[LAD] on the soft synth midi jitters ...

David Olofson david at olofson.net
Tue Oct 5 12:50:10 UTC 2010

On Tuesday 05 October 2010, at 14.39.25, Arnout Engelen <lad at bzzt.net> wrote:
> > Hence it's impossible to accurately honor the frame/time stamp of a midi
> > event. That's what drove drove the experimentation with splitting the
> > audio generation down to tighter blocks.
> Yes, that could be an interesting way to reduce (though not eliminate
> entirely) jitter even at large jack period sizes.

Not only that. As long as the "fragment" initialization overhead can be kept 
low, smaller fragments (within reasonable limits) can also improve throughput 
as a result of smaller memory footprint.

Depending on the design, a synthesizer with a large number of voices playing 
can have a rather large memory footprint (intermediate buffers etc), which can 
be significantly reduced by doing the processing in smaller fragments.

Obviously, this depends a lot on the design and what hardware you're running 
on, but you can be pretty certain that no modern CPU likes the occasional 
short bursts of accesses scattered over a large memory area - especially not 
when other application code keeps pushing your synth code and data out of the 
cache between the audio callbacks.

//David Olofson - Developer, Artist, Open Source Advocate

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