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Diffstat (limited to 'kernel/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml')
| -rw-r--r-- | kernel/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/kernel/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml b/kernel/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml new file mode 100644 index 000000000..098ff4838 --- /dev/null +++ b/kernel/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml @@ -0,0 +1,175 @@ +<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_COMPRESSION_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<<3)</entry> + <entry>Define Huffman Tables</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_DQT</constant></entry> + <entry>(1<<4)</entry> + <entry>Define Quantization Tables</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_DRI</constant></entry> + <entry>(1<<5)</entry> + <entry>Define Restart Interval</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_COM</constant></entry> + <entry>(1<<6)</entry> + <entry>Comment segment</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_MARKER_APP</constant></entry> + <entry>(1<<7)</entry> + <entry>App segment, driver will always use APP0</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + </refsect1> +</refentry> |