Apostolos Dimitromanolakis wrote:
I would be interested in this project too. What I'm looking for is actuallay an anti-reverb that will be able to cancel reverbs in a listening room, well always in conjunction with the listener position.
Then I think DRC (digital room correction) is for you: http://freshmeat.net/projects/drc/ This works with bruteFIR http://www.ludd.luth.se/~torger/brutefir.html But I must confess: I have not understand how to use the result of drc in bruteFIR. For a reverb convolution I think only the first steps of the DRC process are necessary, but I haven't understand what to do there, too. And unfortunately the only DRC tutorial is for windows only :-(( And it doesn't explain the steps, it just shows them ...
The other useful thing would be a phase-filter to correct the phases coming out from a two or three way loudspeaker to get clarity in the sound similar to high-end speakers.
As far as I understand what DRC does, this is one of the postprocessing steps.
I'm surprised that you mind modern consumer soundcards not linear, after all the sigma-delta converters used in most of todays soundcards are supposed to be perfectly linear and it was one of the reasons of their adoption.
Oh, I don't want to state, that all consumer soundcards are
nonlinear. I have a very old Soundblaster AWE 32 and found that
the waveform coming out when playing an mls signal cannot be
computed to an impulse response by mls2imp. (And looks very bad)
I hope to find some time to make a website showing the
waveforms and my experiences.
With a more modern USB AD/DA converter (Tascam US-122) I can
compute the IR both from a direct loop (what gives something very near to a dirac) and from my alesis microverb.
And since the onboard sound of my ASUS motherboard with nvidia
nforce2 chipset gives similar results (though not so bad, but
still unusable), my only explanation (after examining the code
and process) was the unlinearity of the two soundcards. (But I don't fully understand the whole process)
Maybe, if I post the waveforms, someone can give a better
explanation.
Another effect appears, when I fed the mls signal dircetly through a reverb (ladspa, gverb). After the impulse, there is a constant noise tail ...
Uwe
-- voiceINTERconnect www.voiceinterconnect.de ... smart speech applications from germany
