| 摘要 |
At a time of compression, two sound waveform segments each having single pitch length are cut-out from an input sound waveform at a time point represented by a current pointer and at a time point advanced from the time point by a single pitch period, respectively, and then, by adding the two sound waveform segments to each other after being multiplied by window functions, a single sound waveformn segment being compressed is produced. Next, the pointer is moved on the input sound waveform according to a compression rate, and then, a similar operation is repeated to produce a sound signal being compressed. At a time of expansion, two sound waveform segments each having double pitch length are cut-out from the sound waveform thus compressed at a time point represented by the current pointer and at a time point delayed from the time point by the single pitch period, respectively, and then, by adding the two sound wave segments to each other after being multiplied by window functions, a single synthesized sound wave form segment is obtained. Next, the pointer is moved on the sound waveform being compressed according to an expansion rate, and then, by repeating a similar operation, a sound signal being expanded is obtained.
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