pvshift

pvshift — Shift the frequency components of a pv stream, stretching/compressing its spectrum.

Description

Shift the frequency components of a pv stream, stretching/compressing its spectrum.

Syntax

fsig pvshift fsigin, kshift, klowest[, kkeepform, igain, kcoefs]

Performance

fsig -- output pv stream

fsigin -- input pv stream

kshift -- shift amount (in Hz, positive or negative).

klowest -- lowest frequency to be shifted.

kkeepform -- attempt to keep input signal formants; 0: do not keep formants; 1: keep formants using a liftered cepstrum method; 2: keep formants by using a true envelope method (defaults to 0).

kgain -- amplitude scaling (defaults to 1).

kcoefs -- number of cepstrum coefs used in formant preservation (defaults to 80).

This opcode will shift the components of a pv stream, from a certain frequency upwards, up or down a fixed amount (in Hz). It can be used to transform a harmonic spectrum into an inharmonic one. The kkeepform flag can be used to try and preserve formants for possibly interesting and unusual spectral modifications.

[Warning] Warning

It is unsafe to use the same f-variable for both input and output of pvs opcodes. Using the same one might lead to undefined behavior on some opcodes. Use a different one on the left and right sides of the opcode.

Examples

Example 676. Example

asig  in                                 ; get the signal in

fsig  pvsanal   asig, 1024, 256, 1024, 1 ; analyse it
ftps  pvshift   fsig, 100, 0             ; add 100 Hz to each component
atps  pvsynth   ftps                     ; synthesise it


Depending on the input, this will transform a pitched sound into an inharmonic, bell-like sound.

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

Example 677. Example of the pvshift opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

<CsoundSynthesizer>
<CsOptions>
-odac
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 16
nchnls = 1
0dbfs = 1

;; example written by joachim heintz 2009

instr 1
ishift		=		p4; shift amount in Hz
ilowest	=		p5; lowest frequency to be shifted
ikeepform	=		p6; 0=no formant keeping, 1=keep by amps, 2=keep by spectral envelope
ifftsize	=		1024
ioverlap	=		ifftsize / 4
iwinsize	=		ifftsize
iwinshape	=		1; von-Hann window
Sfile		=		"fox.wav"
ain		soundin	Sfile
fftin		pvsanal	ain, ifftsize, ioverlap, iwinsize, iwinshape; fft-analysis of file
fshift		pvshift  	fftin, ishift, ilowest, ikeepform; shift frequencies
aout		pvsynth	fshift; resynthesize
		out		aout
endin

</CsInstruments>
<CsScore>
i 1 0 2.757 0 0 0; no shift at all
i 1 3 2.757 100 0 0; shift all frequencies by 100 Hz
i 1 6 2.757 200 0 0; by 200 Hz
i 1 9 2.757 200 0 1; keep formants by method 1
i 1 12 2.757 200 0 2; by method 2
i 1 15 2.757 200 1000 0; shift by 200 Hz but just above 1000 Hz
i 1 18 2.757 1000 500 0; shift by 1000 Hz above 500 Hz
i 1 21 2.757 1000 300 0; above 300 Hz
e
</CsScore>
</CsoundSynthesizer>


See Also

pvsanal, pvsynth, pvsadsyn

Credits

Author: Victor Lazzarini
November 2004

New plugin in version 5

November 2004.