projects / deliverable / linux.git / blame
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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 | ||
| 9 | *man VIDIOC_G_OUTPUT(2)* | |
| 10 | ||
| 11 | VIDIOC_S_OUTPUT | |
| 12 | Query or select the current video output | |
| 13 | ||
| 14 | ||
| 15 | Synopsis | |
| 16 | ======== | |
| 17 | ||
| 18 | .. c:function:: int ioctl( int fd, int request, int *argp ) | |
| 19 | ||
| 20 | Arguments | |
| 21 | ========= | |
| 22 | ||
| 23 | ``fd`` | |
| 24 | File descriptor returned by :ref:`open() <func-open>`. | |
| 25 | ||
| 26 | ``request`` | |
| 27 | VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT | |
| 28 | ||
| 29 | ``argp`` | |
| 30 | ||
| 31 | ||
| 32 | Description | |
| 33 | =========== | |
| 34 | ||
| 35 | To query the current video output applications call the | |
| 4e03cb76 | 36 | :ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a pointer to an integer where the driver |
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37 | stores the number of the output, as in the struct |
| 38 | :ref:`v4l2_output <v4l2-output>` ``index`` field. This ioctl will | |
| 39 | fail only when there are no video outputs, returning the EINVAL error | |
| 40 | code. | |
| 41 | ||
| 42 | To select a video output applications store the number of the desired | |
| 2212ff25 | 43 | output in an integer and call the :ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a |
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44 | pointer to this integer. Side effects are possible. For example outputs |
| 45 | may support different video standards, so the driver may implicitly | |
| 46 | switch the current standard. standard. Because of these possible side | |
| 47 | effects applications must select an output before querying or | |
| 48 | negotiating any other parameters. | |
| 49 | ||
| 50 | Information about video outputs is available using the | |
| 7347081e | 51 | :ref:`VIDIOC_ENUMOUTPUT` ioctl. |
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52 | |
| 53 | ||
| 54 | Return Value | |
| 55 | ============ | |
| 56 | ||
| 57 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
| 58 | appropriately. The generic error codes are described at the | |
| 59 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
| 60 | ||
| 61 | EINVAL | |
| 62 | The number of the video output is out of bounds, or there are no | |
| 63 | video outputs at all. | |
| 64 | ||
| 65 | ||
| 66 | .. ------------------------------------------------------------------------------ | |
| 67 | .. This file was automatically converted from DocBook-XML with the dbxml | |
| 68 | .. library (https://github.com/return42/sphkerneldoc). The origin XML comes | |
| 69 | .. from the linux kernel, refer to: | |
| 70 | .. | |
| 71 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook | |
| 72 | .. ------------------------------------------------------------------------------ |