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
10input</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
53automatically, similar to sensing the video standard. To do so, applications
54call <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
56returned in the preset field of &v4l2-dv-preset;. If the preset could not be
57detected because there was no signal, or the signal was unreliable, or the
58signal did not map to a supported preset, then the value V4L2_DV_INVALID is
59returned.</para>
60  </refsect1>
61
62  <refsect1>
63    &return-value;
64  </refsect1>
65</refentry>
66