Second Generation Perceptual Coding: The Hybrid Coder

In recent years several advanced bit rate reduction algorithms for high quality digital audio have been proposed. The best results have been obtained using frequency domain techniques. The two basic approaches are subband coders and transform coders. The subband coders use a filter bank, implemented in any number of ways, with the filter bandwidths of the individual bands set according to the critical bands. Transform coders, on the other hand, are equivalent to a filter bank with many equal bandwidth filters, where sets of the filter outputs are grouped by critical bands.