A new multiple path search technique for residual vector quantizers

Multiple path searching can provide varying degrees of joint search optimization of residual vector quantizer encoder stages. A short coming of the conventional multiple path M-search algorithm, however, is that joint search optimization of encoder stages is limited to consecutive stages. A new iterated multipath (IM)-search algorithm is introduced that is not subject to any particular ordering of the residual quantizer stages. The IM-search algorithm may be combined with the sequential M-search algorithm to provide additional enhancement of residual vector quantization encoder performance. Furthermore, additional details of design methods for residual quantizers with separate, and, in general, different encoder and decoder cookbooks are given. Separate encoder and decoder cookbooks facilitate the use and design of various suboptimal, but computationally efficient encoder structures, while maintaining the use of decoder stage codebooks which satisfy necessary conditions for the joint optimality of direct sum codebooks