Removing Post-Production Music from a Clip?

A

armadillo

Well-known member
I have a clip of footage that has been edited in post to add a music track (studio version) and I am wondering if it is possible to substantially remove this music from the clip if I just "subtract" a track of the song from the audio of the edited clip...

Is there some method that will allow this to be achieved?
 
armadillo said:
I have a clip of footage that has been edited in post to add a music track (studio version) and I am wondering if it is possible to substantially remove this music from the clip if I just "subtract" a track of the song from the audio of the edited clip...

Is there some method that will allow this to be achieved?
Click to expand...

I presume deleting the audio track altogether is not desired...

If you line up the 'audio' of the track, and the audio of the music 'exactly', then invert the 'music' track, that is shift the music 180 degrees out of phase, then during the playing, adust the amplitude of the 'music' to cancel the music in the 'audio' track... you may be able to minimize the music in the resulting 'subtraction'.

But because it is 'mixed' there's not a really good way to eliminate an element from a mix, especially if there were effects put in, even as simple as changing the volume of the 'music' at some point, or many points during the mixing process.

Since I'm more in to Digital Signal Processing, the 'problem' you pose is more of an academic interest than any practical knowledge of such a procedure...
 
Nope. Once it's in the mix, it's in the mix. This is why most program masters for networks have dialog/M&E (music and effects) splits.

Trying to "cancel" the music out is also going to have nasty, adverse effects on any dialog in that mix.
 
I'll echo the previous post by j1clark.
In theory, provided you have exactly the same soundtrack, you could put it out of phase and by combining it with the current mix it could be faded out (this is how certain "less-instrument" play-along records were created...)

Multiple caveats apply:
1) dialogue might be affected as well (because it may overlap part of the music frequencies); it could create unpleasant artefacts ("hollowness", emphasis of unnatural frequencies, etc)
2) you will need to find the exact level at which the combination of the out-of-phase music will cancel the underlying soundtrack
2a) levels may need to be adjusted on the fly, hence you will need to have good HD based application in order to pull this off by creating manual volume curves..

Let us know if/how you proceed.
Good luck,

Paul
 
I'd try the 180 trick as well. If it is EXACTLY the same, you might get good results. The problems, as mentioned, are also that if they gained up or down that audio, since it is now 24 or 16 bit, you can get artifacts left if your music is not the same amplitude from the processing it went through.

Also, as mentioned, the dialog was probably editing to go with the music, so frequencies that added that required the vocals be dropped down a bit will now cause the vocals to drop down further. Bass is one of those things that eliminates a lot of your dynamic range you can use since it eats so much of it up with the long wavelengths. Without those wavelengths, your audio drops back down (higher frequency content).
 
Thanks everyone for the input. I will proceed and keep you posted... It will be a challenge as the volume of the song fades down into the clip so I'll have to match the volume decrease as well.

At least one thing is working in my favor - the instrumental track is drums and guitars only. No vocals...
 
armadillo said:
Thanks everyone for the input. I will proceed and keep you posted... It will be a challenge as the volume of the song fades down into the clip so I'll have to match the volume decrease as well.

At least one thing is working in my favor - the instrumental track is drums and guitars only. No vocals...
Click to expand...

Better hope that fade is linear :) A lot of audio editing software has exponential fades which make it more difficult to make the same!
 
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