END-TO-END QoS MANAGEMENT FOR ADAPTIVE VIDEO FLOWS

Distributed audio and video applications need to adapt to fluctuations in delivered quality of service (QoS). By trading off temporal and spatial quality to available bandwidth, or manipulating the playout time of continuous media in response to variation in delay, audio and video flows can be made to adapt to fluctuating QoS with minimal perceptual distortion. In this paper we introduce dynamic QoS management (DQM) for the control and management of multi-layer coded flows operating in heterogeneous multimedia networking environments. Two key techniques are proposed: i) an end-to-end dynamic rate shaping scheme which adapts the rate of MPEG-coded [1] flows to the available network resources while minimising the distortion observed at the receiver; and ii) an adaptive network service, which offers ÒhardÓ guarantees to the base layer of multi-layer coded flows, and ÒfairnessÓ guarantees to the enhancement layers based on a bandwidth allocation technique called weighted fair sharing. We also discuss a number of types of media scaling object1 which are used to manage and control end-to-end QoS. These include QoS filters which manipulate multi-layer coded flows [2] as they progress through the communications system, QoS adaptors which scale flows at end-systems based on the flow's measured performance and user supplied QoS scaling policy, and QoS groups which provide baseline QoS for multicast flows.