1 .. SPDX-License-Identifier: GFDL-1.1-no-invari
2 .. c:namespace:: V4L
3
4 .. _hist-v4l2:
5
6 ***********************
7 Changes of the V4L2 API
8 ***********************
9
10 Soon after the V4L API was added to the kernel
11 inflexible. In August 1998 Bill Dirks proposed
12 and began to work on documentation, example dr
13 With the help of other volunteers this eventua
14 not just an extension but a replacement for th
15 another four years and two stable kernel relea
16 finally accepted for inclusion into the kernel
17
18 Early Versions
19 ==============
20
21 1998-08-20: First version.
22
23 1998-08-27: The :c:func:`select()` function wa
24
25 1998-09-10: New video standard interface.
26
27 1998-09-18: The ``VIDIOC_NONCAP`` ioctl was re
28 meaningless ``O_TRUNC`` :c:func:`open()` flag,
29 aliases ``O_NONCAP`` and ``O_NOIO`` were defin
30 this flag if they intend to access controls on
31 applications which need exclusive access. The
32 identifiers are now ordinals instead of flags,
33 ``video_std_construct()`` helper function take
34 transmission arguments.
35
36 1998-09-28: Revamped video standard. Made vide
37 enumerable.
38
39 1998-10-02: The ``id`` field was removed from
40 struct ``video_standard`` and the color subcar
41 renamed. The :ref:`VIDIOC_QUERYSTD` ioctl was
42 renamed to :ref:`VIDIOC_ENUMSTD`,
43 :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` to
44 :ref:`VIDIOC_ENUMINPUT`. A first draft of the
45 Codec API was released.
46
47 1998-11-08: Many minor changes. Most symbols h
48 material changes to struct v4l2_capability.
49
50 1998-11-12: The read/write direction of some i
51
52 1998-11-14: ``V4L2_PIX_FMT_RGB24`` changed to
53 and ``V4L2_PIX_FMT_RGB32`` changed to ``V4L2_P
54 controls are now accessible with the
55 :ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
56 :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls un
57 with ``V4L2_CID_AUDIO``. The ``V4L2_MAJOR`` de
58 ``videodev.h`` since it was only used once in
59 module. The ``YUV422`` and ``YUV411`` planar i
60
61 1998-11-28: A few ioctl symbols changed. Inter
62 output devices were added.
63
64 1999-01-14: A raw VBI capture interface was ad
65
66 1999-01-19: The ``VIDIOC_NEXTBUF`` ioctl was r
67
68 V4L2 Version 0.16 1999-01-31
69 ============================
70
71 1999-01-27: There is now one QBUF ioctl, VIDIO
72 are gone. VIDIOC_QBUF takes a v4l2_buffer as a
73 digital zoom (cropping) controls.
74
75 V4L2 Version 0.18 1999-03-16
76 ============================
77
78 Added a v4l to V4L2 ioctl compatibility layer
79 writers, this changes how you implement your i
80 Driver Writer's Guide. Added some more control
81
82 V4L2 Version 0.19 1999-06-05
83 ============================
84
85 1999-03-18: Fill in the category and catname f
86 objects before passing them to the driver. Req
87 the VIDIOC_QUERYCTRL handlers in the sample dr
88
89 1999-03-31: Better compatibility for v4l memor
90 changes to drivers to fully support new compat
91 Driver Writer's Guide and v4l2cap.c. Added new
92 V4L2_CID_HFLIP, _VFLIP. Changed V4L2_PIX_FMT_Y
93 and _YUV411P to _YUV411P.
94
95 1999-04-04: Added a few more control IDs.
96
97 1999-04-07: Added the button control type.
98
99 1999-05-02: Fixed a typo in videodev.h, and ad
100 V4L2_CTRL_FLAG_GRAYED (later V4L2_CTRL_FLAG_GR
101
102 1999-05-20: Definition of VIDIOC_G_CTRL was wr
103 malfunction of this ioctl.
104
105 1999-06-05: Changed the value of V4L2_CID_WHIT
106
107 V4L2 Version 0.20 (1999-09-10)
108 ==============================
109
110 Version 0.20 introduced a number of changes wh
111 compatible* with 0.19 and earlier versions. Pu
112 to simplify the API, while making it more exte
113 common Linux driver API conventions.
114
115 1. Some typos in ``V4L2_FMT_FLAG`` symbols wer
116 was changed for compatibility with v4l. (19
117
118 2. ``V4L2_TUNER_SUB_LANG1`` was added. (1999-0
119
120 3. All ioctl() commands that used an integer a
121 to an integer. Where it makes sense, ioctls
122 new value in the integer pointed to by the
123 convention in the V4L2 API. The affected io
124 VIDIOC_STREAMON, VIDIOC_STREAMOFF, VIDIOC_S
125 VIDIOC_S_INPUT, VIDIOC_S_OUTPUT, VIDIOC_S_E
126
127 .. code-block:: c
128
129 err = ioctl (fd, VIDIOC_XXX, V4L2_XXX);
130
131 becomes
132
133 .. code-block:: c
134
135 int a = V4L2_XXX; err = ioctl(fd, VIDIO
136
137 4. All the different get- and set-format comma
138 :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and
139 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl ta
140 type field selecting the union member as pa
141 simplify the API by eliminating several ioc
142 driver private data streams without adding
143
144 This change obsoletes the following ioctls:
145 ``VIDIOC_G_INFMT``, ``VIDIOC_S_OUTFMT``, ``
146 ``VIDIOC_S_VBIFMT`` and ``VIDIOC_G_VBIFMT``
147 struct v4l2_format was renamed to struct v4
148 struct v4l2_format is now the enveloping st
149 for all format negotiations.
150
151 5. Similar to the changes above, the ``VIDIOC_
152 ``VIDIOC_S_PARM`` ioctls were merged with `
153 ``VIDIOC_S_OUTPARM``. A ``type`` field in t
154 selects the respective union member.
155
156 This change obsoletes the ``VIDIOC_G_OUTPAR
157 ``VIDIOC_S_OUTPARM`` ioctls.
158
159 6. Control enumeration was simplified, and two
160 introduced and one dropped. The ``catname``
161 ``group`` field.
162
163 Drivers can now flag unsupported and tempor
164 with ``V4L2_CTRL_FLAG_DISABLED`` and ``V4L2
165 respectively. The ``group`` name indicates
166 classification than the ``category``. In ot
167 multiple groups within a category. Controls
168 typically be drawn within a group box. Cont
169 categories might have a greater separation,
170 separate windows.
171
172 7. The struct v4l2_buffer ``timestamp`` was
173 changed to a 64 bit integer, containing the
174 of the frame in nanoseconds. Additionally t
175 absolute system time, not starting from zer
176 stream. The data type name for timestamps i
177 signed 64-bit integer. Output devices shoul
178 until the time in the timestamp field has a
179 follow SGI's lead, and adopt a multimedia t
180 their UST (Unadjusted System Time). See
181 http://web.archive.org/web/\*/http://realit
182 /cpirazzi_engr/lg/time/intro.html. UST uses
183 64-bit signed integers (not struct timeval'
184 units. The UST clock starts at zero when th
185 runs continuously and uniformly. It takes a
186 UST to overflow. There is no way to set the
187 Linux time-of-day clock can be changed peri
188 cause errors if it were being used for time
189 stream. A real UST style clock will require
190 kernel that is not there yet. But in antici
191 timestamp field to a 64-bit integer, and I
192 v4l2_masterclock_gettime() function (used o
193 return a 64-bit integer.
194
195 8. A ``sequence`` field was added to struct v4
196 field counts captured frames, it is ignored
197 capture driver drops a frame, the sequence
198
199 V4L2 Version 0.20 incremental changes
200 =====================================
201
202 1999-12-23: In struct v4l2_vbi_format the
203 ``reserved1`` field became ``offset``. Previou
204 to clear the ``reserved1`` field.
205
206 2000-01-13: The ``V4L2_FMT_FLAG_NOT_INTERLACED
207
208 2000-07-31: The ``linux/poll.h`` header is now
209 ``videodev.h`` for compatibility with the orig
210
211 2000-11-20: ``V4L2_TYPE_VBI_OUTPUT`` and ``V4L
212 added.
213
214 2000-11-25: ``V4L2_TYPE_VBI_INPUT`` was added.
215
216 2000-12-04: A couple typos in symbol names wer
217
218 2001-01-18: To avoid namespace conflicts the `
219 the ``videodev.h`` header file was renamed to
220
221 2001-01-25: A possible driver-level compatibil
222 ``videodev.h`` file in Linux 2.4.0 and the ``v
223 in the ``videodevX`` patch was fixed. Users of
224 ``videodevX`` on Linux 2.4.0 should recompile
225 drivers.
226
227 2001-01-26: A possible kernel-level incompatib
228 ``videodev.h`` file in the ``videodevX`` patch
229 file in Linux 2.2.x with devfs patches applied
230
231 2001-03-02: Certain V4L ioctls which pass data
232 although they are defined with read-only param
233 correctly through the backward compatibility l
234
235 2001-04-13: Big endian 16-bit RGB formats were
236
237 2001-09-17: New YUV formats and the
238 :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>`
239 :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>`
240 (The old ``VIDIOC_G_FREQ`` and ``VIDIOC_S_FREQ
241 multiple tuners into account.)
242
243 2000-09-18: ``V4L2_BUF_TYPE_VBI`` was added. T
244 compatibility* as the :ref:`VIDIOC_G_FMT <VIDI
245 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls may
246 struct ``v4l2_fmt`` ``type`` field does not co
247 ``V4L2_BUF_TYPE_VBI``. In the documentation of
248 the ``offset`` field the ambiguous phrase "ris
249 "leading edge".
250
251 V4L2 Version 0.20 2000-11-23
252 ============================
253
254 A number of changes were made to the raw VBI i
255
256 1. Figures clarifying the line numbering schem
257 API specification. The ``start``\ [0] and `
258 longer count line numbers beginning at zero
259 previous definition was unclear. b) The ``s
260 ordinal numbers. c) There is no point in in
261 numbering scheme. We now use line number as
262 Compatibility: Add one to the start values.
263 the previous semantics may not function cor
264
265 2. The restriction "count[0] > 0 and count[1]
266 "(count[0] + count[1]) > 0". Rationale: Dri
267 resources at scan line granularity and some
268 transmitted only on the first field. The co
269 values will usually be equal is misleading
270 removed. This change *breaks compatibility*
271 Drivers may return ``EINVAL``, applications
272
273 3. Drivers are again permitted to return negat
274 as proposed earlier. Why this feature was d
275 change may *break compatibility* with appli
276 start values being positive. The use of ``E
277 error codes with the :ref:`VIDIOC_S_FMT <VI
278 clarified. The ``EBUSY`` error code was fin
279 ``reserved2`` field which was previously me
280 ``videodev.h`` header file.
281
282 4. New buffer types ``V4L2_TYPE_VBI_INPUT`` an
283 were added. The former is an alias for the
284 latter was missing in the ``videodev.h`` fi
285
286 V4L2 Version 0.20 2002-07-25
287 ============================
288
289 Added sliced VBI interface proposal.
290
291 V4L2 in Linux 2.5.46, 2002-10
292 =============================
293
294 Around October-November 2002, prior to an anno
295 Linux 2.5, the API was revised, drawing from e
296 This unnamed version was finally merged into L
297
298 1. As specified in :ref:`related`, drivers mu
299 functions available under all minor device
300
301 2. The :c:func:`open()` function requires acc
302 ``O_RDWR`` regardless of the device type.
303 exchanging data with applications must sup
304 flag. The ``O_NOIO`` flag, a V4L2 symbol w
305 meaningless ``O_TRUNC`` to indicate access
306 (panel applications) was dropped. Drivers
307 until the application attempts to initiate
308 :ref:`open`.
309
310 3. The struct v4l2_capability changed
311 dramatically. Note that also the size of t
312 which is encoded in the ioctl request code
313 will respond with an ``EINVAL`` error code
314 :ref:`VIDIOC_QUERYCAP` ioctl.
315
316 There are new fields to identify the drive
317 function ``V4L2_CAP_RDS_CAPTURE``, the ``V
318 indicates if the device has any audio conn
319 capability V4L2_CAP_ASYNCIO can be flagged
320 changes the ``type`` field became a bit se
321 ``flags`` field. ``V4L2_FLAG_TUNER`` was r
322 ``V4L2_CAP_TUNER``, ``V4L2_CAP_VIDEO_OVERL
323 ``V4L2_FLAG_PREVIEW`` and ``V4L2_CAP_VBI_C
324 ``V4L2_CAP_VBI_OUTPUT`` replaced ``V4L2_FL
325 ``V4L2_FLAG_READ`` and ``V4L2_FLAG_WRITE``
326 ``V4L2_CAP_READWRITE``.
327
328 The redundant fields ``inputs``, ``outputs
329 removed. These properties can be determine
330 :ref:`video` and :ref:`audio`.
331
332 The somewhat volatile and therefore barely
333 ``maxwidth``, ``maxheight``, ``minwidth``,
334 ``maxframerate`` were removed. This inform
335 described in :ref:`format` and :ref:`stand
336
337 ``V4L2_FLAG_SELECT`` was removed. We belie
338 is important enough to require support of
339 exchanging data with applications. The red
340 ``V4L2_FLAG_MONOCHROME`` flag was removed,
341 available as described in :ref:`format`.
342
343 4. In struct v4l2_input the ``assoc_audio``
344 field and the ``capability`` field and its
345 ``V4L2_INPUT_CAP_AUDIO`` was replaced by t
346 Instead of linking one video input to one
347 reports all audio inputs this video input
348
349 New fields are ``tuner`` (reversing the fo
350 video inputs), ``std`` and ``status``.
351
352 Accordingly struct v4l2_output lost its
353 ``capability`` and ``assoc_audio`` fields.
354 ``modulator`` and ``std`` where added inst
355
356 5. The struct v4l2_audio field ``audio`` was
357 renamed to ``index``, for consistency with
358 capability flag ``V4L2_AUDCAP_STEREO`` was
359 audio input in question supports stereo so
360 ``V4L2_AUDCAP_EFFECTS`` and the correspond
361 where removed. This can be easily implemen
362 (However the same applies to AVL which is
363
364 Again for consistency the struct v4l2_audi
365 to ``index``.
366
367 6. The struct v4l2_tuner ``input`` field was
368 replaced by an ``index`` field, permitting
369 tuners. The link between video inputs and
370 inputs point to their tuner. The ``std`` s
371 simple set (more about this below) and mov
372 A ``type`` field was added.
373
374 Accordingly in struct v4l2_modulator the
375 ``output`` was replaced by an ``index`` fi
376
377 In struct v4l2_frequency the ``port``
378 field was replaced by a ``tuner`` field co
379 tuner or modulator index number. A tuner `
380 and the ``reserved`` field became larger f
381 (satellite tuners in particular).
382
383 7. The idea of completely transparent video s
384 Experience showed that applications must b
385 standards beyond presenting the user a men
386 supported standards with an ioctl applicat
387 standards by :ref:`v4l2_std_id <v4l2-std-i
388 defined in the ``videodev2.h`` header file
389 :ref:`standard`. The :ref:`VIDIOC_G_STD <V
390 :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` now tak
391 type as argument. :ref:`VIDIOC_QUERYSTD` w
392 added to autodetect the received standard,
393 capability. In struct v4l2_standard an
394 ``index`` field was added for
395 :ref:`VIDIOC_ENUMSTD`. A
396 :ref:`v4l2_std_id <v4l2-std-id>` field nam
397 machine readable identifier, also replacin
398 field. The misleading ``framerate`` field
399 ``frameperiod``. The now obsolete ``colors
400 originally needed to distguish between var
401 removed.
402
403 Struct ``v4l2_enumstd`` ceased to be.
404 :ref:`VIDIOC_ENUMSTD` now takes a pointer
405 struct v4l2_standard directly. The
406 information which standards are supported
407 input or output moved into struct v4l2_inp
408 and struct v4l2_output fields named ``std`
409 respectively.
410
411 8. The struct :ref:`v4l2_queryctrl <v4l2-quer
412 ``category`` and ``group`` did not catch o
413 implemented as expected and therefore remo
414
415 9. The :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` i
416 negotiate data formats as with
417 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`, but wi
418 programming the hardware and regardless of
419
420 In struct v4l2_format the ``fmt`` union wa
421 extended to contain struct v4l2_window. Al
422 image format negotiations are now possible
423 ``VIDIOC_S_FMT`` and ``VIDIOC_TRY_FMT``; i
424 and ``VIDIOC_S_WIN`` ioctls to prepare for
425 removed. The ``type`` field changed to typ
426 the buffer type names changed as follows.
427
428
429 .. flat-table::
430 :header-rows: 1
431 :stub-columns: 0
432
433 * - Old defines
434 - enum v4l2_buf_type
435 * - ``V4L2_BUF_TYPE_CAPTURE``
436 - ``V4L2_BUF_TYPE_VIDEO_CAPTURE``
437 * - ``V4L2_BUF_TYPE_CODECIN``
438 - Omitted for now
439 * - ``V4L2_BUF_TYPE_CODECOUT``
440 - Omitted for now
441 * - ``V4L2_BUF_TYPE_EFFECTSIN``
442 - Omitted for now
443 * - ``V4L2_BUF_TYPE_EFFECTSIN2``
444 - Omitted for now
445 * - ``V4L2_BUF_TYPE_EFFECTSOUT``
446 - Omitted for now
447 * - ``V4L2_BUF_TYPE_VIDEOOUT``
448 - ``V4L2_BUF_TYPE_VIDEO_OUTPUT``
449 * - ``-``
450 - ``V4L2_BUF_TYPE_VIDEO_OVERLAY``
451 * - ``-``
452 - ``V4L2_BUF_TYPE_VBI_CAPTURE``
453 * - ``-``
454 - ``V4L2_BUF_TYPE_VBI_OUTPUT``
455 * - ``-``
456 - ``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE
457 * - ``-``
458 - ``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT`
459 * - ``V4L2_BUF_TYPE_PRIVATE_BASE``
460 - ``V4L2_BUF_TYPE_PRIVATE`` (but thi
461
462 10. In struct v4l2_fmtdesc a enum v4l2_buf_typ
463 added as in struct v4l2_format. The ``VIDI
464 longer needed and was removed. These calls
465 :ref:`VIDIOC_ENUM_FMT` with type ``V4L2_BU
466
467 11. In struct v4l2_pix_format the ``depth``
468 field was removed, assuming applications w
469 by its four-character-code already know th
470 do not care about it. The same rationale l
471 ``V4L2_FMT_FLAG_COMPRESSED`` flag. The
472 ``V4L2_FMT_FLAG_SWCONVECOMPRESSED`` flag w
473 are not supposed to convert images in kern
474 of conversion functions should be provided
475 ``V4L2_FMT_FLAG_BYTESPERLINE`` flag was re
476 set the ``bytesperline`` field to zero to
477 Since the remaining flags were replaced as
478 itself was removed.
479
480 The interlace flags were replaced by a enu
481 newly added ``field`` field.
482
483 .. flat-table::
484 :header-rows: 1
485 :stub-columns: 0
486
487 * - Old flag
488 - enum v4l2_field
489 * - ``V4L2_FMT_FLAG_NOT_INTERLACED``
490 - ?
491 * - ``V4L2_FMT_FLAG_INTERLACED`` = ``V
492 - ``V4L2_FIELD_INTERLACED``
493 * - ``V4L2_FMT_FLAG_TOPFIELD`` = ``V4L
494 - ``V4L2_FIELD_TOP``
495 * - ``V4L2_FMT_FLAG_BOTFIELD`` = ``V4L
496 - ``V4L2_FIELD_BOTTOM``
497 * - ``-``
498 - ``V4L2_FIELD_SEQ_TB``
499 * - ``-``
500 - ``V4L2_FIELD_SEQ_BT``
501 * - ``-``
502 - ``V4L2_FIELD_ALTERNATE``
503
504 The color space flags were replaced by a e
505 a newly added ``colorspace`` field, where
506 ``V4L2_COLORSPACE_SMPTE170M``, ``V4L2_COLO
507 ``V4L2_COLORSPACE_470_SYSTEM_M`` or
508 ``V4L2_COLORSPACE_470_SYSTEM_BG`` replaces
509
510 12. In struct v4l2_requestbuffers the
511 ``type`` field was properly defined as enu
512 changed as mentioned above. A new ``memory
513 enum v4l2_memory was added to distinguish
514 I/O methods using buffers allocated by the
515 application. See :ref:`io` for details.
516
517 13. In struct v4l2_buffer the ``type`` field w
518 properly defined as enum v4l2_buf_type.
519 Buffer types changed as mentioned above. A
520 enum v4l2_field was added to indicate if a
521 buffer contains a top or bottom field. The
522 removed. Since no unadjusted system time c
523 kernel as planned, the ``timestamp`` field
524 stamp_t, an unsigned 64 bit integer expres
525 nanoseconds, to struct timeval. With the a
526 of a second memory mapping method the ``of
527 union ``m``, and a new ``memory`` field of
528 was added to distinguish between
529 I/O methods. See :ref:`io` for details.
530
531 The ``V4L2_BUF_REQ_CONTIG`` flag was used
532 layer, after changes to this code it was n
533 ``V4L2_BUF_ATTR_DEVICEMEM`` flag would ind
534 indeed allocated in device memory rather t
535 memory. It was barely useful and so was re
536
537 14. In struct v4l2_framebuffer the
538 ``base[3]`` array anticipating double- and
539 off-screen video memory, however without d
540 mechanism, was replaced by a single pointe
541 ``V4L2_FBUF_CAP_SCALEUP`` and ``V4L2_FBUF_
542 removed. Applications can determine this c
543 using the new cropping and scaling interfa
544 ``V4L2_FBUF_CAP_CLIPPING`` flag was replac
545 ``V4L2_FBUF_CAP_LIST_CLIPPING`` and
546 ``V4L2_FBUF_CAP_BITMAP_CLIPPING``.
547
548 15. In struct v4l2_clip the ``x``, ``y``,
549 ``width`` and ``height`` field moved into
550 type struct v4l2_rect. The ``x`` and ``y``
551 fields were renamed to ``left`` and ``top`
552 context dependent origin.
553
554 16. In struct v4l2_window the ``x``, ``y``,
555 ``width`` and ``height`` field moved into
556 above. A ``field`` field of type enum v4l2
557 distinguish between field and frame (inter
558
559 17. The digital zoom interface, including stru
560 struct ``v4l2_zoom``, ``V4L2_ZOOM_NONCAP``
561 ``V4L2_ZOOM_WHILESTREAMING`` was replaced
562 scaling interface. The previously unused
563 struct v4l2_cropcap and struct v4l2_crop
564 where redefined for this purpose. See :ref
565
566 18. In struct v4l2_vbi_format the
567 ``SAMPLE_FORMAT`` field now contains a fou
568 to identify video image formats and ``V4L2
569 the ``V4L2_VBI_SF_UBYTE`` define. The ``re
570 extended.
571
572 19. In struct v4l2_captureparm the type of
573 the ``timeperframe`` field changed from un
574 struct v4l2_fract. This allows the accurat
575 expression of multiples of the NTSC-M fram
576 field ``readbuffers`` was added to control
577 read I/O mode.
578
579 Similar changes were made to struct v4l2_o
580
581 20. The struct ``v4l2_performance`` and
582 ``VIDIOC_G_PERF`` ioctl were dropped. Exce
583 :ref:`read/write I/O method <rw>`, which i
584 information is already available to applic
585
586 21. The example transformation from RGB to YCb
587 V4L2 documentation was inaccurate, this ha
588 :ref:`pixfmt`.
589
590 V4L2 2003-06-19
591 ===============
592
593 1. A new capability flag ``V4L2_CAP_RADIO`` wa
594 Prior to this change radio devices would id
595 exactly one tuner whose type field reads ``
596
597 2. An optional driver access priority mechanis
598 :ref:`app-pri` for details.
599
600 3. The audio input and output interface was fo
601
602 Previously the :ref:`VIDIOC_G_AUDIO <VIDIOC
603 enumerate the available audio inputs. An io
604 current audio input, if more than one combi
605 input, did not exist. So ``VIDIOC_G_AUDIO``
606 ``VIDIOC_G_AUDIO_OLD``, this ioctl was remo
607 :ref:`VIDIOC_ENUMAUDIO` ioctl was added to
608 enumerate audio inputs, while
609 :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` now
610 audio input.
611
612 The same changes were made to
613 :ref:`VIDIOC_G_AUDOUT <VIDIOC_G_AUDOUT>` an
614 :ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>
615
616 Until further the "videodev" module will au
617 between the old and new ioctls, but drivers
618 updated to successfully compile again.
619
620 4. The :ref:`VIDIOC_OVERLAY` ioctl was incorre
621 defined with write-read parameter. It was c
622 while the write-read version was renamed to
623 The old ioctl was removed on Kernel 2.6.39.
624 "videodev" kernel module will automatically
625 version, so drivers must be recompiled, but
626
627 5. :ref:`overlay` incorrectly stated that clip
628 regions where the video can be seen. Correc
629 rectangles define regions where *no* video
630 the graphics surface can be seen.
631
632 6. The :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` an
633 :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls
634 write-only parameter, inconsistent with oth
635 argument. They were changed to write-read,
636 was added to the write-only versions. The o
637 Kernel 2.6.39. Drivers and applications ass
638 need an update.
639
640 V4L2 2003-11-05
641 ===============
642
643 1. In :ref:`pixfmt-rgb` the following pixel fo
644 transferred from Bill Dirks' V4L2 specifica
645 refer to bytes in memory, in ascending addr
646
647
648 .. flat-table::
649 :header-rows: 1
650 :stub-columns: 0
651
652 * - Symbol
653 - In this document prior to revision
654 - Corrected
655 * - ``V4L2_PIX_FMT_RGB24``
656 - B, G, R
657 - R, G, B
658 * - ``V4L2_PIX_FMT_BGR24``
659 - R, G, B
660 - B, G, R
661 * - ``V4L2_PIX_FMT_RGB32``
662 - B, G, R, X
663 - R, G, B, X
664 * - ``V4L2_PIX_FMT_BGR32``
665 - R, G, B, X
666 - B, G, R, X
667
668 The ``V4L2_PIX_FMT_BGR24`` example was alwa
669
670 In :ref:`v4l-image-properties` the mapping
671 ``VIDEO_PALETTE_RGB24`` and ``VIDEO_PALETTE
672 pixel formats was accordingly corrected.
673
674 2. Unrelated to the fixes above, drivers may s
675 RGB pixel formats differently. These issues
676 for details see :ref:`pixfmt-rgb`.
677
678 V4L2 in Linux 2.6.6, 2004-05-09
679 ===============================
680
681 1. The :ref:`VIDIOC_CROPCAP` ioctl was incorre
682 defined with read-only parameter. It is now
683 ioctl, while the read-only version was rena
684 ``VIDIOC_CROPCAP_OLD``. The old ioctl was r
685
686 V4L2 in Linux 2.6.8
687 ===================
688
689 1. A new field ``input`` (former ``reserved[0]
690 struct v4l2_buffer. Purpose of this
691 field is to alternate between video inputs
692 with the video capturing process. This func
693 the new ``V4L2_BUF_FLAG_INPUT`` flag. The `
694 longer read-only.
695
696 V4L2 spec erratum 2004-08-01
697 ============================
698
699 1. The return value of the :ref:`func-open` fu
700 documented.
701
702 2. Audio output ioctls end in -AUDOUT, not -AU
703
704 3. In the Current Audio Input example the ``VI
705 the wrong argument.
706
707 4. The documentation of the :ref:`VIDIOC_QBUF`
708 :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctls di
709 struct v4l2_buffer ``memory`` field. It was
710 also missing from examples. Also on the ``V
711 error code was not documented.
712
713 V4L2 in Linux 2.6.14
714 ====================
715
716 1. A new sliced VBI interface was added. It is
717 :ref:`sliced` and replaces the interface fi
718 specification 0.8.
719
720 V4L2 in Linux 2.6.15
721 ====================
722
723 1. The :ref:`VIDIOC_LOG_STATUS` ioctl was adde
724
725 2. New video standards ``V4L2_STD_NTSC_443``,
726 ``V4L2_STD_SECAM_DK`` (a set of SECAM D, K
727 ``V4L2_STD_ATSC`` (a set of ``V4L2_STD_ATSC
728 ``V4L2_STD_ATSC_16_VSB``) were defined. Not
729 set now includes ``V4L2_STD_NTSC_443``. See
730 :ref:`v4l2-std-id`.
731
732 3. The ``VIDIOC_G_COMP`` and ``VIDIOC_S_COMP``
733 ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGCO
734 argument was replaced by a struct
735 ``v4l2_mpeg_compression`` pointer. (The
736 ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGCO
737 in Linux 2.6.25.)
738
739 V4L2 spec erratum 2005-11-27
740 ============================
741
742 The capture example in :ref:`capture-example`
743 :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctl wit
744 cropping is supported. In the video standard s
745 :ref:`standard` the :ref:`VIDIOC_S_STD <VIDIOC
746 the wrong argument type.
747
748 V4L2 spec erratum 2006-01-10
749 ============================
750
751 1. The ``V4L2_IN_ST_COLOR_KILL`` flag in struc
752 indicates if the color killer is enabled, b
753 (The color killer disables color decoding w
754 in the video signal to improve the image qu
755
756 2. :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` is a w
757 write-only as stated on its reference page.
758 as noted above.
759
760 V4L2 spec erratum 2006-02-03
761 ============================
762
763 1. In struct v4l2_captureparm and struct v4l2_
764 field gives the time in seconds, not micros
765
766 V4L2 spec erratum 2006-02-04
767 ============================
768
769 1. The ``clips`` field in struct v4l2_window
770 must point to an array of struct v4l2_clip,
771 a linked list, because drivers ignore the
772 struct v4l2_clip. ``next`` pointer.
773
774 V4L2 in Linux 2.6.17
775 ====================
776
777 1. New video standard macros were added: ``V4L
778 South Korea), and the sets ``V4L2_STD_MN``,
779 ``V4L2_STD_GH`` and ``V4L2_STD_DK``. The ``
780 ``V4L2_STD_SECAM`` sets now include ``V4L2_
781 ``V4L2_STD_SECAM_LC`` respectively.
782
783 2. A new ``V4L2_TUNER_MODE_LANG1_LANG2`` was d
784 languages of a bilingual program. The use o
785 ``V4L2_TUNER_MODE_STEREO`` for this purpose
786 the :ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>`
787
788 V4L2 spec erratum 2006-09-23 (Draft 0.15)
789 =========================================
790
791 1. In various places ``V4L2_BUF_TYPE_SLICED_VB
792 ``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT`` of the
793 not mentioned along with other buffer types
794
795 2. In :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` i
796 struct v4l2_audio ``mode`` field is a flags
797
798 3. :ref:`VIDIOC_QUERYCAP` did not mention the
799 capability flags.
800
801 4. In :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQU
802 applications must initialize the tuner ``ty
803 struct v4l2_frequency before calling
804 :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENC
805
806 5. The ``reserved`` array in struct v4l2_reque
807 not 32.
808
809 6. In :ref:`output` and :ref:`raw-vbi` the dev
810 ``/dev/vout`` which never caught on were re
811
812 7. With Linux 2.6.15 the possible range for VB
813 extended from 224-239 to 224-255. According
814 ``/dev/vbi0`` to ``/dev/vbi31`` are possibl
815
816 V4L2 in Linux 2.6.18
817 ====================
818
819 1. New ioctls :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC
820 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRL
821 :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CT
822 flag to skip unsupported controls with
823 :ref:`VIDIOC_QUERYCTRL`, new control types
824 ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTR
825 (enum v4l2_ctrl_type), and new control flag
826 ``V4L2_CTRL_FLAG_READ_ONLY``, ``V4L2_CTRL_F
827 ``V4L2_CTRL_FLAG_INACTIVE`` and ``V4L2_CTRL
828 (:ref:`control-flags`). See :ref:`extended-
829
830 V4L2 in Linux 2.6.19
831 ====================
832
833 1. In struct v4l2_sliced_vbi_cap a
834 buffer type field was added replacing a res
835 architectures where the size of enum types
836 size of the structure changed. The
837 :ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLI
838 was redefined from being read-only to write
839 initialize the type field and clear the res
840 changes may *break the compatibility* with
841 applications.
842
843 2. The ioctls :ref:`VIDIOC_ENUM_FRAMESIZES`
844 and
845 :ref:`VIDIOC_ENUM_FRAMEINTERVALS`
846 were added.
847
848 3. A new pixel format ``V4L2_PIX_FMT_RGB444``
849 added.
850
851 V4L2 spec erratum 2006-10-12 (Draft 0.17)
852 =========================================
853
854 1. ``V4L2_PIX_FMT_HM12`` (:ref:`reserved-forma
855 4:2:2 format.
856
857 V4L2 in Linux 2.6.21
858 ====================
859
860 1. The ``videodev2.h`` header file is now dual
861 General Public License version two or later
862 BSD-style license.
863
864 V4L2 in Linux 2.6.22
865 ====================
866
867 1. Two new field orders ``V4L2_FIELD_INTERLACE
868 ``V4L2_FIELD_INTERLACED_BT`` were added. Se
869 details.
870
871 2. Three new clipping/blending methods with a
872 inverted local alpha value were added to th
873 See the description of the :ref:`VIDIOC_G_F
874 and :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` io
875
876 A new ``global_alpha`` field was added to s
877 extending the structure. This may **break c
878 applications using a struct v4l2_window dir
879 :ref:`VIDIOC_G/S/TRY_FMT <VIDIOC_G_FMT>` io
880 pointer to a struct v4l2_format parent stru
881 with padding bytes at the end, are not affe
882
883 3. The format of the ``chromakey`` field in st
884 "host order RGB32" to a pixel value in the
885 This may **break compatibility** with exist
886 supporting the "host order RGB32" format ar
887
888 V4L2 in Linux 2.6.24
889 ====================
890
891 1. The pixel formats ``V4L2_PIX_FMT_PAL8``, ``
892 ``V4L2_PIX_FMT_YUV555``, ``V4L2_PIX_FMT_YUV
893 ``V4L2_PIX_FMT_YUV32`` were added.
894
895 V4L2 in Linux 2.6.25
896 ====================
897
898 1. The pixel formats :ref:`V4L2_PIX_FMT_Y16 <V
899 :ref:`V4L2_PIX_FMT_SBGGR16 <V4L2-PIX-FMT-SB
900
901 2. New :ref:`controls <control>` ``V4L2_CID_PO
902 ``V4L2_CID_HUE_AUTO``, ``V4L2_CID_WHITE_BAL
903 ``V4L2_CID_SHARPNESS`` and ``V4L2_CID_BACKL
904 added. The controls ``V4L2_CID_BLACK_LEVEL`
905 ``V4L2_CID_HCENTER`` and ``V4L2_CID_VCENTER
906
907 3. A :ref:`Camera controls class <camera-contr
908 the new controls ``V4L2_CID_EXPOSURE_AUTO``
909 ``V4L2_CID_EXPOSURE_ABSOLUTE``, ``V4L2_CID_
910 ``V4L2_CID_PAN_RELATIVE``, ``V4L2_CID_TILT_
911 ``V4L2_CID_PAN_RESET``, ``V4L2_CID_TILT_RES
912 ``V4L2_CID_PAN_ABSOLUTE``, ``V4L2_CID_TILT_
913 ``V4L2_CID_FOCUS_ABSOLUTE``, ``V4L2_CID_FOC
914 ``V4L2_CID_FOCUS_AUTO``.
915
916 4. The ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MP
917 were superseded by the :ref:`extended contr
918 interface in Linux 2.6.18, where finally re
919 ``videodev2.h`` header file.
920
921 V4L2 in Linux 2.6.26
922 ====================
923
924 1. The pixel formats ``V4L2_PIX_FMT_Y16`` and
925 were added.
926
927 2. Added user controls ``V4L2_CID_CHROMA_AGC``
928 ``V4L2_CID_COLOR_KILLER``.
929
930 V4L2 in Linux 2.6.27
931 ====================
932
933 1. The :ref:`VIDIOC_S_HW_FREQ_SEEK` ioctl
934 and the ``V4L2_CAP_HW_FREQ_SEEK`` capabilit
935
936 2. The pixel formats ``V4L2_PIX_FMT_YVYU``, ``
937 ``V4L2_PIX_FMT_PCA505``, ``V4L2_PIX_FMT_PCA
938 ``V4L2_PIX_FMT_PCA561``, ``V4L2_PIX_FMT_SGB
939 ``V4L2_PIX_FMT_PAC207`` and ``V4L2_PIX_FMT_
940
941 V4L2 in Linux 2.6.28
942 ====================
943
944 1. Added ``V4L2_MPEG_AUDIO_ENCODING_AAC`` and
945 ``V4L2_MPEG_AUDIO_ENCODING_AC3`` MPEG audio
946
947 2. Added ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC
948
949 3. The pixel formats ``V4L2_PIX_FMT_SGRBG10``
950 ``V4L2_PIX_FMT_SGRBG10DPCM8`` were added.
951
952 V4L2 in Linux 2.6.29
953 ====================
954
955 1. The ``VIDIOC_G_CHIP_IDENT`` ioctl was renam
956 ``VIDIOC_G_CHIP_IDENT_OLD`` and ``VIDIOC_DB
957 introduced in its place. The old struct ``v
958 struct ``v4l2_chip_ident_old``.
959
960 2. The pixel formats ``V4L2_PIX_FMT_VYUY``, ``
961 ``V4L2_PIX_FMT_NV61`` were added.
962
963 3. Added camera controls ``V4L2_CID_ZOOM_ABSOL
964 ``V4L2_CID_ZOOM_RELATIVE``, ``V4L2_CID_ZOOM
965 ``V4L2_CID_PRIVACY``.
966
967 V4L2 in Linux 2.6.30
968 ====================
969
970 1. New control flag ``V4L2_CTRL_FLAG_WRITE_ONL
971
972 2. New control ``V4L2_CID_COLORFX`` was added.
973
974 V4L2 in Linux 2.6.32
975 ====================
976
977 1. In order to be easier to compare a V4L2 API
978 V4L2 API is numbered using the Linux Kernel
979
980 2. Finalized the RDS capture API. See :ref:`rd
981
982 3. Added new capabilities for modulators and R
983
984 4. Add description for libv4l API.
985
986 5. Added support for string controls via new t
987 ``V4L2_CTRL_TYPE_STRING``.
988
989 6. Added ``V4L2_CID_BAND_STOP_FILTER`` documen
990
991 7. Added FM Modulator (FM TX) Extended Control
992 ``V4L2_CTRL_CLASS_FM_TX`` and their Control
993
994 8. Added FM Receiver (FM RX) Extended Control
995 ``V4L2_CTRL_CLASS_FM_RX`` and their Control
996
997 9. Added Remote Controller chapter, describing
998 Controller mapping for media devices.
999
1000 V4L2 in Linux 2.6.33
1001 ====================
1002
1003 1. Added support for Digital Video timings in
1004 receivers and transmitters.
1005
1006 V4L2 in Linux 2.6.34
1007 ====================
1008
1009 1. Added ``V4L2_CID_IRIS_ABSOLUTE`` and ``V4L
1010 controls to the :ref:`Camera controls clas
1011
1012 V4L2 in Linux 2.6.37
1013 ====================
1014
1015 1. Remove the vtx (videotext/teletext) API. T
1016 and no hardware exists to verify the API.
1017 applications found that used it. It was or
1018 removal in 2.6.35.
1019
1020 V4L2 in Linux 2.6.39
1021 ====================
1022
1023 1. The old VIDIOC_*_OLD symbols and V4L1 supp
1024
1025 2. Multi-planar API added. Does not affect th
1026 drivers and applications. See :ref:`multi-
1027 for details.
1028
1029 V4L2 in Linux 3.1
1030 =================
1031
1032 1. VIDIOC_QUERYCAP now returns a per-subsyste
1033 per-driver one.
1034
1035 Standardize an error code for invalid ioct
1036
1037 Added V4L2_CTRL_TYPE_BITMASK.
1038
1039 V4L2 in Linux 3.2
1040 =================
1041
1042 1. V4L2_CTRL_FLAG_VOLATILE was added to signa
1043 userspace.
1044
1045 2. Add selection API for extended control ove
1046 Does not affect the compatibility of curre
1047 applications. See :ref:`selection API <sel
1048
1049 V4L2 in Linux 3.3
1050 =================
1051
1052 1. Added ``V4L2_CID_ALPHA_COMPONENT`` control
1053 :ref:`User controls class <control>`.
1054
1055 2. Added the device_caps field to struct v4l2
1056 the new V4L2_CAP_DEVICE_CAPS capability.
1057
1058 V4L2 in Linux 3.4
1059 =================
1060
1061 1. Added :ref:`JPEG compression control class
1062
1063 2. Extended the DV Timings API:
1064 :ref:`VIDIOC_ENUM_DV_TIMINGS`,
1065 :ref:`VIDIOC_QUERY_DV_TIMINGS` and
1066 :ref:`VIDIOC_DV_TIMINGS_CAP`.
1067
1068 V4L2 in Linux 3.5
1069 =================
1070
1071 1. Added integer menus, the new type will be
1072 V4L2_CTRL_TYPE_INTEGER_MENU.
1073
1074 2. Added selection API for V4L2 subdev interf
1075 :ref:`VIDIOC_SUBDEV_G_SELECTION` and
1076 :ref:`VIDIOC_SUBDEV_S_SELECTION <VIDIOC_SU
1077
1078 3. Added ``V4L2_COLORFX_ANTIQUE``, ``V4L2_COL
1079 ``V4L2_COLORFX_AQUA``, ``V4L2_COLORFX_SILH
1080 ``V4L2_COLORFX_SOLARIZATION``, ``V4L2_COLO
1081 ``V4L2_COLORFX_ARBITRARY_CBCR`` menu items
1082 ``V4L2_CID_COLORFX`` control.
1083
1084 4. Added ``V4L2_CID_COLORFX_CBCR`` control.
1085
1086 5. Added camera controls ``V4L2_CID_AUTO_EXPO
1087 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE``,
1088 ``V4L2_CID_IMAGE_STABILIZATION``, ``V4L2_C
1089 ``V4L2_CID_ISO_SENSITIVITY_AUTO``, ``V4L2_
1090 ``V4L2_CID_SCENE_MODE``, ``V4L2_CID_3A_LOC
1091 ``V4L2_CID_AUTO_FOCUS_START``, ``V4L2_CID_
1092 ``V4L2_CID_AUTO_FOCUS_STATUS`` and ``V4L2_
1093
1094 V4L2 in Linux 3.6
1095 =================
1096
1097 1. Replaced ``input`` in struct v4l2_buffer b
1098 ``reserved2`` and removed ``V4L2_BUF_FLAG_
1099
1100 2. Added V4L2_CAP_VIDEO_M2M and V4L2_CAP_VIDE
1101 capabilities.
1102
1103 3. Added support for frequency band enumerati
1104 :ref:`VIDIOC_ENUM_FREQ_BANDS`.
1105
1106 V4L2 in Linux 3.9
1107 =================
1108
1109 1. Added timestamp types to ``flags`` field i
1110 struct v4l2_buffer. See :ref:`buffer-flags
1111
1112 2. Added ``V4L2_EVENT_CTRL_CH_RANGE`` control
1113 :ref:`ctrl-changes-flags`.
1114
1115 V4L2 in Linux 3.10
1116 ==================
1117
1118 1. Removed obsolete and unused DV_PRESET ioct
1119 VIDIOC_S_DV_PRESET, VIDIOC_QUERY_DV_PRESET
1120 VIDIOC_ENUM_DV_PRESET. Remove the related
1121 capability flags V4L2_IN_CAP_PRESETS and V
1122
1123 2. Added new debugging ioctl
1124 :ref:`VIDIOC_DBG_G_CHIP_INFO`.
1125
1126 V4L2 in Linux 3.11
1127 ==================
1128
1129 1. Remove obsolete ``VIDIOC_DBG_G_CHIP_IDENT`
1130
1131 V4L2 in Linux 3.14
1132 ==================
1133
1134 1. In struct v4l2_rect, the type of ``width``
1135 ``height`` fields changed from _s32 to _u3
1136
1137 V4L2 in Linux 3.15
1138 ==================
1139
1140 1. Added Software Defined Radio (SDR) Interfa
1141
1142 V4L2 in Linux 3.16
1143 ==================
1144
1145 1. Added event V4L2_EVENT_SOURCE_CHANGE.
1146
1147 V4L2 in Linux 3.17
1148 ==================
1149
1150 1. Extended struct v4l2_pix_format. Added
1151 format flags.
1152
1153 2. Added compound control types and
1154 :ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYC
1155
1156 V4L2 in Linux 3.18
1157 ==================
1158
1159 1. Added ``V4L2_CID_PAN_SPEED`` and ``V4L2_CI
1160 controls.
1161
1162 V4L2 in Linux 3.19
1163 ==================
1164
1165 1. Rewrote Colorspace chapter, added new enum
1166 and enum v4l2_quantization fields to struc
1167 struct v4l2_pix_format_mplane and struct v
1168
1169 V4L2 in Linux 4.4
1170 =================
1171
1172 1. Renamed ``V4L2_TUNER_ADC`` to ``V4L2_TUNER
1173 ``V4L2_TUNER_ADC`` is deprecated now.
1174
1175 2. Added ``V4L2_CID_RF_TUNER_RF_GAIN`` RF Tun
1176
1177 3. Added transmitter support for Software Def
1178
1179 .. _other:
1180
1181 Relation of V4L2 to other Linux multimedia AP
1182 =============================================
1183
1184 .. _xvideo:
1185
1186 X Video Extension
1187 -----------------
1188
1189 The X Video Extension (abbreviated XVideo or
1190 the X Window system, implemented for example
1191 scope is similar to V4L2, an API to video cap
1192 X clients. Xv allows applications to display
1193 send window contents to a TV output, and capt
1194 in XPixmaps [#f1]_. With their implementation
1195 available across many operating systems and a
1196
1197 Because the driver is embedded into the X ser
1198 advantages over the V4L2 :ref:`video overlay
1199 driver can easily determine the overlay targe
1200 memory or off-screen buffers for a destructiv
1201 the RAMDAC for a non-destructive overlay, sca
1202 the clipping functions of the video capture h
1203 with drawing operations or windows moving or
1204 order.
1205
1206 To combine the advantages of Xv and V4L a spe
1207 XFree86 and XOrg, just programming any overla
1208 device it finds. To enable it ``/etc/X11/XF86
1209 lines:
1210
1211 ::
1212
1213 Section "Module"
1214 Load "v4l"
1215 EndSection
1216
1217 As of XFree86 4.2 this driver still supports
1218 should work just fine with all V4L2 devices t
1219 backward-compatibility layer. Since V4L2 perm
1220 possible (if supported by the V4L2 driver) to
1221 client requested video overlay. Restrictions
1222 and overlay are discussed in :ref:`overlay` a
1223
1224 Only marginally related to V4L2, XFree86 exte
1225 YUV to RGB conversion and scaling for faster
1226 an interface to MPEG-2 decoding hardware. Thi
1227 images captured with V4L2 devices.
1228
1229 Digital Video
1230 -------------
1231
1232 V4L2 does not support digital terrestrial, ca
1233 A separate project aiming at digital receiver
1234 homepage at `https://linuxtv.org <https://lin
1235 DVB API has no connection to the V4L2 API exc
1236 hardware may support both.
1237
1238 Audio Interfaces
1239 ----------------
1240
1241 [to do - OSS/ALSA]
1242
1243 .. _experimental:
1244
1245 Experimental API Elements
1246 =========================
1247
1248 The following V4L2 API elements are currently
1249 change in the future.
1250
1251 - :ref:`VIDIOC_DBG_G_REGISTER` and
1252 :ref:`VIDIOC_DBG_S_REGISTER <VIDIOC_DBG_G_
1253
1254 - :ref:`VIDIOC_DBG_G_CHIP_INFO` ioctl.
1255
1256 .. _obsolete:
1257
1258 Obsolete API Elements
1259 =====================
1260
1261 The following V4L2 API elements were supersed
1262 should not be implemented in new drivers.
1263
1264 - ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGC
1265 Controls, :ref:`extended-controls`.
1266
1267 - VIDIOC_G_DV_PRESET, VIDIOC_S_DV_PRESET,
1268 VIDIOC_ENUM_DV_PRESETS and VIDIOC_QUERY_DV
1269 the DV Timings API (:ref:`dv-timings`).
1270
1271 - ``VIDIOC_SUBDEV_G_CROP`` and ``VIDIOC_SUBD
1272 ``VIDIOC_SUBDEV_G_SELECTION`` and ``VIDIOC
1273 :ref:`VIDIOC_SUBDEV_G_SELECTION`.
1274
1275 .. [#f1]
1276 This is not implemented in XFree86.
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