Dear list!

I am running a csd where I toggle between two impulse responses to convolve with. Something like

if (ktrig == 0) the
 ares pconvolve anoise, "IR1.wav"
elseif (ktrig == 1)
 ares pconvolve anoise, "IR2.wav"
endif

This of course produces bumps when switching from one to the other. Is there a neat and clever way to smoothly "fade" from one to the other?

Regards,
/Anders

That will not work great if you want to continuously swap between the
two sounds as linseg will eventually get to 1 and stay there. Here's a
simple UDO and example that will do want you want.



-+rtaudio=alsa -odac:hw:1,0


0dbfs = 1
ksmps = 60
nchnls = 2


;Fade IO opcode. Rory Walsh
;
;Syntax:
;kLeft, kRight fadeIO trigger, kdur, kamp
;
;trigger: 	toggling between 0 and 1 will trigger the fading
;kdur: 		duration of the fade in seconds
;kamp:		amp scaling factor (0-1)


opcode fadeIO, kk, kkk
ksig init 0
setksmps 1
ktrig, kRise, kamp xin	
if(ktrig==1) then
	kRise = 1/kRise			;set increment size
	ksig = ksig+(kRise/sr)		;rise
	ksig = (ksig>1 ? 1 : ksig)	;limit
	elseif(ktrig==0) then
	kRise = 1/kRise			;set increment size
	ksig = ksig-(kRise/sr)		;fall
	ksig = (ksig<0 ? 0 : ksig)	;limit
endif
xout ksig*kamp, (1-ksig)*kamp
endop

instr 1
;different signals
asig1 oscil 1, 200, 1
asig2 oscil 1, 300, 1

;create simple trigger mech. Toggles between 0 and 1
ktrig oscil 1, .3, 2
ktrig = round(abs(ktrig))

kleft, kright fadeIO ktrig, 1, 1
outs kleft*asig1, kright*asig2

endin



f1 0 1024 10 1
f2 0 2 2 0 1
i1 0 100

linseg won't get reinitialised at the if statement, it will just start
at soon as ktrig==1. But once it reaches 1 it will stay there, so
swapping between the two after that would result in clicks. Your
shorter example is much more versatile and allows swapping over and
back between the two sounds. Why do I never think to use port!?

Hi Rory,

Seems linseg gets (re)initialized at if statement, so it doesn't necessarily stay at 1... Anyway, I came up with a shorter one.

asig1 pconvolve anoise, "IR1.wav"

asig2 pconvolve anoise, "IR2.wav"

ktrig port ktrig, .1, 0

asig = asig1 * (1 - ktrig) + asig2 * ktrig

Takahiko

On Sat, Feb 16, 2013 at 7:45 PM, Rory Walsh <rorywalsh@ear.ie> wrote:

That will not work great if you want to continuously swap between the
two sounds as linseg will eventually get to 1 and stay there. Here's a
simple UDO and example that will do want you want.

<CsoundSynthesizer>
<CsOptions>
-+rtaudio=alsa -odac:hw:1,0
</CsOptions>
<CsInstruments>
0dbfs = 1
ksmps = 60
nchnls = 2


;Fade IO opcode. Rory Walsh
;
;Syntax:
;kLeft, kRight fadeIO trigger, kdur, kamp
;
;trigger:       toggling between 0 and 1 will trigger the fading
;kdur:          duration of the fade in seconds
;kamp:          amp scaling factor (0-1)


opcode fadeIO, kk, kkk
ksig init 0
setksmps 1
ktrig, kRise, kamp xin
if(ktrig==1) then
        kRise = 1/kRise                 ;set increment size
        ksig = ksig+(kRise/sr)          ;rise
        ksig = (ksig>1 ? 1 : ksig)      ;limit
        elseif(ktrig==0) then
        kRise = 1/kRise                 ;set increment size
        ksig = ksig-(kRise/sr)          ;fall
        ksig = (ksig<0 ? 0 : ksig)      ;limit
endif
xout ksig*kamp, (1-ksig)*kamp
endop

instr 1
;different signals
asig1 oscil 1, 200, 1
asig2 oscil 1, 300, 1

;create simple trigger mech. Toggles between 0 and 1
ktrig oscil 1, .3, 2
ktrig = round(abs(ktrig))

kleft, kright fadeIO ktrig, 1, 1
outs kleft*asig1, kright*asig2

endin

</CsInstruments>
<CsScore>
f1 0 1024 10 1
f2 0 2 2 0 1
i1 0 100
</CsScore>
</CsoundSynthesizer>

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