| 摘要 |
The present invention provides a technique for shifting pitch to target pitch without detecting the original pitch directly, and for extracting the pitch of the audio waveform exactly. A phase compensator extracts 2 or more frequency channels each having frequency components of a harmonic overtone whose frequency is 1 or more times as higher than frequency of a fundamental tone of the original sound, from the frequency channels from which the frequency components are extracted by fast Fourier transform. The phase compensator calculates a scaling value to be used for converting the fundamental tone to another target fundamental tone, and performs phase compensation in accordance with the scaling value. A pitch shifter performs pitch scaling in accordance with the scaling value onto the audio data resultant from inverse fast Fourier transform-onto the phase compensated frequency components. Thus, audio data representing the target fundamental tone are generated.
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