diff options
Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-enum-framesizes.xml')
| -rw-r--r-- | Documentation/DocBook/v4l/vidioc-enum-framesizes.xml | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/vidioc-enum-framesizes.xml b/Documentation/DocBook/v4l/vidioc-enum-framesizes.xml new file mode 100644 index 000000000000..6afa4542c818 --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-enum-framesizes.xml @@ -0,0 +1,282 @@ +<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: +--> |