Distortion analysis of hierarchical mixing technique on MPEG surround standard

Distortion due to mixing processes in Moving Picture Expert Group (MPEG) Surround, an audio standard based on spatial audio coding technique, has been studied and reported in this paper. The distortion, particularly introduced due to the hierarchical down-mixing technique applied in MPS, was analytically and experimentally studied. Experiments showed the results consistent to the analysis based on the derived formulation. Tested using 5 audio materials, it is shown that approximately 4 dB additional distortion was introduced in encoding 5 audio channels compared to encoding of 2 audio channels. The results also shows that the distortion, represented as squared-error and then plotted, can be visually identified. This study is very useful for future work on improving MPS performance.