filescal

Phase-locked vocoder processing with onset detection/processing, 'tempo-scaling'.

filescal implements phase-locked vocoder processing from disk files, resampling if necessary.

This opcode allows for time and frequency-independent scaling. Time is advanced internally, but controlled by a tempo scaling parameter; when an onset is detected, timescaling is momentarily stopped to avoid smearing of attacks. The quality of the effect is generally improved with phase locking switched on.

filescal will also scale pitch, independently of frequency, using a transposition factor (k-rate).

Syntax

asig [,asig2] filescal ktimescal, kamp, kpitch, Sfile, klock \
                       [,ifftsize, idecim, ithresh]

Initialization

Sfile -- source soundfile, mono or stereo files are allowed, but need to match the number of outputs.

ifftsize -- FFT size (power-of-two), defaults to 2048.

idecim -- decimation, defaults to 4 (meaning hopsize = fftsize/4)

idbthresh -- threshold based on dB power spectrum ratio between two successive windows. A detected ratio above it will cancel timescaling momentarily, to avoid smearing (defaults to 1)

Performance

ktimescal -- timescaling ratio, < 1 stretch, > 1 contract. Non-negative numbers only.

kamp -- amplitude scaling

kpitch -- grain pitch scaling (1=normal pitch, < 1 lower, > 1 higher; negative, backwards)

klock -- switchec phase-locking on (non-zero) or off (zero).

Examples

Here is an example of the filescal opcode. It uses the file filescal.csd.

Example of the filescal opcode.
<CsoundSynthesizer>
<CsOptions>
</CsOptions>
<CsInstruments>

instr 1
p3 = filelen("fox.wav")/p4
k1 linen 1,0.01,p3,0.1
a1 filescal p4,0.5,1,"fox.wav",1
  out a1*k1
endin

</CsInstruments>
<CsScore>
i1 0 1 1.25
i1 2.5 1 .75
</CsScore>
</CsoundSynthesizer>

Credits

Author: Victor Lazzarini
April 2016

New in version 6.07

April 2016.