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<refentry id="vidioc-subdev-enum-frame-interval">
<refmeta>
<refentrytitle>ioctl VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</refname>
<refpurpose>Enumerate frame intervals</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_subdev_frame_interval_enum *
<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_SUBDEV_ENUM_FRAME_INTERVAL</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>This ioctl lets applications enumerate available frame intervals on a
given sub-device pad. Frame intervals only makes sense for sub-devices that
can control the frame period on their own. This includes, for instance,
image sensors and TV tuners.</para>
<para>For the common use case of image sensors, the frame intervals
available on the sub-device output pad depend on the frame format and size
on the same pad. Applications must thus specify the desired format and size
when enumerating frame intervals.</para>
<para>To enumerate frame intervals applications initialize the
<structfield>index</structfield>, <structfield>pad</structfield>,
<structfield>which</structfield>, <structfield>code</structfield>,
<structfield>width</structfield> and <structfield>height</structfield>
fields of &v4l2-subdev-frame-interval-enum; and call the
<constant>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</constant> ioctl with a pointer
to this structure. Drivers fill the rest of the structure or return
an &EINVAL; if one of the input fields is invalid. All frame intervals are
enumerable by beginning at index zero and incrementing by one until
<errorcode>EINVAL</errorcode> is returned.</para>
<para>Available frame intervals may depend on the current 'try' formats
at other pads of the sub-device, as well as on the current active links. See
&VIDIOC-SUBDEV-G-FMT; for more information about the try formats.</para>
<para>Sub-devices that support the frame interval enumeration ioctl should
implemented it on a single pad only. Its behaviour when supported on
multiple pads of the same sub-device is not defined.</para>
<table pgwide="1" frame="none" id="v4l2-subdev-frame-interval-enum">
<title>struct <structname>v4l2_subdev_frame_interval_enum</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>index</structfield></entry>
<entry>Number of the format in the enumeration, set by the
application.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>pad</structfield></entry>
<entry>Pad number as reported by the media controller API.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>code</structfield></entry>
<entry>The media bus format code, as defined in
<xref linkend="v4l2-mbus-format" />.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>width</structfield></entry>
<entry>Frame width, in pixels.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>height</structfield></entry>
<entry>Frame height, in pixels.</entry>
</row>
<row>
<entry>&v4l2-fract;</entry>
<entry><structfield>interval</structfield></entry>
<entry>Period, in seconds, between consecutive video frames.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>which</structfield></entry>
<entry>Frame intervals to be enumerated, from &v4l2-subdev-format-whence;.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[8]</entry>
<entry>Reserved for future extensions. Applications and drivers must
set the array to zero.</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
<refsect1>
&return-value;
<variablelist>
<varlistentry>
<term><errorcode>EINVAL</errorcode></term>
<listitem>
<para>The &v4l2-subdev-frame-interval-enum;
<structfield>pad</structfield> references a non-existing pad, one of
the <structfield>code</structfield>, <structfield>width</structfield>
or <structfield>height</structfield> fields are invalid for the given
pad or the <structfield>index</structfield> field is out of bounds.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
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