diff options
Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-dqevent.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/vidioc-dqevent.xml | 121 |
1 files changed, 114 insertions, 7 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml index b036f8963353..50ccd33948c1 100644 --- a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml +++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml @@ -64,7 +64,7 @@ <entry>__u32</entry> <entry><structfield>type</structfield></entry> <entry></entry> - <entry>Type of the event.</entry> + <entry>Type of the event, see <xref linkend="event-type" />.</entry> </row> <row> <entry>union</entry> @@ -154,6 +154,113 @@ </tgroup> </table> + <table frame="none" pgwide="1" id="event-type"> + <title>Event Types</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_EVENT_ALL</constant></entry> + <entry>0</entry> + <entry>All events. V4L2_EVENT_ALL is valid only for + VIDIOC_UNSUBSCRIBE_EVENT for unsubscribing all events at once. + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_VSYNC</constant></entry> + <entry>1</entry> + <entry>This event is triggered on the vertical sync. + This event has a &v4l2-event-vsync; associated with it. + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_EOS</constant></entry> + <entry>2</entry> + <entry>This event is triggered when the end of a stream is reached. + This is typically used with MPEG decoders to report to the application + when the last of the MPEG stream has been decoded. + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_CTRL</constant></entry> + <entry>3</entry> + <entry><para>This event requires that the <structfield>id</structfield> + matches the control ID from which you want to receive events. + This event is triggered if the control's value changes, if a + button control is pressed or if the control's flags change. + This event has a &v4l2-event-ctrl; associated with it. This struct + contains much of the same information as &v4l2-queryctrl; and + &v4l2-control;.</para> + + <para>If the event is generated due to a call to &VIDIOC-S-CTRL; or + &VIDIOC-S-EXT-CTRLS;, then the event will <emphasis>not</emphasis> be sent to + the file handle that called the ioctl function. This prevents + nasty feedback loops. If you <emphasis>do</emphasis> want to get the + event, then set the <constant>V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK</constant> + flag. + </para> + + <para>This event type will ensure that no information is lost when + more events are raised than there is room internally. In that + case the &v4l2-event-ctrl; of the second-oldest event is kept, + but the <structfield>changes</structfield> field of the + second-oldest event is ORed with the <structfield>changes</structfield> + field of the oldest event.</para> + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_FRAME_SYNC</constant></entry> + <entry>4</entry> + <entry> + <para>Triggered immediately when the reception of a + frame has begun. This event has a + &v4l2-event-frame-sync; associated with it.</para> + + <para>If the hardware needs to be stopped in the case of a + buffer underrun it might not be able to generate this event. + In such cases the <structfield>frame_sequence</structfield> + field in &v4l2-event-frame-sync; will not be incremented. This + causes two consecutive frame sequence numbers to have n times + frame interval in between them.</para> + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_SOURCE_CHANGE</constant></entry> + <entry>5</entry> + <entry> + <para>This event is triggered when a source parameter change is + detected during runtime by the video device. It can be a + runtime resolution change triggered by a video decoder or the + format change happening on an input connector. + This event requires that the <structfield>id</structfield> + matches the input index (when used with a video device node) + or the pad index (when used with a subdevice node) from which + you want to receive events.</para> + + <para>This event has a &v4l2-event-src-change; associated + with it. The <structfield>changes</structfield> bitfield denotes + what has changed for the subscribed pad. If multiple events + occurred before application could dequeue them, then the changes + will have the ORed value of all the events generated.</para> + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_MOTION_DET</constant></entry> + <entry>6</entry> + <entry> + <para>Triggered whenever the motion detection state for one or more of the regions + changes. This event has a &v4l2-event-motion-det; associated with it.</para> + </entry> + </row> + <row> + <entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry> + <entry>0x08000000</entry> + <entry>Base event number for driver-private events.</entry> + </row> + </tbody> + </tgroup> + </table> + <table frame="none" pgwide="1" id="v4l2-event-vsync"> <title>struct <structname>v4l2_event_vsync</structname></title> <tgroup cols="3"> @@ -177,7 +284,7 @@ <entry>__u32</entry> <entry><structfield>changes</structfield></entry> <entry></entry> - <entry>A bitmask that tells what has changed. See <xref linkend="changes-flags" />.</entry> + <entry>A bitmask that tells what has changed. See <xref linkend="ctrl-changes-flags" />.</entry> </row> <row> <entry>__u32</entry> @@ -309,8 +416,8 @@ </tgroup> </table> - <table pgwide="1" frame="none" id="changes-flags"> - <title>Changes</title> + <table pgwide="1" frame="none" id="ctrl-changes-flags"> + <title>Control Changes</title> <tgroup cols="3"> &cs-def; <tbody valign="top"> @@ -318,9 +425,9 @@ <entry><constant>V4L2_EVENT_CTRL_CH_VALUE</constant></entry> <entry>0x0001</entry> <entry>This control event was triggered because the value of the control - changed. Special case: if a button control is pressed, then this - event is sent as well, even though there is not explicit value - associated with a button control.</entry> + changed. Special cases: Volatile controls do no generate this event; + If a control has the <constant>V4L2_CTRL_FLAG_EXECUTE_ON_WRITE</constant> + flag set, then this event is sent as well, regardless its value.</entry> </row> <row> <entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry> |