[iiwusynth-devel] Modulators and soundfonts

[M. Nentwig]

Hello again,

debugging sometimes feels to me like being a blind man looking in a dark
room for a black cat.
This morning I tried to find the reason, that no modulators appear in
the voice generation, even though the sound font loads them.
And finally I realized that I'm in a dark room looking for a black cat,
which isn't there :-)

There was a discussion in May (libsoundfont version of iiwusynth),
including this:

> Note that the API is not complete yet. It lacks the removal of a sfont

> loader (tricky since all presets and sample data has to be removed).
It
> also doesn't handle modulators yet.

Right...
But now that the synthesizer does handle modulators, it would be time to
support them on the soundfont end.
This shouldn't be a major challenge; the rules for adding or replacing
modulators are quite similar to those for generators - this could even
be put into the same loop.
The 16 bit source and destination info from the sound font have both to
be split into into type, polarity, direction, CC flag and index - some &
and >> will do the job. Then those numbers are set on the next free
modulator, increase the number of modulators and that's it.

But then, why didn't I just implement it? Well, the reason is, that it
was not obvious to me, how to get the modulator information from the
soundfont in iiwu_defsfont. I have a feeling, that something may be
missing there.
Before I start fiddling around with that file (which looks quite scary
to me at the moment - I'd have to spend some hours just to understand
the list structures, macros etc), I was wondering, if this makes sense.
But as I see from the discussion about libsoundfont, there will be two
parallel versions: One using libsoundfont, for Swami, one with the
default soundfont loader (for everything else). Is that right? Or would
it make sense to abandon the default loader and use libsoundfont
instead?

Cheers

Markus

PS:
If you look at the changes I've made, it might remind you of a legal
document - so many references to the standard.
One motivation was, that the default 'GM' modulators have to follow the
specs to the letter. Otherwise there will be trouble, when a sound font
tries to override them (to get rid of them), but the definitions do not
match.