Re: [fluid-dev] MIDI control change - brightness

[Josh Green]

On Mon, 2005-06-20 at 13:33 +0100, Gerald Pye wrote:
> Josh Green wrote:
> > This effect can be easily achieved by adding a modulator.
> 
>       This appears to have opened a whole can of worms about which I know 
> nothing!
> 

No problems, I'll try and explain.

> > Swami has
> > support for global modulators (which can be thought of as session
> > modulators, which don't actually get saved to files).
> 
>       Forgive my ignorance, but of what use would they be if, once Swami is 
> closed, 
> nothing is remembered? How does Fluid then produce the required effect.
> 

They are useful from within a Swami session, since you can create effect
modulators that apply to every instrument (the alternative currently is
quite tedious, create the same modulators for every preset).  This would
be much more useful if Swami was more robust as far as a sampler
frontend, which is the plan for the next version of Swami.  In my
opinion modulators are usually very specific to ones own MIDI gear, so
are more useful to define for ones session for all instruments.  Perhaps
this could be implemented in FluidSynth though too, and loaded via XML
files or something, for those who still want to use just FluidSynth.

> >  With modulators
> > you can use pretty much any MIDI controller to modulate almost all
> > SoundFont parameters (well useful ones anyways).
> 
>       Clearly I have to go away and do a lot of digging about this, since I'm 
> completely in the dark at the moment. But I wonder if you could give me a 
> quick 
> clue: I've found the 'modulators' bit in Swami (always wondered what that was 
> for...) and it seems as though it's tied to a specific patch. If I click 
> 'new' 
> then I see that the panel at the right showing 'source', 'amount source', a 
> multiplier symbol and 'destination'. I might guess that 'destination' should 
> be 
> 'patch', but that doesn't seem to be offered in the drop-down menu. I'm a bit 
> lost also about what 'source' and 'amount source' should be: I can see 
> controller number 74 in the list for both of those and I would guess that I 
> should select it for one or the other but what of the other input to the 
> multiplier?
> 
>       If this is something that can't be answered in a few words, don't worry 
> because 
> I don't want to waste bandwith and bore everyone else on the list - I'll go 
> off 
> and see what I can find out with Google.
> 

Some steps to creating a filter cutoff modulator for a preset
(unfortunately its more than a few words :)

- Right-click on the preset and select "Global Zone" if it doesn't
already have one
- Select the Global Zone in the Preset
- Click the "Edit modulators" toolbar icon
- Click the "New" button in the modulator editor
- Select the new modulator in the list (click on it)
- Under the "Source" frame you will see the controller mapping function
selector, this determines how the value of the controller affects the
value of the modulator (it defaults to linear/unipolar/positive, which
is fine for this example, so just leave it for now)
- In the Source controller selector choose "CC 74 Undefined"
- In the Destination frame choose "Pitch/Effects" from the upper drop
down list (this selector is used to group effects so as to make
selection easier)
- In the second selector you should now be able to select "Filter
Cutoff"
- The Amount Source controller allows you to add yet another controller
source (which is not usually used, so just leave it at "No Controller")
- The last thing to do is set the "Amount" value.  Unfortunately I never
got around to showing this value in user friendly units, so its actually
the raw SoundFont parameter.  For the filter cutoff, -4000 should
provide a bit of modulation over the controller range.

For the mapping function, bi-polar linear also comes in handy, since it
will allow you to increase or decrease an effect value (the center of
the control should have no effect).  This is the third icon from the
left in the first row of the mapping function selector drop down icon
grid.  You can think of bi-polar linear as mapping from -1 to 1 over the
range of the controller, which then gets multiplied by the amount and
added to the destination effect.

>       Cheers,
> 
>               Gerald.

Hope that helps, and wasn't too overwhelming :)  Just goes to show,
there needs to be a nice tutorial and manual for this piece of software.
Cheers.
        Josh Green