| 摘要 |
A method for compressing a digital audio input signal to provide a recording signal in which the input signal is divided into frames comprising plural samples. Each frame is transformed into a block of spectral coefficients, which are divided into plural bands. For each band, block floating is applied to the spectral coefficients therein; a block floating coefficient is generated; the spectral coefficients are quantized with an adaptive number of bits to provide quantized spectral coefficients; and a word length is generated. Finally, there is added to the recording signal a block of data derived from the block of spectral coefficients and consisting of the quantized spectral coefficients, a main word length and a main block floating coefficient for each band, and a reserve word length at least for each lower frequency band. In a variation, zero bits are allocated to quantize the spectral coefficients in bands higher in frequency than a highest usable band. The block of data consists of the quantized spectral coefficients, at least one word length, and at least one block floating coefficient, for each band up to the highest usable band; and data indicating the number of bands up to the highest usable band.
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