Documentation/DocBook/v4l/vidioc-g-sliced-vbi-cap.xml

   1 <refentry id="vidioc-g-sliced-vbi-cap">
   2   <refmeta>
   3     <refentrytitle>ioctl VIDIOC_G_SLICED_VBI_CAP</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>VIDIOC_G_SLICED_VBI_CAP</refname>
   9     <refpurpose>Query sliced VBI capabilities</refpurpose>
  10   </refnamediv>
  11
  12   <refsynopsisdiv>
  13     <funcsynopsis>
  14       <funcprototype>
  15         <funcdef>int <function>ioctl</function></funcdef>
  16         <paramdef>int <parameter>fd</parameter></paramdef>
  17         <paramdef>int <parameter>request</parameter></paramdef>
  18         <paramdef>struct v4l2_sliced_vbi_cap *<parameter>argp</parameter></paramdef>
  19       </funcprototype>
  20     </funcsynopsis>
  21   </refsynopsisdiv>
  22
  23   <refsect1>
  24     <title>Arguments</title>
  25
  26     <variablelist>
  27       <varlistentry>
  28         <term><parameter>fd</parameter></term>
  29         <listitem>
  30           <para>&fd;</para>
  31         </listitem>
  32       </varlistentry>
  33       <varlistentry>
  34         <term><parameter>request</parameter></term>
  35         <listitem>
  36           <para>VIDIOC_G_SLICED_VBI_CAP</para>
  37         </listitem>
  38       </varlistentry>
  39       <varlistentry>
  40         <term><parameter>argp</parameter></term>
  41         <listitem>
  42           <para></para>
  43         </listitem>
  44       </varlistentry>
  45     </variablelist>
  46   </refsect1>
  47
  48   <refsect1>
  49     <title>Description</title>
  50
  51     <para>To find out which data services are supported by a sliced
  52 VBI capture or output device, applications initialize the
  53 <structfield>type</structfield> field of a &v4l2-sliced-vbi-cap;,
  54 clear the <structfield>reserved</structfield> array and
  55 call the <constant>VIDIOC_G_SLICED_VBI_CAP</constant> ioctl. The
  56 driver fills in the remaining fields or returns an &EINVAL; if the
  57 sliced VBI API is unsupported or <structfield>type</structfield>
  58 is invalid.</para>
  59
  60     <para>Note the <structfield>type</structfield> field was added,
  61 and the ioctl changed from read-only to write-read, in Linux 2.6.19.</para>
  62
  63     <table pgwide="1" frame="none" id="v4l2-sliced-vbi-cap">
  64       <title>struct <structname>v4l2_sliced_vbi_cap</structname></title>
  65       <tgroup cols="5">
  66         <colspec colname="c1" colwidth="3*" />
  67         <colspec colname="c2" colwidth="3*" />
  68         <colspec colname="c3" colwidth="2*" />
  69         <colspec colname="c4" colwidth="2*" />
  70         <colspec colname="c5" colwidth="2*" />
  71         <spanspec spanname="hspan" namest="c3" nameend="c5" />
  72         <tbody valign="top">
  73           <row>
  74             <entry>__u16</entry>
  75             <entry><structfield>service_set</structfield></entry>
  76             <entry spanname="hspan">A set of all data services
  77 supported by the driver. Equal to the union of all elements of the
  78 <structfield>service_lines </structfield> array.</entry>
  79           </row>
  80           <row>
  81             <entry>__u16</entry>
  82             <entry><structfield>service_lines</structfield>[2][24]</entry>
  83             <entry spanname="hspan">Each element of this array
  84 contains a set of data services the hardware can look for or insert
  85 into a particular scan line. Data services are defined in <xref
  86                 linkend="vbi-services" />. Array indices map to ITU-R
  87 line numbers (see also <xref
  88                 linkend="vbi-525" /> and <xref
  89 linkend="vbi-625" />) as follows:</entry>
  90           </row>
  91           <row>
  92             <entry></entry>
  93             <entry></entry>
  94             <entry>Element</entry>
  95             <entry>525 line systems</entry>
  96             <entry>625 line systems</entry>
  97           </row>
  98           <row>
  99             <entry></entry>
 100             <entry></entry>
 101             <entry><structfield>service_lines</structfield>[0][1]</entry>
 102             <entry align="center">1</entry>
 103             <entry align="center">1</entry>
 104           </row>
 105           <row>
 106             <entry></entry>
 107             <entry></entry>
 108             <entry><structfield>service_lines</structfield>[0][23]</entry>
 109             <entry align="center">23</entry>
 110             <entry align="center">23</entry>
 111           </row>
 112           <row>
 113             <entry></entry>
 114             <entry></entry>
 115             <entry><structfield>service_lines</structfield>[1][1]</entry>
 116             <entry align="center">264</entry>
 117             <entry align="center">314</entry>
 118           </row>
 119           <row>
 120             <entry></entry>
 121             <entry></entry>
 122             <entry><structfield>service_lines</structfield>[1][23]</entry>
 123             <entry align="center">286</entry>
 124             <entry align="center">336</entry>
 125           </row>
 126           <row>
 127             <entry></entry>
 128           </row>
 129           <row>
 130             <entry></entry>
 131             <entry></entry>
 132             <entry spanname="hspan">The number of VBI lines the
 133 hardware can capture or output per frame, or the number of services it
 134 can identify on a given line may be limited. For example on PAL line
 135 16 the hardware may be able to look for a VPS or Teletext signal, but
 136 not both at the same time. Applications can learn about these limits
 137 using the &VIDIOC-S-FMT; ioctl as described in <xref
 138                 linkend="sliced" />.</entry>
 139           </row>
 140           <row>
 141             <entry></entry>
 142           </row>
 143           <row>
 144             <entry></entry>
 145             <entry></entry>
 146             <entry spanname="hspan">Drivers must set
 147 <structfield>service_lines</structfield>[0][0] and
 148 <structfield>service_lines</structfield>[1][0] to zero.</entry>
 149           </row>
 150           <row>
 151             <entry>&v4l2-buf-type;</entry>
 152             <entry><structfield>type</structfield></entry>
 153             <entry>Type of the data stream, see <xref
 154                   linkend="v4l2-buf-type" />. Should be
 155 <constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> or
 156 <constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant>.</entry>
 157           </row>
 158           <row>
 159             <entry>__u32</entry>
 160             <entry><structfield>reserved</structfield>[3]</entry>
 161             <entry spanname="hspan">This array is reserved for future
 162 extensions. Applications and drivers must set it to zero.</entry>
 163           </row>
 164         </tbody>
 165       </tgroup>
 166     </table>
 167
 168     <!-- See also dev-sliced-vbi.sgml -->
 169     <table pgwide="1" frame="none" id="vbi-services">
 170       <title>Sliced VBI services</title>
 171       <tgroup cols="5">
 172         <colspec colname="c1" colwidth="2*" />
 173         <colspec colname="c2" colwidth="1*" />
 174         <colspec colname="c3" colwidth="1*" />
 175         <colspec colname="c4" colwidth="2*" />
 176         <colspec colname="c5" colwidth="2*" />
 177         <spanspec spanname='rlp' namest='c3' nameend='c5' />
 178         <thead>
 179           <row>
 180             <entry>Symbol</entry>
 181             <entry>Value</entry>
 182             <entry>Reference</entry>
 183             <entry>Lines, usually</entry>
 184             <entry>Payload</entry>
 185           </row>
 186         </thead>
 187         <tbody valign="top">
 188           <row>
 189             <entry><constant>V4L2_SLICED_TELETEXT_B</constant> (Teletext
 190 System B)</entry>
 191             <entry>0x0001</entry>
 192             <entry><xref linkend="ets300706" />, <xref linkend="itu653" /></entry>
 193             <entry>PAL/SECAM line 7-22, 320-335 (second field 7-22)</entry>
 194             <entry>Last 42 of the 45 byte Teletext packet, that is
 195 without clock run-in and framing code, lsb first transmitted.</entry>
 196           </row>
 197           <row>
 198             <entry><constant>V4L2_SLICED_VPS</constant></entry>
 199             <entry>0x0400</entry>
 200             <entry><xref linkend="ets300231" /></entry>
 201             <entry>PAL line 16</entry>
 202             <entry>Byte number 3 to 15 according to Figure 9 of
 203 ETS&nbsp;300&nbsp;231, lsb first transmitted.</entry>
 204           </row>
 205           <row>
 206             <entry><constant>V4L2_SLICED_CAPTION_525</constant></entry>
 207             <entry>0x1000</entry>
 208             <entry><xref linkend="eia608" /></entry>
 209             <entry>NTSC line 21, 284 (second field 21)</entry>
 210             <entry>Two bytes in transmission order, including parity
 211 bit, lsb first transmitted.</entry>
 212           </row>
 213           <row>
 214             <entry><constant>V4L2_SLICED_WSS_625</constant></entry>
 215             <entry>0x4000</entry>
 216             <entry><xref linkend="en300294" />, <xref linkend="itu1119" /></entry>
 217             <entry>PAL/SECAM line 23</entry>
 218             <entry><screen>
 219 Byte        0                 1
 220      msb         lsb  msb           lsb
 221 Bit  7 6 5 4 3 2 1 0  x x 13 12 11 10 9
 222 </screen></entry>
 223           </row>
 224           <row>
 225             <entry><constant>V4L2_SLICED_VBI_525</constant></entry>
 226             <entry>0x1000</entry>
 227             <entry spanname="rlp">Set of services applicable to 525
 228 line systems.</entry>
 229           </row>
 230           <row>
 231             <entry><constant>V4L2_SLICED_VBI_625</constant></entry>
 232             <entry>0x4401</entry>
 233             <entry spanname="rlp">Set of services applicable to 625
 234 line systems.</entry>
 235           </row>
 236         </tbody>
 237       </tgroup>
 238     </table>
 239
 240   </refsect1>
 241
 242   <refsect1>
 243     &return-value;
 244
 245     <variablelist>
 246       <varlistentry>
 247         <term><errorcode>EINVAL</errorcode></term>
 248         <listitem>
 249           <para>The device does not support sliced VBI capturing or
 250 output, or the value in the <structfield>type</structfield> field is
 251 wrong.</para>
 252         </listitem>
 253       </varlistentry>
 254     </variablelist>
 255   </refsect1>
 256 </refentry>
 257
 258 <!--
 259 Local Variables:
 260 mode: sgml
 261 sgml-parent-document: "v4l2.sgml"
 262 indent-tabs-mode: nil
 263 End:
 264 -->