While suppressing deterioration of the sound quality of the extended band, the amount of coded bits allocated to the spectrum coding of the extended band is reduced. In the subband to be compressed, the band compression unit 105 makes a combination in which the subband spectrum is grouped by two samples in sequence from the low band side, selects a spectrum having a large absolute amplitude among the combinations, and uses the selected spectrum as a frequency. Arrange it by narrowing it to the low end side on the axis. The number of units recalculation unit 106 redistributes the bits saved in the subband subjected to band compression to a low range outside the extended band, and redistributes the number of units based on the redistributed bits.
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