1 .. Permission is granted to copy, distribute and/or modify this
2 .. document under the terms of the GNU Free Documentation License,
3 .. Version 1.1 or any later version published by the Free Software
4 .. Foundation, with no Invariant Sections, no Front-Cover Texts
5 .. and no Back-Cover Texts. A copy of the license is included at
6 .. Documentation/media/uapi/fdl-appendix.rst.
8 .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
10 .. _extended-controls:
20 The control mechanism as originally designed was meant to be used for
21 user settings (brightness, saturation, etc). However, it turned out to
22 be a very useful model for implementing more complicated driver APIs
23 where each driver implements only a subset of a larger API.
25 The MPEG encoding API was the driving force behind designing and
26 implementing this extended control mechanism: the MPEG standard is quite
27 large and the currently supported hardware MPEG encoders each only
28 implement a subset of this standard. Further more, many parameters
29 relating to how the video is encoded into an MPEG stream are specific to
30 the MPEG encoding chip since the MPEG standard only defines the format
31 of the resulting MPEG stream, not how the video is actually encoded into
34 Unfortunately, the original control API lacked some features needed for
35 these new uses and so it was extended into the (not terribly originally
36 named) extended control API.
38 Even though the MPEG encoding API was the first effort to use the
39 Extended Control API, nowadays there are also other classes of Extended
40 Controls, such as Camera Controls and FM Transmitter Controls. The
41 Extended Controls API as well as all Extended Controls classes are
42 described in the following text.
45 The Extended Control API
46 ========================
48 Three new ioctls are available:
49 :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
50 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and
51 :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. These ioctls act
52 on arrays of controls (as opposed to the
53 :ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
54 :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls that act on a single
55 control). This is needed since it is often required to atomically change
56 several controls at once.
58 Each of the new ioctls expects a pointer to a struct
59 :c:type:`v4l2_ext_controls`. This structure
60 contains a pointer to the control array, a count of the number of
61 controls in that array and a control class. Control classes are used to
62 group similar controls into a single class. For example, control class
63 ``V4L2_CTRL_CLASS_USER`` contains all user controls (i. e. all controls
64 that can also be set using the old :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>`
65 ioctl). Control class ``V4L2_CTRL_CLASS_MPEG`` contains all controls
66 relating to MPEG encoding, etc.
68 All controls in the control array must belong to the specified control
69 class. An error is returned if this is not the case.
71 It is also possible to use an empty control array (``count`` == 0) to check
72 whether the specified control class is supported.
74 The control array is a struct
75 :c:type:`v4l2_ext_control` array. The
76 struct :c:type:`v4l2_ext_control` is very similar to
77 struct :c:type:`v4l2_control`, except for the fact that
78 it also allows for 64-bit values and pointers to be passed.
80 Since the struct :c:type:`v4l2_ext_control` supports
81 pointers it is now also possible to have controls with compound types
82 such as N-dimensional arrays and/or structures. You need to specify the
83 ``V4L2_CTRL_FLAG_NEXT_COMPOUND`` when enumerating controls to actually
84 be able to see such compound controls. In other words, these controls
85 with compound types should only be used programmatically.
87 Since such compound controls need to expose more information about
88 themselves than is possible with
89 :ref:`VIDIOC_QUERYCTRL` the
90 :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>` ioctl was added. In
91 particular, this ioctl gives the dimensions of the N-dimensional array
92 if this control consists of more than one element.
96 #. It is important to realize that due to the flexibility of controls it is
97 necessary to check whether the control you want to set actually is
98 supported in the driver and what the valid range of values is. So use
99 the :ref:`VIDIOC_QUERYCTRL` (or :ref:`VIDIOC_QUERY_EXT_CTRL
100 <VIDIOC_QUERYCTRL>`) and :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>`
101 ioctls to check this.
103 #. It is possible that some of the menu indices in a control of
104 type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
105 will return an error). A good example is the list of supported MPEG
106 audio bitrates. Some drivers only support one or two bitrates, others
107 support a wider range.
109 All controls use machine endianness.
112 Enumerating Extended Controls
113 =============================
115 The recommended way to enumerate over the extended controls is by using
116 :ref:`VIDIOC_QUERYCTRL` in combination with the
117 ``V4L2_CTRL_FLAG_NEXT_CTRL`` flag:
122 struct v4l2_queryctrl qctrl;
124 qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
125 while (0 == ioctl (fd, VIDIOC_QUERYCTRL, &qctrl)) {
127 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
130 The initial control ID is set to 0 ORed with the
131 ``V4L2_CTRL_FLAG_NEXT_CTRL`` flag. The ``VIDIOC_QUERYCTRL`` ioctl will
132 return the first control with a higher ID than the specified one. When
133 no such controls are found an error is returned.
135 If you want to get all controls within a specific control class, then
136 you can set the initial ``qctrl.id`` value to the control class and add
137 an extra check to break out of the loop when a control of another
138 control class is found:
143 qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
144 while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &qctrl)) {
145 if (V4L2_CTRL_ID2CLASS(qctrl.id) != V4L2_CTRL_CLASS_MPEG)
148 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
151 The 32-bit ``qctrl.id`` value is subdivided into three bit ranges: the
152 top 4 bits are reserved for flags (e. g. ``V4L2_CTRL_FLAG_NEXT_CTRL``)
153 and are not actually part of the ID. The remaining 28 bits form the
154 control ID, of which the most significant 12 bits define the control
155 class and the least significant 16 bits identify the control within the
156 control class. It is guaranteed that these last 16 bits are always
157 non-zero for controls. The range of 0x1000 and up are reserved for
158 driver-specific controls. The macro ``V4L2_CTRL_ID2CLASS(id)`` returns
159 the control class ID based on a control ID.
161 If the driver does not support extended controls, then
162 ``VIDIOC_QUERYCTRL`` will fail when used in combination with
163 ``V4L2_CTRL_FLAG_NEXT_CTRL``. In that case the old method of enumerating
164 control should be used (see :ref:`enum_all_controls`). But if it is
165 supported, then it is guaranteed to enumerate over all controls,
166 including driver-private controls.
169 Creating Control Panels
170 =======================
172 It is possible to create control panels for a graphical user interface
173 where the user can select the various controls. Basically you will have
174 to iterate over all controls using the method described above. Each
175 control class starts with a control of type
176 ``V4L2_CTRL_TYPE_CTRL_CLASS``. ``VIDIOC_QUERYCTRL`` will return the name
177 of this control class which can be used as the title of a tab page
178 within a control panel.
180 The flags field of struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` also
181 contains hints on the behavior of the control. See the
182 :ref:`VIDIOC_QUERYCTRL` documentation for more
188 Codec Control Reference
189 =======================
191 Below all controls within the Codec control class are described. First
192 the generic controls, then controls specific for certain hardware.
196 These controls are applicable to all codecs and not just MPEG. The
197 defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
198 were originally made for MPEG codecs and later extended to cover all
202 Generic Codec Controls
203 ----------------------
211 ``V4L2_CID_MPEG_CLASS (class)``
212 The Codec class descriptor. Calling
213 :ref:`VIDIOC_QUERYCTRL` for this control will
214 return a description of this control class. This description can be
215 used as the caption of a Tab page in a GUI, for example.
217 .. _v4l2-mpeg-stream-type:
219 ``V4L2_CID_MPEG_STREAM_TYPE``
222 enum v4l2_mpeg_stream_type -
223 The MPEG-1, -2 or -4 output stream type. One cannot assume anything
224 here. Each hardware MPEG encoder tends to support different subsets
225 of the available MPEG stream types. This control is specific to
226 multiplexed MPEG streams. The currently defined stream types are:
234 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_PS``
235 - MPEG-2 program stream
236 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_TS``
237 - MPEG-2 transport stream
238 * - ``V4L2_MPEG_STREAM_TYPE_MPEG1_SS``
239 - MPEG-1 system stream
240 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_DVD``
241 - MPEG-2 DVD-compatible stream
242 * - ``V4L2_MPEG_STREAM_TYPE_MPEG1_VCD``
243 - MPEG-1 VCD-compatible stream
244 * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD``
245 - MPEG-2 SVCD-compatible stream
249 ``V4L2_CID_MPEG_STREAM_PID_PMT (integer)``
250 Program Map Table Packet ID for the MPEG transport stream (default
253 ``V4L2_CID_MPEG_STREAM_PID_AUDIO (integer)``
254 Audio Packet ID for the MPEG transport stream (default 256)
256 ``V4L2_CID_MPEG_STREAM_PID_VIDEO (integer)``
257 Video Packet ID for the MPEG transport stream (default 260)
259 ``V4L2_CID_MPEG_STREAM_PID_PCR (integer)``
260 Packet ID for the MPEG transport stream carrying PCR fields (default
263 ``V4L2_CID_MPEG_STREAM_PES_ID_AUDIO (integer)``
264 Audio ID for MPEG PES
266 ``V4L2_CID_MPEG_STREAM_PES_ID_VIDEO (integer)``
267 Video ID for MPEG PES
269 .. _v4l2-mpeg-stream-vbi-fmt:
271 ``V4L2_CID_MPEG_STREAM_VBI_FMT``
274 enum v4l2_mpeg_stream_vbi_fmt -
275 Some cards can embed VBI data (e. g. Closed Caption, Teletext) into
276 the MPEG stream. This control selects whether VBI data should be
277 embedded, and if so, what embedding method should be used. The list
278 of possible VBI formats depends on the driver. The currently defined
279 VBI format types are:
283 .. tabularcolumns:: |p{6 cm}|p{11.5cm}|
289 * - ``V4L2_MPEG_STREAM_VBI_FMT_NONE``
290 - No VBI in the MPEG stream
291 * - ``V4L2_MPEG_STREAM_VBI_FMT_IVTV``
292 - VBI in private packets, IVTV format (documented in the kernel
294 ``Documentation/media/v4l-drivers/cx2341x.rst``)
298 .. _v4l2-mpeg-audio-sampling-freq:
300 ``V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ``
303 enum v4l2_mpeg_audio_sampling_freq -
304 MPEG Audio sampling frequency. Possible values are:
312 * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100``
314 * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000``
316 * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000``
321 .. _v4l2-mpeg-audio-encoding:
323 ``V4L2_CID_MPEG_AUDIO_ENCODING``
326 enum v4l2_mpeg_audio_encoding -
327 MPEG Audio encoding. This control is specific to multiplexed MPEG
328 streams. Possible values are:
336 * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_1``
337 - MPEG-1/2 Layer I encoding
338 * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_2``
339 - MPEG-1/2 Layer II encoding
340 * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_3``
341 - MPEG-1/2 Layer III encoding
342 * - ``V4L2_MPEG_AUDIO_ENCODING_AAC``
343 - MPEG-2/4 AAC (Advanced Audio Coding)
344 * - ``V4L2_MPEG_AUDIO_ENCODING_AC3``
345 - AC-3 aka ATSC A/52 encoding
349 .. _v4l2-mpeg-audio-l1-bitrate:
351 ``V4L2_CID_MPEG_AUDIO_L1_BITRATE``
354 enum v4l2_mpeg_audio_l1_bitrate -
355 MPEG-1/2 Layer I bitrate. Possible values are:
363 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_32K``
365 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_64K``
367 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_96K``
369 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_128K``
371 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_160K``
373 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_192K``
375 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_224K``
377 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_256K``
379 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_288K``
381 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_320K``
383 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_352K``
385 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_384K``
387 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_416K``
389 * - ``V4L2_MPEG_AUDIO_L1_BITRATE_448K``
394 .. _v4l2-mpeg-audio-l2-bitrate:
396 ``V4L2_CID_MPEG_AUDIO_L2_BITRATE``
399 enum v4l2_mpeg_audio_l2_bitrate -
400 MPEG-1/2 Layer II bitrate. Possible values are:
408 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_32K``
410 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_48K``
412 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_56K``
414 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_64K``
416 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_80K``
418 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_96K``
420 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_112K``
422 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_128K``
424 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_160K``
426 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_192K``
428 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_224K``
430 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_256K``
432 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_320K``
434 * - ``V4L2_MPEG_AUDIO_L2_BITRATE_384K``
439 .. _v4l2-mpeg-audio-l3-bitrate:
441 ``V4L2_CID_MPEG_AUDIO_L3_BITRATE``
444 enum v4l2_mpeg_audio_l3_bitrate -
445 MPEG-1/2 Layer III bitrate. Possible values are:
453 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_32K``
455 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_40K``
457 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_48K``
459 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_56K``
461 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_64K``
463 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_80K``
465 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_96K``
467 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_112K``
469 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_128K``
471 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_160K``
473 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_192K``
475 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_224K``
477 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_256K``
479 * - ``V4L2_MPEG_AUDIO_L3_BITRATE_320K``
484 ``V4L2_CID_MPEG_AUDIO_AAC_BITRATE (integer)``
485 AAC bitrate in bits per second.
487 .. _v4l2-mpeg-audio-ac3-bitrate:
489 ``V4L2_CID_MPEG_AUDIO_AC3_BITRATE``
492 enum v4l2_mpeg_audio_ac3_bitrate -
493 AC-3 bitrate. Possible values are:
501 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_32K``
503 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_40K``
505 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_48K``
507 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_56K``
509 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_64K``
511 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_80K``
513 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_96K``
515 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_112K``
517 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_128K``
519 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_160K``
521 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_192K``
523 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_224K``
525 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_256K``
527 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_320K``
529 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_384K``
531 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_448K``
533 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_512K``
535 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_576K``
537 * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_640K``
542 .. _v4l2-mpeg-audio-mode:
544 ``V4L2_CID_MPEG_AUDIO_MODE``
547 enum v4l2_mpeg_audio_mode -
548 MPEG Audio mode. Possible values are:
556 * - ``V4L2_MPEG_AUDIO_MODE_STEREO``
558 * - ``V4L2_MPEG_AUDIO_MODE_JOINT_STEREO``
560 * - ``V4L2_MPEG_AUDIO_MODE_DUAL``
562 * - ``V4L2_MPEG_AUDIO_MODE_MONO``
567 .. _v4l2-mpeg-audio-mode-extension:
569 ``V4L2_CID_MPEG_AUDIO_MODE_EXTENSION``
572 enum v4l2_mpeg_audio_mode_extension -
573 Joint Stereo audio mode extension. In Layer I and II they indicate
574 which subbands are in intensity stereo. All other subbands are coded
575 in stereo. Layer III is not (yet) supported. Possible values are:
583 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4``
584 - Subbands 4-31 in intensity stereo
585 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8``
586 - Subbands 8-31 in intensity stereo
587 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12``
588 - Subbands 12-31 in intensity stereo
589 * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16``
590 - Subbands 16-31 in intensity stereo
594 .. _v4l2-mpeg-audio-emphasis:
596 ``V4L2_CID_MPEG_AUDIO_EMPHASIS``
599 enum v4l2_mpeg_audio_emphasis -
600 Audio Emphasis. Possible values are:
608 * - ``V4L2_MPEG_AUDIO_EMPHASIS_NONE``
610 * - ``V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS``
611 - 50/15 microsecond emphasis
612 * - ``V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17``
617 .. _v4l2-mpeg-audio-crc:
619 ``V4L2_CID_MPEG_AUDIO_CRC``
622 enum v4l2_mpeg_audio_crc -
623 CRC method. Possible values are:
631 * - ``V4L2_MPEG_AUDIO_CRC_NONE``
633 * - ``V4L2_MPEG_AUDIO_CRC_CRC16``
634 - 16 bit parity check
638 ``V4L2_CID_MPEG_AUDIO_MUTE (boolean)``
639 Mutes the audio when capturing. This is not done by muting audio
640 hardware, which can still produce a slight hiss, but in the encoder
641 itself, guaranteeing a fixed and reproducible audio bitstream. 0 =
644 .. _v4l2-mpeg-audio-dec-playback:
646 ``V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK``
649 enum v4l2_mpeg_audio_dec_playback -
650 Determines how monolingual audio should be played back. Possible
655 .. tabularcolumns:: |p{9.0cm}|p{8.5cm}|
661 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO``
662 - Automatically determines the best playback mode.
663 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO``
665 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT``
666 - Left channel playback.
667 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT``
668 - Right channel playback.
669 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO``
671 * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO``
672 - Stereo playback with swapped left and right channels.
676 .. _v4l2-mpeg-audio-dec-multilingual-playback:
678 ``V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK``
681 enum v4l2_mpeg_audio_dec_playback -
682 Determines how multilingual audio should be played back.
684 .. _v4l2-mpeg-video-encoding:
686 ``V4L2_CID_MPEG_VIDEO_ENCODING``
689 enum v4l2_mpeg_video_encoding -
690 MPEG Video encoding method. This control is specific to multiplexed
691 MPEG streams. Possible values are:
699 * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_1``
700 - MPEG-1 Video encoding
701 * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_2``
702 - MPEG-2 Video encoding
703 * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC``
704 - MPEG-4 AVC (H.264) Video encoding
708 .. _v4l2-mpeg-video-aspect:
710 ``V4L2_CID_MPEG_VIDEO_ASPECT``
713 enum v4l2_mpeg_video_aspect -
714 Video aspect. Possible values are:
722 * - ``V4L2_MPEG_VIDEO_ASPECT_1x1``
723 * - ``V4L2_MPEG_VIDEO_ASPECT_4x3``
724 * - ``V4L2_MPEG_VIDEO_ASPECT_16x9``
725 * - ``V4L2_MPEG_VIDEO_ASPECT_221x100``
729 ``V4L2_CID_MPEG_VIDEO_B_FRAMES (integer)``
730 Number of B-Frames (default 2)
732 ``V4L2_CID_MPEG_VIDEO_GOP_SIZE (integer)``
733 GOP size (default 12)
735 ``V4L2_CID_MPEG_VIDEO_GOP_CLOSURE (boolean)``
736 GOP closure (default 1)
738 ``V4L2_CID_MPEG_VIDEO_PULLDOWN (boolean)``
739 Enable 3:2 pulldown (default 0)
741 .. _v4l2-mpeg-video-bitrate-mode:
743 ``V4L2_CID_MPEG_VIDEO_BITRATE_MODE``
746 enum v4l2_mpeg_video_bitrate_mode -
747 Video bitrate mode. Possible values are:
755 * - ``V4L2_MPEG_VIDEO_BITRATE_MODE_VBR``
757 * - ``V4L2_MPEG_VIDEO_BITRATE_MODE_CBR``
762 ``V4L2_CID_MPEG_VIDEO_BITRATE (integer)``
763 Video bitrate in bits per second.
765 ``V4L2_CID_MPEG_VIDEO_BITRATE_PEAK (integer)``
766 Peak video bitrate in bits per second. Must be larger or equal to
767 the average video bitrate. It is ignored if the video bitrate mode
768 is set to constant bitrate.
770 ``V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION (integer)``
771 For every captured frame, skip this many subsequent frames (default
774 ``V4L2_CID_MPEG_VIDEO_MUTE (boolean)``
775 "Mutes" the video to a fixed color when capturing. This is useful
776 for testing, to produce a fixed video bitstream. 0 = unmuted, 1 =
779 ``V4L2_CID_MPEG_VIDEO_MUTE_YUV (integer)``
780 Sets the "mute" color of the video. The supplied 32-bit integer is
781 interpreted as follows (bit 0 = least significant bit):
790 - V chrominance information
792 - U chrominance information
794 - Y luminance information
800 .. _v4l2-mpeg-video-dec-pts:
802 ``V4L2_CID_MPEG_VIDEO_DEC_PTS (integer64)``
803 This read-only control returns the 33-bit video Presentation Time
804 Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of the
805 currently displayed frame. This is the same PTS as is used in
806 :ref:`VIDIOC_DECODER_CMD`.
808 .. _v4l2-mpeg-video-dec-frame:
810 ``V4L2_CID_MPEG_VIDEO_DEC_FRAME (integer64)``
811 This read-only control returns the frame counter of the frame that
812 is currently displayed (decoded). This value is reset to 0 whenever
813 the decoder is started.
815 ``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
816 If enabled the decoder expects to receive a single slice per buffer,
817 otherwise the decoder expects a single frame in per buffer.
818 Applicable to the decoder, all codecs.
820 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_ENABLE (boolean)``
821 Enable writing sample aspect ratio in the Video Usability
822 Information. Applicable to the H264 encoder.
824 .. _v4l2-mpeg-video-h264-vui-sar-idc:
826 ``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_IDC``
829 enum v4l2_mpeg_video_h264_vui_sar_idc -
830 VUI sample aspect ratio indicator for H.264 encoding. The value is
831 defined in the table E-1 in the standard. Applicable to the H264
840 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_UNSPECIFIED``
842 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_1x1``
844 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_12x11``
846 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_10x11``
848 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_16x11``
850 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_40x33``
852 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_24x11``
854 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_20x11``
856 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_32x11``
858 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_80x33``
860 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_18x11``
862 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_15x11``
864 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_64x33``
866 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_160x99``
868 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_4x3``
870 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_3x2``
872 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_2x1``
874 * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_EXTENDED``
879 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_WIDTH (integer)``
880 Extended sample aspect ratio width for H.264 VUI encoding.
881 Applicable to the H264 encoder.
883 ``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_HEIGHT (integer)``
884 Extended sample aspect ratio height for H.264 VUI encoding.
885 Applicable to the H264 encoder.
887 .. _v4l2-mpeg-video-h264-level:
889 ``V4L2_CID_MPEG_VIDEO_H264_LEVEL``
892 enum v4l2_mpeg_video_h264_level -
893 The level information for the H264 video elementary stream.
894 Applicable to the H264 encoder. Possible values are:
902 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_0``
904 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1B``
906 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_1``
908 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_2``
910 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_3``
912 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_0``
914 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_1``
916 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_2``
918 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_0``
920 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_1``
922 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_2``
924 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_0``
926 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_1``
928 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_2``
930 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_0``
932 * - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_1``
937 .. _v4l2-mpeg-video-mpeg4-level:
939 ``V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL``
942 enum v4l2_mpeg_video_mpeg4_level -
943 The level information for the MPEG4 elementary stream. Applicable to
944 the MPEG4 encoder. Possible values are:
952 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_0``
954 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_0B``
956 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_1``
958 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_2``
960 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_3``
962 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_3B``
964 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_4``
966 * - ``V4L2_MPEG_VIDEO_MPEG4_LEVEL_5``
971 .. _v4l2-mpeg-video-h264-profile:
973 ``V4L2_CID_MPEG_VIDEO_H264_PROFILE``
976 enum v4l2_mpeg_video_h264_profile -
977 The profile information for H264. Applicable to the H264 encoder.
986 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE``
988 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_CONSTRAINED_BASELINE``
989 - Constrained Baseline profile
990 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_MAIN``
992 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED``
994 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH``
996 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10``
998 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422``
1000 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE``
1001 - High 444 Predictive profile
1002 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10_INTRA``
1003 - High 10 Intra profile
1004 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422_INTRA``
1005 - High 422 Intra profile
1006 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_INTRA``
1007 - High 444 Intra profile
1008 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_CAVLC_444_INTRA``
1009 - CAVLC 444 Intra profile
1010 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE``
1011 - Scalable Baseline profile
1012 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH``
1013 - Scalable High profile
1014 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH_INTRA``
1015 - Scalable High Intra profile
1016 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH``
1017 - Stereo High profile
1018 * - ``V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH``
1019 - Multiview High profile
1023 .. _v4l2-mpeg-video-mpeg4-profile:
1025 ``V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE``
1028 enum v4l2_mpeg_video_mpeg4_profile -
1029 The profile information for MPEG4. Applicable to the MPEG4 encoder.
1030 Possible values are:
1038 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_SIMPLE``
1040 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_ADVANCED_SIMPLE``
1041 - Advanced Simple profile
1042 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_CORE``
1044 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_SIMPLE_SCALABLE``
1045 - Simple Scalable profile
1046 * - ``V4L2_MPEG_VIDEO_MPEG4_PROFILE_ADVANCED_CODING_EFFICIENCY``
1051 ``V4L2_CID_MPEG_VIDEO_MAX_REF_PIC (integer)``
1052 The maximum number of reference pictures used for encoding.
1053 Applicable to the encoder.
1055 .. _v4l2-mpeg-video-multi-slice-mode:
1057 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE``
1060 enum v4l2_mpeg_video_multi_slice_mode -
1061 Determines how the encoder should handle division of frame into
1062 slices. Applicable to the encoder. Possible values are:
1066 .. tabularcolumns:: |p{8.7cm}|p{8.8cm}|
1072 * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_SINGLE``
1073 - Single slice per frame.
1074 * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``
1075 - Multiple slices with set maximum number of macroblocks per slice.
1076 * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``
1077 - Multiple slice with set maximum size in bytes per slice.
1081 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB (integer)``
1082 The maximum number of macroblocks in a slice. Used when
1083 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1084 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``. Applicable to the
1087 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES (integer)``
1088 The maximum size of a slice in bytes. Used when
1089 ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
1090 ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``. Applicable to the
1093 .. _v4l2-mpeg-video-h264-loop-filter-mode:
1095 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_MODE``
1098 enum v4l2_mpeg_video_h264_loop_filter_mode -
1099 Loop filter mode for H264 encoder. Possible values are:
1103 .. tabularcolumns:: |p{14.0cm}|p{3.5cm}|
1109 * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_ENABLED``
1110 - Loop filter is enabled.
1111 * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED``
1112 - Loop filter is disabled.
1113 * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
1114 - Loop filter is disabled at the slice boundary.
1118 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)``
1119 Loop filter alpha coefficient, defined in the H264 standard.
1120 This value corresponds to the slice_alpha_c0_offset_div2 slice header
1121 field, and should be in the range of -6 to +6, inclusive. The actual alpha
1122 offset FilterOffsetA is twice this value.
1123 Applicable to the H264 encoder.
1125 ``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)``
1126 Loop filter beta coefficient, defined in the H264 standard.
1127 This corresponds to the slice_beta_offset_div2 slice header field, and
1128 should be in the range of -6 to +6, inclusive. The actual beta offset
1129 FilterOffsetB is twice this value.
1130 Applicable to the H264 encoder.
1132 .. _v4l2-mpeg-video-h264-entropy-mode:
1134 ``V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE``
1137 enum v4l2_mpeg_video_h264_entropy_mode -
1138 Entropy coding mode for H264 - CABAC/CAVALC. Applicable to the H264
1139 encoder. Possible values are:
1147 * - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CAVLC``
1148 - Use CAVLC entropy coding.
1149 * - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CABAC``
1150 - Use CABAC entropy coding.
1154 ``V4L2_CID_MPEG_VIDEO_H264_8X8_TRANSFORM (boolean)``
1155 Enable 8X8 transform for H264. Applicable to the H264 encoder.
1157 ``V4L2_CID_MPEG_VIDEO_CYCLIC_INTRA_REFRESH_MB (integer)``
1158 Cyclic intra macroblock refresh. This is the number of continuous
1159 macroblocks refreshed every frame. Each frame a successive set of
1160 macroblocks is refreshed until the cycle completes and starts from
1161 the top of the frame. Applicable to H264, H263 and MPEG4 encoder.
1163 ``V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE (boolean)``
1164 Frame level rate control enable. If this control is disabled then
1165 the quantization parameter for each frame type is constant and set
1166 with appropriate controls (e.g.
1167 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP``). If frame rate control is
1168 enabled then quantization parameter is adjusted to meet the chosen
1169 bitrate. Minimum and maximum value for the quantization parameter
1170 can be set with appropriate controls (e.g.
1171 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP``). Applicable to encoders.
1173 ``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE (boolean)``
1174 Macroblock level rate control enable. Applicable to the MPEG4 and
1177 ``V4L2_CID_MPEG_VIDEO_MPEG4_QPEL (boolean)``
1178 Quarter pixel motion estimation for MPEG4. Applicable to the MPEG4
1181 ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (integer)``
1182 Quantization parameter for an I frame for H263. Valid range: from 1
1185 ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP (integer)``
1186 Minimum quantization parameter for H263. Valid range: from 1 to 31.
1188 ``V4L2_CID_MPEG_VIDEO_H263_MAX_QP (integer)``
1189 Maximum quantization parameter for H263. Valid range: from 1 to 31.
1191 ``V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (integer)``
1192 Quantization parameter for an P frame for H263. Valid range: from 1
1195 ``V4L2_CID_MPEG_VIDEO_H263_B_FRAME_QP (integer)``
1196 Quantization parameter for an B frame for H263. Valid range: from 1
1199 ``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_QP (integer)``
1200 Quantization parameter for an I frame for H264. Valid range: from 0
1203 ``V4L2_CID_MPEG_VIDEO_H264_MIN_QP (integer)``
1204 Minimum quantization parameter for H264. Valid range: from 0 to 51.
1206 ``V4L2_CID_MPEG_VIDEO_H264_MAX_QP (integer)``
1207 Maximum quantization parameter for H264. Valid range: from 0 to 51.
1209 ``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP (integer)``
1210 Quantization parameter for an P frame for H264. Valid range: from 0
1213 ``V4L2_CID_MPEG_VIDEO_H264_B_FRAME_QP (integer)``
1214 Quantization parameter for an B frame for H264. Valid range: from 0
1217 ``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
1218 Quantization parameter for an I frame for MPEG4. Valid range: from 1
1221 ``V4L2_CID_MPEG_VIDEO_MPEG4_MIN_QP (integer)``
1222 Minimum quantization parameter for MPEG4. Valid range: from 1 to 31.
1224 ``V4L2_CID_MPEG_VIDEO_MPEG4_MAX_QP (integer)``
1225 Maximum quantization parameter for MPEG4. Valid range: from 1 to 31.
1227 ``V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (integer)``
1228 Quantization parameter for an P frame for MPEG4. Valid range: from 1
1231 ``V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (integer)``
1232 Quantization parameter for an B frame for MPEG4. Valid range: from 1
1235 ``V4L2_CID_MPEG_VIDEO_VBV_SIZE (integer)``
1236 The Video Buffer Verifier size in kilobytes, it is used as a
1237 limitation of frame skip. The VBV is defined in the standard as a
1238 mean to verify that the produced stream will be successfully
1239 decoded. The standard describes it as "Part of a hypothetical
1240 decoder that is conceptually connected to the output of the encoder.
1241 Its purpose is to provide a constraint on the variability of the
1242 data rate that an encoder or editing process may produce.".
1243 Applicable to the MPEG1, MPEG2, MPEG4 encoders.
1245 .. _v4l2-mpeg-video-vbv-delay:
1247 ``V4L2_CID_MPEG_VIDEO_VBV_DELAY (integer)``
1248 Sets the initial delay in milliseconds for VBV buffer control.
1250 .. _v4l2-mpeg-video-hor-search-range:
1252 ``V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (integer)``
1253 Horizontal search range defines maximum horizontal search area in
1254 pixels to search and match for the present Macroblock (MB) in the
1255 reference picture. This V4L2 control macro is used to set horizontal
1256 search range for motion estimation module in video encoder.
1258 .. _v4l2-mpeg-video-vert-search-range:
1260 ``V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (integer)``
1261 Vertical search range defines maximum vertical search area in pixels
1262 to search and match for the present Macroblock (MB) in the reference
1263 picture. This V4L2 control macro is used to set vertical search
1264 range for motion estimation module in video encoder.
1266 .. _v4l2-mpeg-video-force-key-frame:
1268 ``V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (button)``
1269 Force a key frame for the next queued buffer. Applicable to
1270 encoders. This is a general, codec-agnostic keyframe control.
1272 ``V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE (integer)``
1273 The Coded Picture Buffer size in kilobytes, it is used as a
1274 limitation of frame skip. The CPB is defined in the H264 standard as
1275 a mean to verify that the produced stream will be successfully
1276 decoded. Applicable to the H264 encoder.
1278 ``V4L2_CID_MPEG_VIDEO_H264_I_PERIOD (integer)``
1279 Period between I-frames in the open GOP for H264. In case of an open
1280 GOP this is the period between two I-frames. The period between IDR
1281 (Instantaneous Decoding Refresh) frames is taken from the GOP_SIZE
1282 control. An IDR frame, which stands for Instantaneous Decoding
1283 Refresh is an I-frame after which no prior frames are referenced.
1284 This means that a stream can be restarted from an IDR frame without
1285 the need to store or decode any previous frames. Applicable to the
1288 .. _v4l2-mpeg-video-header-mode:
1290 ``V4L2_CID_MPEG_VIDEO_HEADER_MODE``
1293 enum v4l2_mpeg_video_header_mode -
1294 Determines whether the header is returned as the first buffer or is
1295 it returned together with the first frame. Applicable to encoders.
1296 Possible values are:
1300 .. tabularcolumns:: |p{10.3cm}|p{7.2cm}|
1306 * - ``V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE``
1307 - The stream header is returned separately in the first buffer.
1308 * - ``V4L2_MPEG_VIDEO_HEADER_MODE_JOINED_WITH_1ST_FRAME``
1309 - The stream header is returned together with the first encoded
1314 ``V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (boolean)``
1315 Repeat the video sequence headers. Repeating these headers makes
1316 random access to the video stream easier. Applicable to the MPEG1, 2
1319 ``V4L2_CID_MPEG_VIDEO_DECODER_MPEG4_DEBLOCK_FILTER (boolean)``
1320 Enabled the deblocking post processing filter for MPEG4 decoder.
1321 Applicable to the MPEG4 decoder.
1323 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_RES (integer)``
1324 vop_time_increment_resolution value for MPEG4. Applicable to the
1327 ``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_INC (integer)``
1328 vop_time_increment value for MPEG4. Applicable to the MPEG4
1331 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FRAME_PACKING (boolean)``
1332 Enable generation of frame packing supplemental enhancement
1333 information in the encoded bitstream. The frame packing SEI message
1334 contains the arrangement of L and R planes for 3D viewing.
1335 Applicable to the H264 encoder.
1337 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_CURRENT_FRAME_0 (boolean)``
1338 Sets current frame as frame0 in frame packing SEI. Applicable to the
1341 .. _v4l2-mpeg-video-h264-sei-fp-arrangement-type:
1343 ``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE``
1346 enum v4l2_mpeg_video_h264_sei_fp_arrangement_type -
1347 Frame packing arrangement type for H264 SEI. Applicable to the H264
1348 encoder. Possible values are:
1350 .. tabularcolumns:: |p{12cm}|p{5.5cm}|
1356 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_CHEKERBOARD``
1357 - Pixels are alternatively from L and R.
1358 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_COLUMN``
1359 - L and R are interlaced by column.
1360 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_ROW``
1361 - L and R are interlaced by row.
1362 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_SIDE_BY_SIDE``
1363 - L is on the left, R on the right.
1364 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TOP_BOTTOM``
1365 - L is on top, R on bottom.
1366 * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TEMPORAL``
1367 - One view per frame.
1371 ``V4L2_CID_MPEG_VIDEO_H264_FMO (boolean)``
1372 Enables flexible macroblock ordering in the encoded bitstream. It is
1373 a technique used for restructuring the ordering of macroblocks in
1374 pictures. Applicable to the H264 encoder.
1376 .. _v4l2-mpeg-video-h264-fmo-map-type:
1378 ``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE``
1381 enum v4l2_mpeg_video_h264_fmo_map_type -
1382 When using FMO, the map type divides the image in different scan
1383 patterns of macroblocks. Applicable to the H264 encoder. Possible
1386 .. tabularcolumns:: |p{12.5cm}|p{5.0cm}|
1392 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_INTERLEAVED_SLICES``
1393 - Slices are interleaved one after other with macroblocks in run
1395 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_SCATTERED_SLICES``
1396 - Scatters the macroblocks based on a mathematical function known to
1397 both encoder and decoder.
1398 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_FOREGROUND_WITH_LEFT_OVER``
1399 - Macroblocks arranged in rectangular areas or regions of interest.
1400 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_BOX_OUT``
1401 - Slice groups grow in a cyclic way from centre to outwards.
1402 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_RASTER_SCAN``
1403 - Slice groups grow in raster scan pattern from left to right.
1404 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_WIPE_SCAN``
1405 - Slice groups grow in wipe scan pattern from top to bottom.
1406 * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_EXPLICIT``
1407 - User defined map type.
1411 ``V4L2_CID_MPEG_VIDEO_H264_FMO_SLICE_GROUP (integer)``
1412 Number of slice groups in FMO. Applicable to the H264 encoder.
1414 .. _v4l2-mpeg-video-h264-fmo-change-direction:
1416 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_DIRECTION``
1419 enum v4l2_mpeg_video_h264_fmo_change_dir -
1420 Specifies a direction of the slice group change for raster and wipe
1421 maps. Applicable to the H264 encoder. Possible values are:
1429 * - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_RIGHT``
1430 - Raster scan or wipe right.
1431 * - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_LEFT``
1432 - Reverse raster scan or wipe left.
1436 ``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_RATE (integer)``
1437 Specifies the size of the first slice group for raster and wipe map.
1438 Applicable to the H264 encoder.
1440 ``V4L2_CID_MPEG_VIDEO_H264_FMO_RUN_LENGTH (integer)``
1441 Specifies the number of consecutive macroblocks for the interleaved
1442 map. Applicable to the H264 encoder.
1444 ``V4L2_CID_MPEG_VIDEO_H264_ASO (boolean)``
1445 Enables arbitrary slice ordering in encoded bitstream. Applicable to
1448 ``V4L2_CID_MPEG_VIDEO_H264_ASO_SLICE_ORDER (integer)``
1449 Specifies the slice order in ASO. Applicable to the H264 encoder.
1450 The supplied 32-bit integer is interpreted as follows (bit 0 = least
1462 - Slice position or order
1466 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING (boolean)``
1467 Enables H264 hierarchical coding. Applicable to the H264 encoder.
1469 .. _v4l2-mpeg-video-h264-hierarchical-coding-type:
1471 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_TYPE``
1474 enum v4l2_mpeg_video_h264_hierarchical_coding_type -
1475 Specifies the hierarchical coding type. Applicable to the H264
1476 encoder. Possible values are:
1484 * - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_B``
1485 - Hierarchical B coding.
1486 * - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_P``
1487 - Hierarchical P coding.
1491 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (integer)``
1492 Specifies the number of hierarchical coding layers. Applicable to
1495 ``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (integer)``
1496 Specifies a user defined QP for each layer. Applicable to the H264
1497 encoder. The supplied 32-bit integer is interpreted as follows (bit
1498 0 = least significant bit):
1513 .. _v4l2-mpeg-mpeg2:
1515 ``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS (struct)``
1516 Specifies the slice parameters (as extracted from the bitstream) for the
1517 associated MPEG-2 slice data. This includes the necessary parameters for
1518 configuring a stateless hardware decoding pipeline for MPEG-2.
1519 The bitstream parameters are defined according to :ref:`mpeg2part2`.
1523 This compound control is not yet part of the public kernel API and
1524 it is expected to change.
1526 .. c:type:: v4l2_ctrl_mpeg2_slice_params
1528 .. cssclass:: longtable
1530 .. flat-table:: struct v4l2_ctrl_mpeg2_slice_params
1537 - Size (in bits) of the current slice data.
1539 - ``data_bit_offset``
1540 - Offset (in bits) to the video data in the current slice data.
1541 * - struct :c:type:`v4l2_mpeg2_sequence`
1543 - Structure with MPEG-2 sequence metadata, merging relevant fields from
1544 the sequence header and sequence extension parts of the bitstream.
1545 * - struct :c:type:`v4l2_mpeg2_picture`
1547 - Structure with MPEG-2 picture metadata, merging relevant fields from
1548 the picture header and picture coding extension parts of the bitstream.
1550 - ``quantiser_scale_code``
1551 - Code used to determine the quantization scale to use for the IDCT.
1553 - ``backward_ref_index``
1554 - Index for the V4L2 buffer to use as backward reference, used with
1555 B-coded and P-coded frames.
1557 - ``forward_ref_index``
1558 - Index for the V4L2 buffer to use as forward reference, used with
1561 .. c:type:: v4l2_mpeg2_sequence
1563 .. cssclass:: longtable
1565 .. flat-table:: struct v4l2_mpeg2_sequence
1571 - ``horizontal_size``
1572 - The width of the displayable part of the frame's luminance component.
1575 - The height of the displayable part of the frame's luminance component.
1577 - ``vbv_buffer_size``
1578 - Used to calculate the required size of the video buffering verifier,
1579 defined (in bits) as: 16 * 1024 * vbv_buffer_size.
1581 - ``profile_and_level_indication``
1582 - The current profile and level indication as extracted from the
1585 - ``progressive_sequence``
1586 - Indication that all the frames for the sequence are progressive instead
1590 - The chrominance sub-sampling format (1: 4:2:0, 2: 4:2:2, 3: 4:4:4).
1592 .. c:type:: v4l2_mpeg2_picture
1594 .. cssclass:: longtable
1596 .. flat-table:: struct v4l2_mpeg2_picture
1602 - ``picture_coding_type``
1603 - Picture coding type for the frame covered by the current slice
1604 (V4L2_MPEG2_PICTURE_CODING_TYPE_I, V4L2_MPEG2_PICTURE_CODING_TYPE_P or
1605 V4L2_MPEG2_PICTURE_CODING_TYPE_B).
1608 - Motion vector codes.
1610 - ``intra_dc_precision``
1611 - Precision of Discrete Cosine transform (0: 8 bits precision,
1612 1: 9 bits precision, 2: 10 bits precision, 3: 11 bits precision).
1614 - ``picture_structure``
1615 - Picture structure (1: interlaced top field, 2: interlaced bottom field,
1616 3: progressive frame).
1618 - ``top_field_first``
1619 - If set to 1 and interlaced stream, top field is output first.
1621 - ``frame_pred_frame_dct``
1622 - If set to 1, only frame-DCT and frame prediction are used.
1624 - ``concealment_motion_vectors``
1625 - If set to 1, motion vectors are coded for intra macroblocks.
1628 - This flag affects the inverse quantization process.
1630 - ``intra_vlc_format``
1631 - This flag affects the decoding of transform coefficient data.
1633 - ``alternate_scan``
1634 - This flag affects the decoding of transform coefficient data.
1636 - ``repeat_first_field``
1637 - This flag affects the decoding process of progressive frames.
1639 - ``progressive_frame``
1640 - Indicates whether the current frame is progressive.
1642 ``V4L2_CID_MPEG_VIDEO_MPEG2_QUANTIZATION (struct)``
1643 Specifies quantization matrices (as extracted from the bitstream) for the
1644 associated MPEG-2 slice data.
1648 This compound control is not yet part of the public kernel API and
1649 it is expected to change.
1651 .. c:type:: v4l2_ctrl_mpeg2_quantization
1653 .. cssclass:: longtable
1655 .. flat-table:: struct v4l2_ctrl_mpeg2_quantization
1661 - ``load_intra_quantiser_matrix``
1662 - One bit to indicate whether to load the ``intra_quantiser_matrix`` data.
1664 - ``load_non_intra_quantiser_matrix``
1665 - One bit to indicate whether to load the ``non_intra_quantiser_matrix``
1668 - ``load_chroma_intra_quantiser_matrix``
1669 - One bit to indicate whether to load the
1670 ``chroma_intra_quantiser_matrix`` data, only relevant for non-4:2:0 YUV
1673 - ``load_chroma_non_intra_quantiser_matrix``
1674 - One bit to indicate whether to load the
1675 ``chroma_non_intra_quantiser_matrix`` data, only relevant for non-4:2:0
1678 - ``intra_quantiser_matrix[64]``
1679 - The quantization matrix coefficients for intra-coded frames, in zigzag
1680 scanning order. It is relevant for both luma and chroma components,
1681 although it can be superseded by the chroma-specific matrix for
1682 non-4:2:0 YUV formats.
1684 - ``non_intra_quantiser_matrix[64]``
1685 - The quantization matrix coefficients for non-intra-coded frames, in
1686 zigzag scanning order. It is relevant for both luma and chroma
1687 components, although it can be superseded by the chroma-specific matrix
1688 for non-4:2:0 YUV formats.
1690 - ``chroma_intra_quantiser_matrix[64]``
1691 - The quantization matrix coefficients for the chominance component of
1692 intra-coded frames, in zigzag scanning order. Only relevant for
1693 non-4:2:0 YUV formats.
1695 - ``chroma_non_intra_quantiser_matrix[64]``
1696 - The quantization matrix coefficients for the chrominance component of
1697 non-intra-coded frames, in zigzag scanning order. Only relevant for
1698 non-4:2:0 YUV formats.
1700 MFC 5.1 MPEG Controls
1701 ---------------------
1703 The following MPEG class controls deal with MPEG decoding and encoding
1704 settings that are specific to the Multi Format Codec 5.1 device present
1705 in the S5P family of SoCs by Samsung.
1708 .. _mfc51-control-id:
1713 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY_ENABLE (boolean)``
1714 If the display delay is enabled then the decoder is forced to return
1715 a CAPTURE buffer (decoded frame) after processing a certain number
1716 of OUTPUT buffers. The delay can be set through
1717 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY``. This
1718 feature can be used for example for generating thumbnails of videos.
1719 Applicable to the H264 decoder.
1721 ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY (integer)``
1722 Display delay value for H264 decoder. The decoder is forced to
1723 return a decoded frame after the set 'display delay' number of
1724 frames. If this number is low it may result in frames returned out
1725 of dispaly order, in addition the hardware may still be using the
1726 returned buffer as a reference picture for subsequent frames.
1728 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P (integer)``
1729 The number of reference pictures used for encoding a P picture.
1730 Applicable to the H264 encoder.
1732 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING (boolean)``
1733 Padding enable in the encoder - use a color instead of repeating
1734 border pixels. Applicable to encoders.
1736 ``V4L2_CID_MPEG_MFC51_VIDEO_PADDING_YUV (integer)``
1737 Padding color in the encoder. Applicable to encoders. The supplied
1738 32-bit integer is interpreted as follows (bit 0 = least significant
1748 - V chrominance information
1750 - U chrominance information
1752 - Y luminance information
1758 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
1759 Reaction coefficient for MFC rate control. Applicable to encoders.
1763 #. Valid only when the frame level RC is enabled.
1765 #. For tight CBR, this field must be small (ex. 2 ~ 10). For
1766 VBR, this field must be large (ex. 100 ~ 1000).
1768 #. It is not recommended to use the greater number than
1769 FRAME_RATE * (10^9 / BIT_RATE).
1771 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
1772 Adaptive rate control for dark region. Valid only when H.264 and
1773 macroblock level RC is enabled
1774 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1777 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_SMOOTH (boolean)``
1778 Adaptive rate control for smooth region. Valid only when H.264 and
1779 macroblock level RC is enabled
1780 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1783 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC (boolean)``
1784 Adaptive rate control for static region. Valid only when H.264 and
1785 macroblock level RC is enabled
1786 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1789 ``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_ACTIVITY (boolean)``
1790 Adaptive rate control for activity region. Valid only when H.264 and
1791 macroblock level RC is enabled
1792 (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
1795 .. _v4l2-mpeg-mfc51-video-frame-skip-mode:
1797 ``V4L2_CID_MPEG_MFC51_VIDEO_FRAME_SKIP_MODE``
1800 enum v4l2_mpeg_mfc51_video_frame_skip_mode -
1801 Indicates in what conditions the encoder should skip frames. If
1802 encoding a frame would cause the encoded stream to be larger then a
1803 chosen data limit then the frame will be skipped. Possible values
1807 .. tabularcolumns:: |p{9.0cm}|p{8.5cm}|
1813 * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_DISABLED``
1814 - Frame skip mode is disabled.
1815 * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_LEVEL_LIMIT``
1816 - Frame skip mode enabled and buffer limit is set by the chosen
1817 level and is defined by the standard.
1818 * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_BUF_LIMIT``
1819 - Frame skip mode enabled and buffer limit is set by the VBV
1820 (MPEG1/2/4) or CPB (H264) buffer size control.
1824 ``V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT (integer)``
1825 Enable rate-control with fixed target bit. If this setting is
1826 enabled, then the rate control logic of the encoder will calculate
1827 the average bitrate for a GOP and keep it below or equal the set
1828 bitrate target. Otherwise the rate control logic calculates the
1829 overall average bitrate for the stream and keeps it below or equal
1830 to the set bitrate. In the first case the average bitrate for the
1831 whole stream will be smaller then the set bitrate. This is caused
1832 because the average is calculated for smaller number of frames, on
1833 the other hand enabling this setting will ensure that the stream
1834 will meet tight bandwidth constraints. Applicable to encoders.
1836 .. _v4l2-mpeg-mfc51-video-force-frame-type:
1838 ``V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE``
1841 enum v4l2_mpeg_mfc51_video_force_frame_type -
1842 Force a frame type for the next queued buffer. Applicable to
1843 encoders. Possible values are:
1851 * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_DISABLED``
1852 - Forcing a specific frame type disabled.
1853 * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_I_FRAME``
1855 * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_NOT_CODED``
1856 - Force a non-coded frame.
1861 CX2341x MPEG Controls
1862 ---------------------
1864 The following MPEG class controls deal with MPEG encoding settings that
1865 are specific to the Conexant CX23415 and CX23416 MPEG encoding chips.
1868 .. _cx2341x-control-id:
1873 .. _v4l2-mpeg-cx2341x-video-spatial-filter-mode:
1875 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE``
1878 enum v4l2_mpeg_cx2341x_video_spatial_filter_mode -
1879 Sets the Spatial Filter mode (default ``MANUAL``). Possible values
1888 * - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL``
1889 - Choose the filter manually
1890 * - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO``
1891 - Choose the filter automatically
1895 ``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER (integer (0-15))``
1896 The setting for the Spatial Filter. 0 = off, 15 = maximum. (Default
1899 .. _luma-spatial-filter-type:
1901 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE``
1904 enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type -
1905 Select the algorithm to use for the Luma Spatial Filter (default
1906 ``1D_HOR``). Possible values:
1910 .. tabularcolumns:: |p{14.5cm}|p{3.0cm}|
1916 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF``
1918 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR``
1919 - One-dimensional horizontal
1920 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT``
1921 - One-dimensional vertical
1922 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE``
1923 - Two-dimensional separable
1924 * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE``
1925 - Two-dimensional symmetrical non-separable
1929 .. _chroma-spatial-filter-type:
1931 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE``
1934 enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type -
1935 Select the algorithm for the Chroma Spatial Filter (default
1936 ``1D_HOR``). Possible values are:
1944 * - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF``
1946 * - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR``
1947 - One-dimensional horizontal
1951 .. _v4l2-mpeg-cx2341x-video-temporal-filter-mode:
1953 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE``
1956 enum v4l2_mpeg_cx2341x_video_temporal_filter_mode -
1957 Sets the Temporal Filter mode (default ``MANUAL``). Possible values
1966 * - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL``
1967 - Choose the filter manually
1968 * - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO``
1969 - Choose the filter automatically
1973 ``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER (integer (0-31))``
1974 The setting for the Temporal Filter. 0 = off, 31 = maximum. (Default
1975 is 8 for full-scale capturing and 0 for scaled capturing.)
1977 .. _v4l2-mpeg-cx2341x-video-median-filter-type:
1979 ``V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE``
1982 enum v4l2_mpeg_cx2341x_video_median_filter_type -
1983 Median Filter Type (default ``OFF``). Possible values are:
1991 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF``
1993 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR``
1995 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT``
1997 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT``
1998 - Horizontal and vertical filter
1999 * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG``
2004 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
2005 Threshold above which the luminance median filter is enabled
2008 ``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP (integer (0-255))``
2009 Threshold below which the luminance median filter is enabled
2012 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
2013 Threshold above which the chroma median filter is enabled (default
2016 ``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP (integer (0-255))``
2017 Threshold below which the chroma median filter is enabled (default
2020 ``V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS (boolean)``
2021 The CX2341X MPEG encoder can insert one empty MPEG-2 PES packet into
2022 the stream between every four video frames. The packet size is 2048
2023 bytes, including the packet_start_code_prefix and stream_id
2024 fields. The stream_id is 0xBF (private stream 2). The payload
2025 consists of 0x00 bytes, to be filled in by the application. 0 = do
2026 not insert, 1 = insert packets.
2029 VPX Control Reference
2030 ---------------------
2032 The VPX controls include controls for encoding parameters of VPx video
2041 .. _v4l2-vpx-num-partitions:
2043 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS``
2046 enum v4l2_vp8_num_partitions -
2047 The number of token partitions to use in VP8 encoder. Possible
2056 * - ``V4L2_CID_MPEG_VIDEO_VPX_1_PARTITION``
2057 - 1 coefficient partition
2058 * - ``V4L2_CID_MPEG_VIDEO_VPX_2_PARTITIONS``
2059 - 2 coefficient partitions
2060 * - ``V4L2_CID_MPEG_VIDEO_VPX_4_PARTITIONS``
2061 - 4 coefficient partitions
2062 * - ``V4L2_CID_MPEG_VIDEO_VPX_8_PARTITIONS``
2063 - 8 coefficient partitions
2067 ``V4L2_CID_MPEG_VIDEO_VPX_IMD_DISABLE_4X4 (boolean)``
2068 Setting this prevents intra 4x4 mode in the intra mode decision.
2070 .. _v4l2-vpx-num-ref-frames:
2072 ``V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES``
2075 enum v4l2_vp8_num_ref_frames -
2076 The number of reference pictures for encoding P frames. Possible
2079 .. tabularcolumns:: |p{7.9cm}|p{9.6cm}|
2085 * - ``V4L2_CID_MPEG_VIDEO_VPX_1_REF_FRAME``
2086 - Last encoded frame will be searched
2087 * - ``V4L2_CID_MPEG_VIDEO_VPX_2_REF_FRAME``
2088 - Two frames will be searched among the last encoded frame, the
2089 golden frame and the alternate reference (altref) frame. The
2090 encoder implementation will decide which two are chosen.
2091 * - ``V4L2_CID_MPEG_VIDEO_VPX_3_REF_FRAME``
2092 - The last encoded frame, the golden frame and the altref frame will
2097 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_LEVEL (integer)``
2098 Indicates the loop filter level. The adjustment of the loop filter
2099 level is done via a delta value against a baseline loop filter
2102 ``V4L2_CID_MPEG_VIDEO_VPX_FILTER_SHARPNESS (integer)``
2103 This parameter affects the loop filter. Anything above zero weakens
2104 the deblocking effect on the loop filter.
2106 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD (integer)``
2107 Sets the refresh period for the golden frame. The period is defined
2108 in number of frames. For a value of 'n', every nth frame starting
2109 from the first key frame will be taken as a golden frame. For eg.
2110 for encoding sequence of 0, 1, 2, 3, 4, 5, 6, 7 where the golden
2111 frame refresh period is set as 4, the frames 0, 4, 8 etc will be
2112 taken as the golden frames as frame 0 is always a key frame.
2114 .. _v4l2-vpx-golden-frame-sel:
2116 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_SEL``
2119 enum v4l2_vp8_golden_frame_sel -
2120 Selects the golden frame for encoding. Possible values are:
2126 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2132 * - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_PREV``
2133 - Use the (n-2)th frame as a golden frame, current frame index being
2135 * - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_REF_PERIOD``
2136 - Use the previous specific frame indicated by
2137 ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD`` as a
2145 ``V4L2_CID_MPEG_VIDEO_VPX_MIN_QP (integer)``
2146 Minimum quantization parameter for VP8.
2148 ``V4L2_CID_MPEG_VIDEO_VPX_MAX_QP (integer)``
2149 Maximum quantization parameter for VP8.
2151 ``V4L2_CID_MPEG_VIDEO_VPX_I_FRAME_QP (integer)``
2152 Quantization parameter for an I frame for VP8.
2154 ``V4L2_CID_MPEG_VIDEO_VPX_P_FRAME_QP (integer)``
2155 Quantization parameter for a P frame for VP8.
2157 .. _v4l2-mpeg-video-vp8-profile:
2159 ``V4L2_CID_MPEG_VIDEO_VP8_PROFILE``
2162 enum v4l2_mpeg_video_vp8_profile -
2163 This control allows selecting the profile for VP8 encoder.
2164 This is also used to enumerate supported profiles by VP8 encoder or decoder.
2165 Possible values are:
2171 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_0``
2173 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_1``
2175 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_2``
2177 * - ``V4L2_MPEG_VIDEO_VP8_PROFILE_3``
2180 .. _v4l2-mpeg-video-vp9-profile:
2182 ``V4L2_CID_MPEG_VIDEO_VP9_PROFILE``
2185 enum v4l2_mpeg_video_vp9_profile -
2186 This control allows selecting the profile for VP9 encoder.
2187 This is also used to enumerate supported profiles by VP9 encoder or decoder.
2188 Possible values are:
2194 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_0``
2196 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_1``
2198 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_2``
2200 * - ``V4L2_MPEG_VIDEO_VP9_PROFILE_3``
2204 High Efficiency Video Coding (HEVC/H.265) Control Reference
2205 -----------------------------------------------------------
2207 The HEVC/H.265 controls include controls for encoding parameters of HEVC/H.265
2211 .. _hevc-control-id:
2213 HEVC/H.265 Control IDs
2214 ^^^^^^^^^^^^^^^^^^^^^^
2216 ``V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP (integer)``
2217 Minimum quantization parameter for HEVC.
2218 Valid range: from 0 to 51.
2220 ``V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP (integer)``
2221 Maximum quantization parameter for HEVC.
2222 Valid range: from 0 to 51.
2224 ``V4L2_CID_MPEG_VIDEO_HEVC_I_FRAME_QP (integer)``
2225 Quantization parameter for an I frame for HEVC.
2226 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2227 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2229 ``V4L2_CID_MPEG_VIDEO_HEVC_P_FRAME_QP (integer)``
2230 Quantization parameter for a P frame for HEVC.
2231 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2232 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2234 ``V4L2_CID_MPEG_VIDEO_HEVC_B_FRAME_QP (integer)``
2235 Quantization parameter for a B frame for HEVC.
2236 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2237 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2239 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_QP (boolean)``
2240 HIERARCHICAL_QP allows the host to specify the quantization parameter
2241 values for each temporal layer through HIERARCHICAL_QP_LAYER. This is
2242 valid only if HIERARCHICAL_CODING_LAYER is greater than 1. Setting the
2243 control value to 1 enables setting of the QP values for the layers.
2245 .. _v4l2-hevc-hier-coding-type:
2247 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_TYPE``
2250 enum v4l2_mpeg_video_hevc_hier_coding_type -
2251 Selects the hierarchical coding type for encoding. Possible values are:
2257 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2263 * - ``V4L2_MPEG_VIDEO_HEVC_HIERARCHICAL_CODING_B``
2264 - Use the B frame for hierarchical coding.
2265 * - ``V4L2_MPEG_VIDEO_HEVC_HIERARCHICAL_CODING_P``
2266 - Use the P frame for hierarchical coding.
2273 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_LAYER (integer)``
2274 Selects the hierarchical coding layer. In normal encoding
2275 (non-hierarchial coding), it should be zero. Possible values are [0, 6].
2276 0 indicates HIERARCHICAL CODING LAYER 0, 1 indicates HIERARCHICAL CODING
2279 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L0_QP (integer)``
2280 Indicates quantization parameter for hierarchical coding layer 0.
2281 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2282 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2284 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L1_QP (integer)``
2285 Indicates quantization parameter for hierarchical coding layer 1.
2286 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2287 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2289 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L2_QP (integer)``
2290 Indicates quantization parameter for hierarchical coding layer 2.
2291 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2292 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2294 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L3_QP (integer)``
2295 Indicates quantization parameter for hierarchical coding layer 3.
2296 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2297 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2299 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L4_QP (integer)``
2300 Indicates quantization parameter for hierarchical coding layer 4.
2301 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2302 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2304 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L5_QP (integer)``
2305 Indicates quantization parameter for hierarchical coding layer 5.
2306 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2307 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2309 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_QP (integer)``
2310 Indicates quantization parameter for hierarchical coding layer 6.
2311 Valid range: [V4L2_CID_MPEG_VIDEO_HEVC_MIN_QP,
2312 V4L2_CID_MPEG_VIDEO_HEVC_MAX_QP].
2314 .. _v4l2-hevc-profile:
2316 ``V4L2_CID_MPEG_VIDEO_HEVC_PROFILE``
2319 enum v4l2_mpeg_video_hevc_profile -
2320 Select the desired profile for HEVC encoder.
2326 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2332 * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN``
2334 * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN_STILL_PICTURE``
2335 - Main still picture profile.
2336 * - ``V4L2_MPEG_VIDEO_HEVC_PROFILE_MAIN_10``
2344 .. _v4l2-hevc-level:
2346 ``V4L2_CID_MPEG_VIDEO_HEVC_LEVEL``
2349 enum v4l2_mpeg_video_hevc_level -
2350 Selects the desired level for HEVC encoder.
2356 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2362 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_1``
2364 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_2``
2366 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_2_1``
2368 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_3``
2370 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_3_1``
2372 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_4``
2374 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_4_1``
2376 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5``
2378 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5_1``
2380 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_5_2``
2382 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6``
2384 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6_1``
2386 * - ``V4L2_MPEG_VIDEO_HEVC_LEVEL_6_2``
2394 ``V4L2_CID_MPEG_VIDEO_HEVC_FRAME_RATE_RESOLUTION (integer)``
2395 Indicates the number of evenly spaced subintervals, called ticks, within
2396 one second. This is a 16 bit unsigned integer and has a maximum value up to
2397 0xffff and a minimum value of 1.
2401 ``V4L2_CID_MPEG_VIDEO_HEVC_TIER``
2404 enum v4l2_mpeg_video_hevc_tier -
2405 TIER_FLAG specifies tiers information of the HEVC encoded picture. Tier
2406 were made to deal with applications that differ in terms of maximum bit
2407 rate. Setting the flag to 0 selects HEVC tier as Main tier and setting
2408 this flag to 1 indicates High tier. High tier is for applications requiring
2415 .. tabularcolumns:: |p{9.0cm}|p{8.0cm}|
2421 * - ``V4L2_MPEG_VIDEO_HEVC_TIER_MAIN``
2423 * - ``V4L2_MPEG_VIDEO_HEVC_TIER_HIGH``
2431 ``V4L2_CID_MPEG_VIDEO_HEVC_MAX_PARTITION_DEPTH (integer)``
2432 Selects HEVC maximum coding unit depth.
2434 .. _v4l2-hevc-loop-filter-mode:
2436 ``V4L2_CID_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE``
2439 enum v4l2_mpeg_video_hevc_loop_filter_mode -
2440 Loop filter mode for HEVC encoder. Possible values are:
2446 .. tabularcolumns:: |p{10.7cm}|p{6.3cm}|
2452 * - ``V4L2_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE_DISABLED``
2453 - Loop filter is disabled.
2454 * - ``V4L2_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE_ENABLED``
2455 - Loop filter is enabled.
2456 * - ``V4L2_MPEG_VIDEO_HEVC_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
2457 - Loop filter is disabled at the slice boundary.
2464 ``V4L2_CID_MPEG_VIDEO_HEVC_LF_BETA_OFFSET_DIV2 (integer)``
2465 Selects HEVC loop filter beta offset. The valid range is [-6, +6].
2467 ``V4L2_CID_MPEG_VIDEO_HEVC_LF_TC_OFFSET_DIV2 (integer)``
2468 Selects HEVC loop filter tc offset. The valid range is [-6, +6].
2470 .. _v4l2-hevc-refresh-type:
2472 ``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_TYPE``
2475 enum v4l2_mpeg_video_hevc_hier_refresh_type -
2476 Selects refresh type for HEVC encoder.
2477 Host has to specify the period into
2478 V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_PERIOD.
2484 .. tabularcolumns:: |p{8.0cm}|p{9.0cm}|
2490 * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_NONE``
2491 - Use the B frame for hierarchical coding.
2492 * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_CRA``
2493 - Use CRA (Clean Random Access Unit) picture encoding.
2494 * - ``V4L2_MPEG_VIDEO_HEVC_REFRESH_IDR``
2495 - Use IDR (Instantaneous Decoding Refresh) picture encoding.
2502 ``V4L2_CID_MPEG_VIDEO_HEVC_REFRESH_PERIOD (integer)``
2503 Selects the refresh period for HEVC encoder.
2504 This specifies the number of I pictures between two CRA/IDR pictures.
2505 This is valid only if REFRESH_TYPE is not 0.
2507 ``V4L2_CID_MPEG_VIDEO_HEVC_LOSSLESS_CU (boolean)``
2508 Indicates HEVC lossless encoding. Setting it to 0 disables lossless
2509 encoding. Setting it to 1 enables lossless encoding.
2511 ``V4L2_CID_MPEG_VIDEO_HEVC_CONST_INTRA_PRED (boolean)``
2512 Indicates constant intra prediction for HEVC encoder. Specifies the
2513 constrained intra prediction in which intra largest coding unit (LCU)
2514 prediction is performed by using residual data and decoded samples of
2515 neighboring intra LCU only. Setting the value to 1 enables constant intra
2516 prediction and setting the value to 0 disables constant intra prediction.
2518 ``V4L2_CID_MPEG_VIDEO_HEVC_WAVEFRONT (boolean)``
2519 Indicates wavefront parallel processing for HEVC encoder. Setting it to 0
2520 disables the feature and setting it to 1 enables the wavefront parallel
2523 ``V4L2_CID_MPEG_VIDEO_HEVC_GENERAL_PB (boolean)``
2524 Setting the value to 1 enables combination of P and B frame for HEVC
2527 ``V4L2_CID_MPEG_VIDEO_HEVC_TEMPORAL_ID (boolean)``
2528 Indicates temporal identifier for HEVC encoder which is enabled by
2529 setting the value to 1.
2531 ``V4L2_CID_MPEG_VIDEO_HEVC_STRONG_SMOOTHING (boolean)``
2532 Indicates bi-linear interpolation is conditionally used in the intra
2533 prediction filtering process in the CVS when set to 1. Indicates bi-linear
2534 interpolation is not used in the CVS when set to 0.
2536 ``V4L2_CID_MPEG_VIDEO_HEVC_MAX_NUM_MERGE_MV_MINUS1 (integer)``
2537 Indicates maximum number of merge candidate motion vectors.
2538 Values are from 0 to 4.
2540 ``V4L2_CID_MPEG_VIDEO_HEVC_TMV_PREDICTION (boolean)``
2541 Indicates temporal motion vector prediction for HEVC encoder. Setting it to
2542 1 enables the prediction. Setting it to 0 disables the prediction.
2544 ``V4L2_CID_MPEG_VIDEO_HEVC_WITHOUT_STARTCODE (boolean)``
2545 Specifies if HEVC generates a stream with a size of the length field
2546 instead of start code pattern. The size of the length field is configurable
2547 through the V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD control. Setting
2548 the value to 0 disables encoding without startcode pattern. Setting the
2549 value to 1 will enables encoding without startcode pattern.
2551 .. _v4l2-hevc-size-of-length-field:
2553 ``V4L2_CID_MPEG_VIDEO_HEVC_SIZE_OF_LENGTH_FIELD``
2556 enum v4l2_mpeg_video_hevc_size_of_length_field -
2557 Indicates the size of length field.
2558 This is valid when encoding WITHOUT_STARTCODE_ENABLE is enabled.
2564 .. tabularcolumns:: |p{6.0cm}|p{11.0cm}|
2570 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_0``
2571 - Generate start code pattern (Normal).
2572 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_1``
2573 - Generate size of length field instead of start code pattern and length is 1.
2574 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_2``
2575 - Generate size of length field instead of start code pattern and length is 2.
2576 * - ``V4L2_MPEG_VIDEO_HEVC_SIZE_4``
2577 - Generate size of length field instead of start code pattern and length is 4.
2583 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L0_BR (integer)``
2584 Indicates bit rate for hierarchical coding layer 0 for HEVC encoder.
2586 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L1_BR (integer)``
2587 Indicates bit rate for hierarchical coding layer 1 for HEVC encoder.
2589 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L2_BR (integer)``
2590 Indicates bit rate for hierarchical coding layer 2 for HEVC encoder.
2592 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L3_BR (integer)``
2593 Indicates bit rate for hierarchical coding layer 3 for HEVC encoder.
2595 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L4_BR (integer)``
2596 Indicates bit rate for hierarchical coding layer 4 for HEVC encoder.
2598 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L5_BR (integer)``
2599 Indicates bit rate for hierarchical coding layer 5 for HEVC encoder.
2601 ``V4L2_CID_MPEG_VIDEO_HEVC_HIER_CODING_L6_BR (integer)``
2602 Indicates bit rate for hierarchical coding layer 6 for HEVC encoder.
2604 ``V4L2_CID_MPEG_VIDEO_REF_NUMBER_FOR_PFRAMES (integer)``
2605 Selects number of P reference pictures required for HEVC encoder.
2606 P-Frame can use 1 or 2 frames for reference.
2608 ``V4L2_CID_MPEG_VIDEO_PREPEND_SPSPPS_TO_IDR (integer)``
2609 Indicates whether to generate SPS and PPS at every IDR. Setting it to 0
2610 disables generating SPS and PPS at every IDR. Setting it to one enables
2611 generating SPS and PPS at every IDR.
2614 .. _camera-controls:
2616 Camera Control Reference
2617 ========================
2619 The Camera class includes controls for mechanical (or equivalent
2620 digital) features of a device such as controllable lenses or sensors.
2623 .. _camera-control-id:
2628 ``V4L2_CID_CAMERA_CLASS (class)``
2629 The Camera class descriptor. Calling
2630 :ref:`VIDIOC_QUERYCTRL` for this control will
2631 return a description of this control class.
2633 .. _v4l2-exposure-auto-type:
2635 ``V4L2_CID_EXPOSURE_AUTO``
2638 enum v4l2_exposure_auto_type -
2639 Enables automatic adjustments of the exposure time and/or iris
2640 aperture. The effect of manual changes of the exposure time or iris
2641 aperture while these features are enabled is undefined, drivers
2642 should ignore such requests. Possible values are:
2650 * - ``V4L2_EXPOSURE_AUTO``
2651 - Automatic exposure time, automatic iris aperture.
2652 * - ``V4L2_EXPOSURE_MANUAL``
2653 - Manual exposure time, manual iris.
2654 * - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
2655 - Manual exposure time, auto iris.
2656 * - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
2657 - Auto exposure time, manual iris.
2661 ``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
2662 Determines the exposure time of the camera sensor. The exposure time
2663 is limited by the frame interval. Drivers should interpret the
2664 values as 100 µs units, where the value 1 stands for 1/10000th of a
2665 second, 10000 for 1 second and 100000 for 10 seconds.
2667 ``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
2668 When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
2669 ``APERTURE_PRIORITY``, this control determines if the device may
2670 dynamically vary the frame rate. By default this feature is disabled
2671 (0) and the frame rate must remain constant.
2673 ``V4L2_CID_AUTO_EXPOSURE_BIAS (integer menu)``
2674 Determines the automatic exposure compensation, it is effective only
2675 when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
2676 ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
2677 terms of EV, drivers should interpret the values as 0.001 EV units,
2678 where the value 1000 stands for +1 EV.
2680 Increasing the exposure compensation value is equivalent to
2681 decreasing the exposure value (EV) and will increase the amount of
2682 light at the image sensor. The camera performs the exposure
2683 compensation by adjusting absolute exposure time and/or aperture.
2685 .. _v4l2-exposure-metering:
2687 ``V4L2_CID_EXPOSURE_METERING``
2690 enum v4l2_exposure_metering -
2691 Determines how the camera measures the amount of light available for
2692 the frame exposure. Possible values are:
2694 .. tabularcolumns:: |p{8.5cm}|p{9.0cm}|
2700 * - ``V4L2_EXPOSURE_METERING_AVERAGE``
2701 - Use the light information coming from the entire frame and average
2702 giving no weighting to any particular portion of the metered area.
2703 * - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
2704 - Average the light information coming from the entire frame giving
2705 priority to the center of the metered area.
2706 * - ``V4L2_EXPOSURE_METERING_SPOT``
2707 - Measure only very small area at the center of the frame.
2708 * - ``V4L2_EXPOSURE_METERING_MATRIX``
2709 - A multi-zone metering. The light intensity is measured in several
2710 points of the frame and the results are combined. The algorithm of
2711 the zones selection and their significance in calculating the
2712 final value is device dependent.
2716 ``V4L2_CID_PAN_RELATIVE (integer)``
2717 This control turns the camera horizontally by the specified amount.
2718 The unit is undefined. A positive value moves the camera to the
2719 right (clockwise when viewed from above), a negative value to the
2720 left. A value of zero does not cause motion. This is a write-only
2723 ``V4L2_CID_TILT_RELATIVE (integer)``
2724 This control turns the camera vertically by the specified amount.
2725 The unit is undefined. A positive value moves the camera up, a
2726 negative value down. A value of zero does not cause motion. This is
2727 a write-only control.
2729 ``V4L2_CID_PAN_RESET (button)``
2730 When this control is set, the camera moves horizontally to the
2733 ``V4L2_CID_TILT_RESET (button)``
2734 When this control is set, the camera moves vertically to the default
2737 ``V4L2_CID_PAN_ABSOLUTE (integer)``
2738 This control turns the camera horizontally to the specified
2739 position. Positive values move the camera to the right (clockwise
2740 when viewed from above), negative values to the left. Drivers should
2741 interpret the values as arc seconds, with valid values between -180
2742 * 3600 and +180 * 3600 inclusive.
2744 ``V4L2_CID_TILT_ABSOLUTE (integer)``
2745 This control turns the camera vertically to the specified position.
2746 Positive values move the camera up, negative values down. Drivers
2747 should interpret the values as arc seconds, with valid values
2748 between -180 * 3600 and +180 * 3600 inclusive.
2750 ``V4L2_CID_FOCUS_ABSOLUTE (integer)``
2751 This control sets the focal point of the camera to the specified
2752 position. The unit is undefined. Positive values set the focus
2753 closer to the camera, negative values towards infinity.
2755 ``V4L2_CID_FOCUS_RELATIVE (integer)``
2756 This control moves the focal point of the camera by the specified
2757 amount. The unit is undefined. Positive values move the focus closer
2758 to the camera, negative values towards infinity. This is a
2761 ``V4L2_CID_FOCUS_AUTO (boolean)``
2762 Enables continuous automatic focus adjustments. The effect of manual
2763 focus adjustments while this feature is enabled is undefined,
2764 drivers should ignore such requests.
2766 ``V4L2_CID_AUTO_FOCUS_START (button)``
2767 Starts single auto focus process. The effect of setting this control
2768 when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
2769 drivers should ignore such requests.
2771 ``V4L2_CID_AUTO_FOCUS_STOP (button)``
2772 Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
2773 control. It is effective only when the continuous autofocus is
2774 disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
2777 .. _v4l2-auto-focus-status:
2779 ``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
2780 The automatic focus status. This is a read-only control.
2782 Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
2783 control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
2786 .. tabularcolumns:: |p{6.5cm}|p{11.0cm}|
2792 * - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
2793 - Automatic focus is not active.
2794 * - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
2795 - Automatic focusing is in progress.
2796 * - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
2797 - Focus has been reached.
2798 * - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
2799 - Automatic focus has failed, the driver will not transition from
2800 this state until another action is performed by an application.
2804 .. _v4l2-auto-focus-range:
2806 ``V4L2_CID_AUTO_FOCUS_RANGE``
2809 enum v4l2_auto_focus_range -
2810 Determines auto focus distance range for which lens may be adjusted.
2812 .. tabularcolumns:: |p{6.5cm}|p{11.0cm}|
2818 * - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
2819 - The camera automatically selects the focus range.
2820 * - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
2821 - Normal distance range, limited for best automatic focus
2823 * - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
2824 - Macro (close-up) auto focus. The camera will use its minimum
2825 possible distance for auto focus.
2826 * - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
2827 - The lens is set to focus on an object at infinite distance.
2831 ``V4L2_CID_ZOOM_ABSOLUTE (integer)``
2832 Specify the objective lens focal length as an absolute value. The
2833 zoom unit is driver-specific and its value should be a positive
2836 ``V4L2_CID_ZOOM_RELATIVE (integer)``
2837 Specify the objective lens focal length relatively to the current
2838 value. Positive values move the zoom lens group towards the
2839 telephoto direction, negative values towards the wide-angle
2840 direction. The zoom unit is driver-specific. This is a write-only
2843 ``V4L2_CID_ZOOM_CONTINUOUS (integer)``
2844 Move the objective lens group at the specified speed until it
2845 reaches physical device limits or until an explicit request to stop
2846 the movement. A positive value moves the zoom lens group towards the
2847 telephoto direction. A value of zero stops the zoom lens group
2848 movement. A negative value moves the zoom lens group towards the
2849 wide-angle direction. The zoom speed unit is driver-specific.
2851 ``V4L2_CID_IRIS_ABSOLUTE (integer)``
2852 This control sets the camera's aperture to the specified value. The
2853 unit is undefined. Larger values open the iris wider, smaller values
2856 ``V4L2_CID_IRIS_RELATIVE (integer)``
2857 This control modifies the camera's aperture by the specified amount.
2858 The unit is undefined. Positive values open the iris one step
2859 further, negative values close it one step further. This is a
2862 ``V4L2_CID_PRIVACY (boolean)``
2863 Prevent video from being acquired by the camera. When this control
2864 is set to ``TRUE`` (1), no image can be captured by the camera.
2865 Common means to enforce privacy are mechanical obturation of the
2866 sensor and firmware image processing, but the device is not
2867 restricted to these methods. Devices that implement the privacy
2868 control must support read access and may support write access.
2870 ``V4L2_CID_BAND_STOP_FILTER (integer)``
2871 Switch the band-stop filter of a camera sensor on or off, or specify
2872 its strength. Such band-stop filters can be used, for example, to
2873 filter out the fluorescent light component.
2875 .. _v4l2-auto-n-preset-white-balance:
2877 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE``
2880 enum v4l2_auto_n_preset_white_balance -
2881 Sets white balance to automatic, manual or a preset. The presets
2882 determine color temperature of the light as a hint to the camera for
2883 white balance adjustments resulting in most accurate color
2884 representation. The following white balance presets are listed in
2885 order of increasing color temperature.
2887 .. tabularcolumns:: |p{7.0 cm}|p{10.5cm}|
2893 * - ``V4L2_WHITE_BALANCE_MANUAL``
2894 - Manual white balance.
2895 * - ``V4L2_WHITE_BALANCE_AUTO``
2896 - Automatic white balance adjustments.
2897 * - ``V4L2_WHITE_BALANCE_INCANDESCENT``
2898 - White balance setting for incandescent (tungsten) lighting. It
2899 generally cools down the colors and corresponds approximately to
2900 2500...3500 K color temperature range.
2901 * - ``V4L2_WHITE_BALANCE_FLUORESCENT``
2902 - White balance preset for fluorescent lighting. It corresponds
2903 approximately to 4000...5000 K color temperature.
2904 * - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
2905 - With this setting the camera will compensate for fluorescent H
2907 * - ``V4L2_WHITE_BALANCE_HORIZON``
2908 - White balance setting for horizon daylight. It corresponds
2909 approximately to 5000 K color temperature.
2910 * - ``V4L2_WHITE_BALANCE_DAYLIGHT``
2911 - White balance preset for daylight (with clear sky). It corresponds
2912 approximately to 5000...6500 K color temperature.
2913 * - ``V4L2_WHITE_BALANCE_FLASH``
2914 - With this setting the camera will compensate for the flash light.
2915 It slightly warms up the colors and corresponds roughly to
2916 5000...5500 K color temperature.
2917 * - ``V4L2_WHITE_BALANCE_CLOUDY``
2918 - White balance preset for moderately overcast sky. This option
2919 corresponds approximately to 6500...8000 K color temperature
2921 * - ``V4L2_WHITE_BALANCE_SHADE``
2922 - White balance preset for shade or heavily overcast sky. It
2923 corresponds approximately to 9000...10000 K color temperature.
2927 .. _v4l2-wide-dynamic-range:
2929 ``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
2930 Enables or disables the camera's wide dynamic range feature. This
2931 feature allows to obtain clear images in situations where intensity
2932 of the illumination varies significantly throughout the scene, i.e.
2933 there are simultaneously very dark and very bright areas. It is most
2934 commonly realized in cameras by combining two subsequent frames with
2935 different exposure times. [#f1]_
2937 .. _v4l2-image-stabilization:
2939 ``V4L2_CID_IMAGE_STABILIZATION (boolean)``
2940 Enables or disables image stabilization.
2942 ``V4L2_CID_ISO_SENSITIVITY (integer menu)``
2943 Determines ISO equivalent of an image sensor indicating the sensor's
2944 sensitivity to light. The numbers are expressed in arithmetic scale,
2945 as per :ref:`iso12232` standard, where doubling the sensor
2946 sensitivity is represented by doubling the numerical ISO value.
2947 Applications should interpret the values as standard ISO values
2948 multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
2949 Drivers will usually support only a subset of standard ISO values.
2950 The effect of setting this control while the
2951 ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
2952 than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
2953 should ignore such requests.
2955 .. _v4l2-iso-sensitivity-auto-type:
2957 ``V4L2_CID_ISO_SENSITIVITY_AUTO``
2960 enum v4l2_iso_sensitivity_type -
2961 Enables or disables automatic ISO sensitivity adjustments.
2969 * - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
2970 - Manual ISO sensitivity.
2971 * - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
2972 - Automatic ISO sensitivity adjustments.
2976 .. _v4l2-scene-mode:
2978 ``V4L2_CID_SCENE_MODE``
2981 enum v4l2_scene_mode -
2982 This control allows to select scene programs as the camera automatic
2983 modes optimized for common shooting scenes. Within these modes the
2984 camera determines best exposure, aperture, focusing, light metering,
2985 white balance and equivalent sensitivity. The controls of those
2986 parameters are influenced by the scene mode control. An exact
2987 behavior in each mode is subject to the camera specification.
2989 When the scene mode feature is not used, this control should be set
2990 to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
2991 controls are accessible. The following scene programs are defined:
2993 .. tabularcolumns:: |p{6.0cm}|p{11.5cm}|
2999 * - ``V4L2_SCENE_MODE_NONE``
3000 - The scene mode feature is disabled.
3001 * - ``V4L2_SCENE_MODE_BACKLIGHT``
3002 - Backlight. Compensates for dark shadows when light is coming from
3003 behind a subject, also by automatically turning on the flash.
3004 * - ``V4L2_SCENE_MODE_BEACH_SNOW``
3005 - Beach and snow. This mode compensates for all-white or bright
3006 scenes, which tend to look gray and low contrast, when camera's
3007 automatic exposure is based on an average scene brightness. To
3008 compensate, this mode automatically slightly overexposes the
3009 frames. The white balance may also be adjusted to compensate for
3010 the fact that reflected snow looks bluish rather than white.
3011 * - ``V4L2_SCENE_MODE_CANDLELIGHT``
3012 - Candle light. The camera generally raises the ISO sensitivity and
3013 lowers the shutter speed. This mode compensates for relatively
3014 close subject in the scene. The flash is disabled in order to
3015 preserve the ambiance of the light.
3016 * - ``V4L2_SCENE_MODE_DAWN_DUSK``
3017 - Dawn and dusk. Preserves the colors seen in low natural light
3018 before dusk and after down. The camera may turn off the flash, and
3019 automatically focus at infinity. It will usually boost saturation
3020 and lower the shutter speed.
3021 * - ``V4L2_SCENE_MODE_FALL_COLORS``
3022 - Fall colors. Increases saturation and adjusts white balance for
3023 color enhancement. Pictures of autumn leaves get saturated reds
3025 * - ``V4L2_SCENE_MODE_FIREWORKS``
3026 - Fireworks. Long exposure times are used to capture the expanding
3027 burst of light from a firework. The camera may invoke image
3029 * - ``V4L2_SCENE_MODE_LANDSCAPE``
3030 - Landscape. The camera may choose a small aperture to provide deep
3031 depth of field and long exposure duration to help capture detail
3032 in dim light conditions. The focus is fixed at infinity. Suitable
3033 for distant and wide scenery.
3034 * - ``V4L2_SCENE_MODE_NIGHT``
3035 - Night, also known as Night Landscape. Designed for low light
3036 conditions, it preserves detail in the dark areas without blowing
3037 out bright objects. The camera generally sets itself to a
3038 medium-to-high ISO sensitivity, with a relatively long exposure
3039 time, and turns flash off. As such, there will be increased image
3040 noise and the possibility of blurred image.
3041 * - ``V4L2_SCENE_MODE_PARTY_INDOOR``
3042 - Party and indoor. Designed to capture indoor scenes that are lit
3043 by indoor background lighting as well as the flash. The camera
3044 usually increases ISO sensitivity, and adjusts exposure for the
3045 low light conditions.
3046 * - ``V4L2_SCENE_MODE_PORTRAIT``
3047 - Portrait. The camera adjusts the aperture so that the depth of
3048 field is reduced, which helps to isolate the subject against a
3049 smooth background. Most cameras recognize the presence of faces in
3050 the scene and focus on them. The color hue is adjusted to enhance
3051 skin tones. The intensity of the flash is often reduced.
3052 * - ``V4L2_SCENE_MODE_SPORTS``
3053 - Sports. Significantly increases ISO and uses a fast shutter speed
3054 to freeze motion of rapidly-moving subjects. Increased image noise
3055 may be seen in this mode.
3056 * - ``V4L2_SCENE_MODE_SUNSET``
3057 - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
3059 * - ``V4L2_SCENE_MODE_TEXT``
3060 - Text. It applies extra contrast and sharpness, it is typically a
3061 black-and-white mode optimized for readability. Automatic focus
3062 may be switched to close-up mode and this setting may also involve
3063 some lens-distortion correction.
3067 ``V4L2_CID_3A_LOCK (bitmask)``
3068 This control locks or unlocks the automatic focus, exposure and
3069 white balance. The automatic adjustments can be paused independently
3070 by setting the corresponding lock bit to 1. The camera then retains
3071 the settings until the lock bit is cleared. The following lock bits
3074 When a given algorithm is not enabled, drivers should ignore
3075 requests to lock it and should return no error. An example might be
3076 an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
3077 ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
3078 value of this control may be changed by exposure, white balance or
3087 * - ``V4L2_LOCK_EXPOSURE``
3088 - Automatic exposure adjustments lock.
3089 * - ``V4L2_LOCK_WHITE_BALANCE``
3090 - Automatic white balance adjustments lock.
3091 * - ``V4L2_LOCK_FOCUS``
3092 - Automatic focus lock.
3096 ``V4L2_CID_PAN_SPEED (integer)``
3097 This control turns the camera horizontally at the specific speed.
3098 The unit is undefined. A positive value moves the camera to the
3099 right (clockwise when viewed from above), a negative value to the
3100 left. A value of zero stops the motion if one is in progress and has
3101 no effect otherwise.
3103 ``V4L2_CID_TILT_SPEED (integer)``
3104 This control turns the camera vertically at the specified speed. The
3105 unit is undefined. A positive value moves the camera up, a negative
3106 value down. A value of zero stops the motion if one is in progress
3107 and has no effect otherwise.
3112 FM Transmitter Control Reference
3113 ================================
3115 The FM Transmitter (FM_TX) class includes controls for common features
3116 of FM transmissions capable devices. Currently this class includes
3117 parameters for audio compression, pilot tone generation, audio deviation
3118 limiter, RDS transmission and tuning power features.
3121 .. _fm-tx-control-id:
3126 ``V4L2_CID_FM_TX_CLASS (class)``
3127 The FM_TX class descriptor. Calling
3128 :ref:`VIDIOC_QUERYCTRL` for this control will
3129 return a description of this control class.
3131 ``V4L2_CID_RDS_TX_DEVIATION (integer)``
3132 Configures RDS signal frequency deviation level in Hz. The range and
3133 step are driver-specific.
3135 ``V4L2_CID_RDS_TX_PI (integer)``
3136 Sets the RDS Programme Identification field for transmission.
3138 ``V4L2_CID_RDS_TX_PTY (integer)``
3139 Sets the RDS Programme Type field for transmission. This encodes up
3140 to 31 pre-defined programme types.
3142 ``V4L2_CID_RDS_TX_PS_NAME (string)``
3143 Sets the Programme Service name (PS_NAME) for transmission. It is
3144 intended for static display on a receiver. It is the primary aid to
3145 listeners in programme service identification and selection. In
3146 Annex E of :ref:`iec62106`, the RDS specification, there is a full
3147 description of the correct character encoding for Programme Service
3148 name strings. Also from RDS specification, PS is usually a single
3149 eight character text. However, it is also possible to find receivers
3150 which can scroll strings sized as 8 x N characters. So, this control
3151 must be configured with steps of 8 characters. The result is it must
3152 always contain a string with size multiple of 8.
3154 ``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
3155 Sets the Radio Text info for transmission. It is a textual
3156 description of what is being broadcasted. RDS Radio Text can be
3157 applied when broadcaster wishes to transmit longer PS names,
3158 programme-related information or any other text. In these cases,
3159 RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``.
3160 The encoding for Radio Text strings is also fully described in Annex
3161 E of :ref:`iec62106`. The length of Radio Text strings depends on
3162 which RDS Block is being used to transmit it, either 32 (2A block)
3163 or 64 (2B block). However, it is also possible to find receivers
3164 which can scroll strings sized as 32 x N or 64 x N characters. So,
3165 this control must be configured with steps of 32 or 64 characters.
3166 The result is it must always contain a string with size multiple of
3169 ``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
3170 Sets the Mono/Stereo bit of the Decoder Identification code. If set,
3171 then the audio was recorded as stereo.
3173 ``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
3175 `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__
3176 bit of the Decoder Identification code. If set, then the audio was
3177 recorded using an artificial head.
3179 ``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
3180 Sets the Compressed bit of the Decoder Identification code. If set,
3181 then the audio is compressed.
3183 ``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
3184 Sets the Dynamic PTY bit of the Decoder Identification code. If set,
3185 then the PTY code is dynamically switched.
3187 ``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)``
3188 If set, then a traffic announcement is in progress.
3190 ``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
3191 If set, then the tuned programme carries traffic announcements.
3193 ``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
3194 If set, then this channel broadcasts music. If cleared, then it
3195 broadcasts speech. If the transmitter doesn't make this distinction,
3196 then it should be set.
3198 ``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
3199 If set, then transmit alternate frequencies.
3201 ``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
3202 The alternate frequencies in kHz units. The RDS standard allows for
3203 up to 25 frequencies to be defined. Drivers may support fewer
3204 frequencies so check the array size.
3206 ``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
3207 Enables or disables the audio deviation limiter feature. The limiter
3208 is useful when trying to maximize the audio volume, minimize
3209 receiver-generated distortion and prevent overmodulation.
3211 ``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
3212 Sets the audio deviation limiter feature release time. Unit is in
3213 useconds. Step and range are driver-specific.
3215 ``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
3216 Configures audio frequency deviation level in Hz. The range and step
3217 are driver-specific.
3219 ``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)``
3220 Enables or disables the audio compression feature. This feature
3221 amplifies signals below the threshold by a fixed gain and compresses
3222 audio signals above the threshold by the ratio of Threshold/(Gain +
3225 ``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
3226 Sets the gain for audio compression feature. It is a dB value. The
3227 range and step are driver-specific.
3229 ``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
3230 Sets the threshold level for audio compression freature. It is a dB
3231 value. The range and step are driver-specific.
3233 ``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
3234 Sets the attack time for audio compression feature. It is a useconds
3235 value. The range and step are driver-specific.
3237 ``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
3238 Sets the release time for audio compression feature. It is a
3239 useconds value. The range and step are driver-specific.
3241 ``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
3242 Enables or disables the pilot tone generation feature.
3244 ``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
3245 Configures pilot tone frequency deviation level. Unit is in Hz. The
3246 range and step are driver-specific.
3248 ``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
3249 Configures pilot tone frequency value. Unit is in Hz. The range and
3250 step are driver-specific.
3252 ``V4L2_CID_TUNE_PREEMPHASIS``
3255 enum v4l2_preemphasis -
3256 Configures the pre-emphasis value for broadcasting. A pre-emphasis
3257 filter is applied to the broadcast to accentuate the high audio
3258 frequencies. Depending on the region, a time constant of either 50
3259 or 75 useconds is used. The enum v4l2_preemphasis defines possible
3260 values for pre-emphasis. Here they are:
3268 * - ``V4L2_PREEMPHASIS_DISABLED``
3269 - No pre-emphasis is applied.
3270 * - ``V4L2_PREEMPHASIS_50_uS``
3271 - A pre-emphasis of 50 uS is used.
3272 * - ``V4L2_PREEMPHASIS_75_uS``
3273 - A pre-emphasis of 75 uS is used.
3277 ``V4L2_CID_TUNE_POWER_LEVEL (integer)``
3278 Sets the output power level for signal transmission. Unit is in
3279 dBuV. Range and step are driver-specific.
3281 ``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
3282 This selects the value of antenna tuning capacitor manually or
3283 automatically if set to zero. Unit, range and step are
3286 For more details about RDS specification, refer to :ref:`iec62106`
3287 document, from CENELEC.
3292 Flash Control Reference
3293 =======================
3295 The V4L2 flash controls are intended to provide generic access to flash
3296 controller devices. Flash controller devices are typically used in
3299 The interface can support both LED and xenon flash devices. As of
3300 writing this, there is no xenon flash driver using this interface.
3303 .. _flash-controls-use-cases:
3309 Unsynchronised LED flash (software strobe)
3310 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3312 Unsynchronised LED flash is controlled directly by the host as the
3313 sensor. The flash must be enabled by the host before the exposure of the
3314 image starts and disabled once it ends. The host is fully responsible
3315 for the timing of the flash.
3317 Example of such device: Nokia N900.
3320 Synchronised LED flash (hardware strobe)
3321 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3323 The synchronised LED flash is pre-programmed by the host (power and
3324 timeout) but controlled by the sensor through a strobe signal from the
3325 sensor to the flash.
3327 The sensor controls the flash duration and timing. This information
3328 typically must be made available to the sensor.
3334 LED flash may be used as torch in conjunction with another use case
3335 involving camera or individually.
3338 .. _flash-control-id:
3343 ``V4L2_CID_FLASH_CLASS (class)``
3344 The FLASH class descriptor.
3346 ``V4L2_CID_FLASH_LED_MODE (menu)``
3347 Defines the mode of the flash LED, the high-power white LED attached
3348 to the flash controller. Setting this control may not be possible in
3349 presence of some faults. See V4L2_CID_FLASH_FAULT.
3357 * - ``V4L2_FLASH_LED_MODE_NONE``
3359 * - ``V4L2_FLASH_LED_MODE_FLASH``
3361 * - ``V4L2_FLASH_LED_MODE_TORCH``
3362 - Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.
3366 ``V4L2_CID_FLASH_STROBE_SOURCE (menu)``
3367 Defines the source of the flash LED strobe.
3369 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
3375 * - ``V4L2_FLASH_STROBE_SOURCE_SOFTWARE``
3376 - The flash strobe is triggered by using the
3377 V4L2_CID_FLASH_STROBE control.
3378 * - ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``
3379 - The flash strobe is triggered by an external source. Typically
3380 this is a sensor, which makes it possible to synchronises the
3381 flash strobe start to exposure start.
3385 ``V4L2_CID_FLASH_STROBE (button)``
3386 Strobe flash. Valid when V4L2_CID_FLASH_LED_MODE is set to
3387 V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
3388 is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
3389 control may not be possible in presence of some faults. See
3390 V4L2_CID_FLASH_FAULT.
3392 ``V4L2_CID_FLASH_STROBE_STOP (button)``
3393 Stop flash strobe immediately.
3395 ``V4L2_CID_FLASH_STROBE_STATUS (boolean)``
3396 Strobe status: whether the flash is strobing at the moment or not.
3397 This is a read-only control.
3399 ``V4L2_CID_FLASH_TIMEOUT (integer)``
3400 Hardware timeout for flash. The flash strobe is stopped after this
3401 period of time has passed from the start of the strobe.
3403 ``V4L2_CID_FLASH_INTENSITY (integer)``
3404 Intensity of the flash strobe when the flash LED is in flash mode
3405 (V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps (mA)
3408 ``V4L2_CID_FLASH_TORCH_INTENSITY (integer)``
3409 Intensity of the flash LED in torch mode
3410 (V4L2_FLASH_LED_MODE_TORCH). The unit should be milliamps (mA)
3411 if possible. Setting this control may not be possible in presence of
3412 some faults. See V4L2_CID_FLASH_FAULT.
3414 ``V4L2_CID_FLASH_INDICATOR_INTENSITY (integer)``
3415 Intensity of the indicator LED. The indicator LED may be fully
3416 independent of the flash LED. The unit should be microamps (uA) if
3419 ``V4L2_CID_FLASH_FAULT (bitmask)``
3420 Faults related to the flash. The faults tell about specific problems
3421 in the flash chip itself or the LEDs attached to it. Faults may
3422 prevent further use of some of the flash controls. In particular,
3423 V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
3424 if the fault affects the flash LED. Exactly which faults have such
3425 an effect is chip dependent. Reading the faults resets the control
3426 and returns the chip to a usable state if possible.
3428 .. tabularcolumns:: |p{8.0cm}|p{9.5cm}|
3434 * - ``V4L2_FLASH_FAULT_OVER_VOLTAGE``
3435 - Flash controller voltage to the flash LED has exceeded the limit
3436 specific to the flash controller.
3437 * - ``V4L2_FLASH_FAULT_TIMEOUT``
3438 - The flash strobe was still on when the timeout set by the user ---
3439 V4L2_CID_FLASH_TIMEOUT control --- has expired. Not all flash
3440 controllers may set this in all such conditions.
3441 * - ``V4L2_FLASH_FAULT_OVER_TEMPERATURE``
3442 - The flash controller has overheated.
3443 * - ``V4L2_FLASH_FAULT_SHORT_CIRCUIT``
3444 - The short circuit protection of the flash controller has been
3446 * - ``V4L2_FLASH_FAULT_OVER_CURRENT``
3447 - Current in the LED power supply has exceeded the limit specific to
3448 the flash controller.
3449 * - ``V4L2_FLASH_FAULT_INDICATOR``
3450 - The flash controller has detected a short or open circuit
3451 condition on the indicator LED.
3452 * - ``V4L2_FLASH_FAULT_UNDER_VOLTAGE``
3453 - Flash controller voltage to the flash LED has been below the
3454 minimum limit specific to the flash controller.
3455 * - ``V4L2_FLASH_FAULT_INPUT_VOLTAGE``
3456 - The input voltage of the flash controller is below the limit under
3457 which strobing the flash at full current will not be possible.The
3458 condition persists until this flag is no longer set.
3459 * - ``V4L2_FLASH_FAULT_LED_OVER_TEMPERATURE``
3460 - The temperature of the LED has exceeded its allowed upper limit.
3464 ``V4L2_CID_FLASH_CHARGE (boolean)``
3465 Enable or disable charging of the xenon flash capacitor.
3467 ``V4L2_CID_FLASH_READY (boolean)``
3468 Is the flash ready to strobe? Xenon flashes require their capacitors
3469 charged before strobing. LED flashes often require a cooldown period
3470 after strobe during which another strobe will not be possible. This
3471 is a read-only control.
3476 JPEG Control Reference
3477 ======================
3479 The JPEG class includes controls for common features of JPEG encoders
3480 and decoders. Currently it includes features for codecs implementing
3481 progressive baseline DCT compression process with Huffman entrophy
3485 .. _jpeg-control-id:
3490 ``V4L2_CID_JPEG_CLASS (class)``
3491 The JPEG class descriptor. Calling
3492 :ref:`VIDIOC_QUERYCTRL` for this control will
3493 return a description of this control class.
3495 ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)``
3496 The chroma subsampling factors describe how each component of an
3497 input image is sampled, in respect to maximum sample rate in each
3498 spatial dimension. See :ref:`itu-t81`, clause A.1.1. for more
3499 details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines
3500 how Cb and Cr components are downsampled after converting an input
3501 image from RGB to Y'CbCr color space.
3503 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
3509 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444``
3510 - No chroma subsampling, each pixel has Y, Cr and Cb values.
3511 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422``
3512 - Horizontally subsample Cr, Cb components by a factor of 2.
3513 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420``
3514 - Subsample Cr, Cb components horizontally and vertically by 2.
3515 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411``
3516 - Horizontally subsample Cr, Cb components by a factor of 4.
3517 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410``
3518 - Subsample Cr, Cb components horizontally by 4 and vertically by 2.
3519 * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY``
3520 - Use only luminance component.
3524 ``V4L2_CID_JPEG_RESTART_INTERVAL (integer)``
3525 The restart interval determines an interval of inserting RSTm
3526 markers (m = 0..7). The purpose of these markers is to additionally
3527 reinitialize the encoder process, in order to process blocks of an
3528 image independently. For the lossy compression processes the restart
3529 interval unit is MCU (Minimum Coded Unit) and its value is contained
3530 in DRI (Define Restart Interval) marker. If
3531 ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm
3532 markers will not be inserted.
3534 .. _jpeg-quality-control:
3536 ``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)``
3537 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control determines trade-off
3538 between image quality and size. It provides simpler method for
3539 applications to control image quality, without a need for direct
3540 reconfiguration of luminance and chrominance quantization tables. In
3541 cases where a driver uses quantization tables configured directly by
3542 an application, using interfaces defined elsewhere,
3543 ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by
3546 The value range of this control is driver-specific. Only positive,
3547 non-zero values are meaningful. The recommended range is 1 - 100,
3548 where larger values correspond to better image quality.
3550 .. _jpeg-active-marker-control:
3552 ``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)``
3553 Specify which JPEG markers are included in compressed stream. This
3554 control is valid only for encoders.
3562 * - ``V4L2_JPEG_ACTIVE_MARKER_APP0``
3563 - Application data segment APP\ :sub:`0`.
3564 * - ``V4L2_JPEG_ACTIVE_MARKER_APP1``
3565 - Application data segment APP\ :sub:`1`.
3566 * - ``V4L2_JPEG_ACTIVE_MARKER_COM``
3568 * - ``V4L2_JPEG_ACTIVE_MARKER_DQT``
3569 - Quantization tables segment.
3570 * - ``V4L2_JPEG_ACTIVE_MARKER_DHT``
3571 - Huffman tables segment.
3575 For more details about JPEG specification, refer to :ref:`itu-t81`,
3576 :ref:`jfif`, :ref:`w3c-jpeg-jfif`.
3579 .. _image-source-controls:
3581 Image Source Control Reference
3582 ==============================
3584 The Image Source control class is intended for low-level control of
3585 image source devices such as image sensors. The devices feature an
3586 analogue to digital converter and a bus transmitter to transmit the
3587 image data out of the device.
3590 .. _image-source-control-id:
3592 Image Source Control IDs
3593 ------------------------
3595 ``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
3596 The IMAGE_SOURCE class descriptor.
3598 ``V4L2_CID_VBLANK (integer)``
3599 Vertical blanking. The idle period after every frame during which no
3600 image data is produced. The unit of vertical blanking is a line.
3601 Every line has length of the image width plus horizontal blanking at
3602 the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
3605 ``V4L2_CID_HBLANK (integer)``
3606 Horizontal blanking. The idle period after every line of image data
3607 during which no image data is produced. The unit of horizontal
3610 ``V4L2_CID_ANALOGUE_GAIN (integer)``
3611 Analogue gain is gain affecting all colour components in the pixel
3612 matrix. The gain operation is performed in the analogue domain
3613 before A/D conversion.
3615 ``V4L2_CID_TEST_PATTERN_RED (integer)``
3616 Test pattern red colour component.
3618 ``V4L2_CID_TEST_PATTERN_GREENR (integer)``
3619 Test pattern green (next to red) colour component.
3621 ``V4L2_CID_TEST_PATTERN_BLUE (integer)``
3622 Test pattern blue colour component.
3624 ``V4L2_CID_TEST_PATTERN_GREENB (integer)``
3625 Test pattern green (next to blue) colour component.
3628 .. _image-process-controls:
3630 Image Process Control Reference
3631 ===============================
3633 The Image Process control class is intended for low-level control of
3634 image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
3635 controls in this class affect processing the image, and do not control
3639 .. _image-process-control-id:
3641 Image Process Control IDs
3642 -------------------------
3644 ``V4L2_CID_IMAGE_PROC_CLASS (class)``
3645 The IMAGE_PROC class descriptor.
3647 ``V4L2_CID_LINK_FREQ (integer menu)``
3648 Data bus frequency. Together with the media bus pixel code, bus type
3649 (clock cycles per sample), the data bus frequency defines the pixel
3650 rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
3651 elsewhere, if the device is not an image sensor). The frame rate can
3652 be calculated from the pixel clock, image width and height and
3653 horizontal and vertical blanking. While the pixel rate control may
3654 be defined elsewhere than in the subdev containing the pixel array,
3655 the frame rate cannot be obtained from that information. This is
3656 because only on the pixel array it can be assumed that the vertical
3657 and horizontal blanking information is exact: no other blanking is
3658 allowed in the pixel array. The selection of frame rate is performed
3659 by selecting the desired horizontal and vertical blanking. The unit
3660 of this control is Hz.
3662 ``V4L2_CID_PIXEL_RATE (64-bit integer)``
3663 Pixel rate in the source pads of the subdev. This control is
3664 read-only and its unit is pixels / second.
3666 ``V4L2_CID_TEST_PATTERN (menu)``
3667 Some capture/display/sensor devices have the capability to generate
3668 test pattern images. These hardware specific test patterns can be
3669 used to test if a device is working properly.
3671 ``V4L2_CID_DEINTERLACING_MODE (menu)``
3672 The video deinterlacing mode (such as Bob, Weave, ...). The menu items are
3673 driver specific and are documented in :ref:`v4l-drivers`.
3675 ``V4L2_CID_DIGITAL_GAIN (integer)``
3676 Digital gain is the value by which all colour components
3677 are multiplied by. Typically the digital gain applied is the
3678 control value divided by e.g. 0x100, meaning that to get no
3679 digital gain the control value needs to be 0x100. The no-gain
3680 configuration is also typically the default.
3685 Digital Video Control Reference
3686 ===============================
3688 The Digital Video control class is intended to control receivers and
3689 transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
3690 `DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__
3691 (Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort
3692 (:ref:`dp`). These controls are generally expected to be private to
3693 the receiver or transmitter subdevice that implements them, so they are
3694 only exposed on the ``/dev/v4l-subdev*`` device node.
3698 Note that these devices can have multiple input or output pads which are
3699 hooked up to e.g. HDMI connectors. Even though the subdevice will
3700 receive or transmit video from/to only one of those pads, the other pads
3701 can still be active when it comes to EDID (Extended Display
3702 Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
3703 Content Protection System, :ref:`hdcp`) processing, allowing the
3704 device to do the fairly slow EDID/HDCP handling in advance. This allows
3705 for quick switching between connectors.
3707 These pads appear in several of the controls in this section as
3708 bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad
3709 1, etc. The maximum value of the control is the set of valid pads.
3714 Digital Video Control IDs
3715 -------------------------
3717 ``V4L2_CID_DV_CLASS (class)``
3718 The Digital Video class descriptor.
3720 ``V4L2_CID_DV_TX_HOTPLUG (bitmask)``
3721 Many connectors have a hotplug pin which is high if EDID information
3722 is available from the source. This control shows the state of the
3723 hotplug pin as seen by the transmitter. Each bit corresponds to an
3724 output pad on the transmitter. If an output pad does not have an
3725 associated hotplug pin, then the bit for that pad will be 0. This
3726 read-only control is applicable to DVI-D, HDMI and DisplayPort
3729 ``V4L2_CID_DV_TX_RXSENSE (bitmask)``
3730 Rx Sense is the detection of pull-ups on the TMDS clock lines. This
3731 normally means that the sink has left/entered standby (i.e. the
3732 transmitter can sense that the receiver is ready to receive video).
3733 Each bit corresponds to an output pad on the transmitter. If an
3734 output pad does not have an associated Rx Sense, then the bit for
3735 that pad will be 0. This read-only control is applicable to DVI-D
3738 ``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)``
3739 When the transmitter sees the hotplug signal from the receiver it
3740 will attempt to read the EDID. If set, then the transmitter has read
3741 at least the first block (= 128 bytes). Each bit corresponds to an
3742 output pad on the transmitter. If an output pad does not support
3743 EDIDs, then the bit for that pad will be 0. This read-only control
3744 is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors.
3746 ``V4L2_CID_DV_TX_MODE``
3749 enum v4l2_dv_tx_mode -
3750 HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI
3751 mode (video + audio + auxiliary data). This control selects which
3752 mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI.
3753 This control is applicable to HDMI connectors.
3755 ``V4L2_CID_DV_TX_RGB_RANGE``
3758 enum v4l2_dv_rgb_range -
3759 Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO
3760 follows the RGB quantization range specified in the standard for the
3761 video interface (ie. :ref:`cea861` for HDMI).
3762 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
3763 standard to be compatible with sinks that have not implemented the
3764 standard correctly (unfortunately quite common for HDMI and DVI-D).
3765 Full range allows all possible values to be used whereas limited
3766 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
3767 the number of bits per component. This control is applicable to VGA,
3768 DVI-A/D, HDMI and DisplayPort connectors.
3770 ``V4L2_CID_DV_TX_IT_CONTENT_TYPE``
3773 enum v4l2_dv_it_content_type -
3774 Configures the IT Content Type of the transmitted video. This
3775 information is sent over HDMI and DisplayPort connectors as part of
3776 the AVI InfoFrame. The term 'IT Content' is used for content that
3777 originates from a computer as opposed to content from a TV broadcast
3778 or an analog source. The enum v4l2_dv_it_content_type defines
3779 the possible content types:
3781 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
3787 * - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS``
3788 - Graphics content. Pixel data should be passed unfiltered and
3789 without analog reconstruction.
3790 * - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO``
3791 - Photo content. The content is derived from digital still pictures.
3792 The content should be passed through with minimal scaling and
3793 picture enhancements.
3794 * - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA``
3796 * - ``V4L2_DV_IT_CONTENT_TYPE_GAME``
3797 - Game content. Audio and video latency should be minimized.
3798 * - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC``
3799 - No IT Content information is available and the ITC bit in the AVI
3800 InfoFrame is set to 0.
3804 ``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)``
3805 Detects whether the receiver receives power from the source (e.g.
3806 HDMI carries 5V on one of the pins). This is often used to power an
3807 eeprom which contains EDID information, such that the source can
3808 read the EDID even if the sink is in standby/power off. Each bit
3809 corresponds to an input pad on the receiver. If an input pad
3810 cannot detect whether power is present, then the bit for that pad
3811 will be 0. This read-only control is applicable to DVI-D, HDMI and
3812 DisplayPort connectors.
3814 ``V4L2_CID_DV_RX_RGB_RANGE``
3817 enum v4l2_dv_rgb_range -
3818 Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO
3819 follows the RGB quantization range specified in the standard for the
3820 video interface (ie. :ref:`cea861` for HDMI).
3821 V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
3822 standard to be compatible with sources that have not implemented the
3823 standard correctly (unfortunately quite common for HDMI and DVI-D).
3824 Full range allows all possible values to be used whereas limited
3825 range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
3826 the number of bits per component. This control is applicable to VGA,
3827 DVI-A/D, HDMI and DisplayPort connectors.
3829 ``V4L2_CID_DV_RX_IT_CONTENT_TYPE``
3832 enum v4l2_dv_it_content_type -
3833 Reads the IT Content Type of the received video. This information is
3834 sent over HDMI and DisplayPort connectors as part of the AVI
3835 InfoFrame. The term 'IT Content' is used for content that originates
3836 from a computer as opposed to content from a TV broadcast or an
3837 analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the
3838 available content types.
3843 FM Receiver Control Reference
3844 =============================
3846 The FM Receiver (FM_RX) class includes controls for common features of
3847 FM Reception capable devices.
3850 .. _fm-rx-control-id:
3855 ``V4L2_CID_FM_RX_CLASS (class)``
3856 The FM_RX class descriptor. Calling
3857 :ref:`VIDIOC_QUERYCTRL` for this control will
3858 return a description of this control class.
3860 ``V4L2_CID_RDS_RECEPTION (boolean)``
3861 Enables/disables RDS reception by the radio tuner
3863 ``V4L2_CID_RDS_RX_PTY (integer)``
3864 Gets RDS Programme Type field. This encodes up to 31 pre-defined
3867 ``V4L2_CID_RDS_RX_PS_NAME (string)``
3868 Gets the Programme Service name (PS_NAME). It is intended for
3869 static display on a receiver. It is the primary aid to listeners in
3870 programme service identification and selection. In Annex E of
3871 :ref:`iec62106`, the RDS specification, there is a full
3872 description of the correct character encoding for Programme Service
3873 name strings. Also from RDS specification, PS is usually a single
3874 eight character text. However, it is also possible to find receivers
3875 which can scroll strings sized as 8 x N characters. So, this control
3876 must be configured with steps of 8 characters. The result is it must
3877 always contain a string with size multiple of 8.
3879 ``V4L2_CID_RDS_RX_RADIO_TEXT (string)``
3880 Gets the Radio Text info. It is a textual description of what is
3881 being broadcasted. RDS Radio Text can be applied when broadcaster
3882 wishes to transmit longer PS names, programme-related information or
3883 any other text. In these cases, RadioText can be used in addition to
3884 ``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is
3885 also fully described in Annex E of :ref:`iec62106`. The length of
3886 Radio Text strings depends on which RDS Block is being used to
3887 transmit it, either 32 (2A block) or 64 (2B block). However, it is
3888 also possible to find receivers which can scroll strings sized as 32
3889 x N or 64 x N characters. So, this control must be configured with
3890 steps of 32 or 64 characters. The result is it must always contain a
3891 string with size multiple of 32 or 64.
3893 ``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)``
3894 If set, then a traffic announcement is in progress.
3896 ``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)``
3897 If set, then the tuned programme carries traffic announcements.
3899 ``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)``
3900 If set, then this channel broadcasts music. If cleared, then it
3901 broadcasts speech. If the transmitter doesn't make this distinction,
3902 then it will be set.
3904 ``V4L2_CID_TUNE_DEEMPHASIS``
3907 enum v4l2_deemphasis -
3908 Configures the de-emphasis value for reception. A de-emphasis filter
3909 is applied to the broadcast to accentuate the high audio
3910 frequencies. Depending on the region, a time constant of either 50
3911 or 75 useconds is used. The enum v4l2_deemphasis defines possible
3912 values for de-emphasis. Here they are:
3920 * - ``V4L2_DEEMPHASIS_DISABLED``
3921 - No de-emphasis is applied.
3922 * - ``V4L2_DEEMPHASIS_50_uS``
3923 - A de-emphasis of 50 uS is used.
3924 * - ``V4L2_DEEMPHASIS_75_uS``
3925 - A de-emphasis of 75 uS is used.
3930 .. _detect-controls:
3932 Detect Control Reference
3933 ========================
3935 The Detect class includes controls for common features of various motion
3936 or object detection capable devices.
3939 .. _detect-control-id:
3944 ``V4L2_CID_DETECT_CLASS (class)``
3945 The Detect class descriptor. Calling
3946 :ref:`VIDIOC_QUERYCTRL` for this control will
3947 return a description of this control class.
3949 ``V4L2_CID_DETECT_MD_MODE (menu)``
3950 Sets the motion detection mode.
3952 .. tabularcolumns:: |p{7.5cm}|p{10.0cm}|
3958 * - ``V4L2_DETECT_MD_MODE_DISABLED``
3959 - Disable motion detection.
3960 * - ``V4L2_DETECT_MD_MODE_GLOBAL``
3961 - Use a single motion detection threshold.
3962 * - ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID``
3963 - The image is divided into a grid, each cell with its own motion
3964 detection threshold. These thresholds are set through the
3965 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID`` matrix control.
3966 * - ``V4L2_DETECT_MD_MODE_REGION_GRID``
3967 - The image is divided into a grid, each cell with its own region
3968 value that specifies which per-region motion detection thresholds
3969 should be used. Each region has its own thresholds. How these
3970 per-region thresholds are set up is driver-specific. The region
3971 values for the grid are set through the
3972 ``V4L2_CID_DETECT_MD_REGION_GRID`` matrix control.
3976 ``V4L2_CID_DETECT_MD_GLOBAL_THRESHOLD (integer)``
3977 Sets the global motion detection threshold to be used with the
3978 ``V4L2_DETECT_MD_MODE_GLOBAL`` motion detection mode.
3980 ``V4L2_CID_DETECT_MD_THRESHOLD_GRID (__u16 matrix)``
3981 Sets the motion detection thresholds for each cell in the grid. To
3982 be used with the ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID`` motion
3983 detection mode. Matrix element (0, 0) represents the cell at the
3984 top-left of the grid.
3986 ``V4L2_CID_DETECT_MD_REGION_GRID (__u8 matrix)``
3987 Sets the motion detection region value for each cell in the grid. To
3988 be used with the ``V4L2_DETECT_MD_MODE_REGION_GRID`` motion
3989 detection mode. Matrix element (0, 0) represents the cell at the
3990 top-left of the grid.
3993 .. _rf-tuner-controls:
3995 RF Tuner Control Reference
3996 ==========================
3998 The RF Tuner (RF_TUNER) class includes controls for common features of
3999 devices having RF tuner.
4001 In this context, RF tuner is radio receiver circuit between antenna and
4002 demodulator. It receives radio frequency (RF) from the antenna and
4003 converts that received signal to lower intermediate frequency (IF) or
4004 baseband frequency (BB). Tuners that could do baseband output are often
4005 called Zero-IF tuners. Older tuners were typically simple PLL tuners
4006 inside a metal box, while newer ones are highly integrated chips
4007 without a metal box "silicon tuners". These controls are mostly
4008 applicable for new feature rich silicon tuners, just because older
4009 tuners does not have much adjustable features.
4011 For more information about RF tuners see
4012 `Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
4013 and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
4017 .. _rf-tuner-control-id:
4019 RF_TUNER Control IDs
4020 --------------------
4022 ``V4L2_CID_RF_TUNER_CLASS (class)``
4023 The RF_TUNER class descriptor. Calling
4024 :ref:`VIDIOC_QUERYCTRL` for this control will
4025 return a description of this control class.
4027 ``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
4028 Enables/disables tuner radio channel bandwidth configuration. In
4029 automatic mode bandwidth configuration is performed by the driver.
4031 ``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
4032 Filter(s) on tuner signal path are used to filter signal according
4033 to receiving party needs. Driver configures filters to fulfill
4034 desired bandwidth requirement. Used when
4035 V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
4036 range and step are driver-specific.
4038 ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
4039 Enables/disables LNA automatic gain control (AGC)
4041 ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
4042 Enables/disables mixer automatic gain control (AGC)
4044 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
4045 Enables/disables IF automatic gain control (AGC)
4047 ``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
4048 The RF amplifier is the very first amplifier on the receiver signal
4049 path, just right after the antenna input. The difference between the
4050 LNA gain and the RF gain in this document is that the LNA gain is
4051 integrated in the tuner chip while the RF gain is a separate chip.
4052 There may be both RF and LNA gain controls in the same device. The
4053 range and step are driver-specific.
4055 ``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
4056 LNA (low noise amplifier) gain is first gain stage on the RF tuner
4057 signal path. It is located very close to tuner antenna input. Used
4058 when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
4059 ``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
4060 differs from the each others. The range and step are
4063 ``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
4064 Mixer gain is second gain stage on the RF tuner signal path. It is
4065 located inside mixer block, where RF signal is down-converted by the
4066 mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
4067 The range and step are driver-specific.
4069 ``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
4070 IF gain is last gain stage on the RF tuner signal path. It is
4071 located on output of RF tuner. It controls signal level of
4072 intermediate frequency output or baseband output. Used when
4073 ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
4074 are driver-specific.
4076 ``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
4077 Is synthesizer PLL locked? RF tuner is receiving given frequency
4078 when that control is set. This is a read-only control.
4081 This control may be changed to a menu control in the future, if more
4082 options are required.