1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 .. c:namespace:: V4L 3 4 .. _VIDIOC_OVERLAY: 5 6 ******************** 7 ioctl VIDIOC_OVERLAY 8 ******************** 9 10 Name 11 ==== 12 13 VIDIOC_OVERLAY - Start or stop video overlay 14 15 Synopsis 16 ======== 17 18 .. c:macro:: VIDIOC_OVERLAY 19 20 ``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)`` 21 22 Arguments 23 ========= 24 25 ``fd`` 26 File descriptor returned by :c:func:`open()`. 27 28 ``argp`` 29 Pointer to an integer. 30 31 Description 32 =========== 33 34 This ioctl is part of the :ref:`video overlay <overlay>` I/O method. 35 Applications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It 36 takes a pointer to an integer which must be set to zero by the 37 application to stop overlay, to one to start. 38 39 Drivers do not support :ref:`VIDIOC_STREAMON` or 40 :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with 41 ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. 42 43 Return Value 44 ============ 45 46 On success 0 is returned, on error -1 and the ``errno`` variable is set 47 appropriately. The generic error codes are described at the 48 :ref:`Generic Error Codes <gen-errors>` chapter. 49 50 EINVAL 51 The overlay parameters have not been set up. See :ref:`overlay` 52 for the necessary steps.
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