| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | .. -*- coding: utf-8; mode: rst -*- |
| 2 | |
| 3 | .. _VIDIOC_G_INPUT: |
| 4 | |
| 5 | ************************************ |
| 6 | ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT |
| 7 | ************************************ |
| 8 | |
| 9 | Name |
| 10 | ==== |
| 11 | |
| 12 | VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input |
| 13 | |
| 14 | |
| 15 | Synopsis |
| 16 | ======== |
| 17 | |
| 18 | .. c:function:: int ioctl( int fd, VIDIOC_G_INPUT, int *argp ) |
| 19 | :name: VIDIOC_G_INPUT |
| 20 | |
| 21 | .. c:function:: int ioctl( int fd, VIDIOC_S_INPUT, int *argp ) |
| 22 | :name: VIDIOC_S_INPUT |
| 23 | |
| 24 | |
| 25 | Arguments |
| 26 | ========= |
| 27 | |
| 28 | ``fd`` |
| 29 | File descriptor returned by :ref:`open() <func-open>`. |
| 30 | |
| 31 | ``argp`` |
| 32 | Pointer an integer with input index. |
| 33 | |
| 34 | |
| 35 | Description |
| 36 | =========== |
| 37 | |
| 38 | To query the current video input applications call the |
| 39 | :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver |
| 40 | stores the number of the input, as in the struct |
| 41 | :c:type:`v4l2_input` ``index`` field. This ioctl will fail |
| 42 | only when there are no video inputs, returning ``EINVAL``. |
| 43 | |
| 44 | To select a video input applications store the number of the desired |
| 45 | input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer |
| 46 | to this integer. Side effects are possible. For example inputs may |
| 47 | support different video standards, so the driver may implicitly switch |
| 48 | the current standard. Because of these possible side effects |
| 49 | applications must select an input before querying or negotiating any |
| 50 | other parameters. |
| 51 | |
| 52 | Information about video inputs is available using the |
| 53 | :ref:`VIDIOC_ENUMINPUT` ioctl. |
| 54 | |
| 55 | |
| 56 | Return Value |
| 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 input is out of bounds. |