[Help] Music and SFX separation

[MeanjohnRambo]

Can you actually separate the sound effects from the music in a movie so let's say you could insert new music over the original score? If it's possible how would you do it?

[deleted user]

Something you might get better answers to in the fanedit forum. I believe they often have to redo sound effects and try getting some SFX and the voice from the center channel.

[Lio]

If by "sound effects" you mean dialogue as well, then as TomArrow said you have some flexibility with the center channel. I think it's common in television shows for the music to not bleed into the center much, if at all. But since movies are mixed for the cinema, the music needs more presence and some of it is brought into the center.
Izotope RX has a pretty good "Dialogue isolate" tool that can successfully scrub away a lot of the music, but if the movie is sound-effect heavy then it'll erase a lot of those too. There's no perfect method of isolating the music/sfx, so you have to take what you can get (and possibly re-do a few sound effects yourself).

[deleted user]

I second that Dialogue isolate is pretty decent. You can also try Dialogue Dereverb as an alternative, although the expressed purpose is a little bit different.

[nafroe]

Yes, this would be great. There was an expanded soundtrack for a film (a couple of soundtracks actually) from La La Land Records which still managed to miss a handful of cues which would make them more complete... Would love to learn how to do this (if at all possible) as the on screen action is quite busy at that moment. I use Audacity. Other than the Vocal Removal plugin, I'm not sure yet what could be used to serve such a purpose.

[The Griff]

What about releases that contain an isolated score (like much of the Twilight Time BDs)? Would they be of any use for doing some sort of phase cancellation?

[LucasGodzilla]

What about releases that contain an isolated score (like much of the Twilight Time BDs)? Would they be of any use for doing some sort of phase cancellation?

I suppose it depends on the release? I've seen numerous releases that have isolated tracks and they almost always seem to be having different timings–as well as sometimes just being a flat out different mix–than the main mix for some reason so unless you're lucky and it syncs up or can be synced up easily, then I suppose it can be used for audio cancellation.

[Lio]

What about releases that contain an isolated score (like much of the Twilight Time BDs)? Would they be of any use for doing some sort of phase cancellation?

Not necessarily. Isolated scores usually aren't potted (i.e. the volume doesn't move up and down to account for dialogue/fx) so that will mess things up obviously. For films where the stems don't exist anymore, an editor will get whatever transfer of the music elements is available and will manually start lining things up. The edits might not be exact and the mixing will probably be different from the movie's audio track (in fact, the music might sound better than in the movie) so that's not helpful either. Phase cancellation would only work, and even then with a lot of hassle, on a recent movie where the editing of the isolated score would exactly match the main audio track and is presumably mixed the same too.

[The Griff]

Thanks fellas. That all makes total sense.