SC Filter UGens and Direct Form 2

superbigio-/[email protected] Fri, 12 Mar 2021 15:46:09 +0000 (UTC)
Newsgroups gmane.comp.audio.supercollider.devel
Message-ID <[email protected]>
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I was skimming through the SC code base and I was suprised to see that all filters in FilterUGens.cpp are implemented using Direct Form II.As far as I know Direct Form II is not the best choice among the 4 forms (DF1, DF2, TDF1, TDF2), because - although optimal as far as memory storage goes - it is prone to numerical instabilities. Is there a specific reason why all standard SC filters are implemented with DF2 ?
Thanks.
- Luigi Castelli
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<html><head></head><body><div class="yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:13px;"><div dir="ltr" data-setdir="false">I was skimming through the SC code base and I was suprised to see that all filters in FilterUGens.cpp are implemented using Direct Form II.</div><div dir="ltr" data-setdir="false">As far as I know Direct Form II is not the best choice among the 4 forms (DF1, DF2, TDF1, TDF2), because - although optimal as far as memory storage goes - it is prone to numerical instabilities. Is there a specific reason why all standard SC filters are implemented with DF2 ?</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Thanks.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="
 false">- Luigi Castelli</div></div></body></html>
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