Pitch Shiftingand

Dynamic Filtering

Rossum (1992a)Digital sampling instrument for digital audio data;

Rossum (1992b)Dynamic digital IIR audio filter and method which provides dynamic digital filtering for audio signals

Digital sampling instrument for digital audio data

• Multi-channel interpolative playback of digital audio data stored in a waveform memory provides improved interpolation of musical sounds by using seven or eight surrounding points.

• Allowed a high channel count, enhanced access to waveform memory to allow improved

• performance parity between computational units and memory. Also, the present

• invention includes techniques which dramatically reduce the amount of memory

• required to store the musical waveforms while still maintaining adequate

• bandwidth and fidelity in the output.

• The traditional approach to implement a sinc function interpolation has been to store the above coefficients in a table in memory.

• The present invention uses a similar approach as sinc function, but stores the function in memory as a seventh or eighth order impulse response of a filter having deep (>90 dB down) notches at integral multiples of the sample rate and peaks only 60 dB to 70 dB down at half-integral multiples of the sample rate.