1<refentry id="vidioc-enumaudioout">
2  <refmeta>
3    <refentrytitle>ioctl VIDIOC_ENUMAUDOUT</refentrytitle>
4    &manvol;
5  </refmeta>
6
7  <refnamediv>
8    <refname>VIDIOC_ENUMAUDOUT</refname>
9    <refpurpose>Enumerate audio outputs</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>struct v4l2_audioout *<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_ENUMAUDOUT</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>To query the attributes of an audio output applications
52initialize the <structfield>index</structfield> field and zero out the
53<structfield>reserved</structfield> array of a &v4l2-audioout; and
54call the <constant>VIDIOC_G_AUDOUT</constant> ioctl with a pointer
55to this structure. Drivers fill the rest of the structure or return an
56&EINVAL; when the index is out of bounds. To enumerate all audio
57outputs applications shall begin at index zero, incrementing by one
58until the driver returns <errorcode>EINVAL</errorcode>.</para>
59
60    <para>Note connectors on a TV card to loop back the received audio
61signal to a sound card are not audio outputs in this sense.</para>
62
63    <para>See <xref linkend="vidioc-g-audioout" /> for a description of
64&v4l2-audioout;.</para>
65  </refsect1>
66
67  <refsect1>
68    &return-value;
69
70    <variablelist>
71      <varlistentry>
72	<term><errorcode>EINVAL</errorcode></term>
73	<listitem>
74	  <para>The number of the audio output is out of bounds.</para>
75	</listitem>
76      </varlistentry>
77    </variablelist>
78  </refsect1>
79</refentry>
80