| 摘要 |
The present invention relates to speech coders and provides a wide-band speech spectral quantizer, and coder using same, that takes into consideration the correlationship among changes in sub-band spectral coefficients with time by quantizing a prediction error obtained by full-band inter-frame prediction. The quantizer comprises: a frame circuit for cutting out frames with a predetermined window length from a speech signal; a first band splitter for making predetermined frequency band splitting and computing each sub-band spectral coefficient; an analyzer for computing spectral coefficient vector of each sub- band; an adder for obtaining a result of subtraction of each sub-band predicted spectral coefficient vector computed in the band splitter from the spectral coefficient vector; a quantizer for quantizing the result of subtraction for the full band, thus outputting a quantized prediction error vector; means for generating a full-band quantized vector by combining the quantized prediction error vectors of all the sub-bands; a synthesizer for outputting a full-band spectral coefficient vector by combining the spectral coefficient vectors of all the sub-bands received from the analyzer; an optimum prediction circuit for computing a full-band predicted spectral coefficient vector from the full-band quantized vector received from the quantizer and the full-band predicted spectral coefficient vector; and a second band splitter for band splitting the full- band predicted spectral coefficient vector, and computing each sub-band predicted spectral coefficient vector.
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