android_kernel_samsung_univ.../Documentation/DocBook/media/v4l/vidioc-dqevent.xml
Arun Kumar K 3cbe6e5bca [media] v4l: Add source change event
This event indicates that the video device has encountered
a source parameter change during runtime. This can typically be a
resolution change detected by a video decoder OR a format change
detected by an input connector.

This needs to be nofified to the userspace and the application may
be expected to reallocate buffers before proceeding. The application
can subscribe to events on a specific pad or input port which
it is interested in.

Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
2014-05-23 19:50:40 -03:00

311 lines
8.9 KiB
XML

<refentry id="vidioc-dqevent">
<refmeta>
<refentrytitle>ioctl VIDIOC_DQEVENT</refentrytitle>
&manvol;
</refmeta>
<refnamediv>
<refname>VIDIOC_DQEVENT</refname>
<refpurpose>Dequeue event</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>int <function>ioctl</function></funcdef>
<paramdef>int <parameter>fd</parameter></paramdef>
<paramdef>int <parameter>request</parameter></paramdef>
<paramdef>struct v4l2_event
*<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_DQEVENT</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>argp</parameter></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>Dequeue an event from a video device. No input is required
for this ioctl. All the fields of the &v4l2-event; structure are
filled by the driver. The file handle will also receive exceptions
which the application may get by e.g. using the select system
call.</para>
<table frame="none" pgwide="1" id="v4l2-event">
<title>struct <structname>v4l2_event</structname></title>
<tgroup cols="4">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry></entry>
<entry>Type of the event.</entry>
</row>
<row>
<entry>union</entry>
<entry><structfield>u</structfield></entry>
<entry></entry>
<entry></entry>
</row>
<row>
<entry></entry>
<entry>&v4l2-event-vsync;</entry>
<entry><structfield>vsync</structfield></entry>
<entry>Event data for event V4L2_EVENT_VSYNC.
</entry>
</row>
<row>
<entry></entry>
<entry>&v4l2-event-ctrl;</entry>
<entry><structfield>ctrl</structfield></entry>
<entry>Event data for event V4L2_EVENT_CTRL.
</entry>
</row>
<row>
<entry></entry>
<entry>&v4l2-event-frame-sync;</entry>
<entry><structfield>frame_sync</structfield></entry>
<entry>Event data for event V4L2_EVENT_FRAME_SYNC.</entry>
</row>
<row>
<entry></entry>
<entry>__u8</entry>
<entry><structfield>data</structfield>[64]</entry>
<entry>Event data. Defined by the event type. The union
should be used to define easily accessible type for
events.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>pending</structfield></entry>
<entry></entry>
<entry>Number of pending events excluding this one.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>sequence</structfield></entry>
<entry></entry>
<entry>Event sequence number. The sequence number is
incremented for every subscribed event that takes place.
If sequence numbers are not contiguous it means that
events have been lost.
</entry>
</row>
<row>
<entry>struct timespec</entry>
<entry><structfield>timestamp</structfield></entry>
<entry></entry>
<entry>Event timestamp.</entry>
</row>
<row>
<entry>u32</entry>
<entry><structfield>id</structfield></entry>
<entry></entry>
<entry>The ID associated with the event source. If the event does not
have an associated ID (this depends on the event type), then this
is 0.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[8]</entry>
<entry></entry>
<entry>Reserved for future extensions. Drivers must set
the array to zero.</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">
&cs-str;
<tbody valign="top">
<row>
<entry>__u8</entry>
<entry><structfield>field</structfield></entry>
<entry>The upcoming field. See &v4l2-field;.</entry>
</row>
</tbody>
</tgroup>
</table>
<table frame="none" pgwide="1" id="v4l2-event-ctrl">
<title>struct <structname>v4l2_event_ctrl</structname></title>
<tgroup cols="4">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>changes</structfield></entry>
<entry></entry>
<entry>A bitmask that tells what has changed. See <xref linkend="changes-flags" />.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry></entry>
<entry>The type of the control. See &v4l2-ctrl-type;.</entry>
</row>
<row>
<entry>union (anonymous)</entry>
<entry></entry>
<entry></entry>
<entry></entry>
</row>
<row>
<entry></entry>
<entry>__s32</entry>
<entry><structfield>value</structfield></entry>
<entry>The 32-bit value of the control for 32-bit control types.
This is 0 for string controls since the value of a string
cannot be passed using &VIDIOC-DQEVENT;.</entry>
</row>
<row>
<entry></entry>
<entry>__s64</entry>
<entry><structfield>value64</structfield></entry>
<entry>The 64-bit value of the control for 64-bit control types.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>flags</structfield></entry>
<entry></entry>
<entry>The control flags. See <xref linkend="control-flags" />.</entry>
</row>
<row>
<entry>__s32</entry>
<entry><structfield>minimum</structfield></entry>
<entry></entry>
<entry>The minimum value of the control. See &v4l2-queryctrl;.</entry>
</row>
<row>
<entry>__s32</entry>
<entry><structfield>maximum</structfield></entry>
<entry></entry>
<entry>The maximum value of the control. See &v4l2-queryctrl;.</entry>
</row>
<row>
<entry>__s32</entry>
<entry><structfield>step</structfield></entry>
<entry></entry>
<entry>The step value of the control. See &v4l2-queryctrl;.</entry>
</row>
<row>
<entry>__s32</entry>
<entry><structfield>default_value</structfield></entry>
<entry></entry>
<entry>The default value value of the control. See &v4l2-queryctrl;.</entry>
</row>
</tbody>
</tgroup>
</table>
<table frame="none" pgwide="1" id="v4l2-event-frame-sync">
<title>struct <structname>v4l2_event_frame_sync</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>frame_sequence</structfield></entry>
<entry>
The sequence number of the frame being received.
</entry>
</row>
</tbody>
</tgroup>
</table>
<table frame="none" pgwide="1" id="v4l2-event-src-change">
<title>struct <structname>v4l2_event_src_change</structname></title>
<tgroup cols="3">
&cs-str;
<tbody valign="top">
<row>
<entry>__u32</entry>
<entry><structfield>changes</structfield></entry>
<entry>
A bitmask that tells what has changed. See <xref linkend="src-changes-flags" />.
</entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="changes-flags">
<title>Changes</title>
<tgroup cols="3">
&cs-def;
<tbody valign="top">
<row>
<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>
</row>
<row>
<entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry>
<entry>0x0002</entry>
<entry>This control event was triggered because the control flags
changed.</entry>
</row>
<row>
<entry><constant>V4L2_EVENT_CTRL_CH_RANGE</constant></entry>
<entry>0x0004</entry>
<entry>This control event was triggered because the minimum,
maximum, step or the default value of the control changed.</entry>
</row>
</tbody>
</tgroup>
</table>
<table pgwide="1" frame="none" id="src-changes-flags">
<title>Source Changes</title>
<tgroup cols="3">
&cs-def;
<tbody valign="top">
<row>
<entry><constant>V4L2_EVENT_SRC_CH_RESOLUTION</constant></entry>
<entry>0x0001</entry>
<entry>This event gets triggered when a resolution change is
detected at an input. This can come from an input connector or
from a video decoder.
</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect1>
<refsect1>
&return-value;
</refsect1>
</refentry>