TIME-VARYING ANALYSIS-SYNTHESIS SYSTEMS BASED ON FILTER BANKS AND POST FILTERING

Perfect reconstruction (PR) time-varying analysis-synthesis filter ban ks are those in which the filters are allowed to change from one set o f PR filter banks to another as the input signal is being processed, S uch systems have the property that, in the absence of coding, they fai thfully reconstruct every sample of the input, Various methods have be en reported for the time-varying filter bank design; all of them, howe ver, utilize structures for conventional PR filter banks, These conven tional structures that have been applied in the past result in differe nt limitations in each method, This paper introduces a new structure f or exactly reconstructing time-varying analysis-synthesis filter banks , This structure consists of the conventional filter bank followed by a time-varying post filter, The new method requires neither the redesi gn of the analysis sections nor the use of any intermediate analysis f ilters during transition periods, It provides a simple and elegant pro cedure for designing time-varying filter banks without the disadvantag es of the previous methods.