[linux-audio-dev] LADSPA proposal ...

[Marcus Andersson]

Mike Rawes wrote:

> 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. :(

Marcus