Download Pitch Shifting and Dynamic Filtering

Pitch Shifting
and
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 halfintegral multiples of the sample rate.