Hi Victor, I did find this wikipedia article just now: http://en.wikipedia.org/wiki/Phase_distortion_synthesis BTW: I'm looking very forward too trying these out Anthony! steven On Dec 5, 2007 11:54 AM, wrote: > Do you know if there is any references on PD in the > literature. Apart from the simple descriptions on Casio > manuals, I never saw anything else. > > yes, the PD technique as I understand it does not seem > to be bandlimited. But I wonder if there are any tricks > that are not documented anywhere. > > Also do you know how to produce the resonant version > of PD? That was an interesting sound. > > Interesting to see the classic topic of waveshaping being > discussed, as well. In these days of fast computers, people > seemed to forget about these great ways of economically > synthesising complex spectra. > > Victor > > > ----- Original Message ----- > From: Anthony Kozar > Date: Wednesday, December 5, 2007 7:40 pm > Subject: Re: [Cs-dev] New opcodes useful? > To: Csound Developer list > > > Well, if my intuitions are correct, using continuous k-rate > > > coefficientswith either the polynomial or chebyshevpoly opcodes > > should produce smooth > > and continuous changes in the output. I have tested the > > latter by > > controlling several harmonics independently and I got smooth > > changes just as > > if I had used additive synthesis with multiple > > oscillators. I would be > > interested to know if there is some mathematical problem that I am > > overlooking. > > > > Regarding the phase distortion opcodes: the reason I was > > questioning their > > utility is that they DO produce aliasing because the derivative > > of the > > resulting signal is discontinuous. I think -- but am not > > sure -- that > > Casio's original implementation of this technique was not 100% > > digital. But > > depending on the genre of music, aliasing is not always a bad > > thing :) > > > > Another use for the PD opcodes is to use them on audio signals > > instead of > > phasors, in which case they behave as piecewise-linear transfer > > functions.This also produces aliasing, but they have definite > > applications as > > alternative distortion techniques. powershape is also > > excellent for > > distortion, although it can produce milder, bandlimited changes too. > > > > At least this is my understanding of everything -- I am not a > > DSP guru ... > > > > Anthony Kozar > > anthonykozar AT sbcglobal DOT net > > http://anthonykozar.net/ > > > > > > > Victor.Lazzarini@nuim.ie wrote on 12/5/07 4:00 AM: > > > > > > Interesting... I am wondering if radical changes tothe the > > transfer function > > > would cause discontinuities inthe output signal. Never thought > > of the > > > question. I'll love to try them. Coincidentally, I was only > > > yesterdayteaching > > > a class on waveshaping. > > > > >> Victor.Lazzarini@nuim.ie wrote on 12/5/07 2:54 AM: > > >> > > >>> PD seem useful. UDOs are also good because they're > > didactical, can you > > >>> do both? > > >> > > >> Thanks. I wrote the phase dist. opcodes (and powershape > > below) a while ago > > >> but I will make UDOs too. > > >> > > >>> How do the waveshaping opcodes you mention > > >>> differ from simply building them with oscillator and table > > >>> lookup? > > >> > > >> They allow for _dynamic_ waveshaping where the transfer > > function varies over > > >> time. I have written the following opcodes so far and > > hope to come up with > > >> some more: > > >> > > >> aout powershape ain, kShapeAmount [, > > ifullscale]>> aout polynomial ain, ka0 > > [, ka1 [, ka2 [...]]] > > >> aout chebyshevpoly ain, ka0 [, ka1 [, ka2 [...]]] > > > > > > ----------------------------------------------------------------- > > -------- > > SF.Net email is sponsored by: The Future of Linux Business White Paper > > from Novell. From the desktop to the data center, Linux is going > > mainstream. Let it simplify your IT future. > > http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 > > _______________________________________________ > > Csound-devel mailing list > > Csound-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/csound-devel > > ------------------------------------------------------------------------- > SF.Net email is sponsored by: The Future of Linux Business White Paper > from Novell. 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