MULTI-STAGE SPEECH CODER WITH TRANSFORM CODING OF PREDICTION RESIDUAL SIGNALS WITH QUANTIZATION BY AUDITORY MODELS

摘要

A speech compression system called "Transform Predictive Coding" or TPC, provides encoding for 7 kHz band speech at 16 kHz sampling at a target bit-rate of 16 or 32 kb/s one or two bits per sample. The system uses short and long term prediction to remove redundancy. The prediction residual is transformed and coded in the frequency domain as shown on the figure by (110) after accepting time domain data from (60) and parameter input from (100), which corrects the spectrum for auditory perception. The TPC coder uses only open-loop quantization as shown by (70) and therefore has low complexity. The speech quality is transparent at 32 kb/s, is very good at 24 kb/s, and is acceptable at 16 kb/s.