linuxaudio.org

On 07/26/2012 07:10 PM, Florian Paul Schmidt wrote:

quoted text
> On 07/26/2012 07:04 PM, Julien Claassen wrote:

>> Hello Flo!

>>   OK, I'm with you so far. So I suppose, that it is possible to

>> process the IR of a time-variant system. The question is: Is it done

>> in any library already optimised for the audio domain?

>>   Thanks and best wishes

>>            Julien

>>

>

> I sense a misunderstanding. With a single constant kernel you can only

> model time-invariant systems. A Leslie is NOT time-invariant. I.e. the

> response changes with time (the speaker rotates). So what you could do

> as a workaround would be to get IRs from the Leslie at various

> positions. Then convolve your input signal with each of them and mix the

> outputs together with the mixing coefficients being a periodic function

> of time.. You could probably get away with calculating only a few of the

> convolutions if your mixing coefficients are sparse, i.e. you only

> crossfade between two consecutive (in time) output signals.. (keep in

> mind the window length of the convolution kernel, though)..

>

> It's of course a tradeoff - You need quite a few IRs to make the

> transitions smooth.. But then it's just a matter of hacking some code

> around an existing convolution engine..

You're pretty much describing

  https://github.com/pantherb/setBfree/blob/master/b_whirl/whirl.c

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