| 摘要 |
A voice code sequence converting device and method for converting a code sequence with low computational complexity by receiving a first code sequence having a pitch period at an input terminal on the input side, converting the first code sequence into a second code sequence having a pitch period, and outputting the second code sequence from an output terminal on the output side. In addition to a circuit for synthesizing a decoded signal from a code sequence of the CELP method on the input side, the voice code sequence converting device has a circuit for directly delivering the LP coefficient and pitch period decoded by an LP coefficient decoding circuit (12) and a pitch component decoding circuit (13) respectively to an LP coefficient encoding circuit (31) and a pitch component calculating circuit (40) on the output side respectively so as to deliver them to code sequence conversion of the output side. Therefore, the LP analysis of the decoded signal by the output side and the selection of a pitch period candidate can be dispensed with. If band expansion is needed by the input and output sides, circuits for band expansion conversion and pitch candidate creation are provided and an encoding circuit is provided in place of pitch component calculating circuit. Interpolation of the LP coefficient and pitch period is performed if the frame length of the input side is greater than that of the output side, or averaging of the LP coefficient and pitch period is performed if the frame length of the input side is less than that of the output side.
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