1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 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 it was criticised as too 11 inflexible. In August 1998 Bill Dirks proposed a number of improvements 12 and began to work on documentation, example drivers and applications. 13 With the help of other volunteers this eventually became the V4L2 API, 14 not just an extension but a replacement for the V4L API. However it took 15 another four years and two stable kernel releases until the new API was 16 finally accepted for inclusion into the kernel in its present form. 17 18 Early Versions 19 ============== 20 21 1998-08-20: First version. 22 23 1998-08-27: The :c:func:`select()` function was introduced. 24 25 1998-09-10: New video standard interface. 26 27 1998-09-18: The ``VIDIOC_NONCAP`` ioctl was replaced by the otherwise 28 meaningless ``O_TRUNC`` :c:func:`open()` flag, and the 29 aliases ``O_NONCAP`` and ``O_NOIO`` were defined. Applications can set 30 this flag if they intend to access controls only, as opposed to capture 31 applications which need exclusive access. The ``VIDEO_STD_XXX`` 32 identifiers are now ordinals instead of flags, and the 33 ``video_std_construct()`` helper function takes id and 34 transmission arguments. 35 36 1998-09-28: Revamped video standard. Made video controls individually 37 enumerable. 38 39 1998-10-02: The ``id`` field was removed from 40 struct ``video_standard`` and the color subcarrier fields were 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 have been renamed. Some 48 material changes to struct v4l2_capability. 49 50 1998-11-12: The read/write direction of some ioctls was misdefined. 51 52 1998-11-14: ``V4L2_PIX_FMT_RGB24`` changed to ``V4L2_PIX_FMT_BGR24``, 53 and ``V4L2_PIX_FMT_RGB32`` changed to ``V4L2_PIX_FMT_BGR32``. Audio 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 under names starting 57 with ``V4L2_CID_AUDIO``. The ``V4L2_MAJOR`` define was removed from 58 ``videodev.h`` since it was only used once in the ``videodev`` kernel 59 module. The ``YUV422`` and ``YUV411`` planar image formats were added. 60 61 1998-11-28: A few ioctl symbols changed. Interfaces for codecs and video 62 output devices were added. 63 64 1999-01-14: A raw VBI capture interface was added. 65 66 1999-01-19: The ``VIDIOC_NEXTBUF`` ioctl was removed. 67 68 V4L2 Version 0.16 1999-01-31 69 ============================ 70 71 1999-01-27: There is now one QBUF ioctl, VIDIOC_QWBUF and VIDIOC_QRBUF 72 are gone. VIDIOC_QBUF takes a v4l2_buffer as a parameter. Added 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 to videodev.c. Driver 79 writers, this changes how you implement your ioctl handler. See the 80 Driver Writer's Guide. Added some more control id codes. 81 82 V4L2 Version 0.19 1999-06-05 83 ============================ 84 85 1999-03-18: Fill in the category and catname fields of v4l2_queryctrl 86 objects before passing them to the driver. Required a minor change to 87 the VIDIOC_QUERYCTRL handlers in the sample drivers. 88 89 1999-03-31: Better compatibility for v4l memory capture ioctls. Requires 90 changes to drivers to fully support new compatibility features, see 91 Driver Writer's Guide and v4l2cap.c. Added new control IDs: 92 V4L2_CID_HFLIP, _VFLIP. Changed V4L2_PIX_FMT_YUV422P to _YUV422P, 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 added the 100 V4L2_CTRL_FLAG_GRAYED (later V4L2_CTRL_FLAG_GRABBED) flag. 101 102 1999-05-20: Definition of VIDIOC_G_CTRL was wrong causing a 103 malfunction of this ioctl. 104 105 1999-06-05: Changed the value of V4L2_CID_WHITENESS. 106 107 V4L2 Version 0.20 (1999-09-10) 108 ============================== 109 110 Version 0.20 introduced a number of changes which were *not backward 111 compatible* with 0.19 and earlier versions. Purpose of these changes was 112 to simplify the API, while making it more extensible and following 113 common Linux driver API conventions. 114 115 1. Some typos in ``V4L2_FMT_FLAG`` symbols were fixed. struct v4l2_clip 116 was changed for compatibility with v4l. (1999-08-30) 117 118 2. ``V4L2_TUNER_SUB_LANG1`` was added. (1999-09-05) 119 120 3. All ioctl() commands that used an integer argument now take a pointer 121 to an integer. Where it makes sense, ioctls will return the actual 122 new value in the integer pointed to by the argument, a common 123 convention in the V4L2 API. The affected ioctls are: VIDIOC_PREVIEW, 124 VIDIOC_STREAMON, VIDIOC_STREAMOFF, VIDIOC_S_FREQ, 125 VIDIOC_S_INPUT, VIDIOC_S_OUTPUT, VIDIOC_S_EFFECT. For example 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, VIDIOC_XXX, &a); 136 137 4. All the different get- and set-format commands were swept into one 138 :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and 139 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl taking a union and a 140 type field selecting the union member as parameter. Purpose is to 141 simplify the API by eliminating several ioctls and to allow new and 142 driver private data streams without adding new ioctls. 143 144 This change obsoletes the following ioctls: ``VIDIOC_S_INFMT``, 145 ``VIDIOC_G_INFMT``, ``VIDIOC_S_OUTFMT``, ``VIDIOC_G_OUTFMT``, 146 ``VIDIOC_S_VBIFMT`` and ``VIDIOC_G_VBIFMT``. The image format 147 struct v4l2_format was renamed to struct v4l2_pix_format, while 148 struct v4l2_format is now the enveloping structure 149 for all format negotiations. 150 151 5. Similar to the changes above, the ``VIDIOC_G_PARM`` and 152 ``VIDIOC_S_PARM`` ioctls were merged with ``VIDIOC_G_OUTPARM`` and 153 ``VIDIOC_S_OUTPARM``. A ``type`` field in the new struct v4l2_streamparm 154 selects the respective union member. 155 156 This change obsoletes the ``VIDIOC_G_OUTPARM`` and 157 ``VIDIOC_S_OUTPARM`` ioctls. 158 159 6. Control enumeration was simplified, and two new control flags were 160 introduced and one dropped. The ``catname`` field was replaced by a 161 ``group`` field. 162 163 Drivers can now flag unsupported and temporarily unavailable controls 164 with ``V4L2_CTRL_FLAG_DISABLED`` and ``V4L2_CTRL_FLAG_GRABBED`` 165 respectively. The ``group`` name indicates a possibly narrower 166 classification than the ``category``. In other words, there may be 167 multiple groups within a category. Controls within a group would 168 typically be drawn within a group box. Controls in different 169 categories might have a greater separation, or may even appear in 170 separate windows. 171 172 7. The struct v4l2_buffer ``timestamp`` was 173 changed to a 64 bit integer, containing the sampling or output time 174 of the frame in nanoseconds. Additionally timestamps will be in 175 absolute system time, not starting from zero at the beginning of a 176 stream. The data type name for timestamps is stamp_t, defined as a 177 signed 64-bit integer. Output devices should not send a buffer out 178 until the time in the timestamp field has arrived. I would like to 179 follow SGI's lead, and adopt a multimedia timestamping system like 180 their UST (Unadjusted System Time). See 181 http://web.archive.org/web/\*/http://reality.sgi.com 182 /cpirazzi_engr/lg/time/intro.html. UST uses timestamps that are 183 64-bit signed integers (not struct timeval's) and given in nanosecond 184 units. The UST clock starts at zero when the system is booted and 185 runs continuously and uniformly. It takes a little over 292 years for 186 UST to overflow. There is no way to set the UST clock. The regular 187 Linux time-of-day clock can be changed periodically, which would 188 cause errors if it were being used for timestamping a multimedia 189 stream. A real UST style clock will require some support in the 190 kernel that is not there yet. But in anticipation, I will change the 191 timestamp field to a 64-bit integer, and I will change the 192 v4l2_masterclock_gettime() function (used only by drivers) to 193 return a 64-bit integer. 194 195 8. A ``sequence`` field was added to struct v4l2_buffer. The ``sequence`` 196 field counts captured frames, it is ignored by output devices. When a 197 capture driver drops a frame, the sequence number of that frame is skipped. 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``. Previously drivers were required 204 to clear the ``reserved1`` field. 205 206 2000-01-13: The ``V4L2_FMT_FLAG_NOT_INTERLACED`` flag was added. 207 208 2000-07-31: The ``linux/poll.h`` header is now included by 209 ``videodev.h`` for compatibility with the original ``videodev.h`` file. 210 211 2000-11-20: ``V4L2_TYPE_VBI_OUTPUT`` and ``V4L2_PIX_FMT_Y41P`` were 212 added. 213 214 2000-11-25: ``V4L2_TYPE_VBI_INPUT`` was added. 215 216 2000-12-04: A couple typos in symbol names were fixed. 217 218 2001-01-18: To avoid namespace conflicts the ``fourcc`` macro defined in 219 the ``videodev.h`` header file was renamed to ``v4l2_fourcc``. 220 221 2001-01-25: A possible driver-level compatibility problem between the 222 ``videodev.h`` file in Linux 2.4.0 and the ``videodev.h`` file included 223 in the ``videodevX`` patch was fixed. Users of an earlier version of 224 ``videodevX`` on Linux 2.4.0 should recompile their V4L and V4L2 225 drivers. 226 227 2001-01-26: A possible kernel-level incompatibility between the 228 ``videodev.h`` file in the ``videodevX`` patch and the ``videodev.h`` 229 file in Linux 2.2.x with devfs patches applied was fixed. 230 231 2001-03-02: Certain V4L ioctls which pass data in both direction 232 although they are defined with read-only parameter, did not work 233 correctly through the backward compatibility layer. [Solution?] 234 235 2001-04-13: Big endian 16-bit RGB formats were added. 236 237 2001-09-17: New YUV formats and the 238 :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` and 239 :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctls were added. 240 (The old ``VIDIOC_G_FREQ`` and ``VIDIOC_S_FREQ`` ioctls did not take 241 multiple tuners into account.) 242 243 2000-09-18: ``V4L2_BUF_TYPE_VBI`` was added. This may *break 244 compatibility* as the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and 245 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls may fail now if the 246 struct ``v4l2_fmt`` ``type`` field does not contain 247 ``V4L2_BUF_TYPE_VBI``. In the documentation of the struct v4l2_vbi_format`, 248 the ``offset`` field the ambiguous phrase "rising edge" was changed to 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 interface. 255 256 1. Figures clarifying the line numbering scheme were added to the V4L2 257 API specification. The ``start``\ [0] and ``start``\ [1] fields no 258 longer count line numbers beginning at zero. Rationale: a) The 259 previous definition was unclear. b) The ``start``\ [] values are 260 ordinal numbers. c) There is no point in inventing a new line 261 numbering scheme. We now use line number as defined by ITU-R, period. 262 Compatibility: Add one to the start values. Applications depending on 263 the previous semantics may not function correctly. 264 265 2. The restriction "count[0] > 0 and count[1] > 0" has been relaxed to 266 "(count[0] + count[1]) > 0". Rationale: Drivers may allocate 267 resources at scan line granularity and some data services are 268 transmitted only on the first field. The comment that both ``count`` 269 values will usually be equal is misleading and pointless and has been 270 removed. This change *breaks compatibility* with earlier versions: 271 Drivers may return ``EINVAL``, applications may not function correctly. 272 273 3. Drivers are again permitted to return negative (unknown) start values 274 as proposed earlier. Why this feature was dropped is unclear. This 275 change may *break compatibility* with applications depending on the 276 start values being positive. The use of ``EBUSY`` and ``EINVAL`` 277 error codes with the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl was 278 clarified. The ``EBUSY`` error code was finally documented, and the 279 ``reserved2`` field which was previously mentioned only in the 280 ``videodev.h`` header file. 281 282 4. New buffer types ``V4L2_TYPE_VBI_INPUT`` and ``V4L2_TYPE_VBI_OUTPUT`` 283 were added. The former is an alias for the old ``V4L2_TYPE_VBI``, the 284 latter was missing in the ``videodev.h`` file. 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 announced feature freeze of 295 Linux 2.5, the API was revised, drawing from experience with V4L2 0.20. 296 This unnamed version was finally merged into Linux 2.5.46. 297 298 1. As specified in :ref:`related`, drivers must make related device 299 functions available under all minor device numbers. 300 301 2. The :c:func:`open()` function requires access mode 302 ``O_RDWR`` regardless of the device type. All V4L2 drivers 303 exchanging data with applications must support the ``O_NONBLOCK`` 304 flag. The ``O_NOIO`` flag, a V4L2 symbol which aliased the 305 meaningless ``O_TRUNC`` to indicate accesses without data exchange 306 (panel applications) was dropped. Drivers must stay in "panel mode" 307 until the application attempts to initiate a data exchange, see 308 :ref:`open`. 309 310 3. The struct v4l2_capability changed 311 dramatically. Note that also the size of the structure changed, 312 which is encoded in the ioctl request code, thus older V4L2 devices 313 will respond with an ``EINVAL`` error code to the new 314 :ref:`VIDIOC_QUERYCAP` ioctl. 315 316 There are new fields to identify the driver, a new RDS device 317 function ``V4L2_CAP_RDS_CAPTURE``, the ``V4L2_CAP_AUDIO`` flag 318 indicates if the device has any audio connectors, another I/O 319 capability V4L2_CAP_ASYNCIO can be flagged. In response to these 320 changes the ``type`` field became a bit set and was merged into the 321 ``flags`` field. ``V4L2_FLAG_TUNER`` was renamed to 322 ``V4L2_CAP_TUNER``, ``V4L2_CAP_VIDEO_OVERLAY`` replaced 323 ``V4L2_FLAG_PREVIEW`` and ``V4L2_CAP_VBI_CAPTURE`` and 324 ``V4L2_CAP_VBI_OUTPUT`` replaced ``V4L2_FLAG_DATA_SERVICE``. 325 ``V4L2_FLAG_READ`` and ``V4L2_FLAG_WRITE`` were merged into 326 ``V4L2_CAP_READWRITE``. 327 328 The redundant fields ``inputs``, ``outputs`` and ``audios`` were 329 removed. These properties can be determined as described in 330 :ref:`video` and :ref:`audio`. 331 332 The somewhat volatile and therefore barely useful fields 333 ``maxwidth``, ``maxheight``, ``minwidth``, ``minheight``, 334 ``maxframerate`` were removed. This information is available as 335 described in :ref:`format` and :ref:`standard`. 336 337 ``V4L2_FLAG_SELECT`` was removed. We believe the select() function 338 is important enough to require support of it in all V4L2 drivers 339 exchanging data with applications. The redundant 340 ``V4L2_FLAG_MONOCHROME`` flag was removed, this information is 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 only flag 345 ``V4L2_INPUT_CAP_AUDIO`` was replaced by the new ``audioset`` field. 346 Instead of linking one video input to one audio input this field 347 reports all audio inputs this video input combines with. 348 349 New fields are ``tuner`` (reversing the former link from tuners to 350 video inputs), ``std`` and ``status``. 351 352 Accordingly struct v4l2_output lost its 353 ``capability`` and ``assoc_audio`` fields. ``audioset``, 354 ``modulator`` and ``std`` where added instead. 355 356 5. The struct v4l2_audio field ``audio`` was 357 renamed to ``index``, for consistency with other structures. A new 358 capability flag ``V4L2_AUDCAP_STEREO`` was added to indicated if the 359 audio input in question supports stereo sound. 360 ``V4L2_AUDCAP_EFFECTS`` and the corresponding ``V4L2_AUDMODE`` flags 361 where removed. This can be easily implemented using controls. 362 (However the same applies to AVL which is still there.) 363 364 Again for consistency the struct v4l2_audioout field ``audio`` was renamed 365 to ``index``. 366 367 6. The struct v4l2_tuner ``input`` field was 368 replaced by an ``index`` field, permitting devices with multiple 369 tuners. The link between video inputs and tuners is now reversed, 370 inputs point to their tuner. The ``std`` substructure became a 371 simple set (more about this below) and moved into struct v4l2_input. 372 A ``type`` field was added. 373 374 Accordingly in struct v4l2_modulator the 375 ``output`` was replaced by an ``index`` field. 376 377 In struct v4l2_frequency the ``port`` 378 field was replaced by a ``tuner`` field containing the respective 379 tuner or modulator index number. A tuner ``type`` field was added 380 and the ``reserved`` field became larger for future extensions 381 (satellite tuners in particular). 382 383 7. The idea of completely transparent video standards was dropped. 384 Experience showed that applications must be able to work with video 385 standards beyond presenting the user a menu. Instead of enumerating 386 supported standards with an ioctl applications can now refer to 387 standards by :ref:`v4l2_std_id <v4l2-std-id>` and symbols 388 defined in the ``videodev2.h`` header file. For details see 389 :ref:`standard`. The :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and 390 :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` now take a pointer to this 391 type as argument. :ref:`VIDIOC_QUERYSTD` was 392 added to autodetect the received standard, if the hardware has this 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 named ``id`` was added as 397 machine readable identifier, also replacing the ``transmission`` 398 field. The misleading ``framerate`` field was renamed to 399 ``frameperiod``. The now obsolete ``colorstandard`` information, 400 originally needed to distguish between variations of standards, were 401 removed. 402 403 Struct ``v4l2_enumstd`` ceased to be. 404 :ref:`VIDIOC_ENUMSTD` now takes a pointer to a 405 struct v4l2_standard directly. The 406 information which standards are supported by a particular video 407 input or output moved into struct v4l2_input 408 and struct v4l2_output fields named ``std``, 409 respectively. 410 411 8. The struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` fields 412 ``category`` and ``group`` did not catch on and/or were not 413 implemented as expected and therefore removed. 414 415 9. The :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>` ioctl was added to 416 negotiate data formats as with 417 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>`, but without the overhead of 418 programming the hardware and regardless of I/O in progress. 419 420 In struct v4l2_format the ``fmt`` union was 421 extended to contain struct v4l2_window. All 422 image format negotiations are now possible with ``VIDIOC_G_FMT``, 423 ``VIDIOC_S_FMT`` and ``VIDIOC_TRY_FMT``; ioctl. The ``VIDIOC_G_WIN`` 424 and ``VIDIOC_S_WIN`` ioctls to prepare for a video overlay were 425 removed. The ``type`` field changed to type enum v4l2_buf_type and 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 this is deprecated) 461 462 10. In struct v4l2_fmtdesc a enum v4l2_buf_type field named ``type`` was 463 added as in struct v4l2_format. The ``VIDIOC_ENUM_FBUFFMT`` ioctl is no 464 longer needed and was removed. These calls can be replaced by 465 :ref:`VIDIOC_ENUM_FMT` with type ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. 466 467 11. In struct v4l2_pix_format the ``depth`` 468 field was removed, assuming applications which recognize the format 469 by its four-character-code already know the color depth, and others 470 do not care about it. The same rationale lead to the removal of the 471 ``V4L2_FMT_FLAG_COMPRESSED`` flag. The 472 ``V4L2_FMT_FLAG_SWCONVECOMPRESSED`` flag was removed because drivers 473 are not supposed to convert images in kernel space. A user library 474 of conversion functions should be provided instead. The 475 ``V4L2_FMT_FLAG_BYTESPERLINE`` flag was redundant. Applications can 476 set the ``bytesperline`` field to zero to get a reasonable default. 477 Since the remaining flags were replaced as well, the ``flags`` field 478 itself was removed. 479 480 The interlace flags were replaced by a enum v4l2_field value in a 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`` = ``V4L2_FMT_FLAG_COMBINED`` 492 - ``V4L2_FIELD_INTERLACED`` 493 * - ``V4L2_FMT_FLAG_TOPFIELD`` = ``V4L2_FMT_FLAG_ODDFIELD`` 494 - ``V4L2_FIELD_TOP`` 495 * - ``V4L2_FMT_FLAG_BOTFIELD`` = ``V4L2_FMT_FLAG_EVENFIELD`` 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 enum v4l2_colorspace value in 505 a newly added ``colorspace`` field, where one of 506 ``V4L2_COLORSPACE_SMPTE170M``, ``V4L2_COLORSPACE_BT878``, 507 ``V4L2_COLORSPACE_470_SYSTEM_M`` or 508 ``V4L2_COLORSPACE_470_SYSTEM_BG`` replaces ``V4L2_FMT_CS_601YUV``. 509 510 12. In struct v4l2_requestbuffers the 511 ``type`` field was properly defined as enum v4l2_buf_type. Buffer types 512 changed as mentioned above. A new ``memory`` field of type 513 enum v4l2_memory was added to distinguish between 514 I/O methods using buffers allocated by the driver or the 515 application. See :ref:`io` for details. 516 517 13. In struct v4l2_buffer the ``type`` field was 518 properly defined as enum v4l2_buf_type. 519 Buffer types changed as mentioned above. A ``field`` field of type 520 enum v4l2_field was added to indicate if a 521 buffer contains a top or bottom field. The old field flags were 522 removed. Since no unadjusted system time clock was added to the 523 kernel as planned, the ``timestamp`` field changed back from type 524 stamp_t, an unsigned 64 bit integer expressing the sample time in 525 nanoseconds, to struct timeval. With the addition 526 of a second memory mapping method the ``offset`` field moved into 527 union ``m``, and a new ``memory`` field of type enum v4l2_memory 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 by the V4L compatibility 532 layer, after changes to this code it was no longer needed. The 533 ``V4L2_BUF_ATTR_DEVICEMEM`` flag would indicate if the buffer was 534 indeed allocated in device memory rather than DMA-able system 535 memory. It was barely useful and so was removed. 536 537 14. In struct v4l2_framebuffer the 538 ``base[3]`` array anticipating double- and triple-buffering in 539 off-screen video memory, however without defining a synchronization 540 mechanism, was replaced by a single pointer. The 541 ``V4L2_FBUF_CAP_SCALEUP`` and ``V4L2_FBUF_CAP_SCALEDOWN`` flags were 542 removed. Applications can determine this capability more accurately 543 using the new cropping and scaling interface. The 544 ``V4L2_FBUF_CAP_CLIPPING`` flag was replaced by 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 a ``c`` substructure of 550 type struct v4l2_rect. The ``x`` and ``y`` 551 fields were renamed to ``left`` and ``top``, i. e. offsets to a 552 context dependent origin. 553 554 16. In struct v4l2_window the ``x``, ``y``, 555 ``width`` and ``height`` field moved into a ``w`` substructure as 556 above. A ``field`` field of type enum v4l2_field was added to 557 distinguish between field and frame (interlaced) overlay. 558 559 17. The digital zoom interface, including struct ``v4l2_zoomcap``, 560 struct ``v4l2_zoom``, ``V4L2_ZOOM_NONCAP`` and 561 ``V4L2_ZOOM_WHILESTREAMING`` was replaced by a new cropping and 562 scaling interface. The previously unused 563 struct v4l2_cropcap and struct v4l2_crop 564 where redefined for this purpose. See :ref:`crop` for details. 565 566 18. In struct v4l2_vbi_format the 567 ``SAMPLE_FORMAT`` field now contains a four-character-code as used 568 to identify video image formats and ``V4L2_PIX_FMT_GREY`` replaces 569 the ``V4L2_VBI_SF_UBYTE`` define. The ``reserved`` field was 570 extended. 571 572 19. In struct v4l2_captureparm the type of 573 the ``timeperframe`` field changed from unsigned long to 574 struct v4l2_fract. This allows the accurate 575 expression of multiples of the NTSC-M frame rate 30000 / 1001. A new 576 field ``readbuffers`` was added to control the driver behaviour in 577 read I/O mode. 578 579 Similar changes were made to struct v4l2_outputparm. 580 581 20. The struct ``v4l2_performance`` and 582 ``VIDIOC_G_PERF`` ioctl were dropped. Except when using the 583 :ref:`read/write I/O method <rw>`, which is limited anyway, this 584 information is already available to applications. 585 586 21. The example transformation from RGB to YCbCr color space in the old 587 V4L2 documentation was inaccurate, this has been corrected in 588 :ref:`pixfmt`. 589 590 V4L2 2003-06-19 591 =============== 592 593 1. A new capability flag ``V4L2_CAP_RADIO`` was added for radio devices. 594 Prior to this change radio devices would identify solely by having 595 exactly one tuner whose type field reads ``V4L2_TUNER_RADIO``. 596 597 2. An optional driver access priority mechanism was added, see 598 :ref:`app-pri` for details. 599 600 3. The audio input and output interface was found to be incomplete. 601 602 Previously the :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` ioctl would 603 enumerate the available audio inputs. An ioctl to determine the 604 current audio input, if more than one combines with the current video 605 input, did not exist. So ``VIDIOC_G_AUDIO`` was renamed to 606 ``VIDIOC_G_AUDIO_OLD``, this ioctl was removed on Kernel 2.6.39. The 607 :ref:`VIDIOC_ENUMAUDIO` ioctl was added to 608 enumerate audio inputs, while 609 :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` now reports the current 610 audio input. 611 612 The same changes were made to 613 :ref:`VIDIOC_G_AUDOUT <VIDIOC_G_AUDOUT>` and 614 :ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>`. 615 616 Until further the "videodev" module will automatically translate 617 between the old and new ioctls, but drivers and applications must be 618 updated to successfully compile again. 619 620 4. The :ref:`VIDIOC_OVERLAY` ioctl was incorrectly 621 defined with write-read parameter. It was changed to write-only, 622 while the write-read version was renamed to ``VIDIOC_OVERLAY_OLD``. 623 The old ioctl was removed on Kernel 2.6.39. Until further the 624 "videodev" kernel module will automatically translate to the new 625 version, so drivers must be recompiled, but not applications. 626 627 5. :ref:`overlay` incorrectly stated that clipping rectangles define 628 regions where the video can be seen. Correct is that clipping 629 rectangles define regions where *no* video shall be displayed and so 630 the graphics surface can be seen. 631 632 6. The :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` and 633 :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls were defined with 634 write-only parameter, inconsistent with other ioctls modifying their 635 argument. They were changed to write-read, while a ``_OLD`` suffix 636 was added to the write-only versions. The old ioctls were removed on 637 Kernel 2.6.39. Drivers and applications assuming a constant parameter 638 need an update. 639 640 V4L2 2003-11-05 641 =============== 642 643 1. In :ref:`pixfmt-rgb` the following pixel formats were incorrectly 644 transferred from Bill Dirks' V4L2 specification. Descriptions below 645 refer to bytes in memory, in ascending address order. 646 647 648 .. flat-table:: 649 :header-rows: 1 650 :stub-columns: 0 651 652 * - Symbol 653 - In this document prior to revision 0.5 654 - 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 always correct. 669 670 In :ref:`v4l-image-properties` the mapping of the V4L 671 ``VIDEO_PALETTE_RGB24`` and ``VIDEO_PALETTE_RGB32`` formats to V4L2 672 pixel formats was accordingly corrected. 673 674 2. Unrelated to the fixes above, drivers may still interpret some V4L2 675 RGB pixel formats differently. These issues have yet to be addressed, 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 incorrectly 682 defined with read-only parameter. It is now defined as write-read 683 ioctl, while the read-only version was renamed to 684 ``VIDIOC_CROPCAP_OLD``. The old ioctl was removed on Kernel 2.6.39. 685 686 V4L2 in Linux 2.6.8 687 =================== 688 689 1. A new field ``input`` (former ``reserved[0]``) was added to the 690 struct v4l2_buffer. Purpose of this 691 field is to alternate between video inputs (e. g. cameras) in step 692 with the video capturing process. This function must be enabled with 693 the new ``V4L2_BUF_FLAG_INPUT`` flag. The ``flags`` field is no 694 longer read-only. 695 696 V4L2 spec erratum 2004-08-01 697 ============================ 698 699 1. The return value of the :ref:`func-open` function was incorrectly 700 documented. 701 702 2. Audio output ioctls end in -AUDOUT, not -AUDIOOUT. 703 704 3. In the Current Audio Input example the ``VIDIOC_G_AUDIO`` ioctl took 705 the wrong argument. 706 707 4. The documentation of the :ref:`VIDIOC_QBUF` and 708 :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctls did not mention the 709 struct v4l2_buffer ``memory`` field. It was 710 also missing from examples. Also on the ``VIDIOC_DQBUF`` page the ``EIO`` 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 documented in 717 :ref:`sliced` and replaces the interface first proposed in V4L2 718 specification 0.8. 719 720 V4L2 in Linux 2.6.15 721 ==================== 722 723 1. The :ref:`VIDIOC_LOG_STATUS` ioctl was added. 724 725 2. New video standards ``V4L2_STD_NTSC_443``, ``V4L2_STD_SECAM_LC``, 726 ``V4L2_STD_SECAM_DK`` (a set of SECAM D, K and K1), and 727 ``V4L2_STD_ATSC`` (a set of ``V4L2_STD_ATSC_8_VSB`` and 728 ``V4L2_STD_ATSC_16_VSB``) were defined. Note the ``V4L2_STD_525_60`` 729 set now includes ``V4L2_STD_NTSC_443``. See also 730 :ref:`v4l2-std-id`. 731 732 3. The ``VIDIOC_G_COMP`` and ``VIDIOC_S_COMP`` ioctl were renamed to 733 ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGCOMP`` respectively. Their 734 argument was replaced by a struct 735 ``v4l2_mpeg_compression`` pointer. (The 736 ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGCOMP`` ioctls where removed 737 in Linux 2.6.25.) 738 739 V4L2 spec erratum 2005-11-27 740 ============================ 741 742 The capture example in :ref:`capture-example` called the 743 :ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctl without checking if 744 cropping is supported. In the video standard selection example in 745 :ref:`standard` the :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` call used 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 struct v4l2_input not only 752 indicates if the color killer is enabled, but also if it is active. 753 (The color killer disables color decoding when it detects no color 754 in the video signal to improve the image quality.) 755 756 2. :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` is a write-read ioctl, not 757 write-only as stated on its reference page. The ioctl changed in 2003 758 as noted above. 759 760 V4L2 spec erratum 2006-02-03 761 ============================ 762 763 1. In struct v4l2_captureparm and struct v4l2_outputparm the ``timeperframe`` 764 field gives the time in seconds, not microseconds. 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, not 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: ``V4L2_STD_NTSC_M_KR`` (NTSC M 778 South Korea), and the sets ``V4L2_STD_MN``, ``V4L2_STD_B``, 779 ``V4L2_STD_GH`` and ``V4L2_STD_DK``. The ``V4L2_STD_NTSC`` and 780 ``V4L2_STD_SECAM`` sets now include ``V4L2_STD_NTSC_M_KR`` and 781 ``V4L2_STD_SECAM_LC`` respectively. 782 783 2. A new ``V4L2_TUNER_MODE_LANG1_LANG2`` was defined to record both 784 languages of a bilingual program. The use of 785 ``V4L2_TUNER_MODE_STEREO`` for this purpose is deprecated now. See 786 the :ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>` section for details. 787 788 V4L2 spec erratum 2006-09-23 (Draft 0.15) 789 ========================================= 790 791 1. In various places ``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` and 792 ``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT`` of the sliced VBI interface were 793 not mentioned along with other buffer types. 794 795 2. In :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` it was clarified that the 796 struct v4l2_audio ``mode`` field is a flags field. 797 798 3. :ref:`VIDIOC_QUERYCAP` did not mention the sliced VBI and radio 799 capability flags. 800 801 4. In :ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` it was clarified that 802 applications must initialize the tuner ``type`` field of 803 struct v4l2_frequency before calling 804 :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>`. 805 806 5. The ``reserved`` array in struct v4l2_requestbuffers has 2 elements, 807 not 32. 808 809 6. In :ref:`output` and :ref:`raw-vbi` the device file names 810 ``/dev/vout`` which never caught on were replaced by ``/dev/video``. 811 812 7. With Linux 2.6.15 the possible range for VBI device minor numbers was 813 extended from 224-239 to 224-255. Accordingly device file names 814 ``/dev/vbi0`` to ``/dev/vbi31`` are possible now. 815 816 V4L2 in Linux 2.6.18 817 ==================== 818 819 1. New ioctls :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, 820 :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and 821 :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` were added, a 822 flag to skip unsupported controls with 823 :ref:`VIDIOC_QUERYCTRL`, new control types 824 ``V4L2_CTRL_TYPE_INTEGER64`` and ``V4L2_CTRL_TYPE_CTRL_CLASS`` 825 (enum v4l2_ctrl_type), and new control flags 826 ``V4L2_CTRL_FLAG_READ_ONLY``, ``V4L2_CTRL_FLAG_UPDATE``, 827 ``V4L2_CTRL_FLAG_INACTIVE`` and ``V4L2_CTRL_FLAG_SLIDER`` 828 (:ref:`control-flags`). See :ref:`extended-controls` for details. 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 reserved field. Note on 835 architectures where the size of enum types differs from int types the 836 size of the structure changed. The 837 :ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl 838 was redefined from being read-only to write-read. Applications must 839 initialize the type field and clear the reserved fields now. These 840 changes may *break the compatibility* with older drivers and 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`` (:ref:`pixfmt-rgb`) was 849 added. 850 851 V4L2 spec erratum 2006-10-12 (Draft 0.17) 852 ========================================= 853 854 1. ``V4L2_PIX_FMT_HM12`` (:ref:`reserved-formats`) is a YUV 4:2:0, not 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 licensed under GNU 861 General Public License version two or later, and under a 3-clause 862 BSD-style license. 863 864 V4L2 in Linux 2.6.22 865 ==================== 866 867 1. Two new field orders ``V4L2_FIELD_INTERLACED_TB`` and 868 ``V4L2_FIELD_INTERLACED_BT`` were added. See enum v4l2_field for 869 details. 870 871 2. Three new clipping/blending methods with a global or straight or 872 inverted local alpha value were added to the video overlay interface. 873 See the description of the :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>` 874 and :ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>` ioctls for details. 875 876 A new ``global_alpha`` field was added to struct v4l2_window, 877 extending the structure. This may **break compatibility** with 878 applications using a struct v4l2_window directly. However the 879 :ref:`VIDIOC_G/S/TRY_FMT <VIDIOC_G_FMT>` ioctls, which take a 880 pointer to a struct v4l2_format parent structure 881 with padding bytes at the end, are not affected. 882 883 3. The format of the ``chromakey`` field in struct v4l2_window changed from 884 "host order RGB32" to a pixel value in the same format as the framebuffer. 885 This may **break compatibility** with existing applications. Drivers 886 supporting the "host order RGB32" format are not known. 887 888 V4L2 in Linux 2.6.24 889 ==================== 890 891 1. The pixel formats ``V4L2_PIX_FMT_PAL8``, ``V4L2_PIX_FMT_YUV444``, 892 ``V4L2_PIX_FMT_YUV555``, ``V4L2_PIX_FMT_YUV565`` and 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 <V4L2-PIX-FMT-Y16>` and 899 :ref:`V4L2_PIX_FMT_SBGGR16 <V4L2-PIX-FMT-SBGGR16>` were added. 900 901 2. New :ref:`controls <control>` ``V4L2_CID_POWER_LINE_FREQUENCY``, 902 ``V4L2_CID_HUE_AUTO``, ``V4L2_CID_WHITE_BALANCE_TEMPERATURE``, 903 ``V4L2_CID_SHARPNESS`` and ``V4L2_CID_BACKLIGHT_COMPENSATION`` were 904 added. The controls ``V4L2_CID_BLACK_LEVEL``, ``V4L2_CID_WHITENESS``, 905 ``V4L2_CID_HCENTER`` and ``V4L2_CID_VCENTER`` were deprecated. 906 907 3. A :ref:`Camera controls class <camera-controls>` was added, with 908 the new controls ``V4L2_CID_EXPOSURE_AUTO``, 909 ``V4L2_CID_EXPOSURE_ABSOLUTE``, ``V4L2_CID_EXPOSURE_AUTO_PRIORITY``, 910 ``V4L2_CID_PAN_RELATIVE``, ``V4L2_CID_TILT_RELATIVE``, 911 ``V4L2_CID_PAN_RESET``, ``V4L2_CID_TILT_RESET``, 912 ``V4L2_CID_PAN_ABSOLUTE``, ``V4L2_CID_TILT_ABSOLUTE``, 913 ``V4L2_CID_FOCUS_ABSOLUTE``, ``V4L2_CID_FOCUS_RELATIVE`` and 914 ``V4L2_CID_FOCUS_AUTO``. 915 916 4. The ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGCOMP`` ioctls, which 917 were superseded by the :ref:`extended controls <extended-controls>` 918 interface in Linux 2.6.18, where finally removed from the 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 ``V4L2_PIX_FMT_SBGGR16`` 925 were added. 926 927 2. Added user controls ``V4L2_CID_CHROMA_AGC`` and 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`` capability were added. 935 936 2. The pixel formats ``V4L2_PIX_FMT_YVYU``, ``V4L2_PIX_FMT_PCA501``, 937 ``V4L2_PIX_FMT_PCA505``, ``V4L2_PIX_FMT_PCA508``, 938 ``V4L2_PIX_FMT_PCA561``, ``V4L2_PIX_FMT_SGBRG8``, 939 ``V4L2_PIX_FMT_PAC207`` and ``V4L2_PIX_FMT_PJPG`` were added. 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 encodings. 946 947 2. Added ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC`` MPEG video encoding. 948 949 3. The pixel formats ``V4L2_PIX_FMT_SGRBG10`` and 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 renamed to 956 ``VIDIOC_G_CHIP_IDENT_OLD`` and ``VIDIOC_DBG_G_CHIP_IDENT`` was 957 introduced in its place. The old struct ``v4l2_chip_ident`` was renamed to 958 struct ``v4l2_chip_ident_old``. 959 960 2. The pixel formats ``V4L2_PIX_FMT_VYUY``, ``V4L2_PIX_FMT_NV16`` and 961 ``V4L2_PIX_FMT_NV61`` were added. 962 963 3. Added camera controls ``V4L2_CID_ZOOM_ABSOLUTE``, 964 ``V4L2_CID_ZOOM_RELATIVE``, ``V4L2_CID_ZOOM_CONTINUOUS`` and 965 ``V4L2_CID_PRIVACY``. 966 967 V4L2 in Linux 2.6.30 968 ==================== 969 970 1. New control flag ``V4L2_CTRL_FLAG_WRITE_ONLY`` was added. 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 and a kernel version, now 978 V4L2 API is numbered using the Linux Kernel version numeration. 979 980 2. Finalized the RDS capture API. See :ref:`rds` for more information. 981 982 3. Added new capabilities for modulators and RDS encoders. 983 984 4. Add description for libv4l API. 985 986 5. Added support for string controls via new type 987 ``V4L2_CTRL_TYPE_STRING``. 988 989 6. Added ``V4L2_CID_BAND_STOP_FILTER`` documentation. 990 991 7. Added FM Modulator (FM TX) Extended Control Class: 992 ``V4L2_CTRL_CLASS_FM_TX`` and their Control IDs. 993 994 8. Added FM Receiver (FM RX) Extended Control Class: 995 ``V4L2_CTRL_CLASS_FM_RX`` and their Control IDs. 996 997 9. Added Remote Controller chapter, describing the default Remote 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 order to support HDTV 1004 receivers and transmitters. 1005 1006 V4L2 in Linux 2.6.34 1007 ==================== 1008 1009 1. Added ``V4L2_CID_IRIS_ABSOLUTE`` and ``V4L2_CID_IRIS_RELATIVE`` 1010 controls to the :ref:`Camera controls class <camera-controls>`. 1011 1012 V4L2 in Linux 2.6.37 1013 ==================== 1014 1015 1. Remove the vtx (videotext/teletext) API. This API was no longer used 1016 and no hardware exists to verify the API. Nor were any userspace 1017 applications found that used it. It was originally scheduled for 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 support were removed. 1024 1025 2. Multi-planar API added. Does not affect the compatibility of current 1026 drivers and applications. See :ref:`multi-planar API <planar-apis>` 1027 for details. 1028 1029 V4L2 in Linux 3.1 1030 ================= 1031 1032 1. VIDIOC_QUERYCAP now returns a per-subsystem version instead of a 1033 per-driver one. 1034 1035 Standardize an error code for invalid ioctl. 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 signal volatile controls to 1043 userspace. 1044 1045 2. Add selection API for extended control over cropping and composing. 1046 Does not affect the compatibility of current drivers and 1047 applications. See :ref:`selection API <selection-api>` for details. 1048 1049 V4L2 in Linux 3.3 1050 ================= 1051 1052 1. Added ``V4L2_CID_ALPHA_COMPONENT`` control to the 1053 :ref:`User controls class <control>`. 1054 1055 2. Added the device_caps field to struct v4l2_capabilities and added 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 <jpeg-controls>`. 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 interface: 1075 :ref:`VIDIOC_SUBDEV_G_SELECTION` and 1076 :ref:`VIDIOC_SUBDEV_S_SELECTION <VIDIOC_SUBDEV_G_SELECTION>`. 1077 1078 3. Added ``V4L2_COLORFX_ANTIQUE``, ``V4L2_COLORFX_ART_FREEZE``, 1079 ``V4L2_COLORFX_AQUA``, ``V4L2_COLORFX_SILHOUETTE``, 1080 ``V4L2_COLORFX_SOLARIZATION``, ``V4L2_COLORFX_VIVID`` and 1081 ``V4L2_COLORFX_ARBITRARY_CBCR`` menu items to the 1082 ``V4L2_CID_COLORFX`` control. 1083 1084 4. Added ``V4L2_CID_COLORFX_CBCR`` control. 1085 1086 5. Added camera controls ``V4L2_CID_AUTO_EXPOSURE_BIAS``, 1087 ``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE``, 1088 ``V4L2_CID_IMAGE_STABILIZATION``, ``V4L2_CID_ISO_SENSITIVITY``, 1089 ``V4L2_CID_ISO_SENSITIVITY_AUTO``, ``V4L2_CID_EXPOSURE_METERING``, 1090 ``V4L2_CID_SCENE_MODE``, ``V4L2_CID_3A_LOCK``, 1091 ``V4L2_CID_AUTO_FOCUS_START``, ``V4L2_CID_AUTO_FOCUS_STOP``, 1092 ``V4L2_CID_AUTO_FOCUS_STATUS`` and ``V4L2_CID_AUTO_FOCUS_RANGE``. 1093 1094 V4L2 in Linux 3.6 1095 ================= 1096 1097 1. Replaced ``input`` in struct v4l2_buffer by 1098 ``reserved2`` and removed ``V4L2_BUF_FLAG_INPUT``. 1099 1100 2. Added V4L2_CAP_VIDEO_M2M and V4L2_CAP_VIDEO_M2M_MPLANE 1101 capabilities. 1102 1103 3. Added support for frequency band enumerations: 1104 :ref:`VIDIOC_ENUM_FREQ_BANDS`. 1105 1106 V4L2 in Linux 3.9 1107 ================= 1108 1109 1. Added timestamp types to ``flags`` field in 1110 struct v4l2_buffer. See :ref:`buffer-flags`. 1111 1112 2. Added ``V4L2_EVENT_CTRL_CH_RANGE`` control event changes flag. See 1113 :ref:`ctrl-changes-flags`. 1114 1115 V4L2 in Linux 3.10 1116 ================== 1117 1118 1. Removed obsolete and unused DV_PRESET ioctls VIDIOC_G_DV_PRESET, 1119 VIDIOC_S_DV_PRESET, VIDIOC_QUERY_DV_PRESET and 1120 VIDIOC_ENUM_DV_PRESET. Remove the related v4l2_input/output 1121 capability flags V4L2_IN_CAP_PRESETS and V4L2_OUT_CAP_PRESETS. 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`` ioctl. 1130 1131 V4L2 in Linux 3.14 1132 ================== 1133 1134 1. In struct v4l2_rect, the type of ``width`` and 1135 ``height`` fields changed from _s32 to _u32. 1136 1137 V4L2 in Linux 3.15 1138 ================== 1139 1140 1. Added Software Defined Radio (SDR) Interface. 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_QUERYCTRL>`. 1155 1156 V4L2 in Linux 3.18 1157 ================== 1158 1159 1. Added ``V4L2_CID_PAN_SPEED`` and ``V4L2_CID_TILT_SPEED`` camera 1160 controls. 1161 1162 V4L2 in Linux 3.19 1163 ================== 1164 1165 1. Rewrote Colorspace chapter, added new enum v4l2_ycbcr_encoding 1166 and enum v4l2_quantization fields to struct v4l2_pix_format, 1167 struct v4l2_pix_format_mplane and struct v4l2_mbus_framefmt. 1168 1169 V4L2 in Linux 4.4 1170 ================= 1171 1172 1. Renamed ``V4L2_TUNER_ADC`` to ``V4L2_TUNER_SDR``. The use of 1173 ``V4L2_TUNER_ADC`` is deprecated now. 1174 1175 2. Added ``V4L2_CID_RF_TUNER_RF_GAIN`` RF Tuner control. 1176 1177 3. Added transmitter support for Software Defined Radio (SDR) Interface. 1178 1179 .. _other: 1180 1181 Relation of V4L2 to other Linux multimedia APIs 1182 =============================================== 1183 1184 .. _xvideo: 1185 1186 X Video Extension 1187 ----------------- 1188 1189 The X Video Extension (abbreviated XVideo or just Xv) is an extension of 1190 the X Window system, implemented for example by the XFree86 project. Its 1191 scope is similar to V4L2, an API to video capture and output devices for 1192 X clients. Xv allows applications to display live video in a window, 1193 send window contents to a TV output, and capture or output still images 1194 in XPixmaps [#f1]_. With their implementation XFree86 makes the extension 1195 available across many operating systems and architectures. 1196 1197 Because the driver is embedded into the X server Xv has a number of 1198 advantages over the V4L2 :ref:`video overlay interface <overlay>`. The 1199 driver can easily determine the overlay target, i. e. visible graphics 1200 memory or off-screen buffers for a destructive overlay. It can program 1201 the RAMDAC for a non-destructive overlay, scaling or color-keying, or 1202 the clipping functions of the video capture hardware, always in sync 1203 with drawing operations or windows moving or changing their stacking 1204 order. 1205 1206 To combine the advantages of Xv and V4L a special Xv driver exists in 1207 XFree86 and XOrg, just programming any overlay capable Video4Linux 1208 device it finds. To enable it ``/etc/X11/XF86Config`` must contain these 1209 lines: 1210 1211 :: 1212 1213 Section "Module" 1214 Load "v4l" 1215 EndSection 1216 1217 As of XFree86 4.2 this driver still supports only V4L ioctls, however it 1218 should work just fine with all V4L2 devices through the V4L2 1219 backward-compatibility layer. Since V4L2 permits multiple opens it is 1220 possible (if supported by the V4L2 driver) to capture video while an X 1221 client requested video overlay. Restrictions of simultaneous capturing 1222 and overlay are discussed in :ref:`overlay` apply. 1223 1224 Only marginally related to V4L2, XFree86 extended Xv to support hardware 1225 YUV to RGB conversion and scaling for faster video playback, and added 1226 an interface to MPEG-2 decoding hardware. This API is useful to display 1227 images captured with V4L2 devices. 1228 1229 Digital Video 1230 ------------- 1231 1232 V4L2 does not support digital terrestrial, cable or satellite broadcast. 1233 A separate project aiming at digital receivers exists. You can find its 1234 homepage at `https://linuxtv.org <https://linuxtv.org>`__. The Linux 1235 DVB API has no connection to the V4L2 API except that drivers for hybrid 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 experimental and may 1249 change in the future. 1250 1251 - :ref:`VIDIOC_DBG_G_REGISTER` and 1252 :ref:`VIDIOC_DBG_S_REGISTER <VIDIOC_DBG_G_REGISTER>` ioctls. 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 superseded by new interfaces and 1262 should not be implemented in new drivers. 1263 1264 - ``VIDIOC_G_MPEGCOMP`` and ``VIDIOC_S_MPEGCOMP`` ioctls. Use Extended 1265 Controls, :ref:`extended-controls`. 1266 1267 - VIDIOC_G_DV_PRESET, VIDIOC_S_DV_PRESET, 1268 VIDIOC_ENUM_DV_PRESETS and VIDIOC_QUERY_DV_PRESET ioctls. Use 1269 the DV Timings API (:ref:`dv-timings`). 1270 1271 - ``VIDIOC_SUBDEV_G_CROP`` and ``VIDIOC_SUBDEV_S_CROP`` ioctls. Use 1272 ``VIDIOC_SUBDEV_G_SELECTION`` and ``VIDIOC_SUBDEV_S_SELECTION``, 1273 :ref:`VIDIOC_SUBDEV_G_SELECTION`. 1274 1275 .. [#f1] 1276 This is not implemented in XFree86.
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