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-BAND SIGNALS. IN GENERAL, THIS ASSUMPTION IS NOT TRUE BECAUSE THE SYNTHESIS FILTERS MODIFY OR SPREAD THE QUANTIZATION NOISE. A THEORETICAL FRAMEWORK FOR DERIVING AN OPTIMUM BIT ALLOCATION THAT ACCOUNTS FOR SYNTHESIS-FILTER NOISE SPREADING IS DISCLOSED. IN CONCEPT, THE PROBLEM OF FINDING AN OPTIMAL BIT ALLOCATION CAN BE EXPRESSED AS A LINEAR OPTIMIZATION PROBLEM IN A MULTIDIMENSIONAL COORDINATE SPACE. SIMPLIFIED PROCESSES DERIVED FROM THIS THEORETICAL FRAMEWORK ARE DISCLOSED THAT CAN OBTAIN NEAROPTIMAL SOLUTIONS USING MODEST COMPUTATIONAL RESOURCES. (FIGURE 9)