<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API" /><link rel="up" href="apa.html" title="Appendix A. Function Reference" /><link rel="prev" href="re34.html" title="ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO" /><link rel="next" href="re36.html" title="ioctl VIDIOC_G_CROP, VIDIOC_S_CROP" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re34.html">Prev</a> </td><th width="60%" align="center">Appendix A. Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="re36.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT"><a id="vidioc-g-audioout"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT — Query or select the current audio output</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">ioctl</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">request</var>, </td></tr><tr><td> </td><td>struct v4l2_audioout *<var class="pdparam">argp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">ioctl</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">request</var>, </td></tr><tr><td> </td><td>const struct v4l2_audioout *<var class="pdparam">argp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2703855"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>fd</code></em></span></dt><dd><p>File descriptor returned by <a class="link" href="re64.html" title="V4L2 open()"><code class="function">open()</code></a>.</p></dd><dt><span class="term"><em class="parameter"><code>request</code></em></span></dt><dd><p>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</p></dd><dt><span class="term"><em class="parameter"><code>argp</code></em></span></dt><dd><p></p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2703924"></a><h2>Description</h2><p>To query the current audio output applications zero out the <em class="structfield"><code>reserved</code></em> array of a struct <a class="link" href="re35.html#v4l2-audioout" title="Table A.34. struct v4l2_audioout">v4l2_audioout</a> and call the <code class="constant">VIDIOC_G_AUDOUT</code> ioctl with a pointer to this structure. Drivers fill the rest of the structure or return an <span class="errorcode">EINVAL</span> error code when the device has no audio inputs, or none which combine with the current video output.</p><p>Audio outputs have no writable properties. Nevertheless, to select the current audio output applications can initialize the <em class="structfield"><code>index</code></em> field and <em class="structfield"><code>reserved</code></em> array (which in the future may contain writable properties) of a <span class="structname">v4l2_audioout</span> structure and call the <code class="constant">VIDIOC_S_AUDOUT</code> ioctl. Drivers switch to the requested output or return the <span class="errorcode">EINVAL</span> error code when the index is out of bounds. This is a write-only ioctl, it does not return the current audio output attributes as <code class="constant">VIDIOC_G_AUDOUT</code> does.</p><p>Note connectors on a TV card to loop back the received audio signal to a sound card are not audio outputs in this sense.</p><div class="table"><a id="v4l2-audioout"></a><p class="title"><b>Table A.34. struct <span class="structname">v4l2_audioout</span></b></p><div class="table-contents"><table summary="struct v4l2_audioout" width="100%" border="0"><colgroup><col /><col /><col /></colgroup><tbody valign="top"><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>index</code></em></td><td valign="top">Identifies the audio output, set by the driver or application.</td></tr><tr><td valign="top">__u8</td><td valign="top"><em class="structfield"><code>name</code></em>[32]</td><td valign="top">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.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>capability</code></em></td><td valign="top">Audio capability flags, none defined yet. Drivers must set this field to zero.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>mode</code></em></td><td valign="top">Audio mode, none defined yet. Drivers and applications (on <code class="constant">VIDIOC_S_AUDOUT</code>) must set this field to zero.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>reserved</code></em>[2]</td><td valign="top">Reserved for future extensions. Drivers and applications must set the array to zero.</td></tr></tbody></table></div></div><br class="table-break" /></div><div class="refsect1" title="Return Value"><a id="id2704142"></a><h2>Return Value</h2><p>On success <span class="returnvalue">0</span> is returned, on error <span class="returnvalue">-1</span> and the <code class="varname">errno</code> variable is set appropriately:</p><div class="variablelist"><dl><dt><span class="term"><span class="errorcode">EINVAL</span></span></dt><dd><p>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, or there are no audio outputs at all and the ioctl is not supported.</p></dd><dt><span class="term"><span class="errorcode">EBUSY</span></span></dt><dd><p>I/O is in progress, the output cannot be switched.</p></dd></dl></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re34.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="apa.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re36.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> ioctl VIDIOC_G_CROP, VIDIOC_S_CROP</td></tr></table></div></body></html>
