8kb/s低复杂性代数码激励线性预测语音编码

A Low Complexity ACELP Speech Codec

基于码激励线性预测（ＣＥＬＰ）语音编码技术，提出一种低复杂性８Ｋｂ／ｓ代数码激励线性预测（ＡＣＥＬＰ）语音编码。代数码本中的码矢量具有多值脉冲幅度，码本搜索采用次最佳部分码本快速搜索法，基频延迟仅采用整数延迟，增益系数与ＬＳＰ频率采用标量量化。解码器中采用自适应基频前置滤波器与频谱后置滤波器，以进一步提高再生语音的质量。

An 8kb/s ACELP speech codec is proposed.Its encoding algorithm is based on Code-Excited Linear Prediction(CELP)with a multi-level pulse amplitude Algebraic Codebook(ACELP).Only integer pitch delay is searched.There are eight non-zero pulses with fixed amplitudes,each of+1,or+05,or-1,or-05,or zero,in each algebraic codevector of length of 64 samples.An effcient non-exhaustive codebook search method is developed.The codevector's gain and LSP frequencies are scalarly quantized.A pitch prefilter and a spectral postfilter are adopted in speech decoder to enhance the reconstructed speech quality.