3cbe6e5bca
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>
311 lines
8.9 KiB
XML
311 lines
8.9 KiB
XML
<refentry id="vidioc-dqevent">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_DQEVENT</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_DQEVENT</refname>
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<refpurpose>Dequeue event</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct v4l2_event
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*<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><parameter>fd</parameter></term>
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<listitem>
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<para>&fd;</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>request</parameter></term>
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<listitem>
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<para>VIDIOC_DQEVENT</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>argp</parameter></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<para>Dequeue an event from a video device. No input is required
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for this ioctl. All the fields of the &v4l2-event; structure are
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filled by the driver. The file handle will also receive exceptions
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which the application may get by e.g. using the select system
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call.</para>
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<table frame="none" pgwide="1" id="v4l2-event">
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<title>struct <structname>v4l2_event</structname></title>
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<tgroup cols="4">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>type</structfield></entry>
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<entry></entry>
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<entry>Type of the event.</entry>
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</row>
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<row>
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<entry>union</entry>
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<entry><structfield>u</structfield></entry>
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<entry></entry>
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<entry></entry>
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</row>
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<row>
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<entry></entry>
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<entry>&v4l2-event-vsync;</entry>
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<entry><structfield>vsync</structfield></entry>
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<entry>Event data for event V4L2_EVENT_VSYNC.
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</entry>
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</row>
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<row>
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<entry></entry>
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<entry>&v4l2-event-ctrl;</entry>
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<entry><structfield>ctrl</structfield></entry>
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<entry>Event data for event V4L2_EVENT_CTRL.
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</entry>
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</row>
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<row>
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<entry></entry>
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<entry>&v4l2-event-frame-sync;</entry>
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<entry><structfield>frame_sync</structfield></entry>
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<entry>Event data for event V4L2_EVENT_FRAME_SYNC.</entry>
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</row>
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<row>
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<entry></entry>
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<entry>__u8</entry>
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<entry><structfield>data</structfield>[64]</entry>
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<entry>Event data. Defined by the event type. The union
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should be used to define easily accessible type for
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events.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>pending</structfield></entry>
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<entry></entry>
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<entry>Number of pending events excluding this one.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>sequence</structfield></entry>
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<entry></entry>
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<entry>Event sequence number. The sequence number is
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incremented for every subscribed event that takes place.
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If sequence numbers are not contiguous it means that
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events have been lost.
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</entry>
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</row>
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<row>
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<entry>struct timespec</entry>
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<entry><structfield>timestamp</structfield></entry>
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<entry></entry>
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<entry>Event timestamp.</entry>
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</row>
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<row>
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<entry>u32</entry>
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<entry><structfield>id</structfield></entry>
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<entry></entry>
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<entry>The ID associated with the event source. If the event does not
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have an associated ID (this depends on the event type), then this
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is 0.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[8]</entry>
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<entry></entry>
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<entry>Reserved for future extensions. Drivers must set
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the array to zero.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="v4l2-event-vsync">
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<title>struct <structname>v4l2_event_vsync</structname></title>
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<tgroup cols="3">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u8</entry>
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<entry><structfield>field</structfield></entry>
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<entry>The upcoming field. See &v4l2-field;.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="v4l2-event-ctrl">
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<title>struct <structname>v4l2_event_ctrl</structname></title>
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<tgroup cols="4">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>changes</structfield></entry>
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<entry></entry>
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<entry>A bitmask that tells what has changed. See <xref linkend="changes-flags" />.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>type</structfield></entry>
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<entry></entry>
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<entry>The type of the control. See &v4l2-ctrl-type;.</entry>
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</row>
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<row>
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<entry>union (anonymous)</entry>
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<entry></entry>
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<entry></entry>
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<entry></entry>
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</row>
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<row>
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<entry></entry>
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<entry>__s32</entry>
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<entry><structfield>value</structfield></entry>
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<entry>The 32-bit value of the control for 32-bit control types.
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This is 0 for string controls since the value of a string
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cannot be passed using &VIDIOC-DQEVENT;.</entry>
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</row>
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<row>
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<entry></entry>
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<entry>__s64</entry>
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<entry><structfield>value64</structfield></entry>
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<entry>The 64-bit value of the control for 64-bit control types.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>flags</structfield></entry>
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<entry></entry>
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<entry>The control flags. See <xref linkend="control-flags" />.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>minimum</structfield></entry>
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<entry></entry>
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<entry>The minimum value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>maximum</structfield></entry>
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<entry></entry>
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<entry>The maximum value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>step</structfield></entry>
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<entry></entry>
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<entry>The step value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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<row>
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<entry>__s32</entry>
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<entry><structfield>default_value</structfield></entry>
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<entry></entry>
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<entry>The default value value of the control. See &v4l2-queryctrl;.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="v4l2-event-frame-sync">
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<title>struct <structname>v4l2_event_frame_sync</structname></title>
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<tgroup cols="3">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>frame_sequence</structfield></entry>
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<entry>
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The sequence number of the frame being received.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="v4l2-event-src-change">
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<title>struct <structname>v4l2_event_src_change</structname></title>
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<tgroup cols="3">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>changes</structfield></entry>
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<entry>
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A bitmask that tells what has changed. See <xref linkend="src-changes-flags" />.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table pgwide="1" frame="none" id="changes-flags">
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<title>Changes</title>
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<tgroup cols="3">
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&cs-def;
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_EVENT_CTRL_CH_VALUE</constant></entry>
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<entry>0x0001</entry>
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<entry>This control event was triggered because the value of the control
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changed. Special case: if a button control is pressed, then this
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event is sent as well, even though there is not explicit value
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associated with a button control.</entry>
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</row>
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<row>
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<entry><constant>V4L2_EVENT_CTRL_CH_FLAGS</constant></entry>
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<entry>0x0002</entry>
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<entry>This control event was triggered because the control flags
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changed.</entry>
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</row>
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<row>
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<entry><constant>V4L2_EVENT_CTRL_CH_RANGE</constant></entry>
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<entry>0x0004</entry>
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<entry>This control event was triggered because the minimum,
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maximum, step or the default value of the control changed.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table pgwide="1" frame="none" id="src-changes-flags">
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<title>Source Changes</title>
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<tgroup cols="3">
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&cs-def;
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_EVENT_SRC_CH_RESOLUTION</constant></entry>
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<entry>0x0001</entry>
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<entry>This event gets triggered when a resolution change is
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detected at an input. This can come from an input connector or
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from a video decoder.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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&return-value;
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</refsect1>
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</refentry>
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