ADAPTIVE PREDICTIVE CODING ENCODER FOR COMPRESSION OF QUANTIZED DIGITAL AUDIO SIGNALS

In an adaptive predictive coding (APC) encoder for compression of quantized digital audio, the signal-to-quantization noise ratio is improved and more complicated input signal spectra can be processed through use of an input signal frequency spectrum detector employing linear predictive coding (LPC) analysis for setting the coefficients of the requantization error noise filter. The detector operates in synchronism with the predictive and noise filters so as to minimize the number of processing calculations while maximizing processing speed.