1<refentry id="vidioc-g-output"> 2 <refmeta> 3 <refentrytitle>ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</refentrytitle> 4 &manvol; 5 </refmeta> 6 7 <refnamediv> 8 <refname>VIDIOC_G_OUTPUT</refname> 9 <refname>VIDIOC_S_OUTPUT</refname> 10 <refpurpose>Query or select the current video 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>int *<parameter>argp</parameter></paramdef> 20 </funcprototype> 21 </funcsynopsis> 22 </refsynopsisdiv> 23 24 <refsect1> 25 <title>Arguments</title> 26 27 <variablelist> 28 <varlistentry> 29 <term><parameter>fd</parameter></term> 30 <listitem> 31 <para>&fd;</para> 32 </listitem> 33 </varlistentry> 34 <varlistentry> 35 <term><parameter>request</parameter></term> 36 <listitem> 37 <para>VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</para> 38 </listitem> 39 </varlistentry> 40 <varlistentry> 41 <term><parameter>argp</parameter></term> 42 <listitem> 43 <para></para> 44 </listitem> 45 </varlistentry> 46 </variablelist> 47 </refsect1> 48 49 <refsect1> 50 <title>Description</title> 51 52 <para>To query the current video output applications call the 53<constant>VIDIOC_G_OUTPUT</constant> ioctl with a pointer to an integer 54where the driver stores the number of the output, as in the 55&v4l2-output; <structfield>index</structfield> field. This ioctl 56will fail only when there are no video outputs, returning the 57&EINVAL;.</para> 58 59 <para>To select a video output applications store the number of the 60desired output in an integer and call the 61<constant>VIDIOC_S_OUTPUT</constant> ioctl with a pointer to this integer. 62Side effects are possible. For example outputs may support different 63video standards, so the driver may implicitly switch the current 64standard. It is good practice to select an output before querying or 65negotiating any other parameters.</para> 66 67 <para>Information about video outputs is available using the 68&VIDIOC-ENUMOUTPUT; ioctl.</para> 69 </refsect1> 70 71 <refsect1> 72 &return-value; 73 74 <variablelist> 75 <varlistentry> 76 <term><errorcode>EINVAL</errorcode></term> 77 <listitem> 78 <para>The number of the video output is out of bounds, or 79there are no video outputs at all and this ioctl is not 80supported.</para> 81 </listitem> 82 </varlistentry> 83 <varlistentry> 84 <term><errorcode>EBUSY</errorcode></term> 85 <listitem> 86 <para>I/O is in progress, the output cannot be 87switched.</para> 88 </listitem> 89 </varlistentry> 90 </variablelist> 91 </refsect1> 92</refentry> 93 94<!-- 95Local Variables: 96mode: sgml 97sgml-parent-document: "v4l2.sgml" 98indent-tabs-mode: nil 99End: 100--> 101