1 .. SPDX-License-Identifier: GFDL-1.1-no-invari
2 .. c:namespace:: V4L
3
4 .. _VIDIOC_CROPCAP:
5
6 ********************
7 ioctl VIDIOC_CROPCAP
8 ********************
9
10 Name
11 ====
12
13 VIDIOC_CROPCAP - Information about the video c
14
15 Synopsis
16 ========
17
18 .. c:macro:: VIDIOC_CROPCAP
19
20 ``int ioctl(int fd, VIDIOC_CROPCAP, struct v4l
21
22 Arguments
23 =========
24
25 ``fd``
26 File descriptor returned by :c:func:`open(
27
28 ``argp``
29 Pointer to struct :c:type:`v4l2_cropcap`.
30
31 Description
32 ===========
33
34 Applications use this function to query the cr
35 aspect of images and to calculate scale factor
36 field of a v4l2_cropcap structure to the respe
37 type and call the :ref:`VIDIOC_CROPCAP` ioctl
38 structure. Drivers fill the rest of the struct
39 constant except when switching the video stand
40 can occur implicit when switching the video in
41
42 This ioctl must be implemented for video captu
43 support cropping and/or scaling and/or have no
44 overlay devices.
45
46 .. c:type:: v4l2_cropcap
47
48 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm
49
50 .. flat-table:: struct v4l2_cropcap
51 :header-rows: 0
52 :stub-columns: 0
53 :widths: 1 1 2
54
55 * - __u32
56 - ``type``
57 - Type of the data stream, set by the ap
58 are valid here: ``V4L2_BUF_TYPE_VIDEO_
59 ``V4L2_BUF_TYPE_VIDEO_OUTPUT``, ``V4L2
60 ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See :
61 * - struct :ref:`v4l2_rect <v4l2-rect-crop
62 - ``bounds``
63 - Defines the window within capturing or
64 may exclude for example the horizontal
65 areas. The cropping rectangle cannot e
66 and height are defined in pixels, the
67 choose origin and units of the coordin
68 domain.
69 * - struct :ref:`v4l2_rect <v4l2-rect-crop
70 - ``defrect``
71 - Default cropping rectangle, it shall c
72 Assuming pixel aspect 1/1 this could b
73 rectangle for NTSC, a 768 × 576 recta
74 centered over the active picture area.
75 as for ``bounds`` is used.
76 * - struct :c:type:`v4l2_fract`
77 - ``pixelaspect``
78 - This is the pixel aspect (y / x) when
79 ratio of the actual sampling frequency
80 to get square pixels.
81
82 When cropping coordinates refer to squ
83 ``pixelaspect`` to 1/1. Other common v
84 SECAM, 11/10 for NTSC sampled accordin
85
86 .. note::
87 Unfortunately in the case of multiplanar bu
88 (``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE`` and
89 this API was messed up with regards to how
90 should be filled in. Some drivers only acce
91 other drivers only accepted a non-multiplan
92 ``_MPLANE`` at the end).
93
94 Starting with kernel 4.13 both variations a
95
96
97 .. _v4l2-rect-crop:
98
99 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm
100
101 .. flat-table:: struct v4l2_rect
102 :header-rows: 0
103 :stub-columns: 0
104 :widths: 1 1 2
105
106 * - __s32
107 - ``left``
108 - Horizontal offset of the top, left cor
109 pixels.
110 * - __s32
111 - ``top``
112 - Vertical offset of the top, left corne
113 pixels.
114 * - __u32
115 - ``width``
116 - Width of the rectangle, in pixels.
117 * - __u32
118 - ``height``
119 - Height of the rectangle, in pixels.
120
121 Return Value
122 ============
123
124 On success 0 is returned, on error -1 and the
125 appropriately. The generic error codes are des
126 :ref:`Generic Error Codes <gen-errors>` chapte
127
128 EINVAL
129 The struct :c:type:`v4l2_cropcap` ``type``
130 invalid.
131
132 ENODATA
133 Cropping is not supported for this input o
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