| 摘要 |
PCT No. PCT/JP94/02005 Sec. 371 Date Jul. 21, 1995 Sec. 102(e) Date Jul. 21, 1995 PCT Filed Nov. 29, 1994 PCT Pub. No. WO95/15032 PCT Pub. Date Jun. 1, 1995Digital audio data of at least two channels are orthogonal-transformed by orthogonal transform for effecting bit compaction. If, when the time length and window shape of the orthogonal transform block is changed, the correlation between channels is found to be high to a certain extent, the time lengths of the orthogonal transform blocks in each channel is selected to be equal to suppress the difference in sound quality between channels to improve a fixed sound image position feeling and hence a high sound quality. This allows to produce a high sound quality for the same bit rate. A lower bit rate may be used for producing the equivalent sound quality. A method for determining the time length of a processing block which is psychoacoustically more desirable processing block may be provided to enable high efficiency compaction and expansion with a psycho-acoustically optimum sound quality.
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