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Old 06-08-2018, 07:37 AM   #140
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Originally Posted by Sju View Post
So another idea. Do you think it might be useful to be able to invert the action of the Amount parameter, to be able to subtract a spectrum of one signal from another? Could be useful in mixing for fitting together sounds occupying the same frequencies, especially with the new filters so you could target the subtraction to the crucial frequencies.

EDIT: ^ Not sure if I'm thinking about this right.. The obtained spectrum is actually the difference of the two signals, so just inverting it would then actually only subtract the parts that already don't overlap? It'd require a different algorithm to find the overlapping areas, yes?
It would be simple to extend the Amount dial to go down to -100%. This would be equivalent to swapping the reference and the input around.

I'm not at my computer right now to add this and test it, but you can try it yourself by changing "0" to "-1" in this line (2047)
EDIT - released in v1.7.0. Amount dial now goes to -100%, and double-clicking sets it to 0.

For what you're thinking of, you could try using the combined/summed audio as the reference. If you then put Spectrum Matcher on the individual tracks, normally it would make each track sound like the combined reference - but with a negative Amount, it should make it sound less like the reference, exaggerating the most distinctive features of each track.

I don't know what the result will sound like in practice, but that's what I would try first. It's a neat idea, and I'm interested to see if it works.

Originally Posted by Sju View Post
Related to this, are the parameters in Spectrum Matcher automatable, i. e. don't cause zipper noise? Could then use parameter modulation to dynamically change the subtraction Amount with a sidechain signal.
I'm afraid not, for performance reasons basically. It would take about 2x CPU when automation was active. It also ~triples the time it takes to actually load/add/move the plugin (to the order of a couple of seconds on my machine).

I thought that was too high a cost given that it's not its intended use. It sounds to me like what you really want for that is a multi-band EQ with sidechain (which ReaXComp unfortunately does not support).

Possible workaround: copy the curve to ReaFIR (by hand), use wet/dry dial

I have warned against using REAPER's wet/dry dial because things don't add up linearly due to phase shifts - for example, it's possible to have a curve where the 50%/50% result reduces some frequencies below both the 100% wet and 100% dry. If the correction curve is very gentle, you might get away with it, but I don't want to recommend it.

That goes for ReaEQ as well, because the phase shifts are exactly the same.

However, if you copied the spectrum into ReaFIR, the wet/dry dial would work because it's a linear-phase EQ. There isn't a good way to copy that curve across though, it would be by hand.


Last edited by geraintluff; 06-09-2018 at 02:53 AM.
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