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