0001 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
0002 .. c:namespace:: V4L
0003
0004 .. _VIDIOC_OVERLAY:
0005
0006 ********************
0007 ioctl VIDIOC_OVERLAY
0008 ********************
0009
0010 Name
0011 ====
0012
0013 VIDIOC_OVERLAY - Start or stop video overlay
0014
0015 Synopsis
0016 ========
0017
0018 .. c:macro:: VIDIOC_OVERLAY
0019
0020 ``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)``
0021
0022 Arguments
0023 =========
0024
0025 ``fd``
0026 File descriptor returned by :c:func:`open()`.
0027
0028 ``argp``
0029 Pointer to an integer.
0030
0031 Description
0032 ===========
0033
0034 This ioctl is part of the :ref:`video overlay <overlay>` I/O method.
0035 Applications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It
0036 takes a pointer to an integer which must be set to zero by the
0037 application to stop overlay, to one to start.
0038
0039 Drivers do not support :ref:`VIDIOC_STREAMON` or
0040 :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with
0041 ``V4L2_BUF_TYPE_VIDEO_OVERLAY``.
0042
0043 Return Value
0044 ============
0045
0046 On success 0 is returned, on error -1 and the ``errno`` variable is set
0047 appropriately. The generic error codes are described at the
0048 :ref:`Generic Error Codes <gen-errors>` chapter.
0049
0050 EINVAL
0051 The overlay parameters have not been set up. See :ref:`overlay`
0052 for the necessary steps.
