[linux-audio-dev] more on XAP Virtual Voice ID system

David Olofson david at olofson.net
Tue Jan 7 07:56:01 UTC 2003


On Tuesday 07 January 2003 10.23, Steve Harris wrote:
> On Mon, Jan 06, 2003 at 11:17:07 +0100, David Olofson wrote:
> > These "instantiation parameters" are in fact just control events,
> > and they relate to "whatever voice is assigned to the provided
> > VVID".
> >
> > The issue here is this: Where does control data go when there is
> > no voice assigned to the VVID?
>
> They get thrown away.

Right - so you can't play a polyphonic synth with a continous 
velocity controller, unless you track and re-send the controls that 
the synth happens to treat as note parameters.


> > What I'm saying is that if you send the "trigger" event first,
> > followed by the "parameters", you require synths to process a
> > number of control events *before* actually performing the trigger
> > action. That simply does not mix with the way events are supposed
> > to be handled.
>
> Well, I thinik its OK, because the note will not be used to render
> any samples until after all the events have been processed.

But who guarantees that whatever the "trigger" event is, also comes 
with events for the "parameter" controls? It's trivial (but still has 
to be done!) with explicit NOTE_ON events when assuming that NOTE_ON 
means "allocate and start voice NOW", but it's not at all possible if 
the synth triggers on voice control changes.


> > If you really want to your voice allocator to be able to turn
> > down requests based on "parameters"
>
> I think this would be complex.

Not more complex than any "note-on latched" controls - and I don't 
think it's realistic to eliminate those.


//David Olofson - Programmer, Composer, Open Source Advocate

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