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<refentry id="vidioc-query-dv-preset">
<refmeta>
<refentrytitle>ioctl VIDIOC_QUERY_DV_PRESET</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_QUERY_DV_PRESET</refname>
<refpurpose>Sense the DV preset received by the current
input</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>&v4l2-dv-preset; *<parameter>argp</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>fd</parameter></term>
<listitem>
<para>&fd;</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>request</parameter></term>
<listitem>
<para>VIDIOC_QUERY_DV_PRESET</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>The hardware may be able to detect the current DV preset
automatically, similar to sensing the video standard. To do so, applications
call <constant> VIDIOC_QUERY_DV_PRESET</constant> with a pointer to a
&v4l2-dv-preset; type. Once the hardware detects a preset, that preset is
returned in the preset field of &v4l2-dv-preset;. If the preset could not be
detected because there was no signal, or the signal was unreliable, or the
signal did not map to a supported preset, then the value V4L2_DV_INVALID is
returned.</para>
</refsect1>
<refsect1>
&return-value;
<variablelist>
<varlistentry>
<term><errorcode>EINVAL</errorcode></term>
<listitem>
<para>This ioctl is not supported.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><errorcode>EBUSY</errorcode></term>
<listitem>
<para>The device is busy and therefore can not sense the preset</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
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