> Miller (being the author) would know better But the [moog~] object that I see here on Pd extended was written by gunter Geiger.
> it would be super cool to have this as a Pd > abstraction rather than an extern. Dan Wilcox also wanted that as I remember. If you care to help me we could try and do it. I kinda suck at math and all but when I put my mind into it I can do these things I never knew I could :) I've been implementing several filters with [fexpr~] and/or vanilla's raw pole/zero filters. I've kinda done them all, [moog~] is the next on my list. But I probably won't get into this until the 2nd half of january, as I plan to go to some island for my summer break. cheers and happy new year. 2014-12-31 19:42 GMT-02:00 David Medine <dmed...@ucsd.edu>: > Cool, I will definitely check out this SC object. Thanks for that. > > Miller (being the author) would know better than I of course, but I > believe the way that [moog~] works is to use Runge-Kutta to solve the > ordinary differential equation that governs each stage of the filter in its > continuous time representation. This equation (along with a discrete > implementation of the complete filter) is what is described in the paper I > mentioned. Incidentally, using Runge-Kutta (or any appropriate iterative > ODE solver) also abnegates the frequency warping problem. > > I think it might be very difficult to code this up with [fexpr~]. It would > certainly require at least a quadrupling of the sampling rate. Has anyone > out there ever implemented Runge-Kutta with [expr~]? It might also be that > Pd's data structures are an appropriate choice for such a project? Either > way, it would be super cool to have this as a Pd abstraction rather than an > extern. > > -David > > > On 12/31/2014 10:05 AM, Alexandre Torres Porres wrote: > > Hi David, > > > It'd certainly be interesting to see an what actual implementation > > of this does, rather than just some matlab plots. > > An actual implementation is provided in the MoogFF filter in Super > Collider, you can just download and try it out. The code of the object is > also provided somewhere, as it is a source code. > > I'd like to understand pd's [moog~] object one day, and implement it > with [fexpr~] or something. Maybe I'll do this other one as well. > > Cheers > > 2014-12-29 17:20 GMT-02:00 David Medine <dmed...@ucsd.edu>: > >> I believe, though I may be wrong, that the Moog vcf object is based on >> the algorithm described in the 2004 Huovalainen paper (citation [6] in the >> Fontana): >> >> >> http://www.mirlab.org/conference_papers/International_Conference/DAFx%202004/Proc/P_061.pdf >> >> I am a little confused here (in the Fontana) by the author's assertion >> that he can implement a 'delay-free' loop by computing the output first, >> and then finding the states of the filter based on this. I don't quite see >> how this is different from finding the states first and then finding the >> output -- chicken then the egg vs. egg then the chicken. >> >> Still, judging by the plots they provide, they seem to have overcome the >> frequency warping issue (an artifact of unit delay) described by >> Huovalainen. >> >> It'd certainly be interesting to see an what actual implementation of >> this does, rather than just some matlab plots. >> >> -David >> >> >> On 12/28/2014 07:43 PM, Alexandre Torres Porres wrote: >> >> hi, do you know if the moog object comes from this paper? >> >> >> http://quod.lib.umich.edu/cgi/p/pod/dod-idx/preserving-the-structure-of-the-moog-vcf-in-the-digital.pdf?c=icmc;idno=bbp2372.2007.062 >> >> >> _______________________________________________pd-l...@lists.iem.at mailing >> list >> UNSUBSCRIBE and account-management -> >> http://lists.puredata.info/listinfo/pd-list >> >> >> >> _______________________________________________ >> Pd-list@lists.iem.at mailing list >> UNSUBSCRIBE and account-management -> >> http://lists.puredata.info/listinfo/pd-list >> >> > >
_______________________________________________ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list