--- /dev/null
+<refentry id="vidioc-g-audio">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_G_AUDIO</refname>
+ <refname>VIDIOC_S_AUDIO</refname>
+ <refpurpose>Query or select the current audio input and its
+attributes</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_audio *<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_audio *<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_AUDIO, VIDIOC_S_AUDIO</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 input applications zero out the
+<structfield>reserved</structfield> array of a &v4l2-audio;
+and call the <constant>VIDIOC_G_AUDIO</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 input.</para>
+
+ <para>Audio inputs have one writable property, the audio mode. To
+select the current audio input <emphasis>and</emphasis> change the
+audio mode, applications initialize the
+<structfield>index</structfield> and <structfield>mode</structfield>
+fields, and the
+<structfield>reserved</structfield> array of a
+<structname>v4l2_audio</structname> structure and call the
+<constant>VIDIOC_S_AUDIO</constant> ioctl. Drivers may switch to a
+different audio mode if the request cannot be satisfied. However, this
+is a write-only ioctl, it does not return the actual new audio
+mode.</para>
+
+ <table pgwide="1" frame="none" id="v4l2-audio">
+ <title>struct <structname>v4l2_audio</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>index</structfield></entry>
+ <entry>Identifies the audio input, set by the
+driver or application.</entry>
+ </row>
+ <row>
+ <entry>__u8</entry>
+ <entry><structfield>name</structfield>[32]</entry>
+ <entry>Name of the audio input, a NUL-terminated ASCII
+string, for example: "Line In". 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, see <xref
+ linkend="audio-capability" />.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>mode</structfield></entry>
+ <entry>Audio mode flags set by drivers and applications (on
+ <constant>VIDIOC_S_AUDIO</constant> ioctl), see <xref linkend="audio-mode" />.</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>
+
+ <table pgwide="1" frame="none" id="audio-capability">
+ <title>Audio Capability Flags</title>
+ <tgroup cols="3">
+ &cs-def;
+ <tbody valign="top">
+ <row>
+ <entry><constant>V4L2_AUDCAP_STEREO</constant></entry>
+ <entry>0x00001</entry>
+ <entry>This is a stereo input. The flag is intended to
+automatically disable stereo recording etc. when the signal is always
+monaural. The API provides no means to detect if stereo is
+<emphasis>received</emphasis>, unless the audio input belongs to a
+tuner.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_AUDCAP_AVL</constant></entry>
+ <entry>0x00002</entry>
+ <entry>Automatic Volume Level mode is supported.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <table pgwide="1" frame="none" id="audio-mode">
+ <title>Audio Mode Flags</title>
+ <tgroup cols="3">
+ &cs-def;
+ <tbody valign="top">
+ <row>
+ <entry><constant>V4L2_AUDMODE_AVL</constant></entry>
+ <entry>0x00001</entry>
+ <entry>AVL mode is on.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>No audio inputs combine with the current video input,
+or the number of the selected audio input is out of bounds or it does
+not combine.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>
Code Review / kvmfornfv.git / blobdiff