1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _sliced: 5 6************************* 7Sliced VBI Data Interface 8************************* 9 10VBI stands for Vertical Blanking Interval, a gap in the sequence of 11lines of an analog video signal. During VBI no picture information is 12transmitted, allowing some time while the electron beam of a cathode ray 13tube TV returns to the top of the screen. 14 15Sliced VBI devices use hardware to demodulate data transmitted in the 16VBI. V4L2 drivers shall *not* do this by software, see also the 17:ref:`raw VBI interface <raw-vbi>`. The data is passed as short 18packets of fixed size, covering one scan line each. The number of 19packets per video frame is variable. 20 21Sliced VBI capture and output devices are accessed through the same 22character special files as raw VBI devices. When a driver supports both 23interfaces, the default function of a ``/dev/vbi`` device is *raw* VBI 24capturing or output, and the sliced VBI function is only available after 25calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl as defined 26below. Likewise a ``/dev/video`` device may support the sliced VBI API, 27however the default function here is video capturing or output. 28Different file descriptors must be used to pass raw and sliced VBI data 29simultaneously, if this is supported by the driver. 30 31Querying Capabilities 32===================== 33 34Devices supporting the sliced VBI capturing or output API set the 35``V4L2_CAP_SLICED_VBI_CAPTURE`` or ``V4L2_CAP_SLICED_VBI_OUTPUT`` flag 36respectively, in the ``capabilities`` field of struct 37:c:type:`v4l2_capability` returned by the 38:ref:`VIDIOC_QUERYCAP` ioctl. At least one of the 39read/write, streaming or asynchronous :ref:`I/O methods <io>` must be 40supported. Sliced VBI devices may have a tuner or modulator. 41 42Supplemental Functions 43====================== 44 45Sliced VBI devices shall support :ref:`video input or output <video>` 46and :ref:`tuner or modulator <tuner>` ioctls if they have these 47capabilities, and they may support :ref:`control` ioctls. 48The :ref:`video standard <standard>` ioctls provide information vital 49to program a sliced VBI device, therefore must be supported. 50 51.. _sliced-vbi-format-negotitation: 52 53Sliced VBI Format Negotiation 54============================= 55 56To find out which data services are supported by the hardware 57applications can call the 58:ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl. 59All drivers implementing the sliced VBI interface must support this 60ioctl. The results may differ from those of the 61:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl when the number of VBI 62lines the hardware can capture or output per frame, or the number of 63services it can identify on a given line are limited. For example on PAL 64line 16 the hardware may be able to look for a VPS or Teletext signal, 65but not both at the same time. 66 67To determine the currently selected services applications set the 68``type`` field of struct :c:type:`v4l2_format` to 69``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or 70``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``, and the 71:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl fills the ``fmt.sliced`` 72member, a struct 73:c:type:`v4l2_sliced_vbi_format`. 74 75Applications can request different parameters by initializing or 76modifying the ``fmt.sliced`` member and calling the 77:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with a pointer to the 78struct :c:type:`v4l2_format` structure. 79 80The sliced VBI API is more complicated than the raw VBI API because the 81hardware must be told which VBI service to expect on each scan line. Not 82all services may be supported by the hardware on all lines (this is 83especially true for VBI output where Teletext is often unsupported and 84other services can only be inserted in one specific line). In many 85cases, however, it is sufficient to just set the ``service_set`` field 86to the required services and let the driver fill the ``service_lines`` 87array according to hardware capabilities. Only if more precise control 88is needed should the programmer set the ``service_lines`` array 89explicitly. 90 91The :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl modifies the parameters 92according to hardware capabilities. When the driver allocates resources 93at this point, it may return an ``EBUSY`` error code if the required 94resources are temporarily unavailable. Other resource allocation points 95which may return ``EBUSY`` can be the 96:ref:`VIDIOC_STREAMON` ioctl and the first 97:c:func:`read()`, :c:func:`write()` and 98:c:func:`select()` call. 99 100.. c:type:: v4l2_sliced_vbi_format 101 102struct v4l2_sliced_vbi_format 103----------------------------- 104 105.. raw:: latex 106 107 \begingroup 108 \scriptsize 109 \setlength{\tabcolsep}{2pt} 110 111.. tabularcolumns:: |p{.85cm}|p{3.3cm}|p{4.45cm}|p{4.45cm}|p{4.45cm}| 112 113.. cssclass:: longtable 114 115.. flat-table:: 116 :header-rows: 0 117 :stub-columns: 0 118 :widths: 3 3 2 2 2 119 120 * - __u16 121 - ``service_set`` 122 - :cspan:`2` 123 124 If ``service_set`` is non-zero when passed with 125 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or 126 :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`, the ``service_lines`` 127 array will be filled by the driver according to the services 128 specified in this field. For example, if ``service_set`` is 129 initialized with ``V4L2_SLICED_TELETEXT_B | V4L2_SLICED_WSS_625``, 130 a driver for the cx25840 video decoder sets lines 7-22 of both 131 fields [#f1]_ to ``V4L2_SLICED_TELETEXT_B`` and line 23 of the first 132 field to ``V4L2_SLICED_WSS_625``. If ``service_set`` is set to 133 zero, then the values of ``service_lines`` will be used instead. 134 135 On return the driver sets this field to the union of all elements 136 of the returned ``service_lines`` array. It may contain less 137 services than requested, perhaps just one, if the hardware cannot 138 handle more services simultaneously. It may be empty (zero) if 139 none of the requested services are supported by the hardware. 140 * - __u16 141 - ``service_lines``\ [2][24] 142 - :cspan:`2` 143 144 Applications initialize this array with sets of data services the 145 driver shall look for or insert on the respective scan line. 146 Subject to hardware capabilities drivers return the requested set, 147 a subset, which may be just a single service, or an empty set. 148 When the hardware cannot handle multiple services on the same line 149 the driver shall choose one. No assumptions can be made on which 150 service the driver chooses. 151 152 Data services are defined in :ref:`vbi-services2`. Array indices 153 map to ITU-R line numbers\ [#f2]_ as follows: 154 * - 155 - 156 - Element 157 - 525 line systems 158 - 625 line systems 159 * - 160 - 161 - ``service_lines``\ [0][1] 162 - 1 163 - 1 164 * - 165 - 166 - ``service_lines``\ [0][23] 167 - 23 168 - 23 169 * - 170 - 171 - ``service_lines``\ [1][1] 172 - 264 173 - 314 174 * - 175 - 176 - ``service_lines``\ [1][23] 177 - 286 178 - 336 179 * - 180 - 181 - :cspan:`2` Drivers must set ``service_lines`` [0][0] and 182 ``service_lines``\ [1][0] to zero. The 183 ``V4L2_VBI_ITU_525_F1_START``, ``V4L2_VBI_ITU_525_F2_START``, 184 ``V4L2_VBI_ITU_625_F1_START`` and ``V4L2_VBI_ITU_625_F2_START`` 185 defines give the start line numbers for each field for each 525 or 186 625 line format as a convenience. Don't forget that ITU line 187 numbering starts at 1, not 0. 188 * - __u32 189 - ``io_size`` 190 - :cspan:`2` Maximum number of bytes passed by one 191 :c:func:`read()` or :c:func:`write()` call, 192 and the buffer size in bytes for the 193 :ref:`VIDIOC_QBUF` and 194 :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl. Drivers set this field 195 to the size of struct 196 :c:type:`v4l2_sliced_vbi_data` times the 197 number of non-zero elements in the returned ``service_lines`` 198 array (that is the number of lines potentially carrying data). 199 * - __u32 200 - ``reserved``\ [2] 201 - :cspan:`2` This array is reserved for future extensions. 202 203 Applications and drivers must set it to zero. 204 205.. raw:: latex 206 207 \endgroup 208 209.. _vbi-services2: 210 211Sliced VBI services 212------------------- 213 214.. raw:: latex 215 216 \footnotesize 217 218.. tabularcolumns:: |p{4.2cm}|p{1.1cm}|p{2.1cm}|p{2.0cm}|p{6.5cm}| 219 220.. flat-table:: 221 :header-rows: 1 222 :stub-columns: 0 223 :widths: 2 1 1 2 2 224 225 * - Symbol 226 - Value 227 - Reference 228 - Lines, usually 229 - Payload 230 * - ``V4L2_SLICED_TELETEXT_B`` (Teletext System B) 231 - 0x0001 232 - :ref:`ets300706`, 233 234 :ref:`itu653` 235 - PAL/SECAM line 7-22, 320-335 (second field 7-22) 236 - Last 42 of the 45 byte Teletext packet, that is without clock 237 run-in and framing code, lsb first transmitted. 238 * - ``V4L2_SLICED_VPS`` 239 - 0x0400 240 - :ref:`ets300231` 241 - PAL line 16 242 - Byte number 3 to 15 according to Figure 9 of ETS 300 231, lsb 243 first transmitted. 244 * - ``V4L2_SLICED_CAPTION_525`` 245 - 0x1000 246 - :ref:`cea608` 247 - NTSC line 21, 284 (second field 21) 248 - Two bytes in transmission order, including parity bit, lsb first 249 transmitted. 250 * - ``V4L2_SLICED_WSS_625`` 251 - 0x4000 252 - :ref:`itu1119`, 253 254 :ref:`en300294` 255 - PAL/SECAM line 23 256 - See :ref:`v4l2-sliced-wss-625-payload` below. 257 * - ``V4L2_SLICED_VBI_525`` 258 - 0x1000 259 - :cspan:`2` Set of services applicable to 525 line systems. 260 * - ``V4L2_SLICED_VBI_625`` 261 - 0x4401 262 - :cspan:`2` Set of services applicable to 625 line systems. 263 264.. raw:: latex 265 266 \normalsize 267 268Drivers may return an ``EINVAL`` error code when applications attempt to 269read or write data without prior format negotiation, after switching the 270video standard (which may invalidate the negotiated VBI parameters) and 271after switching the video input (which may change the video standard as 272a side effect). The :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl may 273return an ``EBUSY`` error code when applications attempt to change the 274format while i/o is in progress (between a 275:ref:`VIDIOC_STREAMON` and 276:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` call, and after the first 277:c:func:`read()` or :c:func:`write()` call). 278 279.. _v4l2-sliced-wss-625-payload: 280 281V4L2_SLICED_WSS_625 payload 282~~~~~~~~~~~~~~~~~~~~~~~~~~~ 283 284The payload for ``V4L2_SLICED_WSS_625`` is: 285 286 +-----+------------------+-----------------------+ 287 |Byte | 0 | 1 | 288 +-----+--------+---------+-----------+-----------+ 289 | | msb | lsb | msb | lsb | 290 | +-+-+-+--+--+-+-+--+--+-+--+---+---+--+-+--+ 291 | Bit |7|6|5|4 | 3|2|1|0 | x|x|13|12 | 11|10|9|8 | 292 +-----+-+-+-+--+--+-+-+--+--+-+--+---+---+--+-+--+ 293 294Reading and writing sliced VBI data 295=================================== 296 297A single :c:func:`read()` or :c:func:`write()` 298call must pass all data belonging to one video frame. That is an array 299of struct :c:type:`v4l2_sliced_vbi_data` structures with one or 300more elements and a total size not exceeding ``io_size`` bytes. Likewise 301in streaming I/O mode one buffer of ``io_size`` bytes must contain data 302of one video frame. The ``id`` of unused 303struct :c:type:`v4l2_sliced_vbi_data` elements must be zero. 304 305.. c:type:: v4l2_sliced_vbi_data 306 307struct v4l2_sliced_vbi_data 308--------------------------- 309 310.. tabularcolumns:: |p{1.2cm}|p{2.2cm}|p{13.9cm}| 311 312.. flat-table:: 313 :header-rows: 0 314 :stub-columns: 0 315 :widths: 3 1 4 316 317 * - __u32 318 - ``id`` 319 - A flag from :ref:`vbi-services` identifying the type of data in 320 this packet. Only a single bit must be set. When the ``id`` of a 321 captured packet is zero, the packet is empty and the contents of 322 other fields are undefined. Applications shall ignore empty 323 packets. When the ``id`` of a packet for output is zero the 324 contents of the ``data`` field are undefined and the driver must 325 no longer insert data on the requested ``field`` and ``line``. 326 * - __u32 327 - ``field`` 328 - The video field number this data has been captured from, or shall 329 be inserted at. ``0`` for the first field, ``1`` for the second 330 field. 331 * - __u32 332 - ``line`` 333 - The field (as opposed to frame) line number this data has been 334 captured from, or shall be inserted at. See :ref:`vbi-525` and 335 :ref:`vbi-625` for valid values. Sliced VBI capture devices can 336 set the line number of all packets to ``0`` if the hardware cannot 337 reliably identify scan lines. The field number must always be 338 valid. 339 * - __u32 340 - ``reserved`` 341 - This field is reserved for future extensions. Applications and 342 drivers must set it to zero. 343 * - __u8 344 - ``data``\ [48] 345 - The packet payload. See :ref:`vbi-services` for the contents and 346 number of bytes passed for each data type. The contents of padding 347 bytes at the end of this array are undefined, drivers and 348 applications shall ignore them. 349 350Packets are always passed in ascending line number order, without 351duplicate line numbers. The :c:func:`write()` function and 352the :ref:`VIDIOC_QBUF` ioctl must return an ``EINVAL`` 353error code when applications violate this rule. They must also return an 354EINVAL error code when applications pass an incorrect field or line 355number, or a combination of ``field``, ``line`` and ``id`` which has not 356been negotiated with the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` or 357:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. When the line numbers are 358unknown the driver must pass the packets in transmitted order. The 359driver can insert empty packets with ``id`` set to zero anywhere in the 360packet array. 361 362To assure synchronization and to distinguish from frame dropping, when a 363captured frame does not carry any of the requested data services drivers 364must pass one or more empty packets. When an application fails to pass 365VBI data in time for output, the driver must output the last VPS and WSS 366packet again, and disable the output of Closed Caption and Teletext 367data, or output data which is ignored by Closed Caption and Teletext 368decoders. 369 370A sliced VBI device may support :ref:`read/write <rw>` and/or 371streaming (:ref:`memory mapping <mmap>` and/or 372:ref:`user pointer <userp>`) I/O. The latter bears the possibility of 373synchronizing video and VBI data by using buffer timestamps. 374 375Sliced VBI Data in MPEG Streams 376=============================== 377 378If a device can produce an MPEG output stream, it may be capable of 379providing 380:ref:`negotiated sliced VBI services <sliced-vbi-format-negotitation>` 381as data embedded in the MPEG stream. Users or applications control this 382sliced VBI data insertion with the 383:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>` 384control. 385 386If the driver does not provide the 387:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>` 388control, or only allows that control to be set to 389:ref:`V4L2_MPEG_STREAM_VBI_FMT_NONE <v4l2-mpeg-stream-vbi-fmt>`, 390then the device cannot embed sliced VBI data in the MPEG stream. 391 392The 393:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>` 394control does not implicitly set the device driver to capture nor cease 395capturing sliced VBI data. The control only indicates to embed sliced 396VBI data in the MPEG stream, if an application has negotiated sliced VBI 397service be captured. 398 399It may also be the case that a device can embed sliced VBI data in only 400certain types of MPEG streams: for example in an MPEG-2 PS but not an 401MPEG-2 TS. In this situation, if sliced VBI data insertion is requested, 402the sliced VBI data will be embedded in MPEG stream types when 403supported, and silently omitted from MPEG stream types where sliced VBI 404data insertion is not supported by the device. 405 406The following subsections specify the format of the embedded sliced VBI 407data. 408 409MPEG Stream Embedded, Sliced VBI Data Format: NONE 410-------------------------------------------------- 411 412The 413:ref:`V4L2_MPEG_STREAM_VBI_FMT_NONE <v4l2-mpeg-stream-vbi-fmt>` 414embedded sliced VBI format shall be interpreted by drivers as a control 415to cease embedding sliced VBI data in MPEG streams. Neither the device 416nor driver shall insert "empty" embedded sliced VBI data packets in the 417MPEG stream when this format is set. No MPEG stream data structures are 418specified for this format. 419 420MPEG Stream Embedded, Sliced VBI Data Format: IVTV 421-------------------------------------------------- 422 423The 424:ref:`V4L2_MPEG_STREAM_VBI_FMT_IVTV <v4l2-mpeg-stream-vbi-fmt>` 425embedded sliced VBI format, when supported, indicates to the driver to 426embed up to 36 lines of sliced VBI data per frame in an MPEG-2 *Private 427Stream 1 PES* packet encapsulated in an MPEG-2 *Program Pack* in the 428MPEG stream. 429 430*Historical context*: This format specification originates from a 431custom, embedded, sliced VBI data format used by the ``ivtv`` driver. 432This format has already been informally specified in the kernel sources 433in the file ``Documentation/userspace-api/media/drivers/cx2341x-uapi.rst`` . The 434maximum size of the payload and other aspects of this format are driven 435by the CX23415 MPEG decoder's capabilities and limitations with respect 436to extracting, decoding, and displaying sliced VBI data embedded within 437an MPEG stream. 438 439This format's use is *not* exclusive to the ``ivtv`` driver *nor* 440exclusive to CX2341x devices, as the sliced VBI data packet insertion 441into the MPEG stream is implemented in driver software. At least the 442``cx18`` driver provides sliced VBI data insertion into an MPEG-2 PS in 443this format as well. 444 445The following definitions specify the payload of the MPEG-2 *Private 446Stream 1 PES* packets that contain sliced VBI data when 447:ref:`V4L2_MPEG_STREAM_VBI_FMT_IVTV <v4l2-mpeg-stream-vbi-fmt>` 448is set. (The MPEG-2 *Private Stream 1 PES* packet header and 449encapsulating MPEG-2 *Program Pack* header are not detailed here. Please 450refer to the MPEG-2 specifications for details on those packet headers.) 451 452The payload of the MPEG-2 *Private Stream 1 PES* packets that contain 453sliced VBI data is specified by struct 454:c:type:`v4l2_mpeg_vbi_fmt_ivtv`. The 455payload is variable length, depending on the actual number of lines of 456sliced VBI data present in a video frame. The payload may be padded at 457the end with unspecified fill bytes to align the end of the payload to a 4584-byte boundary. The payload shall never exceed 1552 bytes (2 fields 459with 18 lines/field with 43 bytes of data/line and a 4 byte magic 460number). 461 462.. c:type:: v4l2_mpeg_vbi_fmt_ivtv 463 464struct v4l2_mpeg_vbi_fmt_ivtv 465----------------------------- 466 467.. tabularcolumns:: |p{4.2cm}|p{2.0cm}|p{11.1cm}| 468 469.. flat-table:: 470 :header-rows: 0 471 :stub-columns: 0 472 :widths: 1 1 2 473 474 * - __u8 475 - ``magic``\ [4] 476 - A "magic" constant from :ref:`v4l2-mpeg-vbi-fmt-ivtv-magic` that 477 indicates this is a valid sliced VBI data payload and also 478 indicates which member of the anonymous union, ``itv0`` or 479 ``ITV0``, to use for the payload data. 480 * - union { 481 - (anonymous) 482 * - struct :c:type:`v4l2_mpeg_vbi_itv0` 483 - ``itv0`` 484 - The primary form of the sliced VBI data payload that contains 485 anywhere from 1 to 35 lines of sliced VBI data. Line masks are 486 provided in this form of the payload indicating which VBI lines 487 are provided. 488 * - struct :ref:`v4l2_mpeg_vbi_ITV0 <v4l2-mpeg-vbi-itv0-1>` 489 - ``ITV0`` 490 - An alternate form of the sliced VBI data payload used when 36 491 lines of sliced VBI data are present. No line masks are provided 492 in this form of the payload; all valid line mask bits are 493 implcitly set. 494 * - } 495 - 496 497.. _v4l2-mpeg-vbi-fmt-ivtv-magic: 498 499Magic Constants for struct v4l2_mpeg_vbi_fmt_ivtv magic field 500------------------------------------------------------------- 501 502.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}| 503 504.. flat-table:: 505 :header-rows: 1 506 :stub-columns: 0 507 :widths: 3 1 4 508 509 * - Defined Symbol 510 - Value 511 - Description 512 * - ``V4L2_MPEG_VBI_IVTV_MAGIC0`` 513 - "itv0" 514 - Indicates the ``itv0`` member of the union in struct 515 :c:type:`v4l2_mpeg_vbi_fmt_ivtv` is 516 valid. 517 * - ``V4L2_MPEG_VBI_IVTV_MAGIC1`` 518 - "ITV0" 519 - Indicates the ``ITV0`` member of the union in struct 520 :c:type:`v4l2_mpeg_vbi_fmt_ivtv` is 521 valid and that 36 lines of sliced VBI data are present. 522 523 524.. c:type:: v4l2_mpeg_vbi_itv0 525 526.. c:type:: v4l2_mpeg_vbi_ITV0 527 528structs v4l2_mpeg_vbi_itv0 and v4l2_mpeg_vbi_ITV0 529------------------------------------------------- 530 531.. raw:: latex 532 533 \footnotesize 534 535.. tabularcolumns:: |p{4.6cm}|p{2.0cm}|p{10.7cm}| 536 537.. flat-table:: 538 :header-rows: 0 539 :stub-columns: 0 540 :widths: 1 1 2 541 542 * - __le32 543 - ``linemask``\ [2] 544 - Bitmasks indicating the VBI service lines present. These 545 ``linemask`` values are stored in little endian byte order in the 546 MPEG stream. Some reference ``linemask`` bit positions with their 547 corresponding VBI line number and video field are given below. 548 b\ :sub:`0` indicates the least significant bit of a ``linemask`` 549 value: 550 551 552 :: 553 554 linemask[0] b0: line 6 first field 555 linemask[0] b17: line 23 first field 556 linemask[0] b18: line 6 second field 557 linemask[0] b31: line 19 second field 558 linemask[1] b0: line 20 second field 559 linemask[1] b3: line 23 second field 560 linemask[1] b4-b31: unused and set to 0 561 * - struct 562 :c:type:`v4l2_mpeg_vbi_itv0_line` 563 - ``line``\ [35] 564 - This is a variable length array that holds from 1 to 35 lines of 565 sliced VBI data. The sliced VBI data lines present correspond to 566 the bits set in the ``linemask`` array, starting from b\ :sub:`0` 567 of ``linemask``\ [0] up through b\ :sub:`31` of ``linemask``\ [0], 568 and from b\ :sub:`0` of ``linemask``\ [1] up through b\ :sub:`3` of 569 ``linemask``\ [1]. ``line``\ [0] corresponds to the first bit 570 found set in the ``linemask`` array, ``line``\ [1] corresponds to 571 the second bit found set in the ``linemask`` array, etc. If no 572 ``linemask`` array bits are set, then ``line``\ [0] may contain 573 one line of unspecified data that should be ignored by 574 applications. 575 576.. raw:: latex 577 578 \normalsize 579 580.. _v4l2-mpeg-vbi-itv0-1: 581 582struct v4l2_mpeg_vbi_ITV0 583------------------------- 584 585.. tabularcolumns:: |p{5.2cm}|p{2.4cm}|p{9.7cm}| 586 587.. flat-table:: 588 :header-rows: 0 589 :stub-columns: 0 590 :widths: 1 1 2 591 592 * - struct 593 :c:type:`v4l2_mpeg_vbi_itv0_line` 594 - ``line``\ [36] 595 - A fixed length array of 36 lines of sliced VBI data. ``line``\ [0] 596 through ``line``\ [17] correspond to lines 6 through 23 of the 597 first field. ``line``\ [18] through ``line``\ [35] corresponds to 598 lines 6 through 23 of the second field. 599 600 601.. c:type:: v4l2_mpeg_vbi_itv0_line 602 603struct v4l2_mpeg_vbi_itv0_line 604------------------------------ 605 606.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| 607 608.. flat-table:: 609 :header-rows: 0 610 :stub-columns: 0 611 :widths: 1 1 2 612 613 * - __u8 614 - ``id`` 615 - A line identifier value from 616 :ref:`ITV0-Line-Identifier-Constants` that indicates the type of 617 sliced VBI data stored on this line. 618 * - __u8 619 - ``data``\ [42] 620 - The sliced VBI data for the line. 621 622 623.. _ITV0-Line-Identifier-Constants: 624 625Line Identifiers for struct v4l2_mpeg_vbi_itv0_line id field 626------------------------------------------------------------ 627 628.. tabularcolumns:: |p{7.0cm}|p{1.8cm}|p{8.5cm}| 629 630.. flat-table:: 631 :header-rows: 1 632 :stub-columns: 0 633 :widths: 3 1 4 634 635 * - Defined Symbol 636 - Value 637 - Description 638 * - ``V4L2_MPEG_VBI_IVTV_TELETEXT_B`` 639 - 1 640 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 641 description of the line payload. 642 * - ``V4L2_MPEG_VBI_IVTV_CAPTION_525`` 643 - 4 644 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 645 description of the line payload. 646 * - ``V4L2_MPEG_VBI_IVTV_WSS_625`` 647 - 5 648 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 649 description of the line payload. 650 * - ``V4L2_MPEG_VBI_IVTV_VPS`` 651 - 7 652 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a 653 description of the line payload. 654 655 656.. [#f1] 657 According to :ref:`ETS 300 706 <ets300706>` lines 6-22 of the first 658 field and lines 5-22 of the second field may carry Teletext data. 659 660.. [#f2] 661 See also :ref:`vbi-525` and :ref:`vbi-625`. 662