Lines Matching +full:loss +full:- +full:of +full:- +full:signal
1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
13 VIDIOC_DQEVENT - Dequeue event
35 ioctl. All the fields of the struct :c:type:`v4l2_event`
45 .. flat-table:: struct v4l2_event
46 :header-rows: 0
47 :stub-columns: 0
50 * - __u32
51 - ``type``
52 - Type of the event, see :ref:`event-type`.
53 * - union {
54 - ``u``
55 * - struct :c:type:`v4l2_event_vsync`
56 - ``vsync``
57 - Event data for event ``V4L2_EVENT_VSYNC``.
58 * - struct :c:type:`v4l2_event_ctrl`
59 - ``ctrl``
60 - Event data for event ``V4L2_EVENT_CTRL``.
61 * - struct :c:type:`v4l2_event_frame_sync`
62 - ``frame_sync``
63 - Event data for event ``V4L2_EVENT_FRAME_SYNC``.
64 * - struct :c:type:`v4l2_event_motion_det`
65 - ``motion_det``
66 - Event data for event V4L2_EVENT_MOTION_DET.
67 * - struct :c:type:`v4l2_event_src_change`
68 - ``src_change``
69 - Event data for event V4L2_EVENT_SOURCE_CHANGE.
70 * - __u8
71 - ``data``\ [64]
72 - Event data. Defined by the event type. The union should be used to
74 * - }
75 -
76 * - __u32
77 - ``pending``
78 - Number of pending events excluding this one.
79 * - __u32
80 - ``sequence``
81 - Event sequence number. The sequence number is incremented for
84 * - struct timespec
85 - ``timestamp``
86 - Event timestamp. The timestamp has been taken from the
89 * - u32
90 - ``id``
91 - The ID associated with the event source. If the event does not
94 * - __u32
95 - ``reserved``\ [8]
96 - Reserved for future extensions. Drivers must set the array to
104 .. _event-type:
106 .. flat-table:: Event Types
107 :header-rows: 0
108 :stub-columns: 0
111 * - ``V4L2_EVENT_ALL``
112 - 0
113 - All events. V4L2_EVENT_ALL is valid only for
115 * - ``V4L2_EVENT_VSYNC``
116 - 1
117 - This event is triggered on the vertical sync. This event has a
120 * - ``V4L2_EVENT_EOS``
121 - 2
122 - This event is triggered when the end of a stream is reached. This
124 when the last of the MPEG stream has been decoded.
125 * - ``V4L2_EVENT_CTRL``
126 - 3
127 - This event requires that the ``id`` matches the control ID from
132 This struct contains much of the same information as struct
133 :ref:`v4l2_queryctrl <v4l2-queryctrl>` and struct
146 struct :c:type:`v4l2_event_ctrl` of the
147 second-oldest event is kept, but the ``changes`` field of the
148 second-oldest event is ORed with the ``changes`` field of the
150 * - ``V4L2_EVENT_FRAME_SYNC``
151 - 4
152 - Triggered immediately when the reception of a frame has begun.
157 If the hardware needs to be stopped in the case of a buffer
163 * - ``V4L2_EVENT_SOURCE_CHANGE``
164 - 5
165 - This event is triggered when a source parameter change is detected
178 ORed value of all the events generated.
179 * - ``V4L2_EVENT_MOTION_DET``
180 - 6
181 - Triggered whenever the motion detection state for one or more of
185 * - ``V4L2_EVENT_PRIVATE_START``
186 - 0x08000000
187 - Base event number for driver-private events.
194 .. flat-table:: struct v4l2_event_vsync
195 :header-rows: 0
196 :stub-columns: 0
199 * - __u8
200 - ``field``
201 - The upcoming field. See enum :c:type:`v4l2_field`.
208 .. flat-table:: struct v4l2_event_ctrl
209 :header-rows: 0
210 :stub-columns: 0
213 * - __u32
214 - ``changes``
215 - A bitmask that tells what has changed. See
216 :ref:`ctrl-changes-flags`.
217 * - __u32
218 - ``type``
219 - The type of the control. See enum
221 * - union {
222 - (anonymous)
223 * - __s32
224 - ``value``
225 - The 32-bit value of the control for 32-bit control types. This is
226 0 for string controls since the value of a string cannot be passed
228 * - __s64
229 - ``value64``
230 - The 64-bit value of the control for 64-bit control types.
231 * - }
232 -
233 * - __u32
234 - ``flags``
235 - The control flags. See :ref:`control-flags`.
236 * - __s32
237 - ``minimum``
238 - The minimum value of the control. See struct
239 :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
240 * - __s32
241 - ``maximum``
242 - The maximum value of the control. See struct
243 :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
244 * - __s32
245 - ``step``
246 - The step value of the control. See struct
247 :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
248 * - __s32
249 - ``default_value``
250 - The default value of the control. See struct
251 :ref:`v4l2_queryctrl <v4l2-queryctrl>`.
258 .. flat-table:: struct v4l2_event_frame_sync
259 :header-rows: 0
260 :stub-columns: 0
263 * - __u32
264 - ``frame_sequence``
265 - The sequence number of the frame being received.
272 .. flat-table:: struct v4l2_event_src_change
273 :header-rows: 0
274 :stub-columns: 0
277 * - __u32
278 - ``changes``
279 - A bitmask that tells what has changed. See
280 :ref:`src-changes-flags`.
287 .. flat-table:: struct v4l2_event_motion_det
288 :header-rows: 0
289 :stub-columns: 0
292 * - __u32
293 - ``flags``
294 - Currently only one flag is available: if
298 * - __u32
299 - ``frame_sequence``
300 - The sequence number of the frame being received. Only valid if the
302 * - __u32
303 - ``region_mask``
304 - The bitmask of the regions that reported motion. There is at least
307 (see :ref:`detect-controls`) to assign a different region to
314 .. _ctrl-changes-flags:
316 .. flat-table:: Control Changes
317 :header-rows: 0
318 :stub-columns: 0
321 * - ``V4L2_EVENT_CTRL_CH_VALUE``
322 - 0x0001
323 - This control event was triggered because the value of the control
327 * - ``V4L2_EVENT_CTRL_CH_FLAGS``
328 - 0x0002
329 - This control event was triggered because the control flags
331 * - ``V4L2_EVENT_CTRL_CH_RANGE``
332 - 0x0004
333 - This control event was triggered because the minimum, maximum,
334 step or the default value of the control changed.
335 * - ``V4L2_EVENT_CTRL_CH_DIMENSIONS``
336 - 0x0008
337 - This control event was triggered because the dimensions of the
338 control changed. Note that the number of dimensions remains the
344 .. _src-changes-flags:
346 .. flat-table:: Source Changes
347 :header-rows: 0
348 :stub-columns: 0
351 * - ``V4L2_EVENT_SRC_CH_RESOLUTION``
352 - 0x0001
353 - This event gets triggered when a resolution change is detected at
356 any, the signal may also have been lost).
365 video signal and you must stop and restart streaming
369 loss of signal and so restarting streaming I/O is required in order for
370 the hardware to synchronize to the video signal.
375 On success 0 is returned, on error -1 and the ``errno`` variable is set
377 :ref:`Generic Error Codes <gen-errors>` chapter.