/Documentation/DocBook/v4l/vidioc-subscribe-event.xml

  1<refentry id="vidioc-subscribe-event">
  2  <refmeta>
  3    <refentrytitle>ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refentrytitle>
  4    &manvol;
  5  </refmeta>
  6
  7  <refnamediv>
  8    <refname>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refname>
  9    <refpurpose>Subscribe or unsubscribe event</refpurpose>
 10  </refnamediv>
 11
 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>
 23
 24  <refsect1>
 25    <title>Arguments</title>
 26
 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>
 48
 49  <refsect1>
 50    <title>Description</title>
 51
 52    <para>Subscribe or unsubscribe V4L2 event. Subscribed events are
 53    dequeued by using the &VIDIOC-DQEVENT; ioctl.</para>
 54
 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>
 74
 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>
110
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>
124
125  </refsect1>
126</refentry>
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