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Cool, I will definitely check out this SC object. Thanks for that.<br>
<br>
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. <br>
<br>
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.<br>
<br>
-David<br>
<br>
<div class="moz-cite-prefix">On 12/31/2014 10:05 AM, Alexandre
Torres Porres wrote:<br>
</div>
<blockquote
cite="mid:CAEAsFmgrrqCBQGqULSryzOtNZSaPXhca3Kz7iCS35=+7vSY-8w@mail.gmail.com"
type="cite">
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<div dir="ltr">Hi David, <br>
<br>
> <span style="font-size:12.8000001907349px">It'd certainly
be interesting to see an what actual implementation</span>
<div><span style="font-size:12.8000001907349px">> of this
does, rather than just some matlab plots.</span>
<div><br>
</div>
<div>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. </div>
</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>Cheers</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2014-12-29 17:20 GMT-02:00 David Medine
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:dmedine@ucsd.edu" target="_blank">dmedine@ucsd.edu</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> 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):<br>
<a moz-do-not-send="true"
href="http://www.mirlab.org/conference_papers/International_Conference/DAFx%202004/Proc/P_061.pdf"
target="_blank"><br>
http://www.mirlab.org/conference_papers/International_Conference/DAFx%202004/Proc/P_061.pdf</a><br>
<br>
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.<br>
<br>
Still, judging by the plots they provide, they seem to
have overcome the frequency warping issue (an artifact of
unit delay) described by Huovalainen. <br>
<br>
It'd certainly be interesting to see an what actual
implementation of this does, rather than just some matlab
plots.<br>
<br>
-David<span class=""><br>
<br>
<br>
<div>On 12/28/2014 07:43 PM, Alexandre Torres Porres
wrote:<br>
</div>
</span>
<blockquote type="cite"><span class="">
<div dir="ltr">hi, do you know if the moog object
comes from this paper?
<div><br>
</div>
<div><a moz-do-not-send="true"
href="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"
target="_blank">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</a><br>
</div>
</div>
<br>
<fieldset></fieldset>
<br>
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