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diff --git a/Documentation/DocBook/v4l/dev-sliced-vbi.xml b/Documentation/DocBook/v4l/dev-sliced-vbi.xml new file mode 100644 index 0000000..69e789f --- /dev/null +++ b/Documentation/DocBook/v4l/dev-sliced-vbi.xml @@ -0,0 +1,708 @@ + <title>Sliced VBI Data Interface</title> + + <para>VBI stands for Vertical Blanking Interval, a gap in the +sequence of lines of an analog video signal. During VBI no picture +information is transmitted, allowing some time while the electron beam +of a cathode ray tube TV returns to the top of the screen.</para> + + <para>Sliced VBI devices use hardware to demodulate data transmitted +in the VBI. V4L2 drivers shall <emphasis>not</emphasis> do this by +software, see also the <link linkend="raw-vbi">raw VBI +interface</link>. The data is passed as short packets of fixed size, +covering one scan line each. The number of packets per video frame is +variable.</para> + + <para>Sliced VBI capture and output devices are accessed through the +same character special files as raw VBI devices. When a driver +supports both interfaces, the default function of a +<filename>/dev/vbi</filename> device is <emphasis>raw</emphasis> VBI +capturing or output, and the sliced VBI function is only available +after calling the &VIDIOC-S-FMT; ioctl as defined below. Likewise a +<filename>/dev/video</filename> device may support the sliced VBI API, +however the default function here is video capturing or output. +Different file descriptors must be used to pass raw and sliced VBI +data simultaneously, if this is supported by the driver.</para> + + <section> + <title>Querying Capabilities</title> + + <para>Devices supporting the sliced VBI capturing or output API +set the <constant>V4L2_CAP_SLICED_VBI_CAPTURE</constant> or +<constant>V4L2_CAP_SLICED_VBI_OUTPUT</constant> flag respectively, in +the <structfield>capabilities</structfield> field of &v4l2-capability; +returned by the &VIDIOC-QUERYCAP; ioctl. At least one of the +read/write, streaming or asynchronous <link linkend="io">I/O +methods</link> must be supported. Sliced VBI devices may have a tuner +or modulator.</para> + </section> + + <section> + <title>Supplemental Functions</title> + + <para>Sliced VBI devices shall support <link linkend="video">video +input or output</link> and <link linkend="tuner">tuner or +modulator</link> ioctls if they have these capabilities, and they may +support <link linkend="control">control</link> ioctls. The <link +linkend="standard">video standard</link> ioctls provide information +vital to program a sliced VBI device, therefore must be +supported.</para> + </section> + + <section id="sliced-vbi-format-negotitation"> + <title>Sliced VBI Format Negotiation</title> + + <para>To find out which data services are supported by the +hardware applications can call the &VIDIOC-G-SLICED-VBI-CAP; ioctl. +All drivers implementing the sliced VBI interface must support this +ioctl. The results may differ from those of the &VIDIOC-S-FMT; ioctl +when the number of VBI lines the hardware can capture or output per +frame, or the number of services it can identify on a given line are +limited. For example on PAL line 16 the hardware may be able to look +for a VPS or Teletext signal, but not both at the same time.</para> + + <para>To determine the currently selected services applications +set the <structfield>type </structfield> field of &v4l2-format; to +<constant> V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> or <constant> +V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant>, and the &VIDIOC-G-FMT; +ioctl fills the <structfield>fmt.sliced</structfield> member, a +&v4l2-sliced-vbi-format;.</para> + + <para>Applications can request different parameters by +initializing or modifying the <structfield>fmt.sliced</structfield> +member and calling the &VIDIOC-S-FMT; ioctl with a pointer to the +<structname>v4l2_format</structname> structure.</para> + + <para>The sliced VBI API is more complicated than the raw VBI API +because the hardware must be told which VBI service to expect on each +scan line. Not all services may be supported by the hardware on all +lines (this is especially true for VBI output where Teletext is often +unsupported and other services can only be inserted in one specific +line). In many cases, however, it is sufficient to just set the +<structfield>service_set</structfield> field to the required services +and let the driver fill the <structfield>service_lines</structfield> +array according to hardware capabilities. Only if more precise control +is needed should the programmer set the +<structfield>service_lines</structfield> array explicitly.</para> + + <para>The &VIDIOC-S-FMT; ioctl modifies the parameters +according to hardware capabilities. When the driver allocates +resources at this point, it may return an &EBUSY; if the required +resources are temporarily unavailable. Other resource allocation +points which may return <errorcode>EBUSY</errorcode> can be the +&VIDIOC-STREAMON; ioctl and the first &func-read;, &func-write; and +&func-select; call.</para> + + <table frame="none" pgwide="1" id="v4l2-sliced-vbi-format"> + <title>struct +<structname>v4l2_sliced_vbi_format</structname></title> + <tgroup cols="5"> + <colspec colname="c1" colwidth="3*" /> + <colspec colname="c2" colwidth="3*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="2*" /> + <colspec colname="c5" colwidth="2*" /> + <spanspec namest="c3" nameend="c5" spanname="hspan" /> + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>service_set</structfield></entry> + <entry spanname="hspan"><para>If +<structfield>service_set</structfield> is non-zero when passed with +&VIDIOC-S-FMT; or &VIDIOC-TRY-FMT;, the +<structfield>service_lines</structfield> array will be filled by the +driver according to the services specified in this field. For example, +if <structfield>service_set</structfield> is initialized with +<constant>V4L2_SLICED_TELETEXT_B | V4L2_SLICED_WSS_625</constant>, a +driver for the cx25840 video decoder sets lines 7-22 of both +fields<footnote><para>According to <link +linkend="ets300706">ETS 300 706</link> lines 6-22 of the +first field and lines 5-22 of the second field may carry Teletext +data.</para></footnote> to <constant>V4L2_SLICED_TELETEXT_B</constant> +and line 23 of the first field to +<constant>V4L2_SLICED_WSS_625</constant>. If +<structfield>service_set</structfield> is set to zero, then the values +of <structfield>service_lines</structfield> will be used instead. +</para><para>On return the driver sets this field to the union of all +elements of the returned <structfield>service_lines</structfield> +array. It may contain less services than requested, perhaps just one, +if the hardware cannot handle more services simultaneously. It may be +empty (zero) if none of the requested services are supported by the +hardware.</para></entry> + </row> + <row> + <entry>__u16</entry> + <entry><structfield>service_lines</structfield>[2][24]</entry> + <entry spanname="hspan"><para>Applications initialize this +array with sets of data services the driver shall look for or insert +on the respective scan line. Subject to hardware capabilities drivers +return the requested set, a subset, which may be just a single +service, or an empty set. When the hardware cannot handle multiple +services on the same line the driver shall choose one. No assumptions +can be made on which service the driver chooses.</para><para>Data +services are defined in <xref linkend="vbi-services2" />. Array indices +map to ITU-R line numbers (see also <xref linkend="vbi-525" /> and <xref + linkend="vbi-625" />) as follows: <!-- No nested +tables, sigh. --></para></entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry>Element</entry> + <entry>525 line systems</entry> + <entry>625 line systems</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[0][1]</entry> + <entry align="center">1</entry> + <entry align="center">1</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[0][23]</entry> + <entry align="center">23</entry> + <entry align="center">23</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[1][1]</entry> + <entry align="center">264</entry> + <entry align="center">314</entry> + </row> + <row> + <entry></entry> + <entry></entry> + <entry><structfield>service_lines</structfield>[1][23]</entry> + <entry align="center">286</entry> + <entry align="center">336</entry> + </row> + <!-- End of line numbers table. --> + <row> + <entry></entry> + <entry></entry> + <entry spanname="hspan">Drivers must set +<structfield>service_lines</structfield>[0][0] and +<structfield>service_lines</structfield>[1][0] to zero.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>io_size</structfield></entry> + <entry spanname="hspan">Maximum number of bytes passed by +one &func-read; or &func-write; call, and the buffer size in bytes for +the &VIDIOC-QBUF; and &VIDIOC-DQBUF; ioctl. Drivers set this field to +the size of &v4l2-sliced-vbi-data; times the number of non-zero +elements in the returned <structfield>service_lines</structfield> +array (that is the number of lines potentially carrying data).</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[2]</entry> + <entry spanname="hspan">This array is reserved for future +extensions. Applications and drivers must set it to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <!-- See also vidioc-g-sliced-vbi-cap.sgml --> + <table frame="none" pgwide="1" id="vbi-services2"> + <title>Sliced VBI services</title> + <tgroup cols="5"> + <colspec colname="c1" colwidth="2*" /> + <colspec colname="c2" colwidth="1*" /> + <colspec colname="c3" colwidth="1*" /> + <colspec colname="c4" colwidth="2*" /> + <colspec colname="c5" colwidth="2*" /> + <spanspec namest="c3" nameend="c5" spanname="rlp" /> + <thead> + <row> + <entry>Symbol</entry> + <entry>Value</entry> + <entry>Reference</entry> + <entry>Lines, usually</entry> + <entry>Payload</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_SLICED_TELETEXT_B</constant> +(Teletext System B)</entry> + <entry>0x0001</entry> + <entry><xref linkend="ets300706" />, <xref linkend="itu653" /></entry> + <entry>PAL/SECAM line 7-22, 320-335 (second field 7-22)</entry> + <entry>Last 42 of the 45 byte Teletext packet, that is +without clock run-in and framing code, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VPS</constant></entry> + <entry>0x0400</entry> + <entry><xref linkend="ets300231" /></entry> + <entry>PAL line 16</entry> + <entry>Byte number 3 to 15 according to Figure 9 of +ETS 300 231, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_CAPTION_525</constant></entry> + <entry>0x1000</entry> + <entry><xref linkend="eia608" /></entry> + <entry>NTSC line 21, 284 (second field 21)</entry> + <entry>Two bytes in transmission order, including parity +bit, lsb first transmitted.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_WSS_625</constant></entry> + <entry>0x4000</entry> + <entry><xref linkend="itu1119" />, <xref linkend="en300294" /></entry> + <entry>PAL/SECAM line 23</entry> + <entry><screen> +Byte 0 1 + msb lsb msb lsb + Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9 +</screen></entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VBI_525</constant></entry> + <entry>0x1000</entry> + <entry spanname="rlp">Set of services applicable to 525 +line systems.</entry> + </row> + <row> + <entry><constant>V4L2_SLICED_VBI_625</constant></entry> + <entry>0x4401</entry> + <entry spanname="rlp">Set of services applicable to 625 +line systems.</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Drivers may return an &EINVAL; when applications attempt to +read or write data without prior format negotiation, after switching +the video standard (which may invalidate the negotiated VBI +parameters) and after switching the video input (which may change the +video standard as a side effect). The &VIDIOC-S-FMT; ioctl may return +an &EBUSY; when applications attempt to change the format while i/o is +in progress (between a &VIDIOC-STREAMON; and &VIDIOC-STREAMOFF; call, +and after the first &func-read; or &func-write; call).</para> + </section> + + <section> + <title>Reading and writing sliced VBI data</title> + + <para>A single &func-read; or &func-write; call must pass all data +belonging to one video frame. That is an array of +<structname>v4l2_sliced_vbi_data</structname> structures with one or +more elements and a total size not exceeding +<structfield>io_size</structfield> bytes. Likewise in streaming I/O +mode one buffer of <structfield>io_size</structfield> bytes must +contain data of one video frame. The <structfield>id</structfield> of +unused <structname>v4l2_sliced_vbi_data</structname> elements must be +zero.</para> + + <table frame="none" pgwide="1" id="v4l2-sliced-vbi-data"> + <title>struct +<structname>v4l2_sliced_vbi_data</structname></title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>id</structfield></entry> + <entry>A flag from <xref linkend="vbi-services" /> +identifying the type of data in this packet. Only a single bit must be +set. When the <structfield>id</structfield> of a captured packet is +zero, the packet is empty and the contents of other fields are +undefined. Applications shall ignore empty packets. When the +<structfield>id</structfield> of a packet for output is zero the +contents of the <structfield>data</structfield> field are undefined +and the driver must no longer insert data on the requested +<structfield>field</structfield> and +<structfield>line</structfield>.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>field</structfield></entry> + <entry>The video field number this data has been captured +from, or shall be inserted at. <constant>0</constant> for the first +field, <constant>1</constant> for the second field.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>line</structfield></entry> + <entry>The field (as opposed to frame) line number this +data has been captured from, or shall be inserted at. See <xref + linkend="vbi-525" /> and <xref linkend="vbi-625" /> for valid +values. Sliced VBI capture devices can set the line number of all +packets to <constant>0</constant> if the hardware cannot reliably +identify scan lines. The field number must always be valid.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield></entry> + <entry>This field is reserved for future extensions. +Applications and drivers must set it to zero.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>data</structfield>[48]</entry> + <entry>The packet payload. See <xref + linkend="vbi-services" /> for the contents and number of +bytes passed for each data type. The contents of padding bytes at the +end of this array are undefined, drivers and applications shall ignore +them.</entry> + </row> + </tbody> + </tgroup> + </table> + + <para>Packets are always passed in ascending line number order, +without duplicate line numbers. The &func-write; function and the +&VIDIOC-QBUF; ioctl must return an &EINVAL; when applications violate +this rule. They must also return an &EINVAL; when applications pass an +incorrect field or line number, or a combination of +<structfield>field</structfield>, <structfield>line</structfield> and +<structfield>id</structfield> which has not been negotiated with the +&VIDIOC-G-FMT; or &VIDIOC-S-FMT; ioctl. When the line numbers are +unknown the driver must pass the packets in transmitted order. The +driver can insert empty packets with <structfield>id</structfield> set +to zero anywhere in the packet array.</para> + + <para>To assure synchronization and to distinguish from frame +dropping, when a captured frame does not carry any of the requested +data services drivers must pass one or more empty packets. When an +application fails to pass VBI data in time for output, the driver +must output the last VPS and WSS packet again, and disable the output +of Closed Caption and Teletext data, or output data which is ignored +by Closed Caption and Teletext decoders.</para> + + <para>A sliced VBI device may support <link +linkend="rw">read/write</link> and/or streaming (<link +linkend="mmap">memory mapping</link> and/or <link linkend="userp">user +pointer</link>) I/O. The latter bears the possibility of synchronizing +video and VBI data by using buffer timestamps.</para> + + </section> + + <section> + <title>Sliced VBI Data in MPEG Streams</title> + + <para>If a device can produce an MPEG output stream, it may be +capable of providing <link +linkend="sliced-vbi-format-negotitation">negotiated sliced VBI +services</link> as data embedded in the MPEG stream. Users or +applications control this sliced VBI data insertion with the <link +linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link> +control.</para> + + <para>If the driver does not provide the <link +linkend="v4l2-mpeg-stream-vbi-fmt">V4L2_CID_MPEG_STREAM_VBI_FMT</link> +control, or only allows that control to be set to <link +linkend="v4l2-mpeg-stream-vbi-fmt"><constant> +V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link>, then the device +cannot embed sliced VBI data in the MPEG stream.</para> + + <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"> +V4L2_CID_MPEG_STREAM_VBI_FMT</link> control does not implicitly set +the device driver to capture nor cease capturing sliced VBI data. The +control only indicates to embed sliced VBI data in the MPEG stream, if +an application has negotiated sliced VBI service be captured.</para> + + <para>It may also be the case that a device can embed sliced VBI +data in only certain types of MPEG streams: for example in an MPEG-2 +PS but not an MPEG-2 TS. In this situation, if sliced VBI data +insertion is requested, the sliced VBI data will be embedded in MPEG +stream types when supported, and silently omitted from MPEG stream +types where sliced VBI data insertion is not supported by the device. +</para> + + <para>The following subsections specify the format of the +embedded sliced VBI data.</para> + + <section> + <title>MPEG Stream Embedded, Sliced VBI Data Format: NONE</title> + <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant> +V4L2_MPEG_STREAM_VBI_FMT_NONE</constant></link> embedded sliced VBI +format shall be interpreted by drivers as a control to cease +embedding sliced VBI data in MPEG streams. Neither the device nor +driver shall insert "empty" embedded sliced VBI data packets in the +MPEG stream when this format is set. No MPEG stream data structures +are specified for this format.</para> + </section> + + <section> + <title>MPEG Stream Embedded, Sliced VBI Data Format: IVTV</title> + <para>The <link linkend="v4l2-mpeg-stream-vbi-fmt"><constant> +V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> embedded sliced VBI +format, when supported, indicates to the driver to embed up to 36 +lines of sliced VBI data per frame in an MPEG-2 <emphasis>Private +Stream 1 PES</emphasis> packet encapsulated in an MPEG-2 <emphasis> +Program Pack</emphasis> in the MPEG stream.</para> + + <para><emphasis>Historical context</emphasis>: This format +specification originates from a custom, embedded, sliced VBI data +format used by the <filename>ivtv</filename> driver. This format +has already been informally specified in the kernel sources in the +file <filename>Documentation/video4linux/cx2341x/README.vbi</filename> +. The maximum size of the payload and other aspects of this format +are driven by the CX23415 MPEG decoder's capabilities and limitations +with respect to extracting, decoding, and displaying sliced VBI data +embedded within an MPEG stream.</para> + + <para>This format's use is <emphasis>not</emphasis> exclusive to +the <filename>ivtv</filename> driver <emphasis>nor</emphasis> +exclusive to CX2341x devices, as the sliced VBI data packet insertion +into the MPEG stream is implemented in driver software. At least the +<filename>cx18</filename> driver provides sliced VBI data insertion +into an MPEG-2 PS in this format as well.</para> + + <para>The following definitions specify the payload of the +MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packets that contain +sliced VBI data when <link linkend="v4l2-mpeg-stream-vbi-fmt"> +<constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant></link> is set. +(The MPEG-2 <emphasis>Private Stream 1 PES</emphasis> packet header +and encapsulating MPEG-2 <emphasis>Program Pack</emphasis> header are +not detailed here. Please refer to the MPEG-2 specifications for +details on those packet headers.)</para> + + <para>The payload of the MPEG-2 <emphasis>Private Stream 1 PES +</emphasis> packets that contain sliced VBI data is specified by +&v4l2-mpeg-vbi-fmt-ivtv;. The payload is variable +length, depending on the actual number of lines of sliced VBI data +present in a video frame. The payload may be padded at the end with +unspecified fill bytes to align the end of the payload to a 4-byte +boundary. The payload shall never exceed 1552 bytes (2 fields with +18 lines/field with 43 bytes of data/line and a 4 byte magic number). +</para> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv"> + <title>struct <structname>v4l2_mpeg_vbi_fmt_ivtv</structname> + </title> + <tgroup cols="4"> + &cs-ustr; + <tbody valign="top"> + <row> + <entry>__u8</entry> + <entry><structfield>magic</structfield>[4]</entry> + <entry></entry> + <entry>A "magic" constant from <xref + linkend="v4l2-mpeg-vbi-fmt-ivtv-magic" /> that indicates +this is a valid sliced VBI data payload and also indicates which +member of the anonymous union, <structfield>itv0</structfield> or +<structfield>ITV0</structfield>, to use for the payload data.</entry> + </row> + <row> + <entry>union</entry> + <entry>(anonymous)</entry> + </row> + <row> + <entry></entry> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0"> + <structname>v4l2_mpeg_vbi_itv0</structname></link> + </entry> + <entry><structfield>itv0</structfield></entry> + <entry>The primary form of the sliced VBI data payload +that contains anywhere from 1 to 35 lines of sliced VBI data. +Line masks are provided in this form of the payload indicating +which VBI lines are provided.</entry> + </row> + <row> + <entry></entry> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-1"> + <structname>v4l2_mpeg_vbi_ITV0</structname></link> + </entry> + <entry><structfield>ITV0</structfield></entry> + <entry>An alternate form of the sliced VBI data payload +used when 36 lines of sliced VBI data are present. No line masks are +provided in this form of the payload; all valid line mask bits are +implcitly set.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-fmt-ivtv-magic"> + <title>Magic Constants for &v4l2-mpeg-vbi-fmt-ivtv; + <structfield>magic</structfield> field</title> + <tgroup cols="3"> + &cs-def; + <thead> + <row> + <entry align="left">Defined Symbol</entry> + <entry align="left">Value</entry> + <entry align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC0</constant> + </entry> + <entry>"itv0"</entry> + <entry>Indicates the <structfield>itv0</structfield> +member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_MAGIC1</constant> + </entry> + <entry>"ITV0"</entry> + <entry>Indicates the <structfield>ITV0</structfield> +member of the union in &v4l2-mpeg-vbi-fmt-ivtv; is valid and +that 36 lines of sliced VBI data are present.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0"> + <title>struct <structname>v4l2_mpeg_vbi_itv0</structname> + </title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__le32</entry> + <entry><structfield>linemask</structfield>[2]</entry> + <entry><para>Bitmasks indicating the VBI service lines +present. These <structfield>linemask</structfield> values are stored +in little endian byte order in the MPEG stream. Some reference +<structfield>linemask</structfield> bit positions with their +corresponding VBI line number and video field are given below. +b<subscript>0</subscript> indicates the least significant bit of a +<structfield>linemask</structfield> value:<screen> +<structfield>linemask</structfield>[0] b<subscript>0</subscript>: line 6 first field +<structfield>linemask</structfield>[0] b<subscript>17</subscript>: line 23 first field +<structfield>linemask</structfield>[0] b<subscript>18</subscript>: line 6 second field +<structfield>linemask</structfield>[0] b<subscript>31</subscript>: line 19 second field +<structfield>linemask</structfield>[1] b<subscript>0</subscript>: line 20 second field +<structfield>linemask</structfield>[1] b<subscript>3</subscript>: line 23 second field +<structfield>linemask</structfield>[1] b<subscript>4</subscript>-b<subscript>31</subscript>: unused and set to 0</screen></para></entry> + </row> + <row> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line"> + <structname>v4l2_mpeg_vbi_itv0_line</structname></link> + </entry> + <entry><structfield>line</structfield>[35]</entry> + <entry>This is a variable length array that holds from 1 +to 35 lines of sliced VBI data. The sliced VBI data lines present +correspond to the bits set in the <structfield>linemask</structfield> +array, starting from b<subscript>0</subscript> of <structfield> +linemask</structfield>[0] up through b<subscript>31</subscript> of +<structfield>linemask</structfield>[0], and from b<subscript>0 +</subscript> of <structfield>linemask</structfield>[1] up through b +<subscript>3</subscript> of <structfield>linemask</structfield>[1]. +<structfield>line</structfield>[0] corresponds to the first bit +found set in the <structfield>linemask</structfield> array, +<structfield>line</structfield>[1] corresponds to the second bit +found set in the <structfield>linemask</structfield> array, etc. +If no <structfield>linemask</structfield> array bits are set, then +<structfield>line</structfield>[0] may contain one line of +unspecified data that should be ignored by applications.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-1"> + <title>struct <structname>v4l2_mpeg_vbi_ITV0</structname> + </title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>struct <link linkend="v4l2-mpeg-vbi-itv0-line"> + <structname>v4l2_mpeg_vbi_itv0_line</structname></link> + </entry> + <entry><structfield>line</structfield>[36]</entry> + <entry>A fixed length array of 36 lines of sliced VBI +data. <structfield>line</structfield>[0] through <structfield>line +</structfield>[17] correspond to lines 6 through 23 of the +first field. <structfield>line</structfield>[18] through +<structfield>line</structfield>[35] corresponds to lines 6 +through 23 of the second field.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="v4l2-mpeg-vbi-itv0-line"> + <title>struct <structname>v4l2_mpeg_vbi_itv0_line</structname> + </title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u8</entry> + <entry><structfield>id</structfield></entry> + <entry>A line identifier value from +<xref linkend="ITV0-Line-Identifier-Constants" /> that indicates +the type of sliced VBI data stored on this line.</entry> + </row> + <row> + <entry>__u8</entry> + <entry><structfield>data</structfield>[42]</entry> + <entry>The sliced VBI data for the line.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table frame="none" pgwide="1" id="ITV0-Line-Identifier-Constants"> + <title>Line Identifiers for struct <link + linkend="v4l2-mpeg-vbi-itv0-line"><structname> +v4l2_mpeg_vbi_itv0_line</structname></link> <structfield>id +</structfield> field</title> + <tgroup cols="3"> + &cs-def; + <thead> + <row> + <entry align="left">Defined Symbol</entry> + <entry align="left">Value</entry> + <entry align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_TELETEXT_B</constant> + </entry> + <entry>1</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_CAPTION_525</constant> + </entry> + <entry>4</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_WSS_625</constant> + </entry> + <entry>5</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_VBI_IVTV_VPS</constant> + </entry> + <entry>7</entry> + <entry>Refer to <link linkend="vbi-services2"> +Sliced VBI services</link> for a description of the line payload.</entry> + </row> + </tbody> + </tgroup> + </table> + + </section> + </section> + + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> |
