3.35kb/s low bit-ratespeech coding algorithm
Du Wen · Journal of Tsinghua University(Science and Technology) · 2004
In order to improve the quality of the code-excited linear-prediction (CELP) algorithm at low bit-rate, various pulse- dispersion techniques are applied in the encoder and decoder to deliver high quality excitation with little bits. The characteristics of fixed codebook pitch-enhancement and pulse-dispersion technologies were analyzed to developa high-efficiency, unsymmetrical algebraic codebook based on the probability distribution of ideal algebraic codebook pulses. Pitch pre-emphasis technology was used to enhance the pitch search. Both subjective test and computer simulations showed that the speech quality of the integrated 3.35 kb/s unsymmetrical algebraic CELP speech coding algorithm is close to that of the North American Standard IS-54 8 kb/s algorithm.