QUANTIZATION IN PERCEPTUAL AUDIO CODERS WITH COMPENSATION FOR SYNTHESIS FILTER NOISE SPREADING

摘要

Many perceptual split-band coding systems that use analysis and synthesis filters assume the quantization noise introduced by quantizing split-band signals is substantially the same as the noise that results in the output signal obtained by applying the synthesis filters to the quantized split-ban d signals. In general, this assumption is not true because the synthesis filte rs modify or spread the quantization noise. A theoretical framework for derivin g an optimum bit allocation that accounts for synthesis-filter noise spreading is disclosed. In concept, the problem of finding an optimal bit allocation c an be expressed as a linear optimization problem in a multidimensional coordina te space. Simplified processes derived from this theoretical framework are disclosed that can obtain near-optimal solutions using modest computational resources.