Allpass delay chain-based IIR PR filterbank and its application to multiple description subband coding

A class of infinite impulse response (IIR) perfect reconstruction (PR) filterbank is obtained with an allpass delay chain and finite impulse response (FIR) matrices at the analysis side. Such a formulation leads to a filterbank that can be optimized to any desired response. For a first-order allpass, the synthesis bank becomes FIR. Design examples showing warping of the frequency scale and filters with unequal passband widths are presented. The latter part of the work deals with designing a filterbank for a multiple description coding scenario. This is achieved in two parts: by obtaining the MMSE synthesis bank for a given analysis bank and channel state and by optimizing the analysis response to minimize the average distortion in the presence of channel erasures and quantization. The proposed IIR filterbank, as well as the well-known FIR paraunitary filterbank, are optimized for various channels, and their performances for the two-channel case have been compared with the derived optimal performance.