0001 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
0002 .. c:namespace:: V4L
0003
0004 .. _VIDIOC_G_INPUT:
0005
0006 ************************************
0007 ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT
0008 ************************************
0009
0010 Name
0011 ====
0012
0013 VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input
0014
0015 Synopsis
0016 ========
0017
0018 .. c:macro:: VIDIOC_G_INPUT
0019
0020 ``int ioctl(int fd, VIDIOC_G_INPUT, int *argp)``
0021
0022 .. c:macro:: VIDIOC_S_INPUT
0023
0024 ``int ioctl(int fd, VIDIOC_S_INPUT, int *argp)``
0025
0026 Arguments
0027 =========
0028
0029 ``fd``
0030 File descriptor returned by :c:func:`open()`.
0031
0032 ``argp``
0033 Pointer an integer with input index.
0034
0035 Description
0036 ===========
0037
0038 To query the current video input applications call the
0039 :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
0040 stores the number of the input, as in the struct
0041 :c:type:`v4l2_input` ``index`` field. This ioctl will fail
0042 only when there are no video inputs, returning ``EINVAL``.
0043
0044 To select a video input applications store the number of the desired
0045 input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer
0046 to this integer. Side effects are possible. For example inputs may
0047 support different video standards, so the driver may implicitly switch
0048 the current standard. Because of these possible side effects
0049 applications must select an input before querying or negotiating any
0050 other parameters.
0051
0052 Information about video inputs is available using the
0053 :ref:`VIDIOC_ENUMINPUT` ioctl.
0054
0055 Return Value
0056 ============
0057
0058 On success 0 is returned, on error -1 and the ``errno`` variable is set
0059 appropriately. The generic error codes are described at the
0060 :ref:`Generic Error Codes <gen-errors>` chapter.
0061
0062 EINVAL
0063 The number of the video input is out of bounds.
