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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _VIDIOC_OVERLAY:5 6********************7ioctl VIDIOC_OVERLAY8********************9 10Name11====12 13VIDIOC_OVERLAY - Start or stop video overlay14 15Synopsis16========17 18.. c:macro:: VIDIOC_OVERLAY19 20``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)``21 22Arguments23=========24 25``fd``26 File descriptor returned by :c:func:`open()`.27 28``argp``29 Pointer to an integer.30 31Description32===========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. It36takes a pointer to an integer which must be set to zero by the37application to stop overlay, to one to start.38 39Drivers do not support :ref:`VIDIOC_STREAMON` or40:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with41``V4L2_BUF_TYPE_VIDEO_OVERLAY``.42 43Return Value44============45 46On success 0 is returned, on error -1 and the ``errno`` variable is set47appropriately. The generic error codes are described at the48:ref:`Generic Error Codes <gen-errors>` chapter.49 50EINVAL51 The overlay parameters have not been set up. See :ref:`overlay`52 for the necessary steps.53