In analysis-by-synthesis speech coders the computational complexity of the search for an optimum innovation is still high although transformations were proposed to decrease the complexity. This limits practical codebook sizes and vector dimensions (block lengths). In this contribution two new structured frequency domain codebooks are proposed. The first one is a pulse shaped codebook with a reversed search order for the gain and the shape; the second one is a unity magnitude codebook with structured phase. The corresponding algorithms which are based on new insights, result in a drastically reduced search in the transformed domain. The computational complexity increases only proportional to the bit rate and not to the codebook size. >
['Christian G. Gerlach']
CELP speech coding with almost no codebook search