mirror of https://gitee.com/openkylin/linux.git
283 lines
8.7 KiB
XML
283 lines
8.7 KiB
XML
<refentry id="vidioc-enum-framesizes">
|
|
|
|
<refmeta>
|
|
<refentrytitle>ioctl VIDIOC_ENUM_FRAMESIZES</refentrytitle>
|
|
&manvol;
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>VIDIOC_ENUM_FRAMESIZES</refname>
|
|
<refpurpose>Enumerate frame sizes</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_frmsizeenum *<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_FRAMESIZES</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><parameter>argp</parameter></term>
|
|
<listitem>
|
|
<para>Pointer to a &v4l2-frmsizeenum; that contains an index
|
|
and pixel format and receives a frame width and height.</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 allows applications to enumerate all frame sizes
|
|
(&ie; width and height in pixels) that the device supports for the
|
|
given pixel format.</para>
|
|
<para>The supported pixel formats can be obtained by using the
|
|
&VIDIOC-ENUM-FMT; function.</para>
|
|
<para>The return value and the content of the
|
|
<structfield>v4l2_frmsizeenum.type</structfield> field depend on the
|
|
type of frame sizes the device supports. Here are the semantics of the
|
|
function for the different cases:</para>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para><emphasis role="bold">Discrete:</emphasis> The function
|
|
returns success if the given index value (zero-based) is valid. The
|
|
application should increase the index by one for each call until
|
|
<constant>EINVAL</constant> is returned. The
|
|
<structfield>v4l2_frmsizeenum.type</structfield> field is set to
|
|
<constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> by the driver. Of the
|
|
union only the <structfield>discrete</structfield> member is
|
|
valid.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><emphasis role="bold">Step-wise:</emphasis> The function
|
|
returns success if the given index value is zero and
|
|
<constant>EINVAL</constant> for any other index value. The
|
|
<structfield>v4l2_frmsizeenum.type</structfield> field is set to
|
|
<constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant> by the driver. Of the
|
|
union only the <structfield>stepwise</structfield> member is
|
|
valid.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><emphasis role="bold">Continuous:</emphasis> This is a
|
|
special case of the step-wise type above. The function returns success
|
|
if the given index value is zero and <constant>EINVAL</constant> for
|
|
any other index value. The
|
|
<structfield>v4l2_frmsizeenum.type</structfield> field is set to
|
|
<constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant> by the driver. Of
|
|
the union only the <structfield>stepwise</structfield> member is valid
|
|
and the <structfield>step_width</structfield> and
|
|
<structfield>step_height</structfield> values are set to 1.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>When the application calls the function with index zero, it
|
|
must check the <structfield>type</structfield> field to determine the
|
|
type of frame size enumeration the device supports. Only for the
|
|
<constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant> type does it make
|
|
sense to increase the index value to receive more frame sizes.</para>
|
|
<para>Note that the order in which the frame sizes are returned
|
|
has no special meaning. In particular does it not say anything about
|
|
potential default format sizes.</para>
|
|
<para>Applications can assume that the enumeration data does not
|
|
change without any interaction from the application itself. This means
|
|
that the enumeration data is consistent if the application does not
|
|
perform any other ioctl calls while it runs the frame size
|
|
enumeration.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Structs</title>
|
|
|
|
<para>In the structs below, <emphasis>IN</emphasis> denotes a
|
|
value that has to be filled in by the application,
|
|
<emphasis>OUT</emphasis> denotes values that the driver fills in. The
|
|
application should zero out all members except for the
|
|
<emphasis>IN</emphasis> fields.</para>
|
|
|
|
<table pgwide="1" frame="none" id="v4l2-frmsize-discrete">
|
|
<title>struct <structname>v4l2_frmsize_discrete</structname></title>
|
|
<tgroup cols="3">
|
|
&cs-str;
|
|
<tbody valign="top">
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>width</structfield></entry>
|
|
<entry>Width of the frame [pixel].</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>height</structfield></entry>
|
|
<entry>Height of the frame [pixel].</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<table pgwide="1" frame="none" id="v4l2-frmsize-stepwise">
|
|
<title>struct <structname>v4l2_frmsize_stepwise</structname></title>
|
|
<tgroup cols="3">
|
|
&cs-str;
|
|
<tbody valign="top">
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>min_width</structfield></entry>
|
|
<entry>Minimum frame width [pixel].</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>max_width</structfield></entry>
|
|
<entry>Maximum frame width [pixel].</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>step_width</structfield></entry>
|
|
<entry>Frame width step size [pixel].</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>min_height</structfield></entry>
|
|
<entry>Minimum frame height [pixel].</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>max_height</structfield></entry>
|
|
<entry>Maximum frame height [pixel].</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>step_height</structfield></entry>
|
|
<entry>Frame height step size [pixel].</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<table pgwide="1" frame="none" id="v4l2-frmsizeenum">
|
|
<title>struct <structname>v4l2_frmsizeenum</structname></title>
|
|
<tgroup cols="4">
|
|
<colspec colname="c1" />
|
|
<colspec colname="c2" />
|
|
<colspec colname="c3" />
|
|
<colspec colname="c4" />
|
|
<tbody valign="top">
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>index</structfield></entry>
|
|
<entry></entry>
|
|
<entry>IN: Index of the given frame size in the enumeration.</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>pixel_format</structfield></entry>
|
|
<entry></entry>
|
|
<entry>IN: Pixel format for which the frame sizes are enumerated.</entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>type</structfield></entry>
|
|
<entry></entry>
|
|
<entry>OUT: Frame size type the device supports.</entry>
|
|
</row>
|
|
<row>
|
|
<entry>union</entry>
|
|
<entry></entry>
|
|
<entry></entry>
|
|
<entry>OUT: Frame size with the given index.</entry>
|
|
</row>
|
|
<row>
|
|
<entry></entry>
|
|
<entry>&v4l2-frmsize-discrete;</entry>
|
|
<entry><structfield>discrete</structfield></entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry></entry>
|
|
<entry>&v4l2-frmsize-stepwise;</entry>
|
|
<entry><structfield>stepwise</structfield></entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry>__u32</entry>
|
|
<entry><structfield>reserved[2]</structfield></entry>
|
|
<entry></entry>
|
|
<entry>Reserved space for future use.</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Enums</title>
|
|
|
|
<table pgwide="1" frame="none" id="v4l2-frmsizetypes">
|
|
<title>enum <structname>v4l2_frmsizetypes</structname></title>
|
|
<tgroup cols="3">
|
|
&cs-def;
|
|
<tbody valign="top">
|
|
<row>
|
|
<entry><constant>V4L2_FRMSIZE_TYPE_DISCRETE</constant></entry>
|
|
<entry>1</entry>
|
|
<entry>Discrete frame size.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><constant>V4L2_FRMSIZE_TYPE_CONTINUOUS</constant></entry>
|
|
<entry>2</entry>
|
|
<entry>Continuous frame size.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><constant>V4L2_FRMSIZE_TYPE_STEPWISE</constant></entry>
|
|
<entry>3</entry>
|
|
<entry>Step-wise defined frame size.</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
&return-value;
|
|
|
|
<para>See the description section above for a list of return
|
|
values that <varname>errno</varname> can have.</para>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<!--
|
|
Local Variables:
|
|
mode: sgml
|
|
sgml-parent-document: "v4l2.sgml"
|
|
indent-tabs-mode: nil
|
|
End:
|
|
-->
|