Documentation/DocBook/media/v4l/vidioc-query-dv-preset.xml

   1 <refentry id="vidioc-query-dv-preset">
   2   <refmeta>
   3     <refentrytitle>ioctl VIDIOC_QUERY_DV_PRESET</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>VIDIOC_QUERY_DV_PRESET</refname>
   9     <refpurpose>Sense the DV preset received by the current
  10 input</refpurpose>
  11   </refnamediv>
  12
  13   <refsynopsisdiv>
  14     <funcsynopsis>
  15       <funcprototype>
  16         <funcdef>int <function>ioctl</function></funcdef>
  17         <paramdef>int <parameter>fd</parameter></paramdef>
  18         <paramdef>int <parameter>request</parameter></paramdef>
  19         <paramdef>struct v4l2_dv_preset *<parameter>argp</parameter></paramdef>
  20       </funcprototype>
  21     </funcsynopsis>
  22   </refsynopsisdiv>
  23
  24   <refsect1>
  25     <title>Arguments</title>
  26
  27     <variablelist>
  28         <varlistentry>
  29         <term><parameter>fd</parameter></term>
  30         <listitem>
  31           <para>&fd;</para>
  32         </listitem>
  33       </varlistentry>
  34       <varlistentry>
  35         <term><parameter>request</parameter></term>
  36         <listitem>
  37           <para>VIDIOC_QUERY_DV_PRESET</para>
  38         </listitem>
  39       </varlistentry>
  40       <varlistentry>
  41         <term><parameter>argp</parameter></term>
  42         <listitem>
  43           <para></para>
  44         </listitem>
  45       </varlistentry>
  46     </variablelist>
  47   </refsect1>
  48
  49   <refsect1>
  50     <title>Description</title>
  51
  52     <para>The hardware may be able to detect the current DV preset
  53 automatically, similar to sensing the video standard. To do so, applications
  54 call <constant> VIDIOC_QUERY_DV_PRESET</constant> with a pointer to a
  55 &v4l2-dv-preset; type. Once the hardware detects a preset, that preset is
  56 returned in the preset field of &v4l2-dv-preset;. If the preset could not be
  57 detected because there was no signal, or the signal was unreliable, or the
  58 signal did not map to a supported preset, then the value V4L2_DV_INVALID is
  59 returned.</para>
  60   </refsect1>
  61
  62   <refsect1>
  63     &return-value;
  64     <variablelist>
  65       <varlistentry>
  66         <term><errorcode>EINVAL</errorcode></term>
  67         <listitem>
  68           <para>This ioctl is not supported.</para>
  69         </listitem>
  70     </varlistentry>
  71       <varlistentry>
  72         <term><errorcode>EBUSY</errorcode></term>
  73         <listitem>
  74           <para>The device is busy and therefore can not sense the preset</para>
  75         </listitem>
  76       </varlistentry>
  77     </variablelist>
  78   </refsect1>
  79 </refentry>
  80
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