Based on kernel version 3.0.4. Page generated on 2011-10-03 22:07 EST.
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 54 where the driver stores the number of the output, as in the 55 &v4l2-output; <structfield>index</structfield> field. This ioctl 56 will 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 60 desired output in an integer and call the 61 <constant>VIDIOC_S_OUTPUT</constant> ioctl with a pointer to this integer. 62 Side effects are possible. For example outputs may support different 63 video standards, so the driver may implicitly switch the current 64 standard. It is good practice to select an output before querying or 65 negotiating 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 79 there are no video outputs at all and this ioctl is not 80 supported.</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 87 switched.</para> 88 </listitem> 89 </varlistentry> 90 </variablelist> 91 </refsect1> 92 </refentry> 93 94 <!-- 95 Local Variables: 96 mode: sgml 97 sgml-parent-document: "v4l2.sgml" 98 indent-tabs-mode: nil 99 End: 100 -->
