| 摘要 |
A plurality of sets of position code books indicating the pulse position are provided in a multi-set position code book storing circuit (450). In accordance with a pitch prediction signal obtained in an adaptive code book circuit (500), one type of position code book is selected from the plurality of position code books in a position code book selecting circuit (510). From the selected position code book, a position is selected by a sound source quantization circuit (350) so as to minimize distortion of a sound signal. An output of the adaptive code book circuit (500) and an output of the sound source quantization circuit (350) are transferred. Thus, a sound signal can be encoded while suppressing deterioration of the sound quality with a small amount of calculations even when the encoding bit rate is low.
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