Patent ID: 6300553
Filing Date: 2001-10-09
Classification: G10H,Y10S

Abstract:
A pitch shifter for shifting an acoustic signal in pitch to an arbitrary level without any change in reproduction time, said pitch shifter comprising:a sound data input terminal sequentially provided discrete sound data produced by sampling said acoustic signal;a pitch control signal input terminal provided with a pitch control signal indicating a pitch shift ratio;paired read address generators each for generating, based on the pitch control signal provided through said pitch control signal input terminal, a read address differed from each other by a predetermined value;a memory unit including a buffer, for sequentially writing, in the buffer, the sound data provided through said sound data input terminal and reading, from the buffer, paired sound data strings based on integer-part bits of each of the read addresses generated by said read address generators;a filter coefficient string storage for storing, in a predetermined order, N filter coefficient strings corresponding to N sub-filters produced through polyphase decomposition of a low-pass filter for N-fold oversampling wherein N is a power of 2;paired filter coefficient string selectors each for selecting, based on first to log.sub.2 N-th bits of a decimal part of each of the read addresses generated by said read address generators, any one of the N filter coefficient strings stored in said filter coefficient string storage;paired filter operation units each for carrying out a filter operation on each of the paired sound data strings read by said memory unit by using the filter coefficient selected by said filter coefficient string selector; anda crossfader for multiplying each of paired sound data outputted from said filter operation units by a crossfading coefficient, and adding multiplication results together.