[linux-audio-dev] Plugin APIs (again)

David Olofson david at olofson.net
Sun Dec 8 18:33:00 UTC 2002


On Sunday 08 December 2002 12.48, Steve Harris wrote:
[...getting control values...]
> The problem is that the dsp code doesn't always know the real value
> of a controller: if its expensive to calcuate the coefficients you
> normally just calcuate them once for every N samples then
> interpolate the coefficients, which bear no simple relation to the
> controller value.

Good point... However, if you're sending (or at least seeing) the 
input events, why would you need to ask the plugin about anything?

Keep in mind that this is a totally separate issue from plugins that 
actually *send* events. Those can do whatever they like internally - 
but then this is also a non-issue, since those plugins will also 
spontaneously generate ramp events properly.


> If the host is marshaling the events then it should know what the
> last controller value it sent to the instrument was.

It could also figure out what the interpolated value should be at any 
time - whatever use that would be, on this level.


> OT: I think you do want to handle note_on as an event, as you may
> want to process it with an event processing only plugin, eg.
> something to may midi style keyboard events to a gong striker (eg.
> map pitch to position and keep velocity). Or even an arpegiator.

Why does that may any difference whatsoever? Event-only plugins can 
understand controls just as well as synth plugins, right? When 
velocity turns non-zero, you have a "note on". When it turns zero, 
you have a "note off". You don't need a synth core to run as well to 
keep track of that. :-)


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

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