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[linux/fpc-iii.git] / Documentation / DocBook / v4l / vidioc-subscribe-event.xml
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1 <refentry id="vidioc-subscribe-event">
2   <refmeta>
3     <refentrytitle>ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refentrytitle>
4     &manvol;
5   </refmeta>
7   <refnamediv>
8     <refname>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refname>
9     <refpurpose>Subscribe or unsubscribe event</refpurpose>
10   </refnamediv>
12   <refsynopsisdiv>
13     <funcsynopsis>
14       <funcprototype>
15         <funcdef>int <function>ioctl</function></funcdef>
16         <paramdef>int <parameter>fd</parameter></paramdef>
17         <paramdef>int <parameter>request</parameter></paramdef>
18         <paramdef>struct v4l2_event_subscription
19 *<parameter>argp</parameter></paramdef>
20       </funcprototype>
21     </funcsynopsis>
22   </refsynopsisdiv>
24   <refsect1>
25     <title>Arguments</title>
27     <variablelist>
28       <varlistentry>
29         <term><parameter>fd</parameter></term>
30         <listitem>
31           <para>&fd;</para>
32         </listitem>
33       </varlistentry>
34       <varlistentry>
35         <term><parameter>request</parameter></term>
36         <listitem>
37           <para>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</para>
38         </listitem>
39       </varlistentry>
40       <varlistentry>
41         <term><parameter>argp</parameter></term>
42         <listitem>
43           <para></para>
44         </listitem>
45       </varlistentry>
46     </variablelist>
47   </refsect1>
49   <refsect1>
50     <title>Description</title>
52     <para>Subscribe or unsubscribe V4L2 event. Subscribed events are
53     dequeued by using the &VIDIOC-DQEVENT; ioctl.</para>
55     <table frame="none" pgwide="1" id="v4l2-event-subscription">
56       <title>struct <structname>v4l2_event_subscription</structname></title>
57       <tgroup cols="3">
58         &cs-str;
59         <tbody valign="top">
60           <row>
61             <entry>__u32</entry>
62             <entry><structfield>type</structfield></entry>
63             <entry>Type of the event.</entry>
64           </row>
65           <row>
66             <entry>__u32</entry>
67             <entry><structfield>reserved</structfield>[7]</entry>
68             <entry>Reserved for future extensions. Drivers and applications
69             must set the array to zero.</entry>
70           </row>
71         </tbody>
72       </tgroup>
73     </table>
75     <table frame="none" pgwide="1" id="event-type">
76       <title>Event Types</title>
77       <tgroup cols="3">
78         &cs-def;
79         <tbody valign="top">
80           <row>
81             <entry><constant>V4L2_EVENT_ALL</constant></entry>
82             <entry>0</entry>
83             <entry>All events. V4L2_EVENT_ALL is valid only for
84             VIDIOC_UNSUBSCRIBE_EVENT for unsubscribing all events at once.
85             </entry>
86           </row>
87           <row>
88             <entry><constant>V4L2_EVENT_VSYNC</constant></entry>
89             <entry>1</entry>
90             <entry>This event is triggered on the vertical sync.
91             This event has &v4l2-event-vsync; associated with it.
92             </entry>
93           </row>
94           <row>
95             <entry><constant>V4L2_EVENT_EOS</constant></entry>
96             <entry>2</entry>
97             <entry>This event is triggered when the end of a stream is reached.
98             This is typically used with MPEG decoders to report to the application
99             when the last of the MPEG stream has been decoded.
100             </entry>
101           </row>
102           <row>
103             <entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
104             <entry>0x08000000</entry>
105             <entry>Base event number for driver-private events.</entry>
106           </row>
107         </tbody>
108       </tgroup>
109     </table>
111     <table frame="none" pgwide="1" id="v4l2-event-vsync">
112       <title>struct <structname>v4l2_event_vsync</structname></title>
113       <tgroup cols="3">
114         &cs-str;
115         <tbody valign="top">
116           <row>
117             <entry>__u8</entry>
118             <entry><structfield>field</structfield></entry>
119             <entry>The upcoming field. See &v4l2-field;.</entry>
120           </row>
121         </tbody>
122       </tgroup>
123     </table>
125   </refsect1>
126 </refentry>
127 <!--
128 Local Variables:
129 mode: sgml
130 sgml-parent-document: "v4l2.sgml"
131 indent-tabs-mode: nil
132 End: