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학술대회 Efficient Fixed Codebook Search Method for ACELP Speech Codecs
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이응돈, 안재민
International Conference on Hybrid Information Technology (ICHIT) 2006 (LNCS 4413), v.4413, pp.178-187
07MR2600, 하향 1Gbps 디지털 케이블 송수신 시스템 개발, 이수인
There are several sub-optimal search techniques for fast algebraic codebook search of ACELP speech codecs. Focused search method, depth-first tree search method and pulse replacement methods are used to reduce computational complexity of algebraic codebook search. In previous pulse replacement methods, the computational load is increased as the pulse replacement procedure is repeated. In this paper, we propose a fast algebraic codebook search method based on iteration-free pulse replacement. The proposed method is composed of two stages. At the first stage, an initial codevector is determined by the backward filtered target vector or the pulse-position likelihood-estimate vector. At the second stage, after computing pulse contributions for every track the pulse replacement is performed to maximize the search criterion Qk over all combination replacing the pulses of the initial codevector with the most important pulses for every track. The performance of the proposed algebraic codebook search method is measured in terms of the segmental signal to noise ratio (SNRseg) and PESQ (Perceptual Evaluation of Speech Quality) using various speech data. Experimental results show that the proposed method is very efficient in computational complexity and speech quality comparing to previous pulse replacement methods. © Springer-Verlag Berlin Heidelberg 2007.
KSP 제안 키워드
Codebook search, Computational complexity, Depth-first tree search, First stage, Fixed codebook, Iteration-free, Replacement method, Signal noise ratio(SNR), Signal-to-Noise, Sub-optimal search, computational load