Subtracting non-identical audio ?


Ive been trying to extract a movie’s sound effects from its soundtrack, so far with no luck.

Basicaly, Im trying to extract the minigun sound from the Terminator 2 movie from its soundtrack, which I have both synched by hand.

Now those 2 are defenitely not identical, but they are a very close match.
Can I somehow tell the software to sub the soundtrack anyway ?

Right now if I invert/mix the tracks together I just get a louder soundtrack.

Here are my 2 files as .wav’s, so you get the idea…

Also, if it actualy isnt possible, is there any way to use compression or some other effect to basicaly diminish the soundtrack’s presence ?

You’re setting yourself up for disappointment. At least, if these are the only two clips you have to work with.

It’s only possible to do this if the soundtrack wasn’t remixed in any way and it’s at the same volume level. There’s a good chance that both of these things happened (though I’m not sure where you’re getting the soundtrack clip from). If either of those are true, you’ll always have something left over, though it might still be possible to reduce the volume.

In any case, you need a way to line the soundtrack up with the movie, and you won’t be able to do that by ear, you need a section of the movie where you can see a noticeable percussive sound coming through everything. Then you can use that section to line it up properly. I didn’t see anything like that in the two clips you provided, so I wasn’t able to line them up.

From personal experience, I suggest you give up before you waste many hours hoping to get lucky.

Are you talking to the poster who wants to take the sound effects out of Front-Left and Front-Right of a 5.1 movie mix? Something I wanted to ask them. Why are we doing this?


Basicaly Id have to sample the movie audio until there are no (or next to no) sound effects (where you can hear the soundtrack clearly) and use the high notes or drums in the soundtrack to line both clips ?

Once that is done, would the invert/mix method still be “additive” though, considering that even though they are lined up in a much more convincing way, they are most likely not identical due to either movie compression, post-production tweaking or any other factors ?

I guess Id be saving time looking at another method like soundtrack volume reduction trough effects and filters ?
If so, what would be the best approach ?
I was thinking of compressing the lower Decibels to get rid of sounds other then the minigun’s, taking the clearest segment(s) of minigun fire, and looping it afterwards on a separate track .

Are you talking to the poster who wants to take the sound effects out of Front-Left and Front-Right of a 5.1 movie mix?

Afraid not :slight_smile:

You might be better looking somewhere like this:

<<<Once that is done, would the invert/mix method still be “additive” though>>>

I didn’t see an answer in there.

We need to modify a movie sound track because…?

Sometimes the poster is way too close to the problem and the overall task can be completed using a completely different tool or technique.


What I meant by “additive” is that right now, if I were to invert/mix the soundtrack and the movie, Id just amplify the soundtrack instead of reducing it.
The way I understand it is that if I want it to be “subtractive” to the movie audio, I need to match the soundtrack perfectly, and thats where I had concerns about both tracks not being identical in the first place.

The end goal is to have a few seconds of clean minigun fire that I could use into a loop to create a minigun firing sound effect.

I thought that since I have the soundtrack, it would be the easier/more efficient way to invert/mix it, but I might of been wrong …
Ill just try and extract a second or so of it, and clean that, instead of trying to clean the whole track.

You might be better looking somewhere like this: >

A nice website, but Im gonna have to stick with the T2 minigun on this one… Its by far the best gun sound effect I personaly know of. Very mechanic and dry with no excess of bass to ruin it.

Quite correct. If they are not identical it will not work.

You can easily use Audacity to modify sound effects - excessive bass can be fixed using the Equalizer.