Coding Gain in Non-Paraunitary Subband Coding Systems

概要

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This work addresses the problems of bit allocation and coding gain in subband coding system with non-paraunitary filter banks. Since energy conservation does not hold in non-paraunitary filter banks, the model to be adopted for quantizers is important to evaluate the output distortion introduced by subband signal quantization. To evaluate the overall distortion we start with adopting the "gain plus additive noise" model for quantizers, which is more reliable than the "additive noise" model. With this model, the expression for overall reconstruction error variance becomes so complicated that the problem of optimum bit allocation, as required for evaluation of the coding gain, must be numerically solved. So, we propose an approximation method in which we neglect the terms due to correlation among quantization errors in calculating the bit allocation but take them into consideration in evaluating the coding gain, assuming sufficiently high bitrate coding. Application of this approximation method to the SSKF subband coding systems with AR(1) input source shows that the method is very accurate even at low bit rate coding (≈1 bit/sample).
社団法人電子情報通信学会の論文
1996-02-25