linux/Documentation/DocBook/media/v4l/vidioc-enum-dv-timings.xml
Hans Verkuil 663dc7f3a0 [media] DocBook: document when to return ENODATA
ENODATA should be returned if the API used for getting, changing, querying
or enumerating the current video timings is not supported by the current input
or output.
This was decided during the 2012 Media Workshop.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2012-09-26 09:46:39 -03:00

126 lines
3.6 KiB
XML

<refentry id="vidioc-enum-dv-timings">
<refmeta>
<refentrytitle>ioctl VIDIOC_ENUM_DV_TIMINGS</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_ENUM_DV_TIMINGS</refname>
<refpurpose>Enumerate supported Digital Video timings</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>struct v4l2_enum_dv_timings *<parameter>argp</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>fd</parameter></term>
<listitem>
<para>&fd;</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>request</parameter></term>
<listitem>
<para>VIDIOC_ENUM_DV_TIMINGS</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<note>
<title>Experimental</title>
<para>This is an <link linkend="experimental"> experimental </link>
interface and may change in the future.</para>
</note>
<para>While some DV receivers or transmitters support a wide range of timings, others
support only a limited number of timings. With this ioctl applications can enumerate a list
of known supported timings. Call &VIDIOC-DV-TIMINGS-CAP; to check if it also supports other
standards or even custom timings that are not in this list.</para>
<para>To query the available timings, applications initialize the
<structfield>index</structfield> field and zero the reserved array of &v4l2-enum-dv-timings;
and call the <constant>VIDIOC_ENUM_DV_TIMINGS</constant> ioctl with a pointer to this
structure. Drivers fill the rest of the structure or return an
&EINVAL; when the index is out of bounds. To enumerate all supported DV timings,
applications shall begin at index zero, incrementing by one until the
driver returns <errorcode>EINVAL</errorcode>. Note that drivers may enumerate a
different set of DV timings after switching the video input or
output.</para>
<table pgwide="1" frame="none" id="v4l2-enum-dv-timings">
<title>struct <structname>v4l2_enum_dv_timings</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>index</structfield></entry>
<entry>Number of the DV timings, set by the
application.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[3]</entry>
<entry>Reserved for future extensions. Drivers must set the array to zero.</entry>
</row>
<row>
<entry>&v4l2-dv-timings;</entry>
<entry><structfield>timings</structfield></entry>
<entry>The timings.</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
<refsect1>
&return-value;
<variablelist>
<varlistentry>
<term><errorcode>EINVAL</errorcode></term>
<listitem>
<para>The &v4l2-enum-dv-timings; <structfield>index</structfield>
is out of bounds.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><errorcode>ENODATA</errorcode></term>
<listitem>
<para>Digital video presets are not supported for this input or output.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
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