Application of FEC based Multiple Description Coding to Internet Video Streaming and Multicast

Multiple Description (MD) source coding has recently emerged as an attractive framework for robust transmission over channels with transient shutdown characteristics such as the Internet, or wireless systems during a deep fade. The basic idea is to generate multiple independent descriptions of the source such that each description independently describes the source with certain fidelity, and when more than one description is available, they can be synergistically combined to enhance the quality. Most of the prior work has been based on signal processing based approaches and dominated by N = 2 descriptions case. Recently generalized MD (N >2 descriptions) coding through the usage of Forward Error Correction (FEC) codes [1,2] has been proposed and its superiority in comparison to signal processing based schemes has been illustrated. In [1], a fast (O(N)), nearly optimal algorithm (MD-FEC) has been proposed that transforms a prioritized input multiresolution bit stream into a robust MD stream where all the N packets are equally important. Note that while the former is sensitive to the position of losses in the bitstream, the latter is insensitive to them, the quality delivered by the latter being dependent only on the number of descriptions reaching the destination. The optimization problem solved in [1], is concerned with the allocation of the total transmission rate between source and channel bits so as to maximize the expected delivered quality at the receiver, given the state of the channel between the sender and the receiver.