Congestion Adaptation And Layer Prioritization In A Multicast Scalable Video Delivery System
Chen‐Khong Tham, Yung-Sze Gan, Yuming Jiang · 2002
In the absence of a congestion adaptation scheme, a video client selects its desired video quality without knowing whether it can be supported under the current network traffic condition. It may be necessary to adjust the quality setting several times before arriving at a level that is both satisfactory to the user and can be supported by the network. In this paper, we propose an automatic congestion adaptation scheme for a layered multicast system in which the video clients continuously probe the traffic condition in the network and subscribe to the appropriate number of video layers that can be supported by the network in order to achieve the best possible video quality. To further enhance the video quality at the clients, layer prioritization can be implemented such that packets in the base video layer has a lower drop probability than those of the enhancement video layers. As a result, the video clients are still able to receive a decodable video stream even when network congestion occurs. We present results from experiments conducted on an actual IP multicast testbed running Differentiated Services which show the benefits of layer prioritization and the effectiveness of our proposed automatic congestion adaptation scheme.