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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