mirror of https://gitee.com/openkylin/linux.git
265 lines
8.0 KiB
XML
265 lines
8.0 KiB
XML
<refentry id="vidioc-g-sliced-vbi-cap">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_G_SLICED_VBI_CAP</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_G_SLICED_VBI_CAP</refname>
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<refpurpose>Query sliced VBI capabilities</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct v4l2_sliced_vbi_cap *<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><parameter>fd</parameter></term>
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<listitem>
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<para>&fd;</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>request</parameter></term>
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<listitem>
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<para>VIDIOC_G_SLICED_VBI_CAP</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>argp</parameter></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<para>To find out which data services are supported by a sliced
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VBI capture or output device, applications initialize the
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<structfield>type</structfield> field of a &v4l2-sliced-vbi-cap;,
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clear the <structfield>reserved</structfield> array and
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call the <constant>VIDIOC_G_SLICED_VBI_CAP</constant> ioctl. The
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driver fills in the remaining fields or returns an &EINVAL; if the
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sliced VBI API is unsupported or <structfield>type</structfield>
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is invalid.</para>
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<para>Note the <structfield>type</structfield> field was added,
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and the ioctl changed from read-only to write-read, in Linux 2.6.19.</para>
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<table pgwide="1" frame="none" id="v4l2-sliced-vbi-cap">
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<title>struct <structname>v4l2_sliced_vbi_cap</structname></title>
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<tgroup cols="5">
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<colspec colname="c1" colwidth="3*" />
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<colspec colname="c2" colwidth="3*" />
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<colspec colname="c3" colwidth="2*" />
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<colspec colname="c4" colwidth="2*" />
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<colspec colname="c5" colwidth="2*" />
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<spanspec spanname="hspan" namest="c3" nameend="c5" />
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<tbody valign="top">
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<row>
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<entry>__u16</entry>
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<entry><structfield>service_set</structfield></entry>
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<entry spanname="hspan">A set of all data services
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supported by the driver. Equal to the union of all elements of the
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<structfield>service_lines </structfield> array.</entry>
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</row>
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<row>
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<entry>__u16</entry>
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<entry><structfield>service_lines</structfield>[2][24]</entry>
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<entry spanname="hspan">Each element of this array
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contains a set of data services the hardware can look for or insert
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into a particular scan line. Data services are defined in <xref
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linkend="vbi-services" />. Array indices map to ITU-R
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line numbers (see also <xref
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linkend="vbi-525" /> and <xref
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linkend="vbi-625" />) as follows:</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>Element</entry>
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<entry>525 line systems</entry>
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<entry>625 line systems</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry><structfield>service_lines</structfield>[0][1]</entry>
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<entry align="center">1</entry>
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<entry align="center">1</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry><structfield>service_lines</structfield>[0][23]</entry>
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<entry align="center">23</entry>
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<entry align="center">23</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry><structfield>service_lines</structfield>[1][1]</entry>
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<entry align="center">264</entry>
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<entry align="center">314</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry><structfield>service_lines</structfield>[1][23]</entry>
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<entry align="center">286</entry>
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<entry align="center">336</entry>
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</row>
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<row>
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<entry></entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry spanname="hspan">The number of VBI lines the
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hardware can capture or output per frame, or the number of services it
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can identify on a given line may be limited. For example on PAL line
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16 the hardware may be able to look for a VPS or Teletext signal, but
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not both at the same time. Applications can learn about these limits
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using the &VIDIOC-S-FMT; ioctl as described in <xref
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linkend="sliced" />.</entry>
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</row>
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<row>
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<entry></entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry spanname="hspan">Drivers must set
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<structfield>service_lines</structfield>[0][0] and
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<structfield>service_lines</structfield>[1][0] to zero.</entry>
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</row>
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<row>
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<entry>&v4l2-buf-type;</entry>
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<entry><structfield>type</structfield></entry>
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<entry>Type of the data stream, see <xref
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linkend="v4l2-buf-type" />. Should be
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<constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> or
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<constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant>.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[3]</entry>
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<entry spanname="hspan">This array is reserved for future
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extensions. Applications and drivers must set it to zero.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<!-- See also dev-sliced-vbi.sgml -->
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<table pgwide="1" frame="none" id="vbi-services">
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<title>Sliced VBI services</title>
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<tgroup cols="5">
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<colspec colname="c1" colwidth="2*" />
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<colspec colname="c2" colwidth="1*" />
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<colspec colname="c3" colwidth="1*" />
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<colspec colname="c4" colwidth="2*" />
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<colspec colname="c5" colwidth="2*" />
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<spanspec spanname='rlp' namest='c3' nameend='c5' />
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<thead>
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<row>
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<entry>Symbol</entry>
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<entry>Value</entry>
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<entry>Reference</entry>
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<entry>Lines, usually</entry>
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<entry>Payload</entry>
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</row>
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</thead>
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_SLICED_TELETEXT_B</constant> (Teletext
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System B)</entry>
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<entry>0x0001</entry>
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<entry><xref linkend="ets300706" />, <xref linkend="itu653" /></entry>
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<entry>PAL/SECAM line 7-22, 320-335 (second field 7-22)</entry>
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<entry>Last 42 of the 45 byte Teletext packet, that is
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without clock run-in and framing code, lsb first transmitted.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SLICED_VPS</constant></entry>
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<entry>0x0400</entry>
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<entry><xref linkend="ets300231" /></entry>
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<entry>PAL line 16</entry>
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<entry>Byte number 3 to 15 according to Figure 9 of
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ETS 300 231, lsb first transmitted.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SLICED_CAPTION_525</constant></entry>
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<entry>0x1000</entry>
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<entry><xref linkend="eia608" /></entry>
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<entry>NTSC line 21, 284 (second field 21)</entry>
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<entry>Two bytes in transmission order, including parity
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bit, lsb first transmitted.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SLICED_WSS_625</constant></entry>
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<entry>0x4000</entry>
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<entry><xref linkend="en300294" />, <xref linkend="itu1119" /></entry>
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<entry>PAL/SECAM line 23</entry>
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<entry><screen>
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Byte 0 1
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msb lsb msb lsb
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Bit 7 6 5 4 3 2 1 0 x x 13 12 11 10 9
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</screen></entry>
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</row>
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<row>
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<entry><constant>V4L2_SLICED_VBI_525</constant></entry>
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<entry>0x1000</entry>
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<entry spanname="rlp">Set of services applicable to 525
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line systems.</entry>
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</row>
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<row>
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<entry><constant>V4L2_SLICED_VBI_625</constant></entry>
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<entry>0x4401</entry>
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<entry spanname="rlp">Set of services applicable to 625
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line systems.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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&return-value;
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<variablelist>
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<varlistentry>
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<term><errorcode>EINVAL</errorcode></term>
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<listitem>
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<para>The device does not support sliced VBI capturing or
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output, or the value in the <structfield>type</structfield> field is
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wrong.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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</refentry>
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<!--
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Local Variables:
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mode: sgml
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sgml-parent-document: "v4l2.sgml"
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indent-tabs-mode: nil
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End:
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-->
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