There are certain values that the stream handler looks for. For example, when the stream handler requests a stop or a pause on a DDCMD_CONTROL message, the pointer that comes back to the stream handler is a pointer to the cumulative time that the PDD has recorded in real time. So whenever the stream handler requests the device to stop, the PDD honors that request and tells the stream handler the real time the PDD stopped within the stream.
Another value the stream handler looks for is returned on DDCMD_STATUS. This is also a pointer to the cumulative time from the PDD, with respect to when that stream was first started at the stream handler's request.