Efficient coding of LSF parameters using multi-mode predictive multistage matrix quantization

An efficient multi-mode predictive multistage matrix quantization is proposed for very low bit rate quantization of line spectral frequencies (LSF) in LPC based speech coder. One novel aspect of the proposed technique is the mode based predictor and quantizer. Another novel aspect is the optimization of the predictive coefficients considering the mode transition between successive superframes and the connection between predictor and quantizer. Experimental results show that the proposed method yields higher quality LSF quantizer at very low bit rate than those designed with several recently proposed methods.