alt Hacker NewsI'm not sure there's much to be gained by mapping values. Maybe envelope time is comparable since seconds are seconds, but not every synth interpolates ADSR values in the same way (some use just linear or logarithmic interpolation, some high end synths are heavily configurable). Also, other values like filter cutoff impact the sound in dramatically different ways depending on the kind of filter...
Good point - again for this, filter cutoff knob position or MIDI CC value percentage of 0/max value # would be mapped to cutoff frequency Hz #.
And yes, envelope times have different transition formulas between points, like linear vs logarithmic, as you stated. But again, having a direct map for of just A,D,S,R ms times would give you a rough approximation of amp env, save you a ton of time, and honestly, just serve as a sanity check sometimes, when trying to recreate similar "classic" subtractive patches between synths.