[PlanetCCRMA] Denormal problem with TAP Reverb

[Nigel Henry]

On Friday 24 November 2006 09:29, Ken Smith wrote:
> nicholas manojlovic wrote:
> > Ken Smith wrote:
> >> Hi, I seem to be getting what looks like a denormal problem.
> >>
> >> The setup is Intel P4 HT, FC5 2.6.17 CCRMA RDT Kernel SMP, Ardour
> >> ardour-0.99.3-2.rhfc5.ccrma
> >> <http://ccrma.stanford.edu/planetccrma/mirror/fedora/linux/planetccrma/5
> >>/i386/repodata/repoview/ardour-0-0.99.3-2.rhfc5.ccrma.html>:, TAP Plugins
> >> tap-plugins-0.7.0-1.rhfc5.ccrma
> >> <http://ccrma.stanford.edu/planetccrma/mirror/fedora/linux/planetccrma/5
> >>/i386/repodata/repoview/tap-plugins-0-0.7.0-1.rhfc5.ccrma.html>:
> >>
> >>
> >> The project has 3 instances of the TAP Reverb on three busses. If I
> >> reduce the input to the busses to zero, by soloing something for
> >> example, or by lowering a fader to zero, the CPU load pretty quickly
> >> maxes out.
> >>
> >> Is anyone else seeing this?
> >>
> >> Thanks in advance
> >>
> >> Ken
> >
> > Yes, definitely - many times. Which is a shame as I find its one of
> > the few usable plugins around. Ultimately though, the denormal
> > problems have forced me to stop using it.
> >
> > Nic
>
> Thaks Nic, I'll try the external TAP Reverb Editor to see if its any
> different, but somhow I suspect the same algorithm will be in there. I
> agree the TAP reverb is a pretty useful plugin. Maybe it's time to hack
> some code.... ;-)  Ken

This link was on the list a while ago. I think Fernando provided it. 
http://ardour.org/node/139

Most of it is info about what denormals are, but there are a couple of 
workarounds. I havn't tried them, but the dithering one seems interesting, 
where you introduce a background sound low enough to be not detected by the 
human ear, but high enough to prevent the CPU going into denormal mode.

Nigel.