1 .. SPDX-License-Identifier: GFDL-1.1-no-invari 1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L 2 .. c:namespace:: V4L
3 3
4 .. _VIDIOC_G_OUTPUT: 4 .. _VIDIOC_G_OUTPUT:
5 5
6 ************************************** 6 **************************************
7 ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT 7 ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
8 ************************************** 8 **************************************
9 9
10 Name 10 Name
11 ==== 11 ====
12 12
13 VIDIOC_G_OUTPUT - VIDIOC_S_OUTPUT - Query or s 13 VIDIOC_G_OUTPUT - VIDIOC_S_OUTPUT - Query or select the current video output
14 14
15 Synopsis 15 Synopsis
16 ======== 16 ========
17 17
18 .. c:macro:: VIDIOC_G_OUTPUT 18 .. c:macro:: VIDIOC_G_OUTPUT
19 19
20 ``int ioctl(int fd, VIDIOC_G_OUTPUT, int *argp 20 ``int ioctl(int fd, VIDIOC_G_OUTPUT, int *argp)``
21 21
22 .. c:macro:: VIDIOC_S_OUTPUT 22 .. c:macro:: VIDIOC_S_OUTPUT
23 23
24 ``int ioctl(int fd, VIDIOC_S_OUTPUT, int *argp 24 ``int ioctl(int fd, VIDIOC_S_OUTPUT, int *argp)``
25 25
26 Arguments 26 Arguments
27 ========= 27 =========
28 28
29 ``fd`` 29 ``fd``
30 File descriptor returned by :c:func:`open( 30 File descriptor returned by :c:func:`open()`.
31 31
32 ``argp`` 32 ``argp``
33 Pointer to an integer with output index. 33 Pointer to an integer with output index.
34 34
35 Description 35 Description
36 =========== 36 ===========
37 37
38 To query the current video output applications 38 To query the current video output applications call the
39 :ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl 39 :ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a pointer to an integer where the driver
40 stores the number of the output, as in the str 40 stores the number of the output, as in the struct
41 :c:type:`v4l2_output` ``index`` field. This io 41 :c:type:`v4l2_output` ``index`` field. This ioctl will
42 fail only when there are no video outputs, ret 42 fail only when there are no video outputs, returning the ``EINVAL`` error
43 code. 43 code.
44 44
45 To select a video output applications store th 45 To select a video output applications store the number of the desired
46 output in an integer and call the :ref:`VIDIOC 46 output in an integer and call the :ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a
47 pointer to this integer. Side effects are poss 47 pointer to this integer. Side effects are possible. For example outputs
48 may support different video standards, so the 48 may support different video standards, so the driver may implicitly
49 switch the current standard. Because of these 49 switch the current standard. Because of these possible side
50 effects applications must select an output bef 50 effects applications must select an output before querying or
51 negotiating any other parameters. 51 negotiating any other parameters.
52 52
53 Information about video outputs is available u 53 Information about video outputs is available using the
54 :ref:`VIDIOC_ENUMOUTPUT` ioctl. 54 :ref:`VIDIOC_ENUMOUTPUT` ioctl.
55 55
56 Return Value 56 Return Value
57 ============ 57 ============
58 58
59 On success 0 is returned, on error -1 and the 59 On success 0 is returned, on error -1 and the ``errno`` variable is set
60 appropriately. The generic error codes are des 60 appropriately. The generic error codes are described at the
61 :ref:`Generic Error Codes <gen-errors>` chapte 61 :ref:`Generic Error Codes <gen-errors>` chapter.
62 62
63 EINVAL 63 EINVAL
64 The number of the video output is out of b 64 The number of the video output is out of bounds, or there are no
65 video outputs at all. 65 video outputs at all.
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