Subject: Re: [linux-audio-dev] LADSPA unbounded control values
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Wed Nov 22 2000 - 16:24:04 EET
On Wed, Nov 22, 2000 at 02:05:32PM +0000, brian.stafford_AT_ukonline.co.uk wrote:
> On Tue, 21 Nov 2000 20:40:58 -0500, Paul Barton-Davis <pbd_AT_Op.Net> wrote:
> > in the CMT plugin set, there is at least 1 plugin with a control port
> >
> > without an upper bound (mono amplifier). the port is also hinted as
> > being suitable for logarithmic control. i am probably just being
> > dense, but it seems very difficult to pick an arbitrary upper bound
> > *and* use a logarithmic transform and still get meaningful results.
> >
> Seems to me that the term "logarithmic" isn't quite right. If one thinks
> in dB as all engineers should, it's immediately obvious that a 0dB
> reference point must be specified. So my take is that its not the lack
> of an upper bound that's the problem, it's the lack of a 0db reference.
> This applies even if the bounds are set - where is 0dB on the scale? My
> best guess is default to 1.0 and hope for the best.
I'm making all my plugins use dB (this is how I think, and it's the only
sensible scale IMHO), but there isn't a way to hint this, which might
cause problems. I'm usually hinting a range of -70 to +30.
Would I be better of expressing in raw coefficents and hinting that its
logarithmic? This goes against the grain, but if its convention...
- Steve
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