15 May
2004
15 May
'04
9:06 a.m.
On Sat, 15 May 2004 11:46:47 +0200
Marcus Andersson <marcus.t.andersson(a)spray.se> wrote:
Mike Rawes wrote:
That's a good point.
The host could just do a simple linear mapping for small ranges, or it
may want to scale up the range internally so that only a fixed
proportion of the range (say 10%) is linear. Or it may clip the range to
+ve values. Or it could offer them all to the user as configuration
options!
We could add an extra hint for log ranges in 2.x for plugins that want
to assert a particular behaviour... it all gets a bit messy though.
There'd need to be two ranges - the linear range, and then the log
range.
-
Myk
You're right - there's an asymptote at
x=0 - there's no correct way
of
dealing with it. What I've done in the past is do linear conversion
near 0:
to linear:
value > e : log(value)
< -e : -log(-value)
: value / e
to logarithmic
value > 1 : exp(value)
< -1 : -exp(-value)
: value * e
However, it is also perfectly valid to simply clip the lower bound.
What isn't right is for a host to *assume* that the lower bound of a
LOGARITHMIC
port is always > 0. I myself want to be able to specify a logarithmic
frequency port with range + / - 24000 for my oscillator plugins,
without having a host break by doing log(-440) or something.
But how can the host know how close to zero the exp should become
linear? What do you do with a LOGARITHMIC parameter with the range
-1.0 to 1.0? Something is missing here to make the LOGARITHMIC hint
unambiguous. But maybe that's not the goal of LADSPA. :(