Energy first search scheme for spectral envelope vector quantisation of linear predictive coding residual
Fu‐Kun Chen, Pei-Hen Tsai · IET Signal Processing · 2007
Linear predictive coding (LPC) residual is an important component for analysis-by-synthesis speech coders. Using spectral envelope vector quantisation (SEVQ) for LPC residual signals, MPEG-4 harmonic vector excitation coding (HVXC) speech coder is able to change the tone and speed for decoding bitstreams. A modified version is proposed to the simplified hearing-based SEVQ (SSEVQ) approach proposed by Wang and Yang. In addition, the energy first search scheme for SEVQ (EFSEVQ) is proposed in order to reduce the computational complexity of SEVQ for MPEG-4 HVXC speech coder. The proposed EFSEVQ scheme also agrees with human hearing properties. Simulation results reveal that the proposed EFSEVQ search scheme not only reduces the computational complexity but also preserves the quality of encoded speech.