A uniform reconstruction level quantizer with improved performance at low bit rates

Abstract

A modified uniform quantizer which gives better performance at low bit rates is introduced. Two other uniform quantizers are also analyzed in terms of rate-distortion characteristics. It is verified that better rate-distortion characteristics are obtained by using decision levels shifted from the midpoints of quantization intervals. The new decision levels give the optimum round off thresholds. Experimental results show that, applying Laplacian input source, the SNR is improved by 0.87 dB at 0.8 bits/sample compared with a widely used uniform quantizer.