Successive bit‐vector search algorithm for celp vocoders

Abstract

In this paper, we propose a successive bit‐vector search approach to reduce the computational complexity of coded excited linear predictive coding (CELP) speech coders. By decomposing each codevector into several bit‐vectors, the convolution process of the linear predictive coding model can be simplified. With a suggested matching criterion, the proposed method removes a portion of unlikely codevectors in a bit‐vector by bit‐vector fashion. Theoretical analyses and simulation results show that the proposed search method reduces a lot of the computational load for general codebook searches and maintains nearly the same speech quality as the traditional search approach. The proposed method, which reduces the complexity of the CELP speech coders in VLSI realization, can be flexibly embedded with a simple RISC processor to achieve a low‐cost speech coder.