| 摘要 |
A speech encoding and decoding system comprises a speech coding apparatus and a speech decoding apparatus. The speech encoding apparatus orthogonally transforms an input speech signal represented in a time domain into a signal represented in a frequency domain in units of predetermined blocks, smoothes the resulting orthogonal transform coefficients by auxiliary information obtained by analyzing the speech signal, vector-quantizes the smoothed orthogonal transform coefficients to generate a quantization index, extracts a vector quantization error of low frequency components of the vector-quantized smoothed orthogonal transform coefficients, scalar-quantizes the vector quantization error to determine low frequency range correction information, and outputs the auxiliary information, quantization index, and low frequency range correction information. The speech decoding apparatus vector inversely quantizes the quantization index to decode the orthogonal transform coefficients, decodes the auxiliary information and low frequency range correction information, corrects the low frequency components of the decoded orthogonal transform coefficients by the low frequency range correction information, and restores the corrected orthogonal transform coefficients into a state before being smoothed by the auxiliary information, and orthogonally inversely transforms the restored orthogonal transform coefficients to decode the speech signal represented in the time domain.
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