ONVIF PTZ not working with some IP cameras

Not all the cameras support the PTZ “relative mode” or “absolute mode” by invoking ONVIFPTZSetPosition.

If ONVIFPTZSetPosition returns an error, use instead the “continous move” mode with ONVIFPTZStartMove.

If a timeout is specified to ONVIFPTZStartMove, it behaves similarly to the relative mode, stopping the PTZ after the timeout. E.g. with a timeout of 100ms:
VideoGrabber.ONVIFPTZStartMove (“Pan”, true, 1.0, 100)