| <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>&v4l2-event-motion-det;</entry> |
| <entry><structfield>motion_det</structfield></entry> |
| <entry>Event data for event V4L2_EVENT_MOTION_DET.</entry> |
| </row> |
| <row> |
| <entry></entry> |
| <entry>&v4l2-event-src-change;</entry> |
| <entry><structfield>src_change</structfield></entry> |
| <entry>Event data for event V4L2_EVENT_SOURCE_CHANGE.</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 frame="none" pgwide="1" id="v4l2-event-motion-det"> |
| <title>struct <structname>v4l2_event_motion_det</structname></title> |
| <tgroup cols="3"> |
| &cs-str; |
| <tbody valign="top"> |
| <row> |
| <entry>__u32</entry> |
| <entry><structfield>flags</structfield></entry> |
| <entry> |
| Currently only one flag is available: if <constant>V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ</constant> |
| is set, then the <structfield>frame_sequence</structfield> field is valid, |
| otherwise that field should be ignored. |
| </entry> |
| </row> |
| <row> |
| <entry>__u32</entry> |
| <entry><structfield>frame_sequence</structfield></entry> |
| <entry> |
| The sequence number of the frame being received. Only valid if the |
| <constant>V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ</constant> flag was set. |
| </entry> |
| </row> |
| <row> |
| <entry>__u32</entry> |
| <entry><structfield>region_mask</structfield></entry> |
| <entry> |
| The bitmask of the regions that reported motion. There is at least one |
| region. If this field is 0, then no motion was detected at all. |
| If there is no <constant>V4L2_CID_DETECT_MD_REGION_GRID</constant> control |
| (see <xref linkend="detect-controls" />) to assign a different region |
| to each cell in the motion detection grid, then that all cells |
| are automatically assigned to the default region 0. |
| </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> |
