<?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_ENUMAUDOUT</title><meta name="generator" content="DocBook XSL Stylesheets V1.76.1" /><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API" /><link rel="up" href="user-func.html" title="Appendix A. Function Reference" /><link rel="prev" href="vidioc-enumaudio.html" title="ioctl VIDIOC_ENUMAUDIO" /><link rel="next" href="vidioc-enum-dv-presets.html" title="ioctl VIDIOC_ENUM_DV_PRESETS" /></head><body><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> </td><th width="60%" align="center">Appendix A. Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="vidioc-enum-dv-presets.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="ioctl VIDIOC_ENUMAUDOUT"><a id="vidioc-enumaudioout"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>VIDIOC_ENUMAUDOUT — Enumerate audio outputs</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 <strong>fsfuncioctl</strong>(</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><div class="refsect1" title="Arguments"><a id="id3142753"></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="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" title="Description"><a id="id3143432"></a><h2>Description</h2><p>To query the attributes of an audio output applications initialize the <em class="structfield"><code>index</code></em> field and zero out the <em class="structfield"><code>reserved</code></em> array of a struct <a class="link" href="vidioc-g-audioout.html#v4l2-audioout" title="Table A.39. 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 index is out of bounds. To enumerate all audio outputs applications shall begin at index zero, incrementing by one until the driver returns <span class="errorcode">EINVAL</span>.</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><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 struct <a class="link" href="vidioc-g-audioout.html#v4l2-audioout" title="Table A.39. struct v4l2_audioout">v4l2_audioout</a>.</p></div><div class="refsect1" title="Return Value"><a id="id3143500"></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>The number of the audio output is out of bounds, or there are no audio outputs at all and this ioctl is not supported.</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> </td><td width="20%" align="center"><a accesskey="u" href="user-func.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="vidioc-enum-dv-presets.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ioctl VIDIOC_ENUMAUDIO </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> ioctl VIDIOC_ENUM_DV_PRESETS</td></tr></table></div></body></html>
