> There is one more refinement you could use to limit the amount of
> CPU use. Of course the IRs for different source directions will be
> different. But the *signficant* differences are only in the first 100
> ms or so. In many cases the 'tail' of the reverb will sound just the
> same even if the IR is 100% decorrelated with one for another direction.
> That means you need to do the direction-dependent convolution only for
> the initial 100 ms or of the IR. For the rest you can share a single IR
> for all sources. 

Thanks Fons that makes a lot of sense. When preparing the tail-IR, is
this matter of taking the file into an editor and silencing the first
100msec of the channels, perhaps using a ramp function to slope up to
the 100msec point? Also, for the early-reflection-IRs, deleting
everything after 100mcsec?

> You could also experiment with changing
> the relative delay of the direct sound and the reverb sends (no standard
> mixer will allow you to do that easily, but if you use Pd or a similar
> tool it is entirely possible. 
> 
Do you mean some sort of variable delay? Not sure what you mean.


> Since you mention jconvolver, there are two preset files in the source
> distribution that are designed to do this: sala-concerti-cdm and 
> santa-elisabetta. Both use ambisonic IRs which you can download from
> my website. For the concert hall there are IRs corresponding to various
> on-stage source position, and for santa-elisabetta (a small church) there
> are 8 early reflection IRs spaced 45 degrees apart.

Thanks!

Iain

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