[PD] moog

[David Medine]

Sorry, I was thinking of one that Miller wrote that I saw sometime back. 
I haven't actually looked at the one on extended. I will check it out.

Let's stay in touch about this. It sounds like a fun project.


happy new year

On 12/31/2014 02:11 PM, Alexandre Torres Porres wrote:
> > 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 <dmedine at ucsd.edu 
> <mailto:dmedine at 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 <dmedine at ucsd.edu
>>     <mailto:dmedine at 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
>>>
>>>
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>
>

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