Patent ID: 8296143

Claim:
An audio signal processing apparatus comprising: a central processing unit, wherein the central processing unit includes: a frequency band dividing unit that divides an input audio signal into a plurality of bands; a plurality of time stretch/pitch shift processing units that perform at least one of time stretching and pitch shifting respectively by carrying out sine or cosine oscillation of each frequency component on the basis of a result of frequency analysis of a band-divided audio signal obtained as a result of division into the plurality of bands and a required time stretch/pitch shift amount, and performing a synthesis process; and a plurality of phase synchronization processing units that perform phase synchronization process for adjusting phases of time stretch/pitch shift signals outputted by the plurality of time stretch/pitch shift processing units, respectively, the audio signal processing apparatus thereby synthesizing outputs of the plurality of phase synchronization processing units and outputting a result, wherein each of the phase synchronization processing units includes a reference signal generating unit that clips a waveform of an end portion in one frame from the band-divided audio signal once every plurality of frames and transforms the clipped waveform of the end portion on the basis of the time stretch/pitch shift amount to generate and output a reference signal for the phase synchronization process, a cross-fade location calculating unit that calculates cross-fade locations for the phase synchronization process in the plurality of frames, and a cross-fade processing unit that performs a cross-fade process on the time stretch/pitch shift signal, wherein the cross-fade location calculating unit searches a tail portion of a time axis waveform of the time stretch/pitch shift signal in a plurality of frames for the cross-fade locations and detects the cross-fade locations, cross-fade locations being locations at which the time axis waveform of the time stretch/pitch shift signal in the plurality of frames is similar to a waveform of the reference signal on a time axis, and the cross-fade processing unit performs a cross-fade process in a range of a length corresponding to the waveform of the reference signal from the cross-fade position from the time stretch/pitch shift signal to the reference signal at each of the detected cross-fade locations.