1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT</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 A. Function Reference"><link rel="prev" href="vidioc-g-frequency.html" title="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY"><link rel="next" href="vidioc-g-jpegcomp.html" title="ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP"></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_G_INPUT, VIDIOC_S_INPUT</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="vidioc-g-frequency.html">Prev</a> </td><th width="60%" align="center">Appendix A. Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="vidioc-g-jpegcomp.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="vidioc-g-input"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>VIDIOC_G_INPUT, VIDIOC_S_INPUT — Query or select the current video input</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> </td><td>int <var class="pdparam">request</var>, </td></tr><tr><td> </td><td>int *<var class="pdparam">argp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idp1114588908"></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_G_INPUT, VIDIOC_S_INPUT</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="idp1114674004"></a><h2>Description</h2><p>To query the current video input applications call the 2<code class="constant">VIDIOC_G_INPUT</code> ioctl with a pointer to an integer 3where the driver stores the number of the input, as in the 4struct <a class="link" href="vidioc-enuminput.html#v4l2-input" title="Table A.39. struct v4l2_input">v4l2_input</a> <em class="structfield"><code>index</code></em> field. This ioctl will 5fail only when there are no video inputs, returning 6<span class="errorcode">EINVAL</span>.</p><p>To select a video input applications store the number of the 7desired input in an integer and call the 8<code class="constant">VIDIOC_S_INPUT</code> ioctl with a pointer to this 9integer. Side effects are possible. For example inputs may support 10different video standards, so the driver may implicitly switch the 11current standard. Because of these possible side effects applications 12must select an input before querying or negotiating any other parameters.</p><p>Information about video inputs is available using the 13<a class="link" href="vidioc-enuminput.html" title="ioctl VIDIOC_ENUMINPUT"><code class="constant">VIDIOC_ENUMINPUT</code></a> ioctl.</p></div><div class="refsect1"><a name="idp1114677500"></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 19.1. 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 video input 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-g-frequency.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-g-jpegcomp.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY </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_JPEGCOMP, VIDIOC_S_JPEGCOMP</td></tr></table></div></body></html> 14