Sequential design of multiple description scalar quantizers

This paper introduces a new sequential design method for multiple description scalar quantizers (MDSQ's) to generate two or more balanced descriptions. In this design method, a multiple description system is divided into multiple stages, and the m-th stage can be understood intuitively as minimizing the distortion of receiving any m of all the descriptions, while looking ahead to the next stage to reduce the distortion if more descriptions are present. Entropy-constrained sequential MDSQ with two descriptions is shown to achieve the same asymptotic performance as entropy-constrained MDSQ with uniform stepsize. Then this method is applied to the design of sequential MDSQ with three descriptions, for which two slightly different designs are given and compared with a three description system based on unequal loss protection at high rate. The results suggest that if the quality of the decoded source with two or more descriptions (rather than a single description) is most important, general multiple description systems should be favored over unequal loss protection systems. However, if the quality of the decoded source with a single description is most important (in the case of, for example, high channel failure rates), the difference in their performances is not terribly large.

Sequential design of multiple description scalar quantizers Conference Paper