| .. -*- coding: utf-8; mode: rst -*- |
| |
| .. _VIDIOC_G_INPUT: |
| |
| ************************************ |
| ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT |
| ************************************ |
| |
| Name |
| ==== |
| |
| VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input |
| |
| |
| Synopsis |
| ======== |
| |
| .. cpp:function:: int ioctl( int fd, int request, int *argp ) |
| |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :ref:`open() <func-open>`. |
| |
| ``request`` |
| VIDIOC_G_INPUT, VIDIOC_S_INPUT |
| |
| ``argp`` |
| |
| |
| Description |
| =========== |
| |
| To query the current video input applications call the |
| :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver |
| stores the number of the input, as in the struct |
| :ref:`v4l2_input <v4l2-input>` ``index`` field. This ioctl will fail |
| only when there are no video inputs, returning ``EINVAL``. |
| |
| To select a video input applications store the number of the desired |
| input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer |
| to this integer. Side effects are possible. For example inputs may |
| support different video standards, so the driver may implicitly switch |
| the current standard. Because of these possible side effects |
| applications must select an input before querying or negotiating any |
| other parameters. |
| |
| Information about video inputs is available using the |
| :ref:`VIDIOC_ENUMINPUT` ioctl. |
| |
| |
| Return Value |
| ============ |
| |
| On success 0 is returned, on error -1 and the ``errno`` variable is set |
| appropriately. The generic error codes are described at the |
| :ref:`Generic Error Codes <gen-errors>` chapter. |
| |
| EINVAL |
| The number of the video input is out of bounds. |