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Linux kernel mirror (for testing)
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1.. Permission is granted to copy, distribute and/or modify this
2.. document under the terms of the GNU Free Documentation License,
3.. Version 1.1 or any later version published by the Free Software
4.. Foundation, with no Invariant Sections, no Front-Cover Texts
5.. and no Back-Cover Texts. A copy of the license is included at
6.. Documentation/media/uapi/fdl-appendix.rst.
7..
8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
9
10.. _VIDEO_GET_EVENT:
11
12===============
13VIDEO_GET_EVENT
14===============
15
16Name
17----
18
19VIDEO_GET_EVENT
20
21.. attention:: This ioctl is deprecated.
22
23Synopsis
24--------
25
26.. c:function:: int ioctl(fd, VIDEO_GET_EVENT, struct video_event *ev)
27 :name: VIDEO_GET_EVENT
28
29
30Arguments
31---------
32
33.. flat-table::
34 :header-rows: 0
35 :stub-columns: 0
36
37
38 - .. row 1
39
40 - int fd
41
42 - File descriptor returned by a previous call to open().
43
44 - .. row 2
45
46 - int request
47
48 - Equals VIDEO_GET_EVENT for this command.
49
50 - .. row 3
51
52 - struct video_event \*ev
53
54 - Points to the location where the event, if any, is to be stored.
55
56
57Description
58-----------
59
60This ioctl is for Digital TV devices only. To get events from a V4L2 decoder
61use the V4L2 :ref:`VIDIOC_DQEVENT` ioctl instead.
62
63This ioctl call returns an event of type video_event if available. If
64an event is not available, the behavior depends on whether the device is
65in blocking or non-blocking mode. In the latter case, the call fails
66immediately with errno set to ``EWOULDBLOCK``. In the former case, the call
67blocks until an event becomes available. The standard Linux poll()
68and/or select() system calls can be used with the device file descriptor
69to watch for new events. For select(), the file descriptor should be
70included in the exceptfds argument, and for poll(), POLLPRI should be
71specified as the wake-up condition. Read-only permissions are sufficient
72for this ioctl call.
73
74.. c:type:: video_event
75
76.. code-block:: c
77
78 struct video_event {
79 __s32 type;
80 #define VIDEO_EVENT_SIZE_CHANGED 1
81 #define VIDEO_EVENT_FRAME_RATE_CHANGED 2
82 #define VIDEO_EVENT_DECODER_STOPPED 3
83 #define VIDEO_EVENT_VSYNC 4
84 long timestamp;
85 union {
86 video_size_t size;
87 unsigned int frame_rate; /* in frames per 1000sec */
88 unsigned char vsync_field; /* unknown/odd/even/progressive */
89 } u;
90 };
91
92Return Value
93------------
94
95On success 0 is returned, on error -1 and the ``errno`` variable is set
96appropriately. The generic error codes are described at the
97:ref:`Generic Error Codes <gen-errors>` chapter.
98
99.. flat-table::
100 :header-rows: 0
101 :stub-columns: 0
102
103
104 - .. row 1
105
106 - ``EWOULDBLOCK``
107
108 - There is no event pending, and the device is in non-blocking mode.
109
110 - .. row 2
111
112 - ``EOVERFLOW``
113
114 - Overflow in event queue - one or more events were lost.