A comparative study of multiple description video coding in P2P: normal MDSQ versus flexible dead-zones

Multiple-description coding (MDC) encodes a source image or video into several distinct descriptions. Each description can be decoded independently and more than one description can also be decoded jointly so as to deliver a higher quality. One typical design of an MDC encoder is based on the so-called multiple description scalar quantization (MDSQ). A simple MDSQ system is to choose different step-sizes used in all involved quantizers. Another implementation is to apply flexible dead-zones in all quantizers (whereas keeping the same step-size across them). Two issues turn to be particularly important when MDC is used in video streaming applications in the P2P scenario. First, we need to consider more than two descriptions to fit the P2P reality. Second, we have to eliminate any possible drifting errors that are resulted from the use of different reference frames (in different descriptions) at the motion-compensation stage. In this paper, we introduce a DCT-domain translation to solve the mismatching problem in different reference frames. Then, we present some comparative results of the two approaches mentioned above, with detailed pros and cons for each one as well as some practical considerations.