vidioc-g-input.rst (1750B)
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_G_INPUT: 5 6************************************ 7ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT 8************************************ 9 10Name 11==== 12 13VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_G_INPUT 19 20``int ioctl(int fd, VIDIOC_G_INPUT, int *argp)`` 21 22.. c:macro:: VIDIOC_S_INPUT 23 24``int ioctl(int fd, VIDIOC_S_INPUT, int *argp)`` 25 26Arguments 27========= 28 29``fd`` 30 File descriptor returned by :c:func:`open()`. 31 32``argp`` 33 Pointer an integer with input index. 34 35Description 36=========== 37 38To 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 40stores the number of the input, as in the struct 41:c:type:`v4l2_input` ``index`` field. This ioctl will fail 42only when there are no video inputs, returning ``EINVAL``. 43 44To select a video input applications store the number of the desired 45input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer 46to this integer. Side effects are possible. For example inputs may 47support different video standards, so the driver may implicitly switch 48the current standard. Because of these possible side effects 49applications must select an input before querying or negotiating any 50other parameters. 51 52Information about video inputs is available using the 53:ref:`VIDIOC_ENUMINPUT` ioctl. 54 55Return Value 56============ 57 58On success 0 is returned, on error -1 and the ``errno`` variable is set 59appropriately. The generic error codes are described at the 60:ref:`Generic Error Codes <gen-errors>` chapter. 61 62EINVAL 63 The number of the video input is out of bounds.