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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, or
there are no audio outputs at all and this ioctl is not
supported.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
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