Adaptive video distribution using IP multicast

Multicast is a common method for distributing real-time audio and video over the Internet. The Receiver-driven Layered Multicast (RLM) is one of the most popular receiver-based rate adaptation algorithms. However, RLM is relatively slow in adapting changes in the bandwidth of the network. Its adaptive control is based on packet loss rate. A number of extensions and variants of RLM have been proposed in the literature to improve some of these weaknesses. However, the responses of the receivers are improved at the expense of protocol complexity. In this paper, a receiver-based adaptive multimedia system using the RLM protocol for rate control is implemented. The RLM algorithm is modified to minimise congestion in the network and to reduce the processing overhead. We have also investigated whether the interframe jitter is an appropriate measure of the network congestion, and how it can be used to decide whether a receiver can subscribe to a higher layer at a given point of time. A heuristic method is used to determine the interframe jitter values that the system can tolerate. The modified RLM algorithm is also integrated with the encoding and decoding of the MPEG video to evaluate the overall performance. The preliminary results demonstrate that rate control using the inter-frame jitter has better video quality than that using packet loss rate.