[LAD] Some questions about the Jack callback

Fons Adriaensen fons at linuxaudio.org
Sat Sep 20 19:43:50 UTC 2014

On Sat, Sep 20, 2014 at 12:34:28PM -0400, Mark D. McCurry wrote:
> On 09-20, Fons Adriaensen wrote:
> > The thing to be avoided is code that e.g. generates a heavy load
> > every fourth period and does almost nothing in the three periods in
> > between. Or a synth that generates a peak load whenever a voice is
> > started and much less while the note lasts. IIRC yoshi/zyn use FFTs
> > in some of the algorithms, so this sort of thing could happen.
> Yeah, the cost of starting an additive synthesis note can be fairly
> expensive as with a worst case instrument and default settings you'd
> need to do 256 1024-point IFFTs per part and a bunch of math leading
> upto the transform 

Having to do 256 1024-point FFTs just to start a note is insane.
It almost certainly means there is something fundamentally wrong
with the synthesis algorithm used.



A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

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