VIDIOC_OVERLAY — Start or stop video overlay
int ioctl( | int | fd, |
| int | request, | |
| const int * | argp); |
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.
On success 0 is returned, on error -1 and the errno variable is set appropriately:
Video overlay is not supported, or the parameters have not been set up. See Section 4.2, “Video Overlay Interface” for the necessary steps.