ioctl VIDIOC_OVERLAY &manvol; VIDIOC_OVERLAY Start or stop video overlay int ioctl int fd int request const int *argp Arguments fd &fd; request VIDIOC_OVERLAY argp Description This ioctl is part of the video overlay I/O method. Applications call VIDIOC_OVERLAY to start or stop the overlay. It takes a pointer to an integer which must be set to zero by the application to stop overlay, to one to start. Drivers do not support &VIDIOC-STREAMON; or &VIDIOC-STREAMOFF; with V4L2_BUF_TYPE_VIDEO_OVERLAY. &return-value; EINVAL Video overlay is not supported, or the parameters have not been set up. See for the necessary steps.