[Jackit-devel] Re: [linux-audio-dev] [ANNOUNCE] jack_convolve-0.0.1

Florian Schmidt mista.tapas at gmx.net
Sat Jan 29 10:57:04 EST 2005

oops, sent to fons only.. here's the mail to the lists, too. sorry for
duplicate, fons:

On Sat, 29 Jan 2005 16:16:04 +0100
Fons Adriaensen <fons.adriaensen at skynet.be> wrote:

> On Sat, Jan 29, 2005 at 03:43:46PM +0100, Florian Schmidt wrote:
> > Now i grok it.
> > 
> > As a stereo impulse file is a response to a mono impulse placed
> > somewhere in the room, one needs two stereo response files with the
> > impulses created at different points in the room.
> Yep, that's it. Even for a stereo output, you could have more than
> two inputs, each one corresponding to one place in the room.


> > I will adapt the convolver to be able to load more than one response
> > file and provide an input for each. And as many outputs as the response
> > files have channels (for two stereo response files, that's two channels
> > 'cause they are stereo)..
> That would do it. And then of course the input transform is done only
> once, and the additions can be done in the F-domain, so there's also
> only one output transform for each output.


The real cost is in the complex multiplications though. So if anyone
knows how to speed that up with a nifty function using
assembler, prefereably following this interface:

// computes n complex multiplications and _add_s the results to the out buffer
void complex_multiply(unsigned int n, 
                      fftwf_complex *in1, 
                      fftwf_complex *in2, 
                      fftwf_complex *out);

i would be oh so greatful. 

So the TODO list as grown to:

- fix error checking
- add multiple response file support as explained above
- add libsamplerate supprt for converting response files to jack samplerate
- optimize the complex multiplication


Palimm Palimm!

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