[gmpi] Re: Requirements
- From: Marc Poirier <marc@xxxxxxxxxxxxxxxxxxx>
- To: gmpi@xxxxxxxxxxxxx
- Date: Tue, 11 Feb 2003 17:19:16 +0100 (CET)
> > Why bother with normalized parameters then?
>
> Because it's the most convenient way to represent a
> parameter as a knob position (or as Y-axis for a curve).
Yes, but a total nuisance for the DSP plugin component, especially for
descrete value parameters! I think that the recent post (sorry, I forgot
who wrote it, David O?) about separating GUI concerns from the initial
design in order to achieve a cleaner design applies perfectly to this
point. If we were thinking outside of GUI concerns, no one would say that
they prefer to handle parameter values in a normalized range! I think
that this is a chore best offloaded to the GUI. If we have a parameter
curve attribute specified, with the possibility even for custom curve
functions, then the GUI layer, when it's defined, could include simple
convenience methods for interfacing with parameters in a normalized range,
taking into account the curve hints. But there's no need for the DSP
plugin to suffer from this interface convenience.
> Actually it's important to provide host with a conversion
> function, because mapping based on the generic unit (ie log
> scale for a parameter expressed in Hz) is not generally the
> most convenient way to do it.
Right, that's why I suggested that at least the curve attribute be
separate from the unit attribute, so that no assumptions are made. Have
you ever tried tweaking a log-curved LFO rate parameter that ranges from
0.1 Hz to 20 Hz, for example? Ugh, painful! ;) But wonderful for a
pitch parameter that ranges from 40 Hz to 20 kHz... And then
additionally, there can be the possiblity for totally custom curves.
Marc
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