Description

The paulstretch opcode is a lightweight implementation of the PaulStretch time-stretching algorithm by Nasca Octavian Paul. It is ideal for timestretching a signal by very large amounts.

The Paulstretch algorithm works very similarly to other STFT-based timestretching methods, using overlap-add with a hanning window. Unique to paulstretch are the use of scrambled phase and very large window sizes (specified in seconds).

Syntax

asig paulstretch istretch, iwindowsize, ift
    

Initialization

istretch -- Stretch factor.

iwindowsize -- Window size, in seconds.

ift -- source signal function table. Deferred-allocation tables (see GEN01) are accepted, but the opcode expects a mono source.

Examples

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

<CsoundSynthesizer>
<CsOptions>
-o paulstretch.wav -W
</CsOptions>
<CsInstruments>
sr = 44100
ksmps = 100
0dbfs = 1
nchnls = 2

giwav ftgen 0, 0, 0, 1, "fox.wav", 0, 0, 1

instr 1
aout paulstretch 10, 0.2, giwav
outs aout, aout
endin

</CsInstruments>
<CsScore>
i1 0 30

</CsScore>
</CsoundSynthesizer>

Credits