| 摘要 |
PROBLEM TO BE SOLVED: To provide a coding method and a decoding method capable of executing coding and decoding wherein a delay time with respect to a sampling time is small and the processing is simply carried out. SOLUTION: In a linear PCM digital signal with sign-magnitude representation, when a sound pressure level is small, since information components exist only in lower-order digit bits, an elimination means 15a eliminates higher-order digit bits having no information components in response to an input linear PCM digital signal in a sampling unit, and a composite means 18a adds the eliminated number of digits information to restore the original linear PCM digital signal. Further, when the sound pressure level is high, a principle of humans unable to perceive even elimination of changes in a sound pressure level of a degree or below is utilized, the maximum effective number of digits as an output in response to allowable sound quality is determined, an elimination means 17a eliminates lower-order digit bits in excess of the maximum effective number of digits depending on the level of the input linear PCM digital signal in the sampling unit, and the composite means 18a fills the lower-order digits equivalent to the eliminated parts by FILL bits in the case of restoration. COPYRIGHT: (C)2007,JPO&INPIT
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