Waveform reproduction device and method for performing pitch shift reproduction, loop reproduction and long-stream reproduction using compressed waveform samples

摘要

Compressed waveform samples are read out from a memory on the basis of progressive phase information corresponding to a tone pitch. Readout controller controls the readout so as to provide successive compressed waveform samples from the one corresponding to the phase information of a last sampling cycle to the one corresponding to the phase information of a current sampling cycle. Thus, irrespective of the pitch, all the samples existing between the last sampling cycle and the current sampling cycle are read out. Each of the readout samples is decoded and the thus-decoded sample is used as a prediction value for decoding the following sample, so that all the successive compressed waveform samples can be decoded. As the actual sample corresponding to the current sampling cycle, a necessary sample corresponding to the current phase information is selected from among the decoded samples. Loop reproduction is performed by repeating the advance of the phase information between loop start and end locations. Sample generated by decoding the compressed waveform sample corresponding to the loop start location is stored, and when the advance of the loop readout returns from the loop end location to the loop start location, the stored sample is provided as the prediction value for decoding. Long-stream reproduction is carried out by writing, into memory, partial long-stream data and repeating read and write of the partial long-stream on a region of the memory.