<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> <!-- Local Variables: mode: sgml sgml-parent-document: "v4l2.sgml" indent-tabs-mode: nil End: -->