1.. Permission is granted to copy, distribute and/or modify this 2.. document under the terms of the GNU Free Documentation License, 3.. Version 1.1 or any later version published by the Free Software 4.. Foundation, with no Invariant Sections, no Front-Cover Texts 5.. and no Back-Cover Texts. A copy of the license is included at 6.. Documentation/userspace-api/media/fdl-appendix.rst. 7.. 8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections 9 10.. _sliced: 11 12************************* 13Sliced VBI Data Interface 14************************* 15 16VBI stands for Vertical Blanking Interval, a gap in the sequence of 17lines of an analog video signal. During VBI no picture information is 18transmitted, allowing some time while the electron beam of a cathode ray 19tube TV returns to the top of the screen. 20 21Sliced VBI devices use hardware to demodulate data transmitted in the 22VBI. V4L2 drivers shall *not* do this by software, see also the 23:ref:`raw VBI interface <raw-vbi>`. The data is passed as short 24packets of fixed size, covering one scan line each. The number of 25packets per video frame is variable. 26 27Sliced VBI capture and output devices are accessed through the same 28character special files as raw VBI devices. When a driver supports both 29interfaces, the default function of a ``/dev/vbi`` device is *raw* VBI 30capturing or output, and the sliced VBI function is only available after 31calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl as defined 32below. Likewise a ``/dev/video`` device may support the sliced VBI API, 33however the default function here is video capturing or output. 34Different file descriptors must be used to pass raw and sliced VBI data 35simultaneously, if this is supported by the driver. 36 37 38Querying Capabilities 39===================== 40 41Devices supporting the sliced VBI capturing or output API set the 42``V4L2_CAP_SLICED_VBI_CAPTURE`` or ``V4L2_CAP_SLICED_VBI_OUTPUT`` flag 43respectively, in the ``capabilities`` field of struct 44:c:type:`v4l2_capability` returned by the 45:ref:`VIDIOC_QUERYCAP` ioctl. At least one of the 46read/write, streaming or asynchronous :ref:`I/O methods <io>` must be 47supported. Sliced VBI devices may have a tuner or modulator. 48 49 50Supplemental Functions 51====================== 52 53Sliced VBI devices shall support :ref:`video input or output <video>` 54and :ref:`tuner or modulator <tuner>` ioctls if they have these 55capabilities, and they may support :ref:`control` ioctls. 56The :ref:`video standard <standard>` ioctls provide information vital 57to program a sliced VBI device, therefore must be supported. 58 59 60.. _sliced-vbi-format-negotitation: 61 62Sliced VBI Format Negotiation 63============================= 64 65To find out which data services are supported by the hardware 66applications can call the 67:ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl. 68All drivers implementing the sliced VBI interface must support this 69ioctl. The results may differ from those of the 70:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl when the number of VBI 71lines the hardware can capture or output per frame, or the number of 72services it can identify on a given line are limited. For example on PAL 73line 16 the hardware may be able to look for a VPS or Teletext signal, 74but not both at the same time. 75 76To determine the currently selected services applications set the 77``type`` field of struct :c:type:`v4l2_format` to 78``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or 79``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``, and the 80:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl fills the ``fmt.sliced`` 81member, a struct 82:c:type:`v4l2_sliced_vbi_format`. 83 84Applications can request different parameters by initializing or 85modifying the ``fmt.sliced`` member and calling the 86:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with a pointer to the 87struct :c:type:`v4l2_format` structure. 88 89The sliced VBI API is more complicated than the raw VBI API because the 90hardware must be told which VBI service to expect on each scan line. Not 91all services may be supported by the hardware on all lines (this is 92especially true for VBI output where Teletext is often unsupported and 93other services can only be inserted in one specific line). In many 94cases, however, it is sufficient to just set the ``service_set`` field 95to the required services and let the driver fill the ``service_lines`` 96array according to hardware capabilities. Only if more precise control 97is needed should the programmer set the ``service_lines`` array 98explicitly. 99 100The :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl modifies the parameters 101according to hardware capabilities. When the driver allocates resources 102at this point, it may return an ``EBUSY`` error code if the required 103resources are temporarily unavailable. Other resource allocation points 104which may return ``EBUSY`` can be the 105:ref:`VIDIOC_STREAMON` ioctl and the first 106:ref:`read() <func-read>`, :ref:`write() <func-write>` and 107:ref:`select() <func-select>` call. 108 109 110.. c:type:: v4l2_sliced_vbi_format 111 112struct v4l2_sliced_vbi_format 113----------------------------- 114 115.. raw:: latex 116 117 \begingroup 118 \scriptsize 119 \setlength{\tabcolsep}{2pt} 120 121.. tabularcolumns:: |p{.85cm}|p{3.3cm}|p{4.4cm}|p{4.4cm}|p{4.4cm}| 122 123.. cssclass:: longtable 124 125.. flat-table:: 126 :header-rows: 0 127 :stub-columns: 0 128 :widths: 3 3 2 2 2 129 130 * - __u32 131 - ``service_set`` 132 - :cspan:`2` 133 134 If ``service_set`` is non-zero when passed with 135 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or 136 :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`, the ``service_lines`` 137 array will be filled by the driver according to the services 138 specified in this field. For example, if ``service_set`` is 139 initialized with ``V4L2_SLICED_TELETEXT_B | V4L2_SLICED_WSS_625``, 140 a driver for the cx25840 video decoder sets lines 7-22 of both 141 fields [#f1]_ to ``V4L2_SLICED_TELETEXT_B`` and line 23 of the first 142 field to ``V4L2_SLICED_WSS_625``. If ``service_set`` is set to 143 zero, then the values of ``service_lines`` will be used instead. 144 145 On return the driver sets this field to the union of all elements 146 of the returned ``service_lines`` array. It may contain less 147 services than requested, perhaps just one, if the hardware cannot 148 handle more services simultaneously. It may be empty (zero) if 149 none of the requested services are supported by the hardware. 150 * - __u16 151 - ``service_lines``\ [2][24] 152 - :cspan:`2` 153 154 Applications initialize this array with sets of data services the 155 driver shall look for or insert on the respective scan line. 156 Subject to hardware capabilities drivers return the requested set, 157 a subset, which may be just a single service, or an empty set. 158 When the hardware cannot handle multiple services on the same line 159 the driver shall choose one. No assumptions can be made on which 160 service the driver chooses. 161 162 Data services are defined in :ref:`vbi-services2`. Array indices 163 map to ITU-R line numbers\ [#f2]_ as follows: 164 * - 165 - 166 - Element 167 - 525 line systems 168 - 625 line systems 169 * - 170 - 171 - ``service_lines``\ [0][1] 172 - 1 173 - 1 174 * - 175 - 176 - ``service_lines``\ [0][23] 177 - 23 178 - 23 179 * - 180 - 181 - ``service_lines``\ [1][1] 182 - 264 183 - 314 184 * - 185 - 186 - ``service_lines``\ [1][23] 187 - 286 188 - 336 189 * - 190 - 191 - :cspan:`2` Drivers must set ``service_lines`` [0][0] and 192 ``service_lines``\ [1][0] to zero. The 193 ``V4L2_VBI_ITU_525_F1_START``, ``V4L2_VBI_ITU_525_F2_START``, 194 ``V4L2_VBI_ITU_625_F1_START`` and ``V4L2_VBI_ITU_625_F2_START`` 195 defines give the start line numbers for each field for each 525 or 196 625 line format as a convenience. Don't forget that ITU line 197 numbering starts at 1, not 0. 198 * - __u32 199 - ``io_size`` 200 - :cspan:`2` Maximum number of bytes passed by one 201 :ref:`read() <func-read>` or :ref:`write() <func-write>` call, 202 and the buffer size in bytes for the 203 :ref:`VIDIOC_QBUF` and 204 :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl. Drivers set this field 205 to the size of struct 206 :c:type:`v4l2_sliced_vbi_data` times the 207 number of non-zero elements in the returned ``service_lines`` 208 array (that is the number of lines potentially carrying data). 209 * - __u32 210 - ``reserved``\ [2] 211 - :cspan:`2` This array is reserved for future extensions. 212 213 Applications and drivers must set it to zero. 214 215.. raw:: latex 216 217 \endgroup 218 219.. _vbi-services2: 220 221Sliced VBI services 222------------------- 223 224.. raw:: latex 225 226 \scriptsize 227 228.. tabularcolumns:: |p{4.1cm}|p{1.1cm}|p{2.4cm}|p{2.0cm}|p{7.3cm}| 229 230.. flat-table:: 231 :header-rows: 1 232 :stub-columns: 0 233 :widths: 2 1 1 2 2 234 235 * - Symbol 236 - Value 237 - Reference 238 - Lines, usually 239 - Payload 240 * - ``V4L2_SLICED_TELETEXT_B`` (Teletext System B) 241 - 0x0001 242 - :ref:`ets300706`, 243 244 :ref:`itu653` 245 - PAL/SECAM line 7-22, 320-335 (second field 7-22) 246 - Last 42 of the 45 byte Teletext packet, that is without clock 247 run-in and framing code, lsb first transmitted. 248 * - ``V4L2_SLICED_VPS`` 249 - 0x0400 250 - :ref:`ets300231` 251 - PAL line 16 252 - Byte number 3 to 15 according to Figure 9 of ETS 300 231, lsb 253 first transmitted. 254 * - ``V4L2_SLICED_CAPTION_525`` 255 - 0x1000 256 - :ref:`cea608` 257 - NTSC line 21, 284 (second field 21) 258 - Two bytes in transmission order, including parity bit, lsb first 259 transmitted. 260 * - ``V4L2_SLICED_WSS_625`` 261 - 0x4000 262 - :ref:`itu1119`, 263 264 :ref:`en300294` 265 - PAL/SECAM line 23 266 - 267 268 :: 269 270 Byte 0 1 271 msb lsb msb lsb 272 Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9 273 * - ``V4L2_SLICED_VBI_525`` 274 - 0x1000 275 - :cspan:`2` Set of services applicable to 525 line systems. 276 * - ``V4L2_SLICED_VBI_625`` 277 - 0x4401 278 - :cspan:`2` Set of services applicable to 625 line systems. 279 280.. raw:: latex 281 282 \normalsize 283 284 285Drivers may return an ``EINVAL`` error code when applications attempt to 286read or write data without prior format negotiation, after switching the 287video standard (which may invalidate the negotiated VBI parameters) and 288after switching the video input (which may change the video standard as 289a side effect). The :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl may 290return an ``EBUSY`` error code when applications attempt to change the 291format while i/o is in progress (between a 292:ref:`VIDIOC_STREAMON` and 293:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` call, and after the first 294:ref:`read() <func-read>` or :ref:`write() <func-write>` call). 295 296 297Reading and writing sliced VBI data 298=================================== 299 300A single :ref:`read() <func-read>` or :ref:`write() <func-write>` 301call must pass all data belonging to one video frame. That is an array 302of struct :c:type:`v4l2_sliced_vbi_data` structures with one or 303more elements and a total size not exceeding ``io_size`` bytes. Likewise 304in streaming I/O mode one buffer of ``io_size`` bytes must contain data 305of one video frame. The ``id`` of unused 306struct :c:type:`v4l2_sliced_vbi_data` elements must be zero. 307 308 309.. c:type:: v4l2_sliced_vbi_data 310 311struct v4l2_sliced_vbi_data 312--------------------------- 313 314.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| 315 316.. flat-table:: 317 :header-rows: 0 318 :stub-columns: 0 319 :widths: 3 1 4 320 321 * - __u32 322 - ``id`` 323 - A flag from :ref:`vbi-services` identifying the type of data in 324 this packet. Only a single bit must be set. When the ``id`` of a 325 captured packet is zero, the packet is empty and the contents of 326 other fields are undefined. Applications shall ignore empty 327 packets. When the ``id`` of a packet for output is zero the 328 contents of the ``data`` field are undefined and the driver must 329 no longer insert data on the requested ``field`` and ``line``. 330 * - __u32 331 - ``field`` 332 - The video field number this data has been captured from, or shall 333 be inserted at. ``0`` for the first field, ``1`` for the second 334 field. 335 * - __u32 336 - ``line`` 337 - The field (as opposed to frame) line number this data has been 338 captured from, or shall be inserted at. See :ref:`vbi-525` and 339 :ref:`vbi-625` for valid values. Sliced VBI capture devices can 340 set the line number of all packets to ``0`` if the hardware cannot 341 reliably identify scan lines. The field number must always be 342 valid. 343 * - __u32 344 - ``reserved`` 345 - This field is reserved for future extensions. Applications and 346 drivers must set it to zero. 347 * - __u8 348 - ``data``\ [48] 349 - The packet payload. See :ref:`vbi-services` for the contents and 350 number of bytes passed for each data type. The contents of padding 351 bytes at the end of this array are undefined, drivers and 352 applications shall ignore them. 353 354 355Packets are always passed in ascending line number order, without 356duplicate line numbers. The :ref:`write() <func-write>` function and 357the :ref:`VIDIOC_QBUF` ioctl must return an ``EINVAL`` 358error code when applications violate this rule. They must also return an 359EINVAL error code when applications pass an incorrect field or line 360number, or a combination of ``field``, ``line`` and ``id`` which has not 361been negotiated with the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` or 362:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. When the line numbers are 363unknown the driver must pass the packets in transmitted order. The 364driver can insert empty packets with ``id`` set to zero anywhere in the 365packet array. 366 367To assure synchronization and to distinguish from frame dropping, when a 368captured frame does not carry any of the requested data services drivers 369must pass one or more empty packets. When an application fails to pass 370VBI data in time for output, the driver must output the last VPS and WSS 371packet again, and disable the output of Closed Caption and Teletext 372data, or output data which is ignored by Closed Caption and Teletext 373decoders. 374 375A sliced VBI device may support :ref:`read/write <rw>` and/or 376streaming (:ref:`memory mapping <mmap>` and/or 377:ref:`user pointer <userp>`) I/O. The latter bears the possibility of 378synchronizing video and VBI data by using buffer timestamps. 379 380 381Sliced VBI Data in MPEG Streams 382=============================== 383 384If a device can produce an MPEG output stream, it may be capable of 385providing 386:ref:`negotiated sliced VBI services <sliced-vbi-format-negotitation>` 387as data embedded in the MPEG stream. Users or applications control this 388sliced VBI data insertion with the 389:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>` 390control. 391 392If the driver does not provide the 393:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>` 394control, or only allows that control to be set to 395:ref:`V4L2_MPEG_STREAM_VBI_FMT_NONE <v4l2-mpeg-stream-vbi-fmt>`, 396then the device cannot embed sliced VBI data in the MPEG stream. 397 398The 399:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>` 400control does not implicitly set the device driver to capture nor cease 401capturing sliced VBI data. The control only indicates to embed sliced 402VBI data in the MPEG stream, if an application has negotiated sliced VBI 403service be captured. 404 405It may also be the case that a device can embed sliced VBI data in only 406certain types of MPEG streams: for example in an MPEG-2 PS but not an 407MPEG-2 TS. In this situation, if sliced VBI data insertion is requested, 408the sliced VBI data will be embedded in MPEG stream types when 409supported, and silently omitted from MPEG stream types where sliced VBI 410data insertion is not supported by the device. 411 412The following subsections specify the format of the embedded sliced VBI 413data. 414 415 416MPEG Stream Embedded, Sliced VBI Data Format: NONE 417-------------------------------------------------- 418 419The 420:ref:`V4L2_MPEG_STREAM_VBI_FMT_NONE <v4l2-mpeg-stream-vbi-fmt>` 421embedded sliced VBI format shall be interpreted by drivers as a control 422to cease embedding sliced VBI data in MPEG streams. Neither the device 423nor driver shall insert "empty" embedded sliced VBI data packets in the 424MPEG stream when this format is set. No MPEG stream data structures are 425specified for this format. 426 427 428MPEG Stream Embedded, Sliced VBI Data Format: IVTV 429-------------------------------------------------- 430 431The 432:ref:`V4L2_MPEG_STREAM_VBI_FMT_IVTV <v4l2-mpeg-stream-vbi-fmt>` 433embedded sliced VBI format, when supported, indicates to the driver to 434embed up to 36 lines of sliced VBI data per frame in an MPEG-2 *Private 435Stream 1 PES* packet encapsulated in an MPEG-2 *Program Pack* in the 436MPEG stream. 437 438*Historical context*: This format specification originates from a 439custom, embedded, sliced VBI data format used by the ``ivtv`` driver. 440This format has already been informally specified in the kernel sources 441in the file ``Documentation/userspace-api/media/drivers/cx2341x-uapi.rst`` . The 442maximum size of the payload and other aspects of this format are driven 443by the CX23415 MPEG decoder's capabilities and limitations with respect 444to extracting, decoding, and displaying sliced VBI data embedded within 445an MPEG stream. 446 447This format's use is *not* exclusive to the ``ivtv`` driver *nor* 448exclusive to CX2341x devices, as the sliced VBI data packet insertion 449into the MPEG stream is implemented in driver software. At least the 450``cx18`` driver provides sliced VBI data insertion into an MPEG-2 PS in 451this format as well. 452 453The following definitions specify the payload of the MPEG-2 *Private 454Stream 1 PES* packets that contain sliced VBI data when 455:ref:`V4L2_MPEG_STREAM_VBI_FMT_IVTV <v4l2-mpeg-stream-vbi-fmt>` 456is set. (The MPEG-2 *Private Stream 1 PES* packet header and 457encapsulating MPEG-2 *Program Pack* header are not detailed here. Please 458refer to the MPEG-2 specifications for details on those packet headers.) 459 460The payload of the MPEG-2 *Private Stream 1 PES* packets that contain 461sliced VBI data is specified by struct 462:c:type:`v4l2_mpeg_vbi_fmt_ivtv`. The 463payload is variable length, depending on the actual number of lines of 464sliced VBI data present in a video frame. The payload may be padded at 465the end with unspecified fill bytes to align the end of the payload to a 4664-byte boundary. The payload shall never exceed 1552 bytes (2 fields 467with 18 lines/field with 43 bytes of data/line and a 4 byte magic 468number). 469 470 471.. c:type:: v4l2_mpeg_vbi_fmt_ivtv 472 473struct v4l2_mpeg_vbi_fmt_ivtv 474----------------------------- 475 476.. tabularcolumns:: |p{1.0cm}|p{3.8cm}|p{1.0cm}|p{11.2cm}| 477 478.. flat-table:: 479 :header-rows: 0 480 :stub-columns: 0 481 :widths: 1 1 2 482 483 * - __u8 484 - ``magic``\ [4] 485 - A "magic" constant from :ref:`v4l2-mpeg-vbi-fmt-ivtv-magic` that 486 indicates this is a valid sliced VBI data payload and also 487 indicates which member of the anonymous union, ``itv0`` or 488 ``ITV0``, to use for the payload data. 489 * - union { 490 - (anonymous) 491 * - struct :c:type:`v4l2_mpeg_vbi_itv0` 492 - ``itv0`` 493 - The primary form of the sliced VBI data payload that contains 494 anywhere from 1 to 35 lines of sliced VBI data. Line masks are 495 provided in this form of the payload indicating which VBI lines 496 are provided. 497 * - struct :ref:`v4l2_mpeg_vbi_ITV0 <v4l2-mpeg-vbi-itv0-1>` 498 - ``ITV0`` 499 - An alternate form of the sliced VBI data payload used when 36 500 lines of sliced VBI data are present. No line masks are provided 501 in this form of the payload; all valid line mask bits are 502 implcitly set. 503 * - } 504 - 505 506.. _v4l2-mpeg-vbi-fmt-ivtv-magic: 507 508Magic Constants for struct v4l2_mpeg_vbi_fmt_ivtv magic field 509------------------------------------------------------------- 510 511.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| 512 513.. flat-table:: 514 :header-rows: 1 515 :stub-columns: 0 516 :widths: 3 1 4 517 518 * - Defined Symbol 519 - Value 520 - Description 521 * - ``V4L2_MPEG_VBI_IVTV_MAGIC0`` 522 - "itv0" 523 - Indicates the ``itv0`` member of the union in struct 524 :c:type:`v4l2_mpeg_vbi_fmt_ivtv` is 525 valid. 526 * - ``V4L2_MPEG_VBI_IVTV_MAGIC1`` 527 - "ITV0" 528 - Indicates the ``ITV0`` member of the union in struct 529 :c:type:`v4l2_mpeg_vbi_fmt_ivtv` is 530 valid and that 36 lines of sliced VBI data are present. 531 532 533 534.. c:type:: v4l2_mpeg_vbi_itv0 535 536.. c:type:: v4l2_mpeg_vbi_ITV0 537 538structs v4l2_mpeg_vbi_itv0 and v4l2_mpeg_vbi_ITV0 539------------------------------------------------- 540 541.. tabularcolumns:: |p{5.2cm}|p{2.4cm}|p{9.9cm}| 542 543.. flat-table:: 544 :header-rows: 0 545 :stub-columns: 0 546 :widths: 1 1 2 547 548 * - __le32 549 - ``linemask``\ [2] 550 - Bitmasks indicating the VBI service lines present. These 551 ``linemask`` values are stored in little endian byte order in the 552 MPEG stream. Some reference ``linemask`` bit positions with their 553 corresponding VBI line number and video field are given below. 554 b\ :sub:`0` indicates the least significant bit of a ``linemask`` 555 value: 556 557 558 559 :: 560 561 linemask[0] b0: line 6 first field 562 linemask[0] b17: line 23 first field 563 linemask[0] b18: line 6 second field 564 linemask[0] b31: line 19 second field 565 linemask[1] b0: line 20 second field 566 linemask[1] b3: line 23 second field 567 linemask[1] b4-b31: unused and set to 0 568 * - struct 569 :c:type:`v4l2_mpeg_vbi_itv0_line` 570 - ``line``\ [35] 571 - This is a variable length array that holds from 1 to 35 lines of 572 sliced VBI data. The sliced VBI data lines present correspond to 573 the bits set in the ``linemask`` array, starting from b\ :sub:`0` 574 of ``linemask``\ [0] up through b\ :sub:`31` of ``linemask``\ [0], 575 and from b\ :sub:`0` of ``linemask``\ [1] up through b\ :sub:`3` of 576 ``linemask``\ [1]. ``line``\ [0] corresponds to the first bit 577 found set in the ``linemask`` array, ``line``\ [1] corresponds to 578 the second bit found set in the ``linemask`` array, etc. If no 579 ``linemask`` array bits are set, then ``line``\ [0] may contain 580 one line of unspecified data that should be ignored by 581 applications. 582 583 584 585.. _v4l2-mpeg-vbi-itv0-1: 586 587struct v4l2_mpeg_vbi_ITV0 588------------------------- 589 590.. tabularcolumns:: |p{5.2cm}|p{2.4cm}|p{9.9cm}| 591 592.. flat-table:: 593 :header-rows: 0 594 :stub-columns: 0 595 :widths: 1 1 2 596 597 * - struct 598 :c:type:`v4l2_mpeg_vbi_itv0_line` 599 - ``line``\ [36] 600 - A fixed length array of 36 lines of sliced VBI data. ``line``\ [0] 601 through ``line``\ [17] correspond to lines 6 through 23 of the 602 first field. ``line``\ [18] through ``line``\ [35] corresponds to 603 lines 6 through 23 of the second field. 604 605 606 607.. c:type:: v4l2_mpeg_vbi_itv0_line 608 609struct v4l2_mpeg_vbi_itv0_line 610------------------------------ 611 612.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 613 614.. flat-table:: 615 :header-rows: 0 616 :stub-columns: 0 617 :widths: 1 1 2 618 619 * - __u8 620 - ``id`` 621 - A line identifier value from 622 :ref:`ITV0-Line-Identifier-Constants` that indicates the type of 623 sliced VBI data stored on this line. 624 * - __u8 625 - ``data``\ [42] 626 - The sliced VBI data for the line. 627 628 629 630.. _ITV0-Line-Identifier-Constants: 631 632Line Identifiers for struct v4l2_mpeg_vbi_itv0_line id field 633------------------------------------------------------------ 634 635.. tabularcolumns:: |p{7.0cm}|p{1.8cm}|p{8.7cm}| 636 637.. flat-table:: 638 :header-rows: 1 639 :stub-columns: 0 640 :widths: 3 1 4 641 642 * - Defined Symbol 643 - Value 644 - Description 645 * - ``V4L2_MPEG_VBI_IVTV_TELETEXT_B`` 646 - 1 647 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 648 description of the line payload. 649 * - ``V4L2_MPEG_VBI_IVTV_CAPTION_525`` 650 - 4 651 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 652 description of the line payload. 653 * - ``V4L2_MPEG_VBI_IVTV_WSS_625`` 654 - 5 655 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 656 description of the line payload. 657 * - ``V4L2_MPEG_VBI_IVTV_VPS`` 658 - 7 659 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 660 description of the line payload. 661 662 663 664.. [#f1] 665 According to :ref:`ETS 300 706 <ets300706>` lines 6-22 of the first 666 field and lines 5-22 of the second field may carry Teletext data. 667 668.. [#f2] 669 See also :ref:`vbi-525` and :ref:`vbi-625`. 670