Abstract
This paper proposes a model of switched quasi-logarithmic quantizer for speech signal based on G.711 standard with usage of Golomb-Rice (GR) coding. In order to achieve better performances a method with switched quantizer is applied. Variance range is split into quantizers and for each of them a separate quantizer is designed, i.e. the support region is determined. Optimization of the support region and choice of the parameter μ is done in order to obtain a quantizer that obeys G.712 standard and gives minimal average bit rate. Every quantizer within the variance range has own model with a two-stage coder. Two stages are introduced with purpose to reduce the bit rate, whereby GR code plays its role as Variable Length Code (VLC). The first stage uses a GR coder for coding segments of the quantizer’s support region, whereas the second stage applies the coding method with fixed code lengths for coding cells within a segment. GR has simpler and cheaper hardware realization than other VLC codes, Huffman’s for instance, with very satisfying results regarding quality of quantized signal.DOI: http://dx.doi.org/10.5755/j01.eie.23.4.18727
Highlights
The G.711 standard (G.711 quantizer) defines fixed length coding that provides high quality of reconstructed signal for fixed bit rates [1]
It is very important to notice that parameters and Ng are given for the entire range L, whereas support region is different for every quantizer and we introduce the notation xmaxγ
Hereby we try to get with the described two-stage coding method a lower average bit rate than the G.711 standard's coder, which has a constant value of 8 bit/sample
Summary
The G.711 standard (G.711 quantizer) defines fixed length coding that provides high quality of reconstructed signal for fixed bit rates [1]. The G.711.0 standard defines the G.711 quantizer with variable length codes (VLC) and assumes the usage of one of many coding techniques whereby the choice is made upon the input signal’s characteristics [2]. This standard does not examine switched quantizers, and our motivation is to design a switched quantizer with some VLC. Our motivation is to make an analysis of different switched quantizers with -law of compression and GR coding, as well as to determine switched quantizer which satisfies G.712 standard and has the lowest possible average bit rate
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