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+<refentry id="vidioc-g-jpegcomp">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_G_JPEGCOMP</refname>
+ <refname>VIDIOC_S_JPEGCOMP</refname>
+ <refpurpose></refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>v4l2_jpegcompression *<parameter>argp</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>const v4l2_jpegcompression *<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_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>These ioctls are <emphasis role="bold">deprecated</emphasis>.
+ New drivers and applications should use <link linkend="jpeg-controls">
+ JPEG class controls</link> for image quality and JPEG markers control.
+ </para>
+
+ <para>[to do]</para>
+
+ <para>Ronald Bultje elaborates:</para>
+
+ <!-- See video4linux-list@redhat.com on 16 Oct 2002, subject
+"Re: [V4L] Re: v4l2 api / Zoran v4l2_jpegcompression" -->
+
+ <para>APP is some application-specific information. The
+application can set it itself, and it'll be stored in the JPEG-encoded
+fields (eg; interlacing information for in an AVI or so). COM is the
+same, but it's comments, like 'encoded by me' or so.</para>
+
+ <para>jpeg_markers describes whether the huffman tables,
+quantization tables and the restart interval information (all
+JPEG-specific stuff) should be stored in the JPEG-encoded fields.
+These define how the JPEG field is encoded. If you omit them,
+applications assume you've used standard encoding. You usually do want
+to add them.</para>
+
+ <!-- NB VIDIOC_S_JPEGCOMP is w/o. -->
+
+ <table pgwide="1" frame="none" id="v4l2-jpegcompression">
+ <title>struct <structname>v4l2_jpegcompression</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>int</entry>
+ <entry><structfield>quality</structfield></entry>
+ <entry>Deprecated. If <link linkend="jpeg-quality-control"><constant>
+ V4L2_CID_JPEG_IMAGE_QUALITY</constant></link> control is exposed by
+ a driver applications should use it instead and ignore this field.
+ </entry>
+ </row>
+ <row>
+ <entry>int</entry>
+ <entry><structfield>APPn</structfield></entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry>int</entry>
+ <entry><structfield>APP_len</structfield></entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry>char</entry>
+ <entry><structfield>APP_data</structfield>[60]</entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry>int</entry>
+ <entry><structfield>COM_len</structfield></entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry>char</entry>
+ <entry><structfield>COM_data</structfield>[60]</entry>
+ <entry></entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>jpeg_markers</structfield></entry>
+ <entry>See <xref linkend="jpeg-markers"/>. Deprecated.
+ If <link linkend="jpeg-active-marker-control"><constant>
+ V4L2_CID_JPEG_ACTIVE_MARKER</constant></link> control
+ is exposed by a driver applications should use it instead
+ and ignore this field.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <table pgwide="1" frame="none" id="jpeg-markers">
+ <title>JPEG Markers Flags</title>
+ <tgroup cols="3">
+ &cs-def;
+ <tbody valign="top">
+ <row>
+ <entry><constant>V4L2_JPEG_MARKER_DHT</constant></entry>
+ <entry>(1&lt;&lt;3)</entry>
+ <entry>Define Huffman Tables</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_JPEG_MARKER_DQT</constant></entry>
+ <entry>(1&lt;&lt;4)</entry>
+ <entry>Define Quantization Tables</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_JPEG_MARKER_DRI</constant></entry>
+ <entry>(1&lt;&lt;5)</entry>
+ <entry>Define Restart Interval</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_JPEG_MARKER_COM</constant></entry>
+ <entry>(1&lt;&lt;6)</entry>
+ <entry>Comment segment</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_JPEG_MARKER_APP</constant></entry>
+ <entry>(1&lt;&lt;7)</entry>
+ <entry>App segment, driver will always use APP0</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+ </refsect1>
+</refentry>