1*4882a593Smuzhiyun.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2*4882a593Smuzhiyun.. c:namespace:: V4L 3*4882a593Smuzhiyun 4*4882a593Smuzhiyun.. _VIDIOC_OVERLAY: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun******************** 7*4882a593Smuzhiyunioctl VIDIOC_OVERLAY 8*4882a593Smuzhiyun******************** 9*4882a593Smuzhiyun 10*4882a593SmuzhiyunName 11*4882a593Smuzhiyun==== 12*4882a593Smuzhiyun 13*4882a593SmuzhiyunVIDIOC_OVERLAY - Start or stop video overlay 14*4882a593Smuzhiyun 15*4882a593SmuzhiyunSynopsis 16*4882a593Smuzhiyun======== 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun.. c:macro:: VIDIOC_OVERLAY 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)`` 21*4882a593Smuzhiyun 22*4882a593SmuzhiyunArguments 23*4882a593Smuzhiyun========= 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun``fd`` 26*4882a593Smuzhiyun File descriptor returned by :c:func:`open()`. 27*4882a593Smuzhiyun 28*4882a593Smuzhiyun``argp`` 29*4882a593Smuzhiyun Pointer to an integer. 30*4882a593Smuzhiyun 31*4882a593SmuzhiyunDescription 32*4882a593Smuzhiyun=========== 33*4882a593Smuzhiyun 34*4882a593SmuzhiyunThis ioctl is part of the :ref:`video overlay <overlay>` I/O method. 35*4882a593SmuzhiyunApplications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It 36*4882a593Smuzhiyuntakes a pointer to an integer which must be set to zero by the 37*4882a593Smuzhiyunapplication to stop overlay, to one to start. 38*4882a593Smuzhiyun 39*4882a593SmuzhiyunDrivers do not support :ref:`VIDIOC_STREAMON` or 40*4882a593Smuzhiyun:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with 41*4882a593Smuzhiyun``V4L2_BUF_TYPE_VIDEO_OVERLAY``. 42*4882a593Smuzhiyun 43*4882a593SmuzhiyunReturn Value 44*4882a593Smuzhiyun============ 45*4882a593Smuzhiyun 46*4882a593SmuzhiyunOn success 0 is returned, on error -1 and the ``errno`` variable is set 47*4882a593Smuzhiyunappropriately. The generic error codes are described at the 48*4882a593Smuzhiyun:ref:`Generic Error Codes <gen-errors>` chapter. 49*4882a593Smuzhiyun 50*4882a593SmuzhiyunEINVAL 51*4882a593Smuzhiyun The overlay parameters have not been set up. See :ref:`overlay` 52*4882a593Smuzhiyun for the necessary steps. 53