1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>ioctl VIDIOC_ENUMAUDOUT</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API"><link rel="up" href="user-func.html" title="Appendix&#160;A.&#160;Function Reference"><link rel="prev" href="vidioc-enumaudio.html" title="ioctl VIDIOC_ENUMAUDIO"><link rel="next" href="vidioc-enum-dv-timings.html" title="ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">ioctl VIDIOC_ENUMAUDOUT</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="vidioc-enumaudio.html">Prev</a>&#160;</td><th width="60%" align="center">Appendix&#160;A.&#160;Function Reference</th><td width="20%" align="right">&#160;<a accesskey="n" href="vidioc-enum-dv-timings.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="vidioc-enumaudioout"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>VIDIOC_ENUMAUDOUT &#8212; Enumerate audio outputs</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">ioctl</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td>&#160;</td><td>int <var class="pdparam">request</var>, </td></tr><tr><td>&#160;</td><td>struct v4l2_audioout *<var class="pdparam">argp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1112702164"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>fd</code></em></span></dt><dd><p>File descriptor returned by <a class="link" href="func-open.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_ENUMAUDOUT</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"><a name="idp1112748460"></a><h2>Description</h2><p>To query the attributes of an audio output applications
2initialize the <em class="structfield"><code>index</code></em> field and zero out the
3<em class="structfield"><code>reserved</code></em> array of a struct&#160;<a class="link" href="vidioc-g-audioout.html#v4l2-audioout" title="Table&#160;A.54.&#160;struct v4l2_audioout">v4l2_audioout</a> and
4call the <code class="constant">VIDIOC_G_AUDOUT</code> ioctl with a pointer
5to this structure. Drivers fill the rest of the structure or return an
6<span class="errorcode">EINVAL</span> error code when the index is out of bounds. To enumerate all audio
7outputs applications shall begin at index zero, incrementing by one
8until the driver returns <span class="errorcode">EINVAL</span>.</p><p>Note connectors on a TV card to loop back the received audio
9signal to a sound card are not audio outputs in this sense.</p><p>See <a class="xref" href="vidioc-g-audioout.html" title="ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT"><span class="refentrytitle">ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</span>(2)</a> for a description of
10struct&#160;<a class="link" href="vidioc-g-audioout.html#v4l2-audioout" title="Table&#160;A.54.&#160;struct v4l2_audioout">v4l2_audioout</a>.</p></div><div class="refsect1"><a name="idp1112752468"></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. The generic error codes are described at the <a class="link" href="gen_errors.html#gen-errors" title="Table&#160;19.1.&#160;Generic error codes">Generic Error Codes</a> chapter.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="errorcode">EINVAL</span></span></dt><dd><p>The number of the audio output is out of bounds.</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="vidioc-enumaudio.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="user-func.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="vidioc-enum-dv-timings.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ioctl VIDIOC_ENUMAUDIO&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</td></tr></table></div></body></html>
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