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- <refentry id="vidioc-enumaudioout">
- <refmeta>
- <refentrytitle>ioctl VIDIOC_ENUMAUDOUT</refentrytitle>
- &manvol;
- </refmeta>
- <refnamediv>
- <refname>VIDIOC_ENUMAUDOUT</refname>
- <refpurpose>Enumerate audio outputs</refpurpose>
- </refnamediv>
- <refsynopsisdiv>
- <funcsynopsis>
- <funcprototype>
- <funcdef>int <function>ioctl</function></funcdef>
- <paramdef>int <parameter>fd</parameter></paramdef>
- <paramdef>int <parameter>request</parameter></paramdef>
- <paramdef>struct v4l2_audioout *<parameter>argp</parameter></paramdef>
- </funcprototype>
- </funcsynopsis>
- </refsynopsisdiv>
- <refsect1>
- <title>Arguments</title>
- <variablelist>
- <varlistentry>
- <term><parameter>fd</parameter></term>
- <listitem>
- <para>&fd;</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>request</parameter></term>
- <listitem>
- <para>VIDIOC_ENUMAUDOUT</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><parameter>argp</parameter></term>
- <listitem>
- <para></para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect1>
- <refsect1>
- <title>Description</title>
- <para>To query the attributes of an audio output applications
- initialize the <structfield>index</structfield> field and zero out the
- <structfield>reserved</structfield> array of a &v4l2-audioout; and
- call the <constant>VIDIOC_G_AUDOUT</constant> ioctl with a pointer
- to this structure. Drivers fill the rest of the structure or return an
- &EINVAL; when the index is out of bounds. To enumerate all audio
- outputs applications shall begin at index zero, incrementing by one
- until the driver returns <errorcode>EINVAL</errorcode>.</para>
- <para>Note connectors on a TV card to loop back the received audio
- signal to a sound card are not audio outputs in this sense.</para>
- <para>See <xref linkend="vidioc-g-audioout" /> for a description of
- &v4l2-audioout;.</para>
- </refsect1>
- <refsect1>
- &return-value;
- <variablelist>
- <varlistentry>
- <term><errorcode>EINVAL</errorcode></term>
- <listitem>
- <para>The number of the audio output is out of bounds.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect1>
- </refentry>
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