Active Adaptation by Program Delegation in Video on Demand

In order to realize a more exible structure and achieve a richer set of capabilities in the adaptive control of QoS for distributed multimedia systems, this paper seeks to complement the conventionally used passive data passing paradigm with the newer active program passing approach. By timely delegating and redelegating adaptation programs to encapsulate desired feedback control intelligence and data, a ne-grained, dynamic and customizable adaptation to quality of service variations becomes realizable. We describe an experimental prototype that utilizes the above active adaptation approach to regulate video ow for video on demand. Preliminary results show a viable system which has much greater exibility for adaptation than is traditionally possible, and exhibits a smooth, graceful improve-ment/degradation in perceptual QoS during speedup or slowdown.