1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 3.. _VIDIOC_OVERLAY: 4 5******************** 6ioctl VIDIOC_OVERLAY 7******************** 8 9Name 10==== 11 12VIDIOC_OVERLAY - Start or stop video overlay 13 14 15Synopsis 16======== 17 18.. c:function:: int ioctl( int fd, VIDIOC_OVERLAY, const int *argp ) 19 :name: VIDIOC_OVERLAY 20 21 22Arguments 23========= 24 25``fd`` 26 File descriptor returned by :ref:`open() <func-open>`. 27 28``argp`` 29 Pointer to an integer. 30 31 32Description 33=========== 34 35This ioctl is part of the :ref:`video overlay <overlay>` I/O method. 36Applications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It 37takes a pointer to an integer which must be set to zero by the 38application to stop overlay, to one to start. 39 40Drivers do not support :ref:`VIDIOC_STREAMON` or 41:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with 42``V4L2_BUF_TYPE_VIDEO_OVERLAY``. 43 44 45Return Value 46============ 47 48On success 0 is returned, on error -1 and the ``errno`` variable is set 49appropriately. The generic error codes are described at the 50:ref:`Generic Error Codes <gen-errors>` chapter. 51 52EINVAL 53 The overlay parameters have not been set up. See :ref:`overlay` 54 for the necessary steps. 55