Invert/Inverse audio? Like a Difference Matte for audio?

Is there any sort of “invert audio” option?
Acts exact same way like a Difference Matte but for audio?
To hear of just the changes in two mixes listening at the same time?
Or any sort of trick to doing this?

Hey Amanda, long time!
Coincidentally, this is related to a subject that I recently started pondering for no useful reason. From what I’ve gathered, and also following digital media logic, many of the mathematical operations we do visually do have aural correlations in apps like ProTools. I believe the approach was used in criminal forensics before it was used in entertainment.

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What you asked about is called Phase Cancellation

The easiest way to do it I know is to open Resolve (the free version will do) place two mixes on a timeline one under the other (should be perfect in sync) and invert the audio phase of one of the tracks on Fairlight page

Hope this helps



you can do phase cancellation on the flame, but you still need to line up the tracks and play them down. And it’s not always perfect. There’s often a slight difference in mixes that only have a line changed.

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Maybe you could make a dot in action, set the two tracks to animate it, then do a difference matte between the animations . . . . or you could just listen to them.


Ok, not for nothin’, but this actually works. Sometime when I have a moment maybe I’ll build it into a preset.

This is a cool idea, then you could run some kind of script to identify the brightest parts and note the timecodes (Nuke has a tool to do this, the name escapes me now)

Or maybe an audio mix down of the phased tracks would be faster as you could see the waveform.

Which leads me to think why can’t we have picture waveform read out on timeline track like we can with audio.


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I took one last look at this today. The simplest thing I can come up with is to line up the tracks, set all to playback through channels 1 and 2, and flip the phase on one of the tracks. You can then scrub the audio and it will be silent until it hits the point where the two tracks are different. The benefit of this method is that you don’t need to play the tracks in real time. You can find the difference very fast just scrubbing. On smoke keys that’s meta-alt. It would be cool if the wave form monitor showed audio phase as well.


ah yes same technique used by noise canceling headphones they just put the inverted outsode noise back onto your signal bascially. I used this a lot in audacity to find out if a stereo track was Dolby or not. :rofl:


Have a peek at Cargo Cults’ Matchbox.

It might be a bit heavy handed for your needs, but it has some interesting features for both picture and audio change management.

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I use this often.

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How do you get to this “Path Settings” menu like this pic in Resolve 18?

It`s in Fairlight page. Channel strip setting. Davinci Resolve 18.6 manual, page 3634

You can do this in flame.

Let me rephrase my question….

I’m in resolve and have two tracks like in your pic. I see a drop down in that track but don’t see any options for “Path settings” (and also doesn’t match what that page in the manual says) and nothin comes up in the search menu…….is there another menu I’m missing or another way for this window to open……

so, How do you get to this “Path Settings” menu like your pic, in Resolve 18?

Understood, ……but that wasn’t the question.
I also want to try this in resolve.

Click on this:

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Yes, exactly where Tim shows it is

You should be in Fairlight page

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yes! thats what I was looking for! thanks!