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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _sliced:5 6*************************7Sliced VBI Data Interface8*************************9 10VBI stands for Vertical Blanking Interval, a gap in the sequence of11lines of an analog video signal. During VBI no picture information is12transmitted, allowing some time while the electron beam of a cathode ray13tube TV returns to the top of the screen.14 15Sliced VBI devices use hardware to demodulate data transmitted in the16VBI. V4L2 drivers shall *not* do this by software, see also the17:ref:`raw VBI interface <raw-vbi>`. The data is passed as short18packets of fixed size, covering one scan line each. The number of19packets per video frame is variable.20 21Sliced VBI capture and output devices are accessed through the same22character special files as raw VBI devices. When a driver supports both23interfaces, the default function of a ``/dev/vbi`` device is *raw* VBI24capturing or output, and the sliced VBI function is only available after25calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl as defined26below. 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 data29simultaneously, if this is supported by the driver.30 31Querying Capabilities32=====================33 34Devices supporting the sliced VBI capturing or output API set the35``V4L2_CAP_SLICED_VBI_CAPTURE`` or ``V4L2_CAP_SLICED_VBI_OUTPUT`` flag36respectively, in the ``capabilities`` field of struct37:c:type:`v4l2_capability` returned by the38:ref:`VIDIOC_QUERYCAP` ioctl. At least one of the39read/write or streaming :ref:`I/O methods <io>` must be40supported. Sliced VBI devices may have a tuner or modulator.41 42Supplemental Functions43======================44 45Sliced VBI devices shall support :ref:`video input or output <video>`46and :ref:`tuner or modulator <tuner>` ioctls if they have these47capabilities, and they may support :ref:`control` ioctls.48The :ref:`video standard <standard>` ioctls provide information vital49to program a sliced VBI device, therefore must be supported.50 51.. _sliced-vbi-format-negotitation:52 53Sliced VBI Format Negotiation54=============================55 56To find out which data services are supported by the hardware57applications can call the58:ref:`VIDIOC_G_SLICED_VBI_CAP <VIDIOC_G_SLICED_VBI_CAP>` ioctl.59All drivers implementing the sliced VBI interface must support this60ioctl. The results may differ from those of the61:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl when the number of VBI62lines the hardware can capture or output per frame, or the number of63services it can identify on a given line are limited. For example on PAL64line 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 the68``type`` field of struct :c:type:`v4l2_format` to69``V4L2_BUF_TYPE_SLICED_VBI_CAPTURE`` or70``V4L2_BUF_TYPE_SLICED_VBI_OUTPUT``, and the71:ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` ioctl fills the ``fmt.sliced``72member, a struct73:c:type:`v4l2_sliced_vbi_format`.74 75Applications can request different parameters by initializing or76modifying the ``fmt.sliced`` member and calling the77:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with a pointer to the78struct :c:type:`v4l2_format` structure.79 80The sliced VBI API is more complicated than the raw VBI API because the81hardware must be told which VBI service to expect on each scan line. Not82all services may be supported by the hardware on all lines (this is83especially true for VBI output where Teletext is often unsupported and84other services can only be inserted in one specific line). In many85cases, however, it is sufficient to just set the ``service_set`` field86to the required services and let the driver fill the ``service_lines``87array according to hardware capabilities. Only if more precise control88is needed should the programmer set the ``service_lines`` array89explicitly.90 91The :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl modifies the parameters92according to hardware capabilities. When the driver allocates resources93at this point, it may return an ``EBUSY`` error code if the required94resources are temporarily unavailable. Other resource allocation points95which may return ``EBUSY`` can be the96:ref:`VIDIOC_STREAMON` ioctl and the first97:c:func:`read()`, :c:func:`write()` and98:c:func:`select()` call.99 100.. c:type:: v4l2_sliced_vbi_format101 102struct v4l2_sliced_vbi_format103-----------------------------104 105.. raw:: latex106 107 \begingroup108 \scriptsize109 \setlength{\tabcolsep}{2pt}110 111.. tabularcolumns:: |p{.85cm}|p{3.3cm}|p{4.45cm}|p{4.45cm}|p{4.45cm}|112 113.. cssclass:: longtable114 115.. flat-table::116 :header-rows: 0117 :stub-columns: 0118 :widths: 3 3 2 2 2119 120 * - __u16121 - ``service_set``122 - :cspan:`2`123 124 If ``service_set`` is non-zero when passed with125 :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or126 :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`, the ``service_lines``127 array will be filled by the driver according to the services128 specified in this field. For example, if ``service_set`` is129 initialized with ``V4L2_SLICED_TELETEXT_B | V4L2_SLICED_WSS_625``,130 a driver for the cx25840 video decoder sets lines 7-22 of both131 fields [#f1]_ to ``V4L2_SLICED_TELETEXT_B`` and line 23 of the first132 field to ``V4L2_SLICED_WSS_625``. If ``service_set`` is set to133 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 elements136 of the returned ``service_lines`` array. It may contain less137 services than requested, perhaps just one, if the hardware cannot138 handle more services simultaneously. It may be empty (zero) if139 none of the requested services are supported by the hardware.140 * - __u16141 - ``service_lines``\ [2][24]142 - :cspan:`2`143 144 Applications initialize this array with sets of data services the145 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 line149 the driver shall choose one. No assumptions can be made on which150 service the driver chooses.151 152 Data services are defined in :ref:`vbi-services2`. Array indices153 map to ITU-R line numbers\ [#f2]_ as follows:154 * -155 -156 - Element157 - 525 line systems158 - 625 line systems159 * -160 -161 - ``service_lines``\ [0][1]162 - 1163 - 1164 * -165 -166 - ``service_lines``\ [0][23]167 - 23168 - 23169 * -170 -171 - ``service_lines``\ [1][1]172 - 264173 - 314174 * -175 -176 - ``service_lines``\ [1][23]177 - 286178 - 336179 * -180 -181 - :cspan:`2` Drivers must set ``service_lines`` [0][0] and182 ``service_lines``\ [1][0] to zero. The183 ``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 or186 625 line format as a convenience. Don't forget that ITU line187 numbering starts at 1, not 0.188 * - __u32189 - ``io_size``190 - :cspan:`2` Maximum number of bytes passed by one191 :c:func:`read()` or :c:func:`write()` call,192 and the buffer size in bytes for the193 :ref:`VIDIOC_QBUF` and194 :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl. Drivers set this field195 to the size of struct196 :c:type:`v4l2_sliced_vbi_data` times the197 number of non-zero elements in the returned ``service_lines``198 array (that is the number of lines potentially carrying data).199 * - __u32200 - ``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:: latex206 207 \endgroup208 209.. _vbi-services2:210 211Sliced VBI services212-------------------213 214.. raw:: latex215 216 \footnotesize217 218.. tabularcolumns:: |p{4.2cm}|p{1.1cm}|p{2.1cm}|p{2.0cm}|p{6.5cm}|219 220.. flat-table::221 :header-rows: 1222 :stub-columns: 0223 :widths: 2 1 1 2 2224 225 * - Symbol226 - Value227 - Reference228 - Lines, usually229 - Payload230 * - ``V4L2_SLICED_TELETEXT_B`` (Teletext System B)231 - 0x0001232 - :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 clock237 run-in and framing code, lsb first transmitted.238 * - ``V4L2_SLICED_VPS``239 - 0x0400240 - :ref:`ets300231`241 - PAL line 16242 - Byte number 3 to 15 according to Figure 9 of ETS 300 231, lsb243 first transmitted.244 * - ``V4L2_SLICED_CAPTION_525``245 - 0x1000246 - :ref:`cea608`247 - NTSC line 21, 284 (second field 21)248 - Two bytes in transmission order, including parity bit, lsb first249 transmitted.250 * - ``V4L2_SLICED_WSS_625``251 - 0x4000252 - :ref:`itu1119`,253 254 :ref:`en300294`255 - PAL/SECAM line 23256 - See :ref:`v4l2-sliced-wss-625-payload` below.257 * - ``V4L2_SLICED_VBI_525``258 - 0x1000259 - :cspan:`2` Set of services applicable to 525 line systems.260 * - ``V4L2_SLICED_VBI_625``261 - 0x4401262 - :cspan:`2` Set of services applicable to 625 line systems.263 264.. raw:: latex265 266 \normalsize267 268Drivers may return an ``EINVAL`` error code when applications attempt to269read or write data without prior format negotiation, after switching the270video standard (which may invalidate the negotiated VBI parameters) and271after switching the video input (which may change the video standard as272a side effect). The :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl may273return an ``EBUSY`` error code when applications attempt to change the274format while i/o is in progress (between a275:ref:`VIDIOC_STREAMON` and276:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` call, and after the first277:c:func:`read()` or :c:func:`write()` call).278 279.. _v4l2-sliced-wss-625-payload:280 281V4L2_SLICED_WSS_625 payload282~~~~~~~~~~~~~~~~~~~~~~~~~~~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 data295===================================296 297A single :c:func:`read()` or :c:func:`write()`298call must pass all data belonging to one video frame. That is an array299of struct :c:type:`v4l2_sliced_vbi_data` structures with one or300more elements and a total size not exceeding ``io_size`` bytes. Likewise301in streaming I/O mode one buffer of ``io_size`` bytes must contain data302of one video frame. The ``id`` of unused303struct :c:type:`v4l2_sliced_vbi_data` elements must be zero.304 305.. c:type:: v4l2_sliced_vbi_data306 307struct v4l2_sliced_vbi_data308---------------------------309 310.. tabularcolumns:: |p{1.2cm}|p{2.2cm}|p{13.9cm}|311 312.. flat-table::313 :header-rows: 0314 :stub-columns: 0315 :widths: 3 1 4316 317 * - __u32318 - ``id``319 - A flag from :ref:`vbi-services` identifying the type of data in320 this packet. Only a single bit must be set. When the ``id`` of a321 captured packet is zero, the packet is empty and the contents of322 other fields are undefined. Applications shall ignore empty323 packets. When the ``id`` of a packet for output is zero the324 contents of the ``data`` field are undefined and the driver must325 no longer insert data on the requested ``field`` and ``line``.326 * - __u32327 - ``field``328 - The video field number this data has been captured from, or shall329 be inserted at. ``0`` for the first field, ``1`` for the second330 field.331 * - __u32332 - ``line``333 - The field (as opposed to frame) line number this data has been334 captured from, or shall be inserted at. See :ref:`vbi-525` and335 :ref:`vbi-625` for valid values. Sliced VBI capture devices can336 set the line number of all packets to ``0`` if the hardware cannot337 reliably identify scan lines. The field number must always be338 valid.339 * - __u32340 - ``reserved``341 - This field is reserved for future extensions. Applications and342 drivers must set it to zero.343 * - __u8344 - ``data``\ [48]345 - The packet payload. See :ref:`vbi-services` for the contents and346 number of bytes passed for each data type. The contents of padding347 bytes at the end of this array are undefined, drivers and348 applications shall ignore them.349 350Packets are always passed in ascending line number order, without351duplicate line numbers. The :c:func:`write()` function and352the :ref:`VIDIOC_QBUF` ioctl must return an ``EINVAL``353error code when applications violate this rule. They must also return an354EINVAL error code when applications pass an incorrect field or line355number, or a combination of ``field``, ``line`` and ``id`` which has not356been negotiated with the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` or357:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. When the line numbers are358unknown the driver must pass the packets in transmitted order. The359driver can insert empty packets with ``id`` set to zero anywhere in the360packet array.361 362To assure synchronization and to distinguish from frame dropping, when a363captured frame does not carry any of the requested data services drivers364must pass one or more empty packets. When an application fails to pass365VBI data in time for output, the driver must output the last VPS and WSS366packet again, and disable the output of Closed Caption and Teletext367data, or output data which is ignored by Closed Caption and Teletext368decoders.369 370A sliced VBI device may support :ref:`read/write <rw>` and/or371streaming (:ref:`memory mapping <mmap>` and/or372:ref:`user pointer <userp>`) I/O. The latter bears the possibility of373synchronizing video and VBI data by using buffer timestamps.374 375Sliced VBI Data in MPEG Streams376===============================377 378If a device can produce an MPEG output stream, it may be capable of379providing380:ref:`negotiated sliced VBI services <sliced-vbi-format-negotitation>`381as data embedded in the MPEG stream. Users or applications control this382sliced VBI data insertion with the383:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>`384control.385 386If the driver does not provide the387:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>`388control, or only allows that control to be set to389: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 392The393:ref:`V4L2_CID_MPEG_STREAM_VBI_FMT <v4l2-mpeg-stream-vbi-fmt>`394control does not implicitly set the device driver to capture nor cease395capturing sliced VBI data. The control only indicates to embed sliced396VBI data in the MPEG stream, if an application has negotiated sliced VBI397service be captured.398 399It may also be the case that a device can embed sliced VBI data in only400certain types of MPEG streams: for example in an MPEG-2 PS but not an401MPEG-2 TS. In this situation, if sliced VBI data insertion is requested,402the sliced VBI data will be embedded in MPEG stream types when403supported, and silently omitted from MPEG stream types where sliced VBI404data insertion is not supported by the device.405 406The following subsections specify the format of the embedded sliced VBI407data.408 409MPEG Stream Embedded, Sliced VBI Data Format: NONE410--------------------------------------------------411 412The413:ref:`V4L2_MPEG_STREAM_VBI_FMT_NONE <v4l2-mpeg-stream-vbi-fmt>`414embedded sliced VBI format shall be interpreted by drivers as a control415to cease embedding sliced VBI data in MPEG streams. Neither the device416nor driver shall insert "empty" embedded sliced VBI data packets in the417MPEG stream when this format is set. No MPEG stream data structures are418specified for this format.419 420MPEG Stream Embedded, Sliced VBI Data Format: IVTV421--------------------------------------------------422 423The424:ref:`V4L2_MPEG_STREAM_VBI_FMT_IVTV <v4l2-mpeg-stream-vbi-fmt>`425embedded sliced VBI format, when supported, indicates to the driver to426embed up to 36 lines of sliced VBI data per frame in an MPEG-2 *Private427Stream 1 PES* packet encapsulated in an MPEG-2 *Program Pack* in the428MPEG stream.429 430*Historical context*: This format specification originates from a431custom, embedded, sliced VBI data format used by the ``ivtv`` driver.432This format has already been informally specified in the kernel sources433in the file ``Documentation/userspace-api/media/drivers/cx2341x-uapi.rst`` . The434maximum size of the payload and other aspects of this format are driven435by the CX23415 MPEG decoder's capabilities and limitations with respect436to extracting, decoding, and displaying sliced VBI data embedded within437an 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 insertion441into the MPEG stream is implemented in driver software. At least the442``cx18`` driver provides sliced VBI data insertion into an MPEG-2 PS in443this format as well.444 445The following definitions specify the payload of the MPEG-2 *Private446Stream 1 PES* packets that contain sliced VBI data when447:ref:`V4L2_MPEG_STREAM_VBI_FMT_IVTV <v4l2-mpeg-stream-vbi-fmt>`448is set. (The MPEG-2 *Private Stream 1 PES* packet header and449encapsulating MPEG-2 *Program Pack* header are not detailed here. Please450refer to the MPEG-2 specifications for details on those packet headers.)451 452The payload of the MPEG-2 *Private Stream 1 PES* packets that contain453sliced VBI data is specified by struct454:c:type:`v4l2_mpeg_vbi_fmt_ivtv`. The455payload is variable length, depending on the actual number of lines of456sliced VBI data present in a video frame. The payload may be padded at457the end with unspecified fill bytes to align the end of the payload to a4584-byte boundary. The payload shall never exceed 1552 bytes (2 fields459with 18 lines/field with 43 bytes of data/line and a 4 byte magic460number).461 462.. c:type:: v4l2_mpeg_vbi_fmt_ivtv463 464struct v4l2_mpeg_vbi_fmt_ivtv465-----------------------------466 467.. tabularcolumns:: |p{4.2cm}|p{2.0cm}|p{11.1cm}|468 469.. flat-table::470 :header-rows: 0471 :stub-columns: 0472 :widths: 1 1 2473 474 * - __u8475 - ``magic``\ [4]476 - A "magic" constant from :ref:`v4l2-mpeg-vbi-fmt-ivtv-magic` that477 indicates this is a valid sliced VBI data payload and also478 indicates which member of the anonymous union, ``itv0`` or479 ``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 contains485 anywhere from 1 to 35 lines of sliced VBI data. Line masks are486 provided in this form of the payload indicating which VBI lines487 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 36491 lines of sliced VBI data are present. No line masks are provided492 in this form of the payload; all valid line mask bits are493 implicitly set.494 * - }495 -496 497.. _v4l2-mpeg-vbi-fmt-ivtv-magic:498 499Magic Constants for struct v4l2_mpeg_vbi_fmt_ivtv magic field500-------------------------------------------------------------501 502.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|503 504.. flat-table::505 :header-rows: 1506 :stub-columns: 0507 :widths: 3 1 4508 509 * - Defined Symbol510 - Value511 - Description512 * - ``V4L2_MPEG_VBI_IVTV_MAGIC0``513 - "itv0"514 - Indicates the ``itv0`` member of the union in struct515 :c:type:`v4l2_mpeg_vbi_fmt_ivtv` is516 valid.517 * - ``V4L2_MPEG_VBI_IVTV_MAGIC1``518 - "ITV0"519 - Indicates the ``ITV0`` member of the union in struct520 :c:type:`v4l2_mpeg_vbi_fmt_ivtv` is521 valid and that 36 lines of sliced VBI data are present.522 523 524.. c:type:: v4l2_mpeg_vbi_itv0525 526.. c:type:: v4l2_mpeg_vbi_ITV0527 528structs v4l2_mpeg_vbi_itv0 and v4l2_mpeg_vbi_ITV0529-------------------------------------------------530 531.. raw:: latex532 533 \footnotesize534 535.. tabularcolumns:: |p{4.6cm}|p{2.0cm}|p{10.7cm}|536 537.. flat-table::538 :header-rows: 0539 :stub-columns: 0540 :widths: 1 1 2541 542 * - __le32543 - ``linemask``\ [2]544 - Bitmasks indicating the VBI service lines present. These545 ``linemask`` values are stored in little endian byte order in the546 MPEG stream. Some reference ``linemask`` bit positions with their547 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 field555 linemask[0] b17: line 23 first field556 linemask[0] b18: line 6 second field557 linemask[0] b31: line 19 second field558 linemask[1] b0: line 20 second field559 linemask[1] b3: line 23 second field560 linemask[1] b4-b31: unused and set to 0561 * - struct562 :c:type:`v4l2_mpeg_vbi_itv0_line`563 - ``line``\ [35]564 - This is a variable length array that holds from 1 to 35 lines of565 sliced VBI data. The sliced VBI data lines present correspond to566 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` of569 ``linemask``\ [1]. ``line``\ [0] corresponds to the first bit570 found set in the ``linemask`` array, ``line``\ [1] corresponds to571 the second bit found set in the ``linemask`` array, etc. If no572 ``linemask`` array bits are set, then ``line``\ [0] may contain573 one line of unspecified data that should be ignored by574 applications.575 576.. raw:: latex577 578 \normalsize579 580.. _v4l2-mpeg-vbi-itv0-1:581 582struct v4l2_mpeg_vbi_ITV0583-------------------------584 585.. tabularcolumns:: |p{5.2cm}|p{2.4cm}|p{9.7cm}|586 587.. flat-table::588 :header-rows: 0589 :stub-columns: 0590 :widths: 1 1 2591 592 * - struct593 :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 the597 first field. ``line``\ [18] through ``line``\ [35] corresponds to598 lines 6 through 23 of the second field.599 600 601.. c:type:: v4l2_mpeg_vbi_itv0_line602 603struct v4l2_mpeg_vbi_itv0_line604------------------------------605 606.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|607 608.. flat-table::609 :header-rows: 0610 :stub-columns: 0611 :widths: 1 1 2612 613 * - __u8614 - ``id``615 - A line identifier value from616 :ref:`ITV0-Line-Identifier-Constants` that indicates the type of617 sliced VBI data stored on this line.618 * - __u8619 - ``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 field626------------------------------------------------------------627 628.. tabularcolumns:: |p{7.0cm}|p{1.8cm}|p{8.5cm}|629 630.. flat-table::631 :header-rows: 1632 :stub-columns: 0633 :widths: 3 1 4634 635 * - Defined Symbol636 - Value637 - Description638 * - ``V4L2_MPEG_VBI_IVTV_TELETEXT_B``639 - 1640 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a641 description of the line payload.642 * - ``V4L2_MPEG_VBI_IVTV_CAPTION_525``643 - 4644 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a645 description of the line payload.646 * - ``V4L2_MPEG_VBI_IVTV_WSS_625``647 - 5648 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a649 description of the line payload.650 * - ``V4L2_MPEG_VBI_IVTV_VPS``651 - 7652 - Refer to :ref:`Sliced VBI services <vbi-services2>` for a653 description of the line payload.654 655 656.. [#f1]657 According to :ref:`ETS 300 706 <ets300706>` lines 6-22 of the first658 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