Patent ID: 6141637
Filing Date: 2000-10-31
Classification: G10L

Abstract:
A speech encoding and decoding system comprising:a speech coding apparatus including an orthogonal transform device that orthogonally transforms an input speech signal represented in a time domain into a signal represented in a frequency domain in units of predetermined blocks into which said speech signal is divided to determine orthogonal transform coefficients, a speech signal analyzing device that analyzes said speech signal to determine auxiliary information for smoothing said orthogonal transform coefficients, a first calculating device that smoothes said orthogonal transform coefficients by means of said auxiliary information determined by said speech signal analyzing device, a vector quantization device that vector-quantizes said orthogonal transform coefficients smoothed by said first calculating device to generate a quantization index indicative of said smoothed orthogonal transform coefficients vector-quantized by said vector quantization device, a low frequency component error-extracting device that extracts a vector quantization error of low frequency components of said smoothed orthogonal transform coefficients vector-quantized by said vector quantization device, a low frequency range correction information-determining device that scalar-quantizes said vector quantization error extracted by said low frequency component error-extracting device to determine low frequency range correction information, and a synthesis device that synthesizes said auxiliary information from said speech signal analyzing device, said quantization index from said vector quantization device, and said low frequency range correction information from said low frequency range correction information-determining device to output them as an encoded output; anda speech decoding apparatus including a vector inverse quantization device that vector inversely quantizes said quantization index included in said encoded output from said speech encoding apparatus to decode said orthogonal transform coefficients, an auxiliary information decoding device that decodes said auxiliary information included in said encoded output from said speech encoding apparatus, a low frequency range correction information-decoding device that decodes said low frequency range correction information included in said encoded output from said speech encoding apparatus, a second calculating device that corrects said low frequency components of said orthogonal transform coefficients decoded by said vector inverse quantization device by means of said low frequency range correction information decoded by said low frequency range correction information-decoding device, and restores the corrected orthogonal transform coefficients into a state before being smoothed by means of said auxiliary information decoded by said auxiliary information decoding device, and an orthogonal inverse transform device that orthogonally inversely transforms said orthogonal transform coefficients restored into said state before being smoothed by said second calculating device into a signal represented in the time domain to thereby decode said speech signal represented in the time domain.