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Vector predictive quantization of the LPC spectral parameters for low‐rate speech coding

 

作者: Yair Shoham,  

 

期刊: The Journal of the Acoustical Society of America  (AIP Available online 1986)
卷期: Volume 80, issue S1  

页码: 35-35

 

ISSN:0001-4966

 

年代: 1986

 

DOI:10.1121/1.2023762

 

出版商: Acoustical Society of America

 

数据来源: AIP

 

摘要:

Scalar quantization of the LPC parameters requires a high bit rate. Considerably lower rate can be obtained via vector quantization (VQ). However, complexity constraints dictate the use of suboptimal VQ. The use of vector predictive quantization (VPQ) for the LPC parameters is proposed. In VPQ, the suboptimality is compensated for by exploiting the temporal redundancy in the input. VPQ is a two‐stage memory VQ. In the first stage, the input vector is predicted from quantized past vectors, using a set of vector coefficients, held in apredictor codebook. In the second stage, the predicted vector is combined with a residual vector to form the final output. A set of residual vectors is held in aresidual codebook. VPQ was applied to the LPC parameters in the down‐sampled, log‐magnitude spectral domain. The idea was to design an efficient VPQ under the perceptually meaningful log‐likelihood distortion measure, while circumventing the stability problem of the synthesis LPC filter. This VPQ was used in a 4.8 kbit/s CELP coder where only 1.0 kbit/s were allocated to the parameters. The performance was almost indistinguishable from that of a CELP coder with unquantized parameters. [Work supported by NSA.]

 

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