1184610Salfred.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2189002Sed.. c:namespace:: V4L
3184610Salfred
4184610Salfred.. _VIDIOC_OVERLAY:
5184610Salfred
6184610Salfred********************
7184610Salfredioctl VIDIOC_OVERLAY
8184610Salfred********************
9184610Salfred
10184610SalfredName
11184610Salfred====
12184610Salfred
13184610SalfredVIDIOC_OVERLAY - Start or stop video overlay
14184610Salfred
15184610SalfredSynopsis
16184610Salfred========
17184610Salfred
18184610Salfred.. c:macro:: VIDIOC_OVERLAY
19184610Salfred
20184610Salfred``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)``
21184610Salfred
22184610SalfredArguments
23184610Salfred=========
24184610Salfred
25184610Salfred``fd``
26184610Salfred    File descriptor returned by :c:func:`open()`.
27184610Salfred
28184610Salfred``argp``
29184610Salfred    Pointer to an integer.
30184610Salfred
31184610SalfredDescription
32184610Salfred===========
33184610Salfred
34184610SalfredThis ioctl is part of the :ref:`video overlay <overlay>` I/O method.
35184610SalfredApplications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It
36184610Salfredtakes a pointer to an integer which must be set to zero by the
37184610Salfredapplication to stop overlay, to one to start.
38184610Salfred
39184610SalfredDrivers do not support :ref:`VIDIOC_STREAMON` or
40184610Salfred:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with
41184610Salfred``V4L2_BUF_TYPE_VIDEO_OVERLAY``.
42184610Salfred
43184610SalfredReturn Value
44184610Salfred============
45184610Salfred
46184610SalfredOn success 0 is returned, on error -1 and the ``errno`` variable is set
47184610Salfredappropriately. The generic error codes are described at the
48184610Salfred:ref:`Generic Error Codes <gen-errors>` chapter.
49184610Salfred
50184610SalfredEINVAL
51184610Salfred    The overlay parameters have not been set up. See :ref:`overlay`
52184610Salfred    for the necessary steps.
53184610Salfred