03/01/1999 09:00 AM
Computer Engineering
We analyze the effect of the correlation of the delay experienced by the video traffic stream on the quality of the clock recovered by an MPEG-2 decoder. We prove analytically that, for a general input process, high correlation of the delay samples produces a large variance of the recovered clock. We verify the analytical result through actual simulation of an MPEG-2 Systems decoder PLL with correlated traffic patterns (AR processes) as the input. We also show by simulation the effects of bimodal delay distributions, such as those resulting from the PCR-unaware encapsulation scheme, on the quality of the receiver clock. The problem is also brought out in the case of practical networks through an experiment which indicates that the temporal characteristics of the delays encountered by the video stream in a packet network depend heavily on the scheduling disciplines used in the network switches.
