Re: [fluid-dev] SoundFont parameter analysis

[Tom M.]

> The issue is the ModEnv attack and release times. The parameter is set in the 
> PGEN (Preset) area, not the IGEN (Instrument) areas. It is set to 60ms attack 
> and 50ms release, but the sound is more like 1.5sec attack and release, 
> played back in Vienna Viena FluidSynth

The spec says: "Generators at the Preset Level are instead considered 
“relative” and additive to all the default or instrument level generators 
within the Preset Zone."

Both instruments set modEnvAttack and modEnvRelease to 100 ms. The preset 
generator of e.g. Polysynth2 sets them to approx. 70 for attack and approx. 50 
for release. This makes an attack of

100 ms * 70 = 7 sec

and release of

100 ms * 50 = 5 sec.

The modulation in this case affects the filters cut-off freqency. Thus it needs 
7 seconds for the filter to fully open. This is pretty much what I hear. Dont 
know about the 1.5 sec you refer to.

Note however that what you hear is strictly speaking not correct. fluidsynth 
currently processes the modEnvAttack in a linear way. According to the spec 
(8.1.2 #26) it should however be convex. See here for further reading:
https://github.com/FluidSynth/fluidsynth/issues/153

Tom