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+<refentry id="vidioc-g-audioout">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_G_AUDOUT</refname>
+ <refname>VIDIOC_S_AUDOUT</refname>
+ <refpurpose>Query or select the current audio output</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>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>const 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_G_AUDOUT, VIDIOC_S_AUDOUT</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>To query the current audio output applications 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 device has no audio inputs, or none which combine
+with the current video output.</para>
+
+ <para>Audio outputs have no writable properties. Nevertheless, to
+select the current audio output applications can initialize the
+<structfield>index</structfield> field and
+<structfield>reserved</structfield> array (which in the future may
+contain writable properties) of a
+<structname>v4l2_audioout</structname> structure and call the
+<constant>VIDIOC_S_AUDOUT</constant> ioctl. Drivers switch to the
+requested output or return the &EINVAL; when the index is out of
+bounds. This is a write-only ioctl, it does not return the current
+audio output attributes as <constant>VIDIOC_G_AUDOUT</constant>
+does.</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>
+
+ <table pgwide="1" frame="none" id="v4l2-audioout">
+ <title>struct <structname>v4l2_audioout</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>index</structfield></entry>
+ <entry>Identifies the audio output, set by the
+driver or application.</entry>
+ </row>
+ <row>
+ <entry>__u8</entry>
+ <entry><structfield>name</structfield>[32]</entry>
+ <entry>Name of the audio output, a NUL-terminated ASCII
+string, for example: "Line Out". This information is intended for the
+user, preferably the connector label on the device itself.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>capability</structfield></entry>
+ <entry>Audio capability flags, none defined yet. Drivers
+must set this field to zero.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>mode</structfield></entry>
+ <entry>Audio mode, none defined yet. Drivers and
+applications (on <constant>VIDIOC_S_AUDOUT</constant>) must set this
+field to zero.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>reserved</structfield>[2]</entry>
+ <entry>Reserved for future extensions. Drivers and
+applications must set the array to zero.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>No audio outputs combine with the current video
+output, or the number of the selected audio output is out of bounds or
+it does not combine.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>