Statistical Multiplexing based on MPEG-4 Fine Granularity Scalability Coding
Journal of VLSI Signal Processing Systems
Journal of Visual Communication and Image Representation
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There is a significant interlayer correlation between the base and enhancement layers of two-layer signal-to-noise-ratio (SNR) scalable coders. By delaying the enhancement layer bitstream, spatial and temporal interlayer correlations can be minimized or even made negative. Such an arrangement improves the statistical multiplexing gain to the extent that, even taking into account the normally higher bit rate of SNR scalable coders, negatively correlated two-layer sources can be more efficiently multiplexed than their single-layer counterparts. Simulation results suggest that decorrelation be applicable to both weakly and strongly aligned sources and by inferences to any randomly aligned sources there between. Greatest “gains” in cell-loss ratio (CLR) are displayed by strong alignments such that for videoconferencing-type pictures, SNR scalable sources were able to raise aggregate bit rates by up to 38% before overall CLR started to fall below a single-layer performance of 10-4. With correlation dependent on the base/enhancement-layer division of bandwidth, only when the enhancement-layer efficiency is at its worst (close base and enhancement quantizer indexes) is the decorrelation “gain” insufficient to compensate the increase in total SNR scalable coder bit rate