Performance evaluation of subband coding and optimization of its filter coefficients

In this paper, two analytical methods to evaluate coding performance of subband coding are proposed, and optimization of its filter coefficients from the viewpoint of energy compaction property is considered. The first method is based on matrix representation of subband coding in time domain, where the coding gain given by Jayant and Noll is introduced as a performance measure for filter banks with orthogonal property. The second method is based on the optimum bit allocation problem for subband coding (multirate filter bank), where the unified coding gain is derived as a new performance measure which can be applied to arbitrary transform techniques. We then try to find filter coefficients which maximize the unified coding gain according to input characteristics. This approach leads to optimization of filter coefficients from the viewpoint of energy compaction property.