[iiwusynth-devel] Re: Pitch bend, filter, sysex, LADSPA,...

[Peter Hanappe]

On Sat, 2002-04-06 at 19:21, Josh Green wrote:
> On Sat, 2002-04-06 at 09:11, M. Nentwig wrote:
> 
> <cut>
> 
> > =========LADSPA effect unit=========
> > In my opinion, the LADSPA code is now good enough to include it.
> > Several small changes are made in the configuration files, there is now
> > an option --enable-ladspa (default=no) available for ./configure.
> > I have written a small perl-Tk script, that shows a couple of sliders in
> > a window, which allow real-time control of effect parameters (chorus,
> > reverb, overdrive,...)
> > This is not included, but if anybody would like to try, I can make a
> > 'bundle' (soundfont, plugins, script).
> > 
> 
> I'm curious about your LADSPA code. Is this a host? I've seen the LADSPA
> iiwusynth plugin client code in the iiwusynth source tree, but I have a
> feeling your talking about something else. If this is a host that allows
> LADSPA plugins to be added to the iiwusynth chain than, cool! I'd like
> to give it a try. This is one area where iiwusynth could be made really
> pluggable, if one could choose which LADSPA plugin to handle chorus for
> instance, and the control ports were modulated by iiwusynth.. Neato..

Actually, that's a good idea Josh, about using the ladspa plugins for
the chorus. I integrated the chorus effect from sox into the iiwusynth
and it doesn't sound good. Maybe I made errors in the conversion or
don't use the best parameters. However, I guess that Steve Harris'
chorus plugin is a better option. Instead of copy/pasting the code, it
might be smarter to simple load the plugin instead.



> 
> What would be really cool next is to implement real time modulation of
> as many of the sound font parameters as possible :) Sound font
> modulators could then be implimented on top of this. How easy would it
> be to do this? (Peter?) 

Are you thinking about modulating them by sending MIDI events or
controlling them with the LFO used to modulate the pitch, etc...? 



> I've seen a bunch of modulator code in
> iiwusynth, but I'm not sure as to how close it is to working.

It is working. I'm just not sure about how efficient it is when it has
to handle a *lot* of midi events (say you send events every 64 samples).

> A problem I can see with real time modulation of effects is in how the
> API would allow the selection of a voice (in a preset). Perhaps a
> function could be added like:
> 
> iiwu_voice_offset_effect (synth, channel, voice_number, gen_id, amount)
> 
> Since iiwusynth has no idea about the sound font layers (preset, preset
> zones, instrument, instrument zones) when using the sfloader API, it
> would be up to Swami to re-calculate what voices need to be offset. I
> suppose something like a iiwu_voice_offset_effect_global routine would
> be nice too to offset all voices on a particular MIDI channel.

It is currently impossible to address a particular voice inside a
channel. This is somewhat annoying. Imagine we're able to stream large
samples from disk. It would be nice to control these streamed samples
separately. That way, you could actually use the synth as a nice mixer
or audio file sequencer. But you'd need to be able to control voices
individually otherwise the user is limited to 16 samples, one per MIDI
channel.

> > And now I'll go down to the bomb shelter and play some music.
> > 
> 
> Is this for your own protection, or the protection of your neighbors? :)
> 
> > Cheers
> > 
> > Markus
> 
> Lates.
>       Josh Green
> 
>