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Based on kernel version 3.16. Page generated on 2014-08-06 21:39 EST.

1	<refentry id="vidioc-g-output">
2	  <refmeta>
3	    <refentrytitle>ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</refentrytitle>
4	    &manvol;
5	  </refmeta>
6	
7	  <refnamediv>
8	    <refname>VIDIOC_G_OUTPUT</refname>
9	    <refname>VIDIOC_S_OUTPUT</refname>
10	    <refpurpose>Query or select the current video output</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>int *<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_G_OUTPUT, VIDIOC_S_OUTPUT</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>To query the current video output applications call the
53	<constant>VIDIOC_G_OUTPUT</constant> ioctl with a pointer to an integer
54	where the driver stores the number of the output, as in the
55	&v4l2-output; <structfield>index</structfield> field. This ioctl
56	will fail only when there are no video outputs, returning the
57	&EINVAL;.</para>
58	
59	    <para>To select a video output applications store the number of the
60	desired output in an integer and call the
61	<constant>VIDIOC_S_OUTPUT</constant> ioctl with a pointer to this integer.
62	Side effects are possible. For example outputs may support different
63	video standards, so the driver may implicitly switch the current
64	standard.
65	standard. Because of these possible side effects applications
66	must select an output before querying or negotiating any other parameters.</para>
67	
68	    <para>Information about video outputs is available using the
69	&VIDIOC-ENUMOUTPUT; ioctl.</para>
70	  </refsect1>
71	
72	  <refsect1>
73	    &return-value;
74	
75	    <variablelist>
76	      <varlistentry>
77		<term><errorcode>EINVAL</errorcode></term>
78		<listitem>
79		  <para>The number of the video output is out of bounds, or
80	there are no video outputs at all.</para>
81		</listitem>
82	      </varlistentry>
83	    </variablelist>
84	  </refsect1>
85	</refentry>
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