Re: [Sc-devel] Amplitude.kr problem

["Dan Stowell" <danstowell@xxxxxxxxx>]

A while ago Julian reworked the Amplitude UGen slightly to allow the
coefficients to be modulated. Julian, you left some old calc-func code
in there, deactivated using some "#if" macros. Is it OK to remove the
old code? Would make it easier to work on fixing the current code...

Dan


2007/12/13, Josh Parmenter <josh@xxxxxxxxxxxxxxxxx>:
> I think option 1 makes sense. Pitch.kr can take an audio input, so it
> makes sense (to me at least) that Amplitude should be able to also.
>
> Josh
>
> On Dec 13, 2007, at 1:50 PM, Dan Stowell wrote:
>
> > Hi all,
> >
> > Applying Amplitude.kr to an audio-rate signal is allowed, in fact all
> > the examples in the helpfile do this. However, I noticed that the UGen
> > doesn't really handle this case "correctly" - if run at control-rate
> > it simply expects its input to be control rate; the end result on
> > audio-rate input is a dodgy downsampling which can lead to incorrect
> > results.
> >
> > For example, these two should really give similar results but they
> > don't (give them a few seconds to converge):
> >
> > x = {(Amplitude.kr(Impulse.ar(44100/64, 0.0),1,1)).poll}.play // 1
> > x = {(Amplitude.kr(Impulse.ar(44100/64, 0.02),1,1)).poll}.play // 0
> >
> > Same goes for these:
> >
> > x = {(Amplitude.kr(SinOsc.ar(44100/64, 0.0),1,1)).poll}.play // 0.098
> > x = {(Amplitude.kr(SinOsc.ar(44100/64, pi/4),1,1)).poll}.play // 0.77
> >
> > Options for fixing this:
> >
> > (1) Alter the UGen source, add a new calc func to deal with the a-to-k
> > (2) Make Amplitude a subclass of Filter, so it refuses to run k-rate
> > on an a-rate input (unhelpful!)
> > (3) Alter the Amplitude class so it automatically replaces
> > Amplitude.kr(x.ar) with A2K.kr(Amplitude.ar(x.ar))
> >
> > Any particular thoughts?
> >
> > Dan
> >
> > --
> > http://www.mcld.co.uk
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>
> ******************************************
> /* Joshua D. Parmenter
> http://www.realizedsound.net/josh/
>
> "Every composer – at all times and in all cases – gives his own
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> palingenesis." - Luigi Nono
> */
>
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