Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.
1 <refentry id="vidioc-g-audioout"> 2 <refmeta> 3 <refentrytitle>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</refentrytitle> 4 &manvol; 5 </refmeta> 6 7 <refnamediv> 8 <refname>VIDIOC_G_AUDOUT</refname> 9 <refname>VIDIOC_S_AUDOUT</refname> 10 <refpurpose>Query or select the current audio output</refpurpose> 11 </refnamediv> 12 13 <refsynopsisdiv> 14 <funcsynopsis> 15 <funcprototype> 16 <funcdef>int <function>ioctl</function></funcdef> 17 <paramdef>int <parameter>fd</parameter></paramdef> 18 <paramdef>int <parameter>request</parameter></paramdef> 19 <paramdef>struct v4l2_audioout *<parameter>argp</parameter></paramdef> 20 </funcprototype> 21 </funcsynopsis> 22 <funcsynopsis> 23 <funcprototype> 24 <funcdef>int <function>ioctl</function></funcdef> 25 <paramdef>int <parameter>fd</parameter></paramdef> 26 <paramdef>int <parameter>request</parameter></paramdef> 27 <paramdef>const struct v4l2_audioout *<parameter>argp</parameter></paramdef> 28 </funcprototype> 29 </funcsynopsis> 30 </refsynopsisdiv> 31 32 <refsect1> 33 <title>Arguments</title> 34 35 <variablelist> 36 <varlistentry> 37 <term><parameter>fd</parameter></term> 38 <listitem> 39 <para>&fd;</para> 40 </listitem> 41 </varlistentry> 42 <varlistentry> 43 <term><parameter>request</parameter></term> 44 <listitem> 45 <para>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</para> 46 </listitem> 47 </varlistentry> 48 <varlistentry> 49 <term><parameter>argp</parameter></term> 50 <listitem> 51 <para></para> 52 </listitem> 53 </varlistentry> 54 </variablelist> 55 </refsect1> 56 57 <refsect1> 58 <title>Description</title> 59 60 <para>To query the current audio output applications zero out the 61 <structfield>reserved</structfield> array of a &v4l2-audioout; and 62 call the <constant>VIDIOC_G_AUDOUT</constant> ioctl with a pointer 63 to this structure. Drivers fill the rest of the structure or return an 64 &EINVAL; when the device has no audio inputs, or none which combine 65 with the current video output.</para> 66 67 <para>Audio outputs have no writable properties. Nevertheless, to 68 select the current audio output applications can initialize the 69 <structfield>index</structfield> field and 70 <structfield>reserved</structfield> array (which in the future may 71 contain writable properties) of a 72 <structname>v4l2_audioout</structname> structure and call the 73 <constant>VIDIOC_S_AUDOUT</constant> ioctl. Drivers switch to the 74 requested output or return the &EINVAL; when the index is out of 75 bounds. This is a write-only ioctl, it does not return the current 76 audio output attributes as <constant>VIDIOC_G_AUDOUT</constant> 77 does.</para> 78 79 <para>Note connectors on a TV card to loop back the received audio 80 signal to a sound card are not audio outputs in this sense.</para> 81 82 <table pgwide="1" frame="none" id="v4l2-audioout"> 83 <title>struct <structname>v4l2_audioout</structname></title> 84 <tgroup cols="3"> 85 &cs-str; 86 <tbody valign="top"> 87 <row> 88 <entry>__u32</entry> 89 <entry><structfield>index</structfield></entry> 90 <entry>Identifies the audio output, set by the 91 driver or application.</entry> 92 </row> 93 <row> 94 <entry>__u8</entry> 95 <entry><structfield>name</structfield>[32]</entry> 96 <entry>Name of the audio output, a NUL-terminated ASCII 97 string, for example: "Line Out". This information is intended for the 98 user, preferably the connector label on the device itself.</entry> 99 </row> 100 <row> 101 <entry>__u32</entry> 102 <entry><structfield>capability</structfield></entry> 103 <entry>Audio capability flags, none defined yet. Drivers 104 must set this field to zero.</entry> 105 </row> 106 <row> 107 <entry>__u32</entry> 108 <entry><structfield>mode</structfield></entry> 109 <entry>Audio mode, none defined yet. Drivers and 110 applications (on <constant>VIDIOC_S_AUDOUT</constant>) must set this 111 field to zero.</entry> 112 </row> 113 <row> 114 <entry>__u32</entry> 115 <entry><structfield>reserved</structfield>[2]</entry> 116 <entry>Reserved for future extensions. Drivers and 117 applications must set the array to zero.</entry> 118 </row> 119 </tbody> 120 </tgroup> 121 </table> 122 </refsect1> 123 124 <refsect1> 125 &return-value; 126 127 <variablelist> 128 <varlistentry> 129 <term><errorcode>EINVAL</errorcode></term> 130 <listitem> 131 <para>No audio outputs combine with the current video 132 output, or the number of the selected audio output is out of bounds or 133 it does not combine.</para> 134 </listitem> 135 </varlistentry> 136 </variablelist> 137 </refsect1> 138 </refentry>
