/Documentation/DocBook/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
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>&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;. When detection is not
57possible or fails, the value V4L2_DV_INVALID is returned.</para>
58  </refsect1>
59
60  <refsect1>
61    &return-value;
62    <variablelist>
63      <varlistentry>
64	<term><errorcode>EINVAL</errorcode></term>
65	<listitem>
66	  <para>This ioctl is not supported.</para>
67	</listitem>
68    </varlistentry>
69      <varlistentry>
70	<term><errorcode>EBUSY</errorcode></term>
71	<listitem>
72	  <para>The device is busy and therefore can not sense the preset</para>
73	</listitem>
74      </varlistentry>
75    </variablelist>
76  </refsect1>
77</refentry>
78
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