1.. Permission is granted to copy, distribute and/or modify this
2.. document under the terms of the GNU Free Documentation License,
3.. Version 1.1 or any later version published by the Free Software
4.. Foundation, with no Invariant Sections, no Front-Cover Texts
5.. and no Back-Cover Texts. A copy of the license is included at
6.. Documentation/userspace-api/media/fdl-appendix.rst.
7..
8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
9
10.. _VIDIOC_G_INPUT:
11
12************************************
13ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT
14************************************
15
16Name
17====
18
19VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input
20
21
22Synopsis
23========
24
25.. c:function:: int ioctl( int fd, VIDIOC_G_INPUT, int *argp )
26    :name: VIDIOC_G_INPUT
27
28.. c:function:: int ioctl( int fd, VIDIOC_S_INPUT, int *argp )
29    :name: VIDIOC_S_INPUT
30
31
32Arguments
33=========
34
35``fd``
36    File descriptor returned by :ref:`open() <func-open>`.
37
38``argp``
39    Pointer an integer with input index.
40
41
42Description
43===========
44
45To query the current video input applications call the
46:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
47stores the number of the input, as in the struct
48:c:type:`v4l2_input` ``index`` field. This ioctl will fail
49only when there are no video inputs, returning ``EINVAL``.
50
51To select a video input applications store the number of the desired
52input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer
53to this integer. Side effects are possible. For example inputs may
54support different video standards, so the driver may implicitly switch
55the current standard. Because of these possible side effects
56applications must select an input before querying or negotiating any
57other parameters.
58
59Information about video inputs is available using the
60:ref:`VIDIOC_ENUMINPUT` ioctl.
61
62
63Return Value
64============
65
66On success 0 is returned, on error -1 and the ``errno`` variable is set
67appropriately. The generic error codes are described at the
68:ref:`Generic Error Codes <gen-errors>` chapter.
69
70EINVAL
71    The number of the video input is out of bounds.
72