Efficient pitch predictor algorithm in ITU-T G.723.1

The application and implementation of ITU-T G.723.1 speech codec is narrowly limited because of the high computational complexity. A new close-loop pitch search algorithm is presented in this paper. This algorithm is still based on the 5-order pitch predictor. A Weiner-Hopf equation is established from the 20-dimension vector, which is used by the 20-dimension codebook search in G.723.1 algorithm. The equation is further simplified into a Toeplitz equation and the resolution is exactly the optimal pitch predictor gain and is vector quantized with a 5-dimension vector codebook. The synthesized speech quality degrades slightly and the code is compatible with the G.723.1 algorithm while the computational complexity decreases near a half.