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_OVERLAY:
11
12********************
13ioctl VIDIOC_OVERLAY
14********************
15
16Name
17====
18
19VIDIOC_OVERLAY - Start or stop video overlay
20
21
22Synopsis
23========
24
25.. c:function:: int ioctl( int fd, VIDIOC_OVERLAY, const int *argp )
26    :name: VIDIOC_OVERLAY
27
28
29Arguments
30=========
31
32``fd``
33    File descriptor returned by :ref:`open() <func-open>`.
34
35``argp``
36    Pointer to an integer.
37
38
39Description
40===========
41
42This ioctl is part of the :ref:`video overlay <overlay>` I/O method.
43Applications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It
44takes a pointer to an integer which must be set to zero by the
45application to stop overlay, to one to start.
46
47Drivers do not support :ref:`VIDIOC_STREAMON` or
48:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with
49``V4L2_BUF_TYPE_VIDEO_OVERLAY``.
50
51
52Return Value
53============
54
55On success 0 is returned, on error -1 and the ``errno`` variable is set
56appropriately. The generic error codes are described at the
57:ref:`Generic Error Codes <gen-errors>` chapter.
58
59EINVAL
60    The overlay parameters have not been set up. See :ref:`overlay`
61    for the necessary steps.
62