A three-layer scheme for M-channel multiple description image coding
Signal Processing
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This paper introduces a new sequential design method for multiple descriptionscalar quantizers (MDSQ's) to generate two or more balanced descriptions. In thisdesign method, a multiple description system is divided into multiple stages, and them-th stage can be understood intuitively as minimizing the distortion of receiving anym of all the descriptions, while looking ahead to the next stage to reduce thedistortion if more descriptions are present. Entropy-constrained sequential MDSQ withtwo descriptions is shown to achieve the same asymptotic performance as entropy-constrainedMDSQ with uniform stepsize. Then this method is applied to the designof sequential MDSQ with three descriptions, for which two slightly different designsare given and compared with a three description system based on unequal loss protectionat high rate. The results suggest that if the quality of the decoded source withtwo or more descriptions (rather than a single description) is most important, generalmultiple 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 theirperformances is not terribly large.