1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2.. c:namespace:: V4L
3
4.. _VIDIOC_OVERLAY:
5
6********************
7ioctl VIDIOC_OVERLAY
8********************
9
10Name
11====
12
13VIDIOC_OVERLAY - Start or stop video overlay
14
15Synopsis
16========
17
18.. c:macro:: VIDIOC_OVERLAY
19
20``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)``
21
22Arguments
23=========
24
25``fd``
26    File descriptor returned by :c:func:`open()`.
27
28``argp``
29    Pointer to an integer.
30
31Description
32===========
33
34This ioctl is part of the :ref:`video overlay <overlay>` I/O method.
35Applications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It
36takes a pointer to an integer which must be set to zero by the
37application to stop overlay, to one to start.
38
39Drivers do not support :ref:`VIDIOC_STREAMON` or
40:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with
41``V4L2_BUF_TYPE_VIDEO_OVERLAY``.
42
43Return Value
44============
45
46On success 0 is returned, on error -1 and the ``errno`` variable is set
47appropriately. The generic error codes are described at the
48:ref:`Generic Error Codes <gen-errors>` chapter.
49
50EINVAL
51    The overlay parameters have not been set up. See :ref:`overlay`
52    for the necessary steps.
53