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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
af4a4d0d | 3 | .. _VIDIOC_G_OUTPUT: |
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4 | |
5 | ************************************** | |
6 | ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT | |
7 | ************************************** | |
8 | ||
15e7d615 | 9 | Name |
586027ce | 10 | ==== |
5377d91f | 11 | |
586027ce | 12 | VIDIOC_G_OUTPUT - VIDIOC_S_OUTPUT - Query or select the current video output |
5377d91f | 13 | |
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14 | |
15 | Synopsis | |
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16 | ======== |
17 | ||
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18 | .. c:function:: int ioctl( int fd, VIDIOC_G_OUTPUT, int *argp ) |
19 | :name: VIDIOC_G_OUTPUT | |
20 | ||
21 | .. c:function:: int ioctl( int fd, VIDIOC_S_OUTPUT, int *argp ) | |
22 | :name: VIDIOC_S_OUTPUT | |
5377d91f | 23 | |
586027ce | 24 | |
15e7d615 | 25 | Arguments |
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26 | ========= |
27 | ||
28 | ``fd`` | |
29 | File descriptor returned by :ref:`open() <func-open>`. | |
30 | ||
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31 | ``argp`` |
32 | ||
33 | ||
15e7d615 | 34 | Description |
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35 | =========== |
36 | ||
37 | To query the current video output applications call the | |
4e03cb76 | 38 | :ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a pointer to an integer where the driver |
5377d91f | 39 | stores the number of the output, as in the struct |
e8be7e97 | 40 | :c:type:`v4l2_output` ``index`` field. This ioctl will |
cdb4af0f | 41 | fail only when there are no video outputs, returning the ``EINVAL`` error |
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42 | code. |
43 | ||
44 | To select a video output applications store the number of the desired | |
2212ff25 | 45 | output in an integer and call the :ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a |
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46 | pointer to this integer. Side effects are possible. For example outputs |
47 | may support different video standards, so the driver may implicitly | |
48 | switch the current standard. standard. Because of these possible side | |
49 | effects applications must select an output before querying or | |
50 | negotiating any other parameters. | |
51 | ||
52 | Information about video outputs is available using the | |
7347081e | 53 | :ref:`VIDIOC_ENUMOUTPUT` ioctl. |
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54 | |
55 | ||
15e7d615 | 56 | Return Value |
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57 | ============ |
58 | ||
59 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
60 | appropriately. The generic error codes are described at the | |
61 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
62 | ||
63 | EINVAL | |
64 | The number of the video output is out of bounds, or there are no | |
65 | video outputs at all. |