A New Multistage Search of Algebraic CELP Codebooks Based on Trellis Coding

This paper proposes a new multistage technique of algebraic codebook in CELP coders called Trellis Search inspired from the Trellis Coded Quantization (TCQ). This search technique is implemented into the fixed codebook of the standard G.729 for objective and subjective performance evaluation on a large corpus of a testing speech database. Simulations results show that the proposed search scheme reduces the codebook search time by approximately 23% compared to the time of focused search used in the standard G.729. This yields to a reduction of about 8% in the execution time of the coder at the cost of a slight degradation of speech quality but perceptually not noticeable. Key-Words: trellis, algebraic codebook, speech coding, CELP, G.729.