ARM: 7409/1: Do not call flush_cache_user_range with mmap_sem held
[linux/fpc-iii.git] / Documentation / DocBook / v4l / vidioc-g-jpegcomp.xml
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1 <refentry id="vidioc-g-jpegcomp">
2   <refmeta>
3     <refentrytitle>ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</refentrytitle>
4     &manvol;
5   </refmeta>
7   <refnamediv>
8     <refname>VIDIOC_G_JPEGCOMP</refname>
9     <refname>VIDIOC_S_JPEGCOMP</refname>
10     <refpurpose></refpurpose>
11   </refnamediv>
13   <refsynopsisdiv>
14     <funcsynopsis>
15       <funcprototype>
16         <funcdef>int <function>ioctl</function></funcdef>
17         <paramdef>int <parameter>fd</parameter></paramdef>
18         <paramdef>int <parameter>request</parameter></paramdef>
19         <paramdef>v4l2_jpegcompression *<parameter>argp</parameter></paramdef>
20       </funcprototype>
21     </funcsynopsis>
22     <funcsynopsis>
23       <funcprototype>
24         <funcdef>int <function>ioctl</function></funcdef>
25         <paramdef>int <parameter>fd</parameter></paramdef>
26         <paramdef>int <parameter>request</parameter></paramdef>
27         <paramdef>const v4l2_jpegcompression *<parameter>argp</parameter></paramdef>
28       </funcprototype>
29     </funcsynopsis>
30   </refsynopsisdiv>
32   <refsect1>
33     <title>Arguments</title>
35     <variablelist>
36       <varlistentry>
37         <term><parameter>fd</parameter></term>
38         <listitem>
39           <para>&fd;</para>
40         </listitem>
41       </varlistentry>
42       <varlistentry>
43         <term><parameter>request</parameter></term>
44         <listitem>
45           <para>VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP</para>
46         </listitem>
47       </varlistentry>
48       <varlistentry>
49         <term><parameter>argp</parameter></term>
50         <listitem>
51           <para></para>
52         </listitem>
53       </varlistentry>
54     </variablelist>
55   </refsect1>
57   <refsect1>
58     <title>Description</title>
60     <para>[to do]</para>
62     <para>Ronald Bultje elaborates:</para>
64     <!-- See video4linux-list@redhat.com on 16 Oct 2002, subject
65 "Re: [V4L] Re: v4l2 api / Zoran v4l2_jpegcompression" -->
67     <para>APP is some application-specific information. The
68 application can set it itself, and it'll be stored in the JPEG-encoded
69 fields (eg; interlacing information for in an AVI or so). COM is the
70 same, but it's comments, like 'encoded by me' or so.</para>
72     <para>jpeg_markers describes whether the huffman tables,
73 quantization tables and the restart interval information (all
74 JPEG-specific stuff) should be stored in the JPEG-encoded fields.
75 These define how the JPEG field is encoded. If you omit them,
76 applications assume you've used standard encoding. You usually do want
77 to add them.</para>
79     <!-- NB VIDIOC_S_JPEGCOMP is w/o. -->
81     <table pgwide="1" frame="none" id="v4l2-jpegcompression">
82       <title>struct <structname>v4l2_jpegcompression</structname></title>
83       <tgroup cols="3">
84         &cs-str;
85         <tbody valign="top">
86           <row>
87             <entry>int</entry>
88             <entry><structfield>quality</structfield></entry>
89             <entry></entry>
90           </row>
91           <row>
92             <entry>int</entry>
93             <entry><structfield>APPn</structfield></entry>
94             <entry></entry>
95           </row>
96           <row>
97             <entry>int</entry>
98             <entry><structfield>APP_len</structfield></entry>
99             <entry></entry>
100           </row>
101           <row>
102             <entry>char</entry>
103             <entry><structfield>APP_data</structfield>[60]</entry>
104             <entry></entry>
105           </row>
106           <row>
107             <entry>int</entry>
108             <entry><structfield>COM_len</structfield></entry>
109             <entry></entry>
110           </row>
111           <row>
112             <entry>char</entry>
113             <entry><structfield>COM_data</structfield>[60]</entry>
114             <entry></entry>
115           </row>
116           <row>
117             <entry>__u32</entry>
118             <entry><structfield>jpeg_markers</structfield></entry>
119             <entry>See <xref linkend="jpeg-markers" />.</entry>
120           </row>
121         </tbody>
122       </tgroup>
123     </table>
125     <table pgwide="1" frame="none" id="jpeg-markers">
126       <title>JPEG Markers Flags</title>
127       <tgroup cols="3">
128         &cs-def;
129         <tbody valign="top">
130           <row>
131             <entry><constant>V4L2_JPEG_MARKER_DHT</constant></entry>
132             <entry>(1&lt;&lt;3)</entry>
133             <entry>Define Huffman Tables</entry>
134           </row>
135           <row>
136             <entry><constant>V4L2_JPEG_MARKER_DQT</constant></entry>
137             <entry>(1&lt;&lt;4)</entry>
138             <entry>Define Quantization Tables</entry>
139           </row>
140           <row>
141             <entry><constant>V4L2_JPEG_MARKER_DRI</constant></entry>
142             <entry>(1&lt;&lt;5)</entry>
143             <entry>Define Restart Interval</entry>
144           </row>
145           <row>
146             <entry><constant>V4L2_JPEG_MARKER_COM</constant></entry>
147             <entry>(1&lt;&lt;6)</entry>
148             <entry>Comment segment</entry>
149           </row>
150           <row>
151             <entry><constant>V4L2_JPEG_MARKER_APP</constant></entry>
152             <entry>(1&lt;&lt;7)</entry>
153             <entry>App segment, driver will always use APP0</entry>
154           </row>
155         </tbody>
156       </tgroup>
157     </table>
158   </refsect1>
160   <refsect1>
161     &return-value;
163     <variablelist>
164       <varlistentry>
165         <term><errorcode>EINVAL</errorcode></term>
166         <listitem>
167           <para>This ioctl is not supported.</para>
168         </listitem>
169       </varlistentry>
170     </variablelist>
171   </refsect1>
172 </refentry>
174 <!--
175 Local Variables:
176 mode: sgml
177 sgml-parent-document: "v4l2.sgml"
178 indent-tabs-mode: nil
179 End: