blob: 48748499c097516e9ac39b2e8584eb5a8e92c0f2 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
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_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<<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>
|
