0 indicates HIERARCHICAL CODING LAYER 0, 1 indicates HIERARCHICAL CODING
2256 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L0_QP (integer)``
2257 Indicates quantization parameter for hierarchical coding layer 0.
2258 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2259 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2261 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L1_QP (integer)``
2262 Indicates quantization parameter for hierarchical coding layer 1.
2263 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2264 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2266 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L2_QP (integer)``
2267 Indicates quantization parameter for hierarchical coding layer 2.
2268 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2269 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2271 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L3_QP (integer)``
2272 Indicates quantization parameter for hierarchical coding layer 3.
2273 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2274 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2276 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L4_QP (integer)``
2277 Indicates quantization parameter for hierarchical coding layer 4.
2278 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2279 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2281 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L5_QP (integer)``
2282 Indicates quantization parameter for hierarchical coding layer 5.
2283 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2284 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2286 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_QP (integer)``
2287 Indicates quantization parameter for hierarchical coding layer 6.
2288 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2289 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2291 .. _v4l2-hevc-profile:
2293 ``V4L2_CID_MPEG_VIDEO_HEVC_PROFILE``
2296 enum v4l2_mpeg_video_hevc_profile -
2297 Select the desired profile for HEVC encoder.
2303 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2309 * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN``
2311 * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN_STILL_PICTURE``
2312 - Main still picture profile.
2313 * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN_10``
2321 .. _v4l2-hevc-level:
2323 ``V4L2_CID_MPEG_VIDEO_HEVC_LEVEL``
2326 enum v4l2_mpeg_video_hevc_level -
2327 Selects the desired level for HEVC encoder.
2333 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2339 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_1``
2341 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_2``
2343 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_2_1``
2345 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_3``
2347 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_3_1``
2349 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_4``
2351 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_4_1``
2353 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5``
2355 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5_1``
2357 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5_2``
2359 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6``
2361 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6_1``
2363 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6_2``
2371 ``V4L2_CID_MPEG_VIDEO_HEVC_FRAME_RATE_RESOLUTION (integer)``
2372 Indicates the number of evenly spaced subintervals, called ticks, within
2373 one second. This is a 16 bit unsigned integer and has a maximum value up to
2374 0xffff and a minimum value of 1.
2378 ``V4L2_CID_MPEG_VIDEO_HEVC_TIER``
2381 enum v4l2_mpeg_video_hevc_tier -
2382 TIER_FLAG specifies tiers information of the HEVC encoded picture. Tier
2383 were made to deal with applications that differ in terms of maximum bit
2384 rate. Setting the flag to 0 selects HEVC tier as Main tier and setting
2385 this flag to 1 indicates High tier. High tier is for applications requiring
2392 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2398 * - ``V4L2_MPEG_VIDEO_HEVC_TIER_MAIN``
2400 * - ``V4L2_MPEG_VIDEO_HEVC_TIER_HIGH``
2408 ``V4L2_CID_MPEG_VIDEO_HEVC_MAX_PARTITION_DEPTH (integer)``
2409 Selects HEVC maximum coding unit depth.
2411 .. _v4l2-hevc-loop-filter-mode:
2413 ``V4L2_CID_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE``
2416 enum v4l2_mpeg_video_hevc_loop_filter_mode -
2417 Loop filter mode for HEVC encoder. Possible values are:
2423 .. tabularcolumns:: |p{10.7cm}|p{6.3cm}|
2429 * - ``V4L2_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE_DISABLED``
2430 - Loop filter is disabled.
2431 * - ``V4L2_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE_ENABLED``
2432 - Loop filter is enabled.
2433 * - ``V4L2_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
2434 - Loop filter is disabled at the slice boundary.
2441 ``V4L2_CID_MPEG_VIDEO_HEVC_LF_BETA_OFFSET_DIV2 (integer)``
2442 Selects HEVC loop filter beta offset. The valid range is [-6, +6].
2444 ``V4L2_CID_MPEG_VIDEO_HEVC_LF_TC_OFFSET_DIV2 (integer)``
2445 Selects HEVC loop filter tc offset. The valid range is [-6, +6].
2447 .. _v4l2-hevc-refresh-type:
2449 ``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_TYPE``
2452 enum v4l2_mpeg_video_hevc_hier_refresh_type -
2453 Selects refresh type for HEVC encoder.
2454 Host has to specify the period into
2455 V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_PERIOD.
2461 .. tabularcolumns:: |p{8.0cm}|p{9.0cm}|
2467 * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_NONE``
2468 - Use the B frame for hierarchical coding.
2469 * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_CRA``
2470 - Use CRA (Clean Random Access Unit) picture encoding.
2471 * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_IDR``
2472 - Use IDR (Instantaneous Decoding Refresh) picture encoding.
2479 ``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_PERIOD (integer)``
2480 Selects the refresh period for HEVC encoder.
2481 This specifies the number of I pictures between two CRA/IDR pictures.
2482 This is valid only if REFRESH_TYPE is not 0.
2484 ``V4L2_CID_MPEG_VIDEO_HEVC_LOSSLESS_CU (boolean)``
2485 Indicates HEVC lossless encoding. Setting it to 0 disables lossless
2486 encoding. Setting it to 1 enables lossless encoding.
2488 ``V4L2_CID_MPEG_VIDEO_HEVC_CONST_INTRA_PRED (boolean)``
2489 Indicates constant intra prediction for HEVC encoder. Specifies the
2490 constrained intra prediction in which intra largest coding unit (LCU)
2491 prediction is performed by using residual data and decoded samples of
2492 neighboring intra LCU only. Setting the value to 1 enables constant intra
2493 prediction and setting the value to 0 disables constant intra prediction.
2495 ``V4L2_CID_MPEG_VIDEO_HEVC_WAVEFRONT (boolean)``
2496 Indicates wavefront parallel processing for HEVC encoder. Setting it to 0
2497 disables the feature and setting it to 1 enables the wavefront parallel
2500 ``V4L2_CID_MPEG_VIDEO_HEVC_GENERAL_PB (boolean)``
2501 Setting the value to 1 enables combination of P and B frame for HEVC
2504 ``V4L2_CID_MPEG_VIDEO_HEVC_TEMPORAL_ID (boolean)``
2505 Indicates temporal identifier for HEVC encoder which is enabled by
2506 setting the value to 1.
2508 ``V4L2_CID_MPEG_VIDEO_HEVC_STRONG_SMOOTHING (boolean)``
2509 Indicates bi-linear interpolation is conditionally used in the intra
2510 prediction filtering process in the CVS when set to 1. Indicates bi-linear
2511 interpolation is not used in the CVS when set to 0.
2513 ``V4L2_CID_MPEG_VIDEO_HEVC_MAX_NUM_MERGE_MV_MINUS1 (integer)``
2514 Indicates maximum number of merge candidate motion vectors.
2515 Values are from 0 to 4.
2517 ``V4L2_CID_MPEG_VIDEO_HEVC_TMV_PREDICTION (boolean)``
2518 Indicates temporal motion vector prediction for HEVC encoder. Setting it to
2519 1 enables the prediction. Setting it to 0 disables the prediction.
2521 ``V4L2_CID_MPEG_VIDEO_HEVC_WITHOUT_STARTCODE (boolean)``
2522 Specifies if HEVC generates a stream with a size of the length field
2523 instead of start code pattern. The size of the length field is configurable
2524 through the V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD control. Setting
2525 the value to 0 disables encoding without startcode pattern. Setting the
2526 value to 1 will enables encoding without startcode pattern.
2528 .. _v4l2-hevc-size-of-length-field:
2530 ``V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD``
2533 enum v4l2_mpeg_video_hevc_size_of_length_field -
2534 Indicates the size of length field.
2535 This is valid when encoding WITHOUT_STARTCODE_ENABLE is enabled.
2541 .. tabularcolumns:: |p{6.0cm}|p{11.0cm}|
2547 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_0``
2548 - Generate start code pattern (Normal).
2549 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_1``
2550 - Generate size of length field instead of start code pattern and length is 1.
2551 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_2``
2552 - Generate size of length field instead of start code pattern and length is 2.
2553 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_4``
2554 - Generate size of length field instead of start code pattern and length is 4.
2560 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L0_BR (integer)``
2561 Indicates bit rate for hierarchical coding layer 0 for HEVC encoder.
2563 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L1_BR (integer)``
2564 Indicates bit rate for hierarchical coding layer 1 for HEVC encoder.
2566 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L2_BR (integer)``
2567 Indicates bit rate for hierarchical coding layer 2 for HEVC encoder.
2569 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L3_BR (integer)``
2570 Indicates bit rate for hierarchical coding layer 3 for HEVC encoder.
2572 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L4_BR (integer)``
2573 Indicates bit rate for hierarchical coding layer 4 for HEVC encoder.
2575 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L5_BR (integer)``
2576 Indicates bit rate for hierarchical coding layer 5 for HEVC encoder.
2578 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_BR (integer)``
2579 Indicates bit rate for hierarchical coding layer 6 for HEVC encoder.
2581 ``V4L2_CID_MPEG_VIDEO_REF_NUMBER_FOR_PFRAMES (integer)``
2582 Selects number of P reference pictures required for HEVC encoder.
2583 P-Frame can use 1 or 2 frames for reference.
2585 ``V4L2_CID_MPEG_VIDEO_PREPEND_SPSPPS_TO_IDR (integer)``
2586 Indicates whether to generate SPS and PPS at every IDR. Setting it to 0
2587 disables generating SPS and PPS at every IDR. Setting it to one enables
2588 generating SPS and PPS at every IDR.
2591 .. _camera-controls:
2593 Camera Control Reference
2594 ========================
2596 The Camera class includes controls for mechanical (or equivalent
2597 digital) features of a device such as controllable lenses or sensors.
2600 .. _camera-control-id:
2605 ``V4L2_CID_CAMERA_CLASS (class)``
2606 The Camera class descriptor. Calling
2607 :ref:`VIDIOC_QUERYCTRL` for this control will
2608 return a description of this control class.
2610 .. _v4l2-exposure-auto-type:
2612 ``V4L2_CID_EXPOSURE_AUTO``
2615 enum v4l2_exposure_auto_type -
2616 Enables automatic adjustments of the exposure time and/or iris
2617 aperture. The effect of manual changes of the exposure time or iris
2618 aperture while these features are enabled is undefined, drivers
2619 should ignore such requests. Possible values are:
2627 * - ``V4L2_EXPOSURE_AUTO``
2628 - Automatic exposure time, automatic iris aperture.
2629 * - ``V4L2_EXPOSURE_MANUAL``
2630 - Manual exposure time, manual iris.
2631 * - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
2632 - Manual exposure time, auto iris.
2633 * - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
2634 - Auto exposure time, manual iris.
2638 ``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
2639 Determines the exposure time of the camera sensor. The exposure time
2640 is limited by the frame interval. Drivers should interpret the
2641 values as 100 µs units, where the value 1 stands for 1/10000th of a
2642 second, 10000 for 1 second and 100000 for 10 seconds.
2644 ``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
2645 When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
2646 ``APERTURE_PRIORITY``, this control determines if the device may
2647 dynamically vary the frame rate. By default this feature is disabled
2648 (0) and the frame rate must remain constant.
2650 ``V4L2_CID_AUTO_EXPOSURE_BIAS (integer menu)``
2651 Determines the automatic exposure compensation, it is effective only
2652 when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
2653 ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
2654 terms of EV, drivers should interpret the values as 0.001 EV units,
2655 where the value 1000 stands for +1 EV.
2657 Increasing the exposure compensation value is equivalent to
2658 decreasing the exposure value (EV) and will increase the amount of
2659 light at the image sensor. The camera performs the exposure
2660 compensation by adjusting absolute exposure time and/or aperture.
2662 .. _v4l2-exposure-metering:
2664 ``V4L2_CID_EXPOSURE_METERING``
2667 enum v4l2_exposure_metering -
2668 Determines how the camera measures the amount of light available for
2669 the frame exposure. Possible values are:
2671 .. tabularcolumns:: |p{8.5cm}|p{9.0cm}|
2677 * - ``V4L2_EXPOSURE_METERING_AVERAGE``
2678 - Use the light information coming from the entire frame and average
2679 giving no weighting to any particular portion of the metered area.
2680 * - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
2681 - Average the light information coming from the entire frame giving
2682 priority to the center of the metered area.
2683 * - ``V4L2_EXPOSURE_METERING_SPOT``
2684 - Measure only very small area at the center of the frame.
2685 * - ``V4L2_EXPOSURE_METERING_MATRIX``
2686 - A multi-zone metering. The light intensity is measured in several
2687 points of the frame and the results are combined. The algorithm of
2688 the zones selection and their significance in calculating the
2689 final value is device dependent.
2693 ``V4L2_CID_PAN_RELATIVE (integer)``
2694 This control turns the camera horizontally by the specified amount.
2695 The unit is undefined. A positive value moves the camera to the
2696 right (clockwise when viewed from above), a negative value to the
2697 left. A value of zero does not cause motion. This is a write-only
2700 ``V4L2_CID_TILT_RELATIVE (integer)``
2701 This control turns the camera vertically by the specified amount.
2702 The unit is undefined. A positive value moves the camera up, a
2703 negative value down. A value of zero does not cause motion. This is
2704 a write-only control.
2706 ``V4L2_CID_PAN_RESET (button)``
2707 When this control is set, the camera moves horizontally to the
2710 ``V4L2_CID_TILT_RESET (button)``
2711 When this control is set, the camera moves vertically to the default
2714 ``V4L2_CID_PAN_ABSOLUTE (integer)``
2715 This control turns the camera horizontally to the specified
2716 position. Positive values move the camera to the right (clockwise
2717 when viewed from above), negative values to the left. Drivers should
2718 interpret the values as arc seconds, with valid values between -180
2719 * 3600 and +180 * 3600 inclusive.
2721 ``V4L2_CID_TILT_ABSOLUTE (integer)``
2722 This control turns the camera vertically to the specified position.
2723 Positive values move the camera up, negative values down. Drivers
2724 should interpret the values as arc seconds, with valid values
2725 between -180 * 3600 and +180 * 3600 inclusive.
2727 ``V4L2_CID_FOCUS_ABSOLUTE (integer)``
2728 This control sets the focal point of the camera to the specified
2729 position. The unit is undefined. Positive values set the focus
2730 closer to the camera, negative values towards infinity.
2732 ``V4L2_CID_FOCUS_RELATIVE (integer)``
2733 This control moves the focal point of the camera by the specified
2734 amount. The unit is undefined. Positive values move the focus closer
2735 to the camera, negative values towards infinity. This is a
2738 ``V4L2_CID_FOCUS_AUTO (boolean)``
2739 Enables continuous automatic focus adjustments. The effect of manual
2740 focus adjustments while this feature is enabled is undefined,
2741 drivers should ignore such requests.
2743 ``V4L2_CID_AUTO_FOCUS_START (button)``
2744 Starts single auto focus process. The effect of setting this control
2745 when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
2746 drivers should ignore such requests.
2748 ``V4L2_CID_AUTO_FOCUS_STOP (button)``
2749 Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
2750 control. It is effective only when the continuous autofocus is
2751 disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
2754 .. _v4l2-auto-focus-status:
2756 ``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
2757 The automatic focus status. This is a read-only control.
2759 Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
2760 control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
2763 .. tabularcolumns:: |p{6.5cm}|p{11.0cm}|
2769 * - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
2770 - Automatic focus is not active.
2771 * - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
2772 - Automatic focusing is in progress.
2773 * - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
2774 - Focus has been reached.
2775 * - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
2776 - Automatic focus has failed, the driver will not transition from
2777 this state until another action is performed by an application.
2781 .. _v4l2-auto-focus-range:
2783 ``V4L2_CID_AUTO_FOCUS_RANGE``
2786 enum v4l2_auto_focus_range -
2787 Determines auto focus distance range for which lens may be adjusted.
2789 .. tabularcolumns:: |p{6.5cm}|p{11.0cm}|
2795 * - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
2796 - The camera automatically selects the focus range.
2797 * - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
2798 - Normal distance range, limited for best automatic focus
2800 * - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
2801 - Macro (close-up) auto focus. The camera will use its minimum
2802 possible distance for auto focus.
2803 * - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
2804 - The lens is set to focus on an object at infinite distance.
2808 ``V4L2_CID_ZOOM_ABSOLUTE (integer)``
2809 Specify the objective lens focal length as an absolute value. The
2810 zoom unit is driver-specific and its value should be a positive
2813 ``V4L2_CID_ZOOM_RELATIVE (integer)``
2814 Specify the objective lens focal length relatively to the current
2815 value. Positive values move the zoom lens group towards the
2816 telephoto direction, negative values towards the wide-angle
2817 direction. The zoom unit is driver-specific. This is a write-only
2820 ``V4L2_CID_ZOOM_CONTINUOUS (integer)``
2821 Move the objective lens group at the specified speed until it
2822 reaches physical device limits or until an explicit request to stop
2823 the movement. A positive value moves the zoom lens group towards the
2824 telephoto direction. A value of zero stops the zoom lens group
2825 movement. A negative value moves the zoom lens group towards the
2826 wide-angle direction. The zoom speed unit is driver-specific.
2828 ``V4L2_CID_IRIS_ABSOLUTE (integer)``
2829 This control sets the camera's aperture to the specified value. The
2830 unit is undefined. Larger values open the iris wider, smaller values
2833 ``V4L2_CID_IRIS_RELATIVE (integer)``
2834 This control modifies the camera's aperture by the specified amount.
2835 The unit is undefined. Positive values open the iris one step
2836 further, negative values close it one step further. This is a
2839 ``V4L2_CID_PRIVACY (boolean)``
2840 Prevent video from being acquired by the camera. When this control
2841 is set to ``TRUE`` (1), no image can be captured by the camera.
2842 Common means to enforce privacy are mechanical obturation of the
2843 sensor and firmware image processing, but the device is not
2844 restricted to these methods. Devices that implement the privacy
2845 control must support read access and may support write access.
2847 ``V4L2_CID_BAND_STOP_FILTER (integer)``
2848 Switch the band-stop filter of a camera sensor on or off, or specify
2849 its strength. Such band-stop filters can be used, for example, to
2850 filter out the fluorescent light component.
2852 .. _v4l2-auto-n-preset-white-balance:
2854 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE``
2857 enum v4l2_auto_n_preset_white_balance -
2858 Sets white balance to automatic, manual or a preset. The presets
2859 determine color temperature of the light as a hint to the camera for
2860 white balance adjustments resulting in most accurate color
2861 representation. The following white balance presets are listed in
2862 order of increasing color temperature.
2864 .. tabularcolumns:: |p{7.0 cm}|p{10.5cm}|
2870 * - ``V4L2_WHITE_BALANCE_MANUAL``
2871 - Manual white balance.
2872 * - ``V4L2_WHITE_BALANCE_AUTO``
2873 - Automatic white balance adjustments.
2874 * - ``V4L2_WHITE_BALANCE_INCANDESCENT``
2875 - White balance setting for incandescent (tungsten) lighting. It
2876 generally cools down the colors and corresponds approximately to
2877 2500...3500 K color temperature range.
2878 * - ``V4L2_WHITE_BALANCE_FLUORESCENT``
2879 - White balance preset for fluorescent lighting. It corresponds
2880 approximately to 4000...5000 K color temperature.
2881 * - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
2882 - With this setting the camera will compensate for fluorescent H
2884 * - ``V4L2_WHITE_BALANCE_HORIZON``
2885 - White balance setting for horizon daylight. It corresponds
2886 approximately to 5000 K color temperature.
2887 * - ``V4L2_WHITE_BALANCE_DAYLIGHT``
2888 - White balance preset for daylight (with clear sky). It corresponds
2889 approximately to 5000...6500 K color temperature.
2890 * - ``V4L2_WHITE_BALANCE_FLASH``
2891 - With this setting the camera will compensate for the flash light.
2892 It slightly warms up the colors and corresponds roughly to
2893 5000...5500 K color temperature.
2894 * - ``V4L2_WHITE_BALANCE_CLOUDY``
2895 - White balance preset for moderately overcast sky. This option
2896 corresponds approximately to 6500...8000 K color temperature
2898 * - ``V4L2_WHITE_BALANCE_SHADE``
2899 - White balance preset for shade or heavily overcast sky. It
2900 corresponds approximately to 9000...10000 K color temperature.
2904 .. _v4l2-wide-dynamic-range:
2906 ``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
2907 Enables or disables the camera's wide dynamic range feature. This
2908 feature allows to obtain clear images in situations where intensity
2909 of the illumination varies significantly throughout the scene, i.e.
2910 there are simultaneously very dark and very bright areas. It is most
2911 commonly realized in cameras by combining two subsequent frames with
2912 different exposure times. [#f1]_
2914 .. _v4l2-image-stabilization:
2916 ``V4L2_CID_IMAGE_STABILIZATION (boolean)``
2917 Enables or disables image stabilization.
2919 ``V4L2_CID_ISO_SENSITIVITY (integer menu)``
2920 Determines ISO equivalent of an image sensor indicating the sensor's
2921 sensitivity to light. The numbers are expressed in arithmetic scale,
2922 as per :ref:`iso12232` standard, where doubling the sensor
2923 sensitivity is represented by doubling the numerical ISO value.
2924 Applications should interpret the values as standard ISO values
2925 multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
2926 Drivers will usually support only a subset of standard ISO values.
2927 The effect of setting this control while the
2928 ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
2929 than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
2930 should ignore such requests.
2932 .. _v4l2-iso-sensitivity-auto-type:
2934 ``V4L2_CID_ISO_SENSITIVITY_AUTO``
2937 enum v4l2_iso_sensitivity_type -
2938 Enables or disables automatic ISO sensitivity adjustments.
2946 * - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
2947 - Manual ISO sensitivity.
2948 * - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
2949 - Automatic ISO sensitivity adjustments.
2953 .. _v4l2-scene-mode:
2955 ``V4L2_CID_SCENE_MODE``
2958 enum v4l2_scene_mode -
2959 This control allows to select scene programs as the camera automatic
2960 modes optimized for common shooting scenes. Within these modes the
2961 camera determines best exposure, aperture, focusing, light metering,
2962 white balance and equivalent sensitivity. The controls of those
2963 parameters are influenced by the scene mode control. An exact
2964 behavior in each mode is subject to the camera specification.
2966 When the scene mode feature is not used, this control should be set
2967 to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
2968 controls are accessible. The following scene programs are defined:
2970 .. tabularcolumns:: |p{6.0cm}|p{11.5cm}|
2976 * - ``V4L2_SCENE_MODE_NONE``
2977 - The scene mode feature is disabled.
2978 * - ``V4L2_SCENE_MODE_BACKLIGHT``
2979 - Backlight. Compensates for dark shadows when light is coming from
2980 behind a subject, also by automatically turning on the flash.
2981 * - ``V4L2_SCENE_MODE_BEACH_SNOW``
2982 - Beach and snow. This mode compensates for all-white or bright
2983 scenes, which tend to look gray and low contrast, when camera's
2984 automatic exposure is based on an average scene brightness. To
2985 compensate, this mode automatically slightly overexposes the
2986 frames. The white balance may also be adjusted to compensate for
2987 the fact that reflected snow looks bluish rather than white.
2988 * - ``V4L2_SCENE_MODE_CANDLELIGHT``
2989 - Candle light. The camera generally raises the ISO sensitivity and
2990 lowers the shutter speed. This mode compensates for relatively
2991 close subject in the scene. The flash is disabled in order to
2992 preserve the ambiance of the light.
2993 * - ``V4L2_SCENE_MODE_DAWN_DUSK``
2994 - Dawn and dusk. Preserves the colors seen in low natural light
2995 before dusk and after down. The camera may turn off the flash, and
2996 automatically focus at infinity. It will usually boost saturation
2997 and lower the shutter speed.
2998 * - ``V4L2_SCENE_MODE_FALL_COLORS``
2999 - Fall colors. Increases saturation and adjusts white balance for
3000 color enhancement. Pictures of autumn leaves get saturated reds
3002 * - ``V4L2_SCENE_MODE_FIREWORKS``
3003 - Fireworks. Long exposure times are used to capture the expanding
3004 burst of light from a firework. The camera may invoke image
3006 * - ``V4L2_SCENE_MODE_LANDSCAPE``
3007 - Landscape. The camera may choose a small aperture to provide deep
3008 depth of field and long exposure duration to help capture detail
3009 in dim light conditions. The focus is fixed at infinity. Suitable
3010 for distant and wide scenery.
3011 * - ``V4L2_SCENE_MODE_NIGHT``
3012 - Night, also known as Night Landscape. Designed for low light
3013 conditions, it preserves detail in the dark areas without blowing
3014 out bright objects. The camera generally sets itself to a
3015 medium-to-high ISO sensitivity, with a relatively long exposure
3016 time, and turns flash off. As such, there will be increased image
3017 noise and the possibility of blurred image.
3018 * - ``V4L2_SCENE_MODE_PARTY_INDOOR``
3019 - Party and indoor. Designed to capture indoor scenes that are lit
3020 by indoor background lighting as well as the flash. The camera
3021 usually increases ISO sensitivity, and adjusts exposure for the
3022 low light conditions.
3023 * - ``V4L2_SCENE_MODE_PORTRAIT``
3024 - Portrait. The camera adjusts the aperture so that the depth of
3025 field is reduced, which helps to isolate the subject against a
3026 smooth background. Most cameras recognize the presence of faces in
3027 the scene and focus on them. The color hue is adjusted to enhance
3028 skin tones. The intensity of the flash is often reduced.
3029 * - ``V4L2_SCENE_MODE_SPORTS``
3030 - Sports. Significantly increases ISO and uses a fast shutter speed
3031 to freeze motion of rapidly-moving subjects. Increased image noise
3032 may be seen in this mode.
3033 * - ``V4L2_SCENE_MODE_SUNSET``
3034 - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
3036 * - ``V4L2_SCENE_MODE_TEXT``
3037 - Text. It applies extra contrast and sharpness, it is typically a
3038 black-and-white mode optimized for readability. Automatic focus
3039 may be switched to close-up mode and this setting may also involve
3040 some lens-distortion correction.
3044 ``V4L2_CID_3A_LOCK (bitmask)``
3045 This control locks or unlocks the automatic focus, exposure and
3046 white balance. The automatic adjustments can be paused independently
3047 by setting the corresponding lock bit to 1. The camera then retains
3048 the settings until the lock bit is cleared. The following lock bits
3051 When a given algorithm is not enabled, drivers should ignore
3052 requests to lock it and should return no error. An example might be
3053 an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
3054 ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
3055 value of this control may be changed by exposure, white balance or
3064 * - ``V4L2_LOCK_EXPOSURE``
3065 - Automatic exposure adjustments lock.
3066 * - ``V4L2_LOCK_WHITE_BALANCE``
3067 - Automatic white balance adjustments lock.
3068 * - ``V4L2_LOCK_FOCUS``
3069 - Automatic focus lock.
3073 ``V4L2_CID_PAN_SPEED (integer)``
3074 This control turns the camera horizontally at the specific speed.
3075 The unit is undefined. A positive value moves the camera to the
3076 right (clockwise when viewed from above), a negative value to the
3077 left. A value of zero stops the motion if one is in progress and has
3078 no effect otherwise.
3080 ``V4L2_CID_TILT_SPEED (integer)``
3081 This control turns the camera vertically at the specified speed. The
3082 unit is undefined. A positive value moves the camera up, a negative
3083 value down. A value of zero stops the motion if one is in progress
3084 and has no effect otherwise.
3089 FM Transmitter Control Reference
3090 ================================
3092 The FM Transmitter (FM_TX) class includes controls for common features
3093 of FM transmissions capable devices. Currently this class includes
3094 parameters for audio compression, pilot tone generation, audio deviation
3095 limiter, RDS transmission and tuning power features.
3098 .. _fm-tx-control-id:
3103 ``V4L2_CID_FM_TX_CLASS (class)``
3104 The FM_TX class descriptor. Calling
3105 :ref:`VIDIOC_QUERYCTRL` for this control will
3106 return a description of this control class.
3108 ``V4L2_CID_RDS_TX_DEVIATION (integer)``
3109 Configures RDS signal frequency deviation level in Hz. The range and
3110 step are driver-specific.
3112 ``V4L2_CID_RDS_TX_PI (integer)``
3113 Sets the RDS Programme Identification field for transmission.
3115 ``V4L2_CID_RDS_TX_PTY (integer)``
3116 Sets the RDS Programme Type field for transmission. This encodes up
3117 to 31 pre-defined programme types.
3119 ``V4L2_CID_RDS_TX_PS_NAME (string)``
3120 Sets the Programme Service name (PS_NAME) for transmission. It is
3121 intended for static display on a receiver. It is the primary aid to
3122 listeners in programme service identification and selection. In
3123 Annex E of :ref:`iec62106`, the RDS specification, there is a full
3124 description of the correct character encoding for Programme Service
3125 name strings. Also from RDS specification, PS is usually a single
3126 eight character text. However, it is also possible to find receivers
3127 which can scroll strings sized as 8 x N characters. So, this control
3128 must be configured with steps of 8 characters. The result is it must
3129 always contain a string with size multiple of 8.
3131 ``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
3132 Sets the Radio Text info for transmission. It is a textual
3133 description of what is being broadcasted. RDS Radio Text can be
3134 applied when broadcaster wishes to transmit longer PS names,
3135 programme-related information or any other text. In these cases,
3136 RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``.
3137 The encoding for Radio Text strings is also fully described in Annex
3138 E of :ref:`iec62106`. The length of Radio Text strings depends on
3139 which RDS Block is being used to transmit it, either 32 (2A block)
3140 or 64 (2B block). However, it is also possible to find receivers
3141 which can scroll strings sized as 32 x N or 64 x N characters. So,
3142 this control must be configured with steps of 32 or 64 characters.
3143 The result is it must always contain a string with size multiple of
3146 ``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
3147 Sets the Mono/Stereo bit of the Decoder Identification code. If set,
3148 then the audio was recorded as stereo.
3150 ``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
3152 `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__
3153 bit of the Decoder Identification code. If set, then the audio was
3154 recorded using an artificial head.
3156 ``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
3157 Sets the Compressed bit of the Decoder Identification code. If set,
3158 then the audio is compressed.
3160 ``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
3161 Sets the Dynamic PTY bit of the Decoder Identification code. If set,
3162 then the PTY code is dynamically switched.
3164 ``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)``
3165 If set, then a traffic announcement is in progress.
3167 ``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
3168 If set, then the tuned programme carries traffic announcements.
3170 ``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
3171 If set, then this channel broadcasts music. If cleared, then it
3172 broadcasts speech. If the transmitter doesn't make this distinction,
3173 then it should be set.
3175 ``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
3176 If set, then transmit alternate frequencies.
3178 ``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
3179 The alternate frequencies in kHz units. The RDS standard allows for
3180 up to 25 frequencies to be defined. Drivers may support fewer
3181 frequencies so check the array size.
3183 ``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
3184 Enables or disables the audio deviation limiter feature. The limiter
3185 is useful when trying to maximize the audio volume, minimize
3186 receiver-generated distortion and prevent overmodulation.
3188 ``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
3189 Sets the audio deviation limiter feature release time. Unit is in
3190 useconds. Step and range are driver-specific.
3192 ``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
3193 Configures audio frequency deviation level in Hz. The range and step
3194 are driver-specific.
3196 ``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)``
3197 Enables or disables the audio compression feature. This feature
3198 amplifies signals below the threshold by a fixed gain and compresses
3199 audio signals above the threshold by the ratio of Threshold/(Gain +
3202 ``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
3203 Sets the gain for audio compression feature. It is a dB value. The
3204 range and step are driver-specific.
3206 ``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
3207 Sets the threshold level for audio compression freature. It is a dB
3208 value. The range and step are driver-specific.
3210 ``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
3211 Sets the attack time for audio compression feature. It is a useconds
3212 value. The range and step are driver-specific.
3214 ``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
3215 Sets the release time for audio compression feature. It is a
3216 useconds value. The range and step are driver-specific.
3218 ``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
3219 Enables or disables the pilot tone generation feature.
3221 ``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
3222 Configures pilot tone frequency deviation level. Unit is in Hz. The
3223 range and step are driver-specific.
3225 ``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
3226 Configures pilot tone frequency value. Unit is in Hz. The range and
3227 step are driver-specific.
3229 ``V4L2_CID_TUNE_PREEMPHASIS``
3232 enum v4l2_preemphasis -
3233 Configures the pre-emphasis value for broadcasting. A pre-emphasis
3234 filter is applied to the broadcast to accentuate the high audio
3235 frequencies. Depending on the region, a time constant of either 50
3236 or 75 useconds is used. The enum v4l2_preemphasis defines possible
3237 values for pre-emphasis. Here they are:
3245 * - ``V4L2_PREEMPHASIS_DISABLED``
3246 - No pre-emphasis is applied.
3247 * - ``V4L2_PREEMPHASIS_50_uS``
3248 - A pre-emphasis of 50 uS is used.
3249 * - ``V4L2_PREEMPHASIS_75_uS``
3250 - A pre-emphasis of 75 uS is used.
3254 ``V4L2_CID_TUNE_POWER_LEVEL (integer)``
3255 Sets the output power level for signal transmission. Unit is in
3256 dBuV. Range and step are driver-specific.
3258 ``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
3259 This selects the value of antenna tuning capacitor manually or
3260 automatically if set to zero. Unit, range and step are
3263 For more details about RDS specification, refer to :ref:`iec62106`
3264 document, from CENELEC.
3269 Flash Control Reference
3270 =======================
3272 The V4L2 flash controls are intended to provide generic access to flash
3273 controller devices. Flash controller devices are typically used in
3276 The interface can support both LED and xenon flash devices. As of
3277 writing this, there is no xenon flash driver using this interface.
3280 .. _flash-controls-use-cases:
3286 Unsynchronised LED flash (software strobe)
3287 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3289 Unsynchronised LED flash is controlled directly by the host as the
3290 sensor. The flash must be enabled by the host before the exposure of the
3291 image starts and disabled once it ends. The host is fully responsible
3292 for the timing of the flash.
3294 Example of such device: Nokia N900.
3297 Synchronised LED flash (hardware strobe)
3298 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3300 The synchronised LED flash is pre-programmed by the host (power and
3301 timeout) but controlled by the sensor through a strobe signal from the
3302 sensor to the flash.
3304 The sensor controls the flash duration and timing. This information
3305 typically must be made available to the sensor.
3311 LED flash may be used as torch in conjunction with another use case
3312 involving camera or individually.
3315 .. _flash-control-id:
3320 ``V4L2_CID_FLASH_CLASS (class)``
3321 The FLASH class descriptor.
3323 ``V4L2_CID_FLASH_LED_MODE (menu)``
3324 Defines the mode of the flash LED, the high-power white LED attached
3325 to the flash controller. Setting this control may not be possible in
3326 presence of some faults. See V4L2_CID_FLASH_FAULT.
3334 * - ``V4L2_FLASH_LED_MODE_NONE``
3336 * - ``V4L2_FLASH_LED_MODE_FLASH``
3338 * - ``V4L2_FLASH_LED_MODE_TORCH``
3339 - Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.
3343 ``V4L2_CID_FLASH_STROBE_SOURCE (menu)``
3344 Defines the source of the flash LED strobe.
3346 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
3352 * - ``V4L2_FLASH_STROBE_SOURCE_SOFTWARE``
3353 - The flash strobe is triggered by using the
3354 V4L2_CID_FLASH_STROBE control.
3355 * - ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``
3356 - The flash strobe is triggered by an external source. Typically
3357 this is a sensor, which makes it possible to synchronises the
3358 flash strobe start to exposure start.
3362 ``V4L2_CID_FLASH_STROBE (button)``
3363 Strobe flash. Valid when V4L2_CID_FLASH_LED_MODE is set to
3364 V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
3365 is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
3366 control may not be possible in presence of some faults. See
3367 V4L2_CID_FLASH_FAULT.
3369 ``V4L2_CID_FLASH_STROBE_STOP (button)``
3370 Stop flash strobe immediately.
3372 ``V4L2_CID_FLASH_STROBE_STATUS (boolean)``
3373 Strobe status: whether the flash is strobing at the moment or not.
3374 This is a read-only control.
3376 ``V4L2_CID_FLASH_TIMEOUT (integer)``
3377 Hardware timeout for flash. The flash strobe is stopped after this
3378 period of time has passed from the start of the strobe.
3380 ``V4L2_CID_FLASH_INTENSITY (integer)``
3381 Intensity of the flash strobe when the flash LED is in flash mode
3382 (V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps (mA)
3385 ``V4L2_CID_FLASH_TORCH_INTENSITY (integer)``
3386 Intensity of the flash LED in torch mode
3387 (V4L2_FLASH_LED_MODE_TORCH). The unit should be milliamps (mA)
3388 if possible. Setting this control may not be possible in presence of
3389 some faults. See V4L2_CID_FLASH_FAULT.
3391 ``V4L2_CID_FLASH_INDICATOR_INTENSITY (integer)``
3392 Intensity of the indicator LED. The indicator LED may be fully
3393 independent of the flash LED. The unit should be microamps (uA) if
3396 ``V4L2_CID_FLASH_FAULT (bitmask)``
3397 Faults related to the flash. The faults tell about specific problems
3398 in the flash chip itself or the LEDs attached to it. Faults may
3399 prevent further use of some of the flash controls. In particular,
3400 V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
3401 if the fault affects the flash LED. Exactly which faults have such
3402 an effect is chip dependent. Reading the faults resets the control
3403 and returns the chip to a usable state if possible.
3405 .. tabularcolumns:: |p{8.0cm}|p{9.5cm}|
3411 * - ``V4L2_FLASH_FAULT_OVER_VOLTAGE``
3412 - Flash controller voltage to the flash LED has exceeded the limit
3413 specific to the flash controller.
3414 * - ``V4L2_FLASH_FAULT_TIMEOUT``
3415 - The flash strobe was still on when the timeout set by the user ---
3416 V4L2_CID_FLASH_TIMEOUT control --- has expired. Not all flash
3417 controllers may set this in all such conditions.
3418 * - ``V4L2_FLASH_FAULT_OVER_TEMPERATURE``
3419 - The flash controller has overheated.
3420 * - ``V4L2_FLASH_FAULT_SHORT_CIRCUIT``
3421 - The short circuit protection of the flash controller has been
3423 * - ``V4L2_FLASH_FAULT_OVER_CURRENT``
3424 - Current in the LED power supply has exceeded the limit specific to
3425 the flash controller.
3426 * - ``V4L2_FLASH_FAULT_INDICATOR``
3427 - The flash controller has detected a short or open circuit
3428 condition on the indicator LED.
3429 * - ``V4L2_FLASH_FAULT_UNDER_VOLTAGE``
3430 - Flash controller voltage to the flash LED has been below the
3431 minimum limit specific to the flash controller.
3432 * - ``V4L2_FLASH_FAULT_INPUT_VOLTAGE``
3433 - The input voltage of the flash controller is below the limit under
3434 which strobing the flash at full current will not be possible.The
3435 condition persists until this flag is no longer set.
3436 * - ``V4L2_FLASH_FAULT_LED_OVER_TEMPERATURE``
3437 - The temperature of the LED has exceeded its allowed upper limit.
3441 ``V4L2_CID_FLASH_CHARGE (boolean)``
3442 Enable or disable charging of the xenon flash capacitor.
3444 ``V4L2_CID_FLASH_READY (boolean)``
3445 Is the flash ready to strobe? Xenon flashes require their capacitors
3446 charged before strobing. LED flashes often require a cooldown period
3447 after strobe during which another strobe will not be possible. This
3448 is a read-only control.
3453 JPEG Control Reference
3454 ======================
3456 The JPEG class includes controls for common features of JPEG encoders
3457 and decoders. Currently it includes features for codecs implementing
3458 progressive baseline DCT compression process with Huffman entrophy
3462 .. _jpeg-control-id:
3467 ``V4L2_CID_JPEG_CLASS (class)``
3468 The JPEG class descriptor. Calling
3469 :ref:`VIDIOC_QUERYCTRL` for this control will
3470 return a description of this control class.
3472 ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)``
3473 The chroma subsampling factors describe how each component of an
3474 input image is sampled, in respect to maximum sample rate in each
3475 spatial dimension. See :ref:`itu-t81`, clause A.1.1. for more
3476 details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines
3477 how Cb and Cr components are downsampled after converting an input
3478 image from RGB to Y'CbCr color space.
3480 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
3486 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444``
3487 - No chroma subsampling, each pixel has Y, Cr and Cb values.
3488 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422``
3489 - Horizontally subsample Cr, Cb components by a factor of 2.
3490 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420``
3491 - Subsample Cr, Cb components horizontally and vertically by 2.
3492 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411``
3493 - Horizontally subsample Cr, Cb components by a factor of 4.
3494 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410``
3495 - Subsample Cr, Cb components horizontally by 4 and vertically by 2.
3496 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY``
3497 - Use only luminance component.
3501 ``V4L2_CID_JPEG_RESTART_INTERVAL (integer)``
3502 The restart interval determines an interval of inserting RSTm
3503 markers (m = 0..7). The purpose of these markers is to additionally
3504 reinitialize the encoder process, in order to process blocks of an
3505 image independently. For the lossy compression processes the restart
3506 interval unit is MCU (Minimum Coded Unit) and its value is contained
3507 in DRI (Define Restart Interval) marker. If
3508 ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm
3509 markers will not be inserted.
3511 .. _jpeg-quality-control:
3513 ``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)``
3514 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control determines trade-off
3515 between image quality and size. It provides simpler method for
3516 applications to control image quality, without a need for direct
3517 reconfiguration of luminance and chrominance quantization tables. In
3518 cases where a driver uses quantization tables configured directly by
3519 an application, using interfaces defined elsewhere,
3520 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by
3523 The value range of this control is driver-specific. Only positive,
3524 non-zero values are meaningful. The recommended range is 1 - 100,
3525 where larger values correspond to better image quality.
3527 .. _jpeg-active-marker-control:
3529 ``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)``
3530 Specify which JPEG markers are included in compressed stream. This
3531 control is valid only for encoders.
3539 * - ``V4L2_JPEG_ACTIVE_MARKER_APP0``
3540 - Application data segment APP\ :sub:`0`.
3541 * - ``V4L2_JPEG_ACTIVE_MARKER_APP1``
3542 - Application data segment APP\ :sub:`1`.
3543 * - ``V4L2_JPEG_ACTIVE_MARKER_COM``
3545 * - ``V4L2_JPEG_ACTIVE_MARKER_DQT``
3546 - Quantization tables segment.
3547 * - ``V4L2_JPEG_ACTIVE_MARKER_DHT``
3548 - Huffman tables segment.
3552 For more details about JPEG specification, refer to :ref:`itu-t81`,
3553 :ref:`jfif`, :ref:`w3c-jpeg-jfif`.
3556 .. _image-source-controls:
3558 Image Source Control Reference
3559 ==============================
3561 The Image Source control class is intended for low-level control of
3562 image source devices such as image sensors. The devices feature an
3563 analogue to digital converter and a bus transmitter to transmit the
3564 image data out of the device.
3567 .. _image-source-control-id:
3569 Image Source Control IDs
3570 ------------------------
3572 ``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
3573 The IMAGE_SOURCE class descriptor.
3575 ``V4L2_CID_VBLANK (integer)``
3576 Vertical blanking. The idle period after every frame during which no
3577 image data is produced. The unit of vertical blanking is a line.
3578 Every line has length of the image width plus horizontal blanking at
3579 the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
3582 ``V4L2_CID_HBLANK (integer)``
3583 Horizontal blanking. The idle period after every line of image data
3584 during which no image data is produced. The unit of horizontal
3587 ``V4L2_CID_ANALOGUE_GAIN (integer)``
3588 Analogue gain is gain affecting all colour components in the pixel
3589 matrix. The gain operation is performed in the analogue domain
3590 before A/D conversion.
3592 ``V4L2_CID_TEST_PATTERN_RED (integer)``
3593 Test pattern red colour component.
3595 ``V4L2_CID_TEST_PATTERN_GREENR (integer)``
3596 Test pattern green (next to red) colour component.
3598 ``V4L2_CID_TEST_PATTERN_BLUE (integer)``
3599 Test pattern blue colour component.
3601 ``V4L2_CID_TEST_PATTERN_GREENB (integer)``
3602 Test pattern green (next to blue) colour component.
3605 .. _image-process-controls:
3607 Image Process Control Reference
3608 ===============================
3610 The Image Process control class is intended for low-level control of
3611 image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
3612 controls in this class affect processing the image, and do not control
3616 .. _image-process-control-id:
3618 Image Process Control IDs
3619 -------------------------
3621 ``V4L2_CID_IMAGE_PROC_CLASS (class)``
3622 The IMAGE_PROC class descriptor.
3624 ``V4L2_CID_LINK_FREQ (integer menu)``
3625 Data bus frequency. Together with the media bus pixel code, bus type
3626 (clock cycles per sample), the data bus frequency defines the pixel
3627 rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
3628 elsewhere, if the device is not an image sensor). The frame rate can
3629 be calculated from the pixel clock, image width and height and
3630 horizontal and vertical blanking. While the pixel rate control may
3631 be defined elsewhere than in the subdev containing the pixel array,
3632 the frame rate cannot be obtained from that information. This is
3633 because only on the pixel array it can be assumed that the vertical
3634 and horizontal blanking information is exact: no other blanking is
3635 allowed in the pixel array. The selection of frame rate is performed
3636 by selecting the desired horizontal and vertical blanking. The unit
3637 of this control is Hz.
3639 ``V4L2_CID_PIXEL_RATE (64-bit integer)``
3640 Pixel rate in the source pads of the subdev. This control is
3641 read-only and its unit is pixels / second.
3643 ``V4L2_CID_TEST_PATTERN (menu)``
3644 Some capture/display/sensor devices have the capability to generate
3645 test pattern images. These hardware specific test patterns can be
3646 used to test if a device is working properly.
3648 ``V4L2_CID_DEINTERLACING_MODE (menu)``
3649 The video deinterlacing mode (such as Bob, Weave, ...). The menu items are
3650 driver specific and are documented in :ref:`v4l-drivers`.
3652 ``V4L2_CID_DIGITAL_GAIN (integer)``
3653 Digital gain is the value by which all colour components
3654 are multiplied by. Typically the digital gain applied is the
3655 control value divided by e.g. 0x100, meaning that to get no
3656 digital gain the control value needs to be 0x100. The no-gain
3657 configuration is also typically the default.
3662 Digital Video Control Reference
3663 ===============================
3665 The Digital Video control class is intended to control receivers and
3666 transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
3667 `DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__
3668 (Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort
3669 (:ref:`dp`). These controls are generally expected to be private to
3670 the receiver or transmitter subdevice that implements them, so they are
3671 only exposed on the ``/dev/v4l-subdev*`` device node.
3675 Note that these devices can have multiple input or output pads which are
3676 hooked up to e.g. HDMI connectors. Even though the subdevice will
3677 receive or transmit video from/to only one of those pads, the other pads
3678 can still be active when it comes to EDID (Extended Display
3679 Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
3680 Content Protection System, :ref:`hdcp`) processing, allowing the
3681 device to do the fairly slow EDID/HDCP handling in advance. This allows
3682 for quick switching between connectors.
3684 These pads appear in several of the controls in this section as
3685 bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad
3686 1, etc. The maximum value of the control is the set of valid pads.
3691 Digital Video Control IDs
3692 -------------------------
3694 ``V4L2_CID_DV_CLASS (class)``
3695 The Digital Video class descriptor.
3697 ``V4L2_CID_DV_TX_HOTPLUG (bitmask)``
3698 Many connectors have a hotplug pin which is high if EDID information
3699 is available from the source. This control shows the state of the
3700 hotplug pin as seen by the transmitter. Each bit corresponds to an
3701 output pad on the transmitter. If an output pad does not have an
3702 associated hotplug pin, then the bit for that pad will be 0. This
3703 read-only control is applicable to DVI-D, HDMI and DisplayPort
3706 ``V4L2_CID_DV_TX_RXSENSE (bitmask)``
3707 Rx Sense is the detection of pull-ups on the TMDS clock lines. This
3708 normally means that the sink has left/entered standby (i.e. the
3709 transmitter can sense that the receiver is ready to receive video).
3710 Each bit corresponds to an output pad on the transmitter. If an
3711 output pad does not have an associated Rx Sense, then the bit for
3712 that pad will be 0. This read-only control is applicable to DVI-D
3715 ``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)``
3716 When the transmitter sees the hotplug signal from the receiver it
3717 will attempt to read the EDID. If set, then the transmitter has read
3718 at least the first block (= 128 bytes). Each bit corresponds to an
3719 output pad on the transmitter. If an output pad does not support
3720 EDIDs, then the bit for that pad will be 0. This read-only control
3721 is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors.
3723 ``V4L2_CID_DV_TX_MODE``
3726 enum v4l2_dv_tx_mode -
3727 HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI
3728 mode (video + audio + auxiliary data). This control selects which
3729 mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI.
3730 This control is applicable to HDMI connectors.
3732 ``V4L2_CID_DV_TX_RGB_RANGE``
3735 enum v4l2_dv_rgb_range -
3736 Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO
3737 follows the RGB quantization range specified in the standard for the
3738 video interface (ie. :ref:`cea861` for HDMI).
3739 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
3740 standard to be compatible with sinks that have not implemented the
3741 standard correctly (unfortunately quite common for HDMI and DVI-D).
3742 Full range allows all possible values to be used whereas limited
3743 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
3744 the number of bits per component. This control is applicable to VGA,
3745 DVI-A/D, HDMI and DisplayPort connectors.
3747 ``V4L2_CID_DV_TX_IT_CONTENT_TYPE``
3750 enum v4l2_dv_it_content_type -
3751 Configures the IT Content Type of the transmitted video. This
3752 information is sent over HDMI and DisplayPort connectors as part of
3753 the AVI InfoFrame. The term 'IT Content' is used for content that
3754 originates from a computer as opposed to content from a TV broadcast
3755 or an analog source. The enum v4l2_dv_it_content_type defines
3756 the possible content types:
3758 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
3764 * - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS``
3765 - Graphics content. Pixel data should be passed unfiltered and
3766 without analog reconstruction.
3767 * - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO``
3768 - Photo content. The content is derived from digital still pictures.
3769 The content should be passed through with minimal scaling and
3770 picture enhancements.
3771 * - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA``
3773 * - ``V4L2_DV_IT_CONTENT_TYPE_GAME``
3774 - Game content. Audio and video latency should be minimized.
3775 * - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC``
3776 - No IT Content information is available and the ITC bit in the AVI
3777 InfoFrame is set to 0.
3781 ``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)``
3782 Detects whether the receiver receives power from the source (e.g.
3783 HDMI carries 5V on one of the pins). This is often used to power an
3784 eeprom which contains EDID information, such that the source can
3785 read the EDID even if the sink is in standby/power off. Each bit
3786 corresponds to an input pad on the receiver. If an input pad
3787 cannot detect whether power is present, then the bit for that pad
3788 will be 0. This read-only control is applicable to DVI-D, HDMI and
3789 DisplayPort connectors.
3791 ``V4L2_CID_DV_RX_RGB_RANGE``
3794 enum v4l2_dv_rgb_range -
3795 Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO
3796 follows the RGB quantization range specified in the standard for the
3797 video interface (ie. :ref:`cea861` for HDMI).
3798 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
3799 standard to be compatible with sources that have not implemented the
3800 standard correctly (unfortunately quite common for HDMI and DVI-D).
3801 Full range allows all possible values to be used whereas limited
3802 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
3803 the number of bits per component. This control is applicable to VGA,
3804 DVI-A/D, HDMI and DisplayPort connectors.
3806 ``V4L2_CID_DV_RX_IT_CONTENT_TYPE``
3809 enum v4l2_dv_it_content_type -
3810 Reads the IT Content Type of the received video. This information is
3811 sent over HDMI and DisplayPort connectors as part of the AVI
3812 InfoFrame. The term 'IT Content' is used for content that originates
3813 from a computer as opposed to content from a TV broadcast or an
3814 analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the
3815 available content types.
3820 FM Receiver Control Reference
3821 =============================
3823 The FM Receiver (FM_RX) class includes controls for common features of
3824 FM Reception capable devices.
3827 .. _fm-rx-control-id:
3832 ``V4L2_CID_FM_RX_CLASS (class)``
3833 The FM_RX class descriptor. Calling
3834 :ref:`VIDIOC_QUERYCTRL` for this control will
3835 return a description of this control class.
3837 ``V4L2_CID_RDS_RECEPTION (boolean)``
3838 Enables/disables RDS reception by the radio tuner
3840 ``V4L2_CID_RDS_RX_PTY (integer)``
3841 Gets RDS Programme Type field. This encodes up to 31 pre-defined
3844 ``V4L2_CID_RDS_RX_PS_NAME (string)``
3845 Gets the Programme Service name (PS_NAME). It is intended for
3846 static display on a receiver. It is the primary aid to listeners in
3847 programme service identification and selection. In Annex E of
3848 :ref:`iec62106`, the RDS specification, there is a full
3849 description of the correct character encoding for Programme Service
3850 name strings. Also from RDS specification, PS is usually a single
3851 eight character text. However, it is also possible to find receivers
3852 which can scroll strings sized as 8 x N characters. So, this control
3853 must be configured with steps of 8 characters. The result is it must
3854 always contain a string with size multiple of 8.
3856 ``V4L2_CID_RDS_RX_RADIO_TEXT (string)``
3857 Gets the Radio Text info. It is a textual description of what is
3858 being broadcasted. RDS Radio Text can be applied when broadcaster
3859 wishes to transmit longer PS names, programme-related information or
3860 any other text. In these cases, RadioText can be used in addition to
3861 ``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is
3862 also fully described in Annex E of :ref:`iec62106`. The length of
3863 Radio Text strings depends on which RDS Block is being used to
3864 transmit it, either 32 (2A block) or 64 (2B block). However, it is
3865 also possible to find receivers which can scroll strings sized as 32
3866 x N or 64 x N characters. So, this control must be configured with
3867 steps of 32 or 64 characters. The result is it must always contain a
3868 string with size multiple of 32 or 64.
3870 ``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)``
3871 If set, then a traffic announcement is in progress.
3873 ``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)``
3874 If set, then the tuned programme carries traffic announcements.
3876 ``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)``
3877 If set, then this channel broadcasts music. If cleared, then it
3878 broadcasts speech. If the transmitter doesn't make this distinction,
3879 then it will be set.
3881 ``V4L2_CID_TUNE_DEEMPHASIS``
3884 enum v4l2_deemphasis -
3885 Configures the de-emphasis value for reception. A de-emphasis filter
3886 is applied to the broadcast to accentuate the high audio
3887 frequencies. Depending on the region, a time constant of either 50
3888 or 75 useconds is used. The enum v4l2_deemphasis defines possible
3889 values for de-emphasis. Here they are:
3897 * - ``V4L2_DEEMPHASIS_DISABLED``
3898 - No de-emphasis is applied.
3899 * - ``V4L2_DEEMPHASIS_50_uS``
3900 - A de-emphasis of 50 uS is used.
3901 * - ``V4L2_DEEMPHASIS_75_uS``
3902 - A de-emphasis of 75 uS is used.
3907 .. _detect-controls:
3909 Detect Control Reference
3910 ========================
3912 The Detect class includes controls for common features of various motion
3913 or object detection capable devices.
3916 .. _detect-control-id:
3921 ``V4L2_CID_DETECT_CLASS (class)``
3922 The Detect class descriptor. Calling
3923 :ref:`VIDIOC_QUERYCTRL` for this control will
3924 return a description of this control class.
3926 ``V4L2_CID_DETECT_MD_MODE (menu)``
3927 Sets the motion detection mode.
3929 .. tabularcolumns:: |p{7.5cm}|p{10.0cm}|
3935 * - ``V4L2_DETECT_MD_MODE_DISABLED``
3936 - Disable motion detection.
3937 * - ``V4L2_DETECT_MD_MODE_GLOBAL``
3938 - Use a single motion detection threshold.
3939 * - ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID``
3940 - The image is divided into a grid, each cell with its own motion
3941 detection threshold. These thresholds are set through the
3942 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID`` matrix control.
3943 * - ``V4L2_DETECT_MD_MODE_REGION_GRID``
3944 - The image is divided into a grid, each cell with its own region
3945 value that specifies which per-region motion detection thresholds
3946 should be used. Each region has its own thresholds. How these
3947 per-region thresholds are set up is driver-specific. The region
3948 values for the grid are set through the
3949 ``V4L2_CID_DETECT_MD_REGION_GRID`` matrix control.
3953 ``V4L2_CID_DETECT_MD_GLOBAL_THRESHOLD (integer)``
3954 Sets the global motion detection threshold to be used with the
3955 ``V4L2_DETECT_MD_MODE_GLOBAL`` motion detection mode.
3957 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID (__u16 matrix)``
3958 Sets the motion detection thresholds for each cell in the grid. To
3959 be used with the ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID`` motion
3960 detection mode. Matrix element (0, 0) represents the cell at the
3961 top-left of the grid.
3963 ``V4L2_CID_DETECT_MD_REGION_GRID (__u8 matrix)``
3964 Sets the motion detection region value for each cell in the grid. To
3965 be used with the ``V4L2_DETECT_MD_MODE_REGION_GRID`` motion
3966 detection mode. Matrix element (0, 0) represents the cell at the
3967 top-left of the grid.
3970 .. _rf-tuner-controls:
3972 RF Tuner Control Reference
3973 ==========================
3975 The RF Tuner (RF_TUNER) class includes controls for common features of
3976 devices having RF tuner.
3978 In this context, RF tuner is radio receiver circuit between antenna and
3979 demodulator. It receives radio frequency (RF) from the antenna and
3980 converts that received signal to lower intermediate frequency (IF) or
3981 baseband frequency (BB). Tuners that could do baseband output are often
3982 called Zero-IF tuners. Older tuners were typically simple PLL tuners
3983 inside a metal box, whilst newer ones are highly integrated chips
3984 without a metal box "silicon tuners". These controls are mostly
3985 applicable for new feature rich silicon tuners, just because older
3986 tuners does not have much adjustable features.
3988 For more information about RF tuners see
3989 `Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
3990 and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
3994 .. _rf-tuner-control-id:
3996 RF_TUNER Control IDs
3997 --------------------
3999 ``V4L2_CID_RF_TUNER_CLASS (class)``
4000 The RF_TUNER class descriptor. Calling
4001 :ref:`VIDIOC_QUERYCTRL` for this control will
4002 return a description of this control class.
4004 ``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
4005 Enables/disables tuner radio channel bandwidth configuration. In
4006 automatic mode bandwidth configuration is performed by the driver.
4008 ``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
4009 Filter(s) on tuner signal path are used to filter signal according
4010 to receiving party needs. Driver configures filters to fulfill
4011 desired bandwidth requirement. Used when
4012 V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
4013 range and step are driver-specific.
4015 ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
4016 Enables/disables LNA automatic gain control (AGC)
4018 ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
4019 Enables/disables mixer automatic gain control (AGC)
4021 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
4022 Enables/disables IF automatic gain control (AGC)
4024 ``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
4025 The RF amplifier is the very first amplifier on the receiver signal
4026 path, just right after the antenna input. The difference between the
4027 LNA gain and the RF gain in this document is that the LNA gain is
4028 integrated in the tuner chip while the RF gain is a separate chip.
4029 There may be both RF and LNA gain controls in the same device. The
4030 range and step are driver-specific.
4032 ``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
4033 LNA (low noise amplifier) gain is first gain stage on the RF tuner
4034 signal path. It is located very close to tuner antenna input. Used
4035 when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
4036 ``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
4037 differs from the each others. The range and step are
4040 ``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
4041 Mixer gain is second gain stage on the RF tuner signal path. It is
4042 located inside mixer block, where RF signal is down-converted by the
4043 mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
4044 The range and step are driver-specific.
4046 ``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
4047 IF gain is last gain stage on the RF tuner signal path. It is
4048 located on output of RF tuner. It controls signal level of
4049 intermediate frequency output or baseband output. Used when
4050 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
4051 are driver-specific.
4053 ``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
4054 Is synthesizer PLL locked? RF tuner is receiving given frequency
4055 when that control is set. This is a read-only control.
4058 This control may be changed to a menu control in the future, if more
4059 options are required.