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[linux-2.6.34-lpc32xx.git] / Documentation / DocBook / v4l / vidioc-overlay.xml
1 <refentry id="vidioc-overlay">
2   <refmeta>
3     <refentrytitle>ioctl VIDIOC_OVERLAY</refentrytitle>
4     &manvol;
5   </refmeta>
6
7   <refnamediv>
8     <refname>VIDIOC_OVERLAY</refname>
9     <refpurpose>Start or stop video overlay</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>const int *<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_OVERLAY</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>This ioctl is part of the <link linkend="overlay">video
52     overlay</link> I/O method. Applications call
53     <constant>VIDIOC_OVERLAY</constant> to start or stop the
54     overlay. It takes a pointer to an integer which must be set to
55     zero by the application to stop overlay, to one to start.</para>
56
57     <para>Drivers do not support &VIDIOC-STREAMON; or
58 &VIDIOC-STREAMOFF; with <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para>
59   </refsect1>
60
61   <refsect1>
62     &return-value;
63
64     <variablelist>
65       <varlistentry>
66         <term><errorcode>EINVAL</errorcode></term>
67         <listitem>
68           <para>Video overlay is not supported, or the
69 parameters have not been set up. See <xref
70 linkend="overlay" /> for the necessary steps.</para>
71         </listitem>
72       </varlistentry>
73     </variablelist>
74   </refsect1>
75 </refentry>
76
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