how do people isolate specific audio tracks from a file without access to the master tapes? Such as when someone makes an isolated vocal or bass track of a song or when someone makes a mashup of instruments from one song with the vocals from another.

Question

Such as when people make “isolated bass/vocal,” tracks of popular songs or make a meme mashup of one song with he vocal line of another over it?

In: Technology

Answer 1

There are many different approaches. To add to what other folks have said, these days you can use neural networks that have been trained to do the job. [Spleeter](https://github.com/deezer/spleeter) is one such software. Basically, a computer “learns” what different instruments sound like, and can then identify the different parts in the spectrum of the full song, and then cuts out those bits separately. It works well with clear, well defined, loud instruments in simple tracks; not so much with things buried in a complicated mix (where even a human would have a hard time picking them out).

Others have also mentioned that if you have the instrumental track, you can subtract it from the full track to get just the vocals. This works rather well for some tracks, but the two tracks have to be perfectly aligned for that to work directly. There is software that can help with this by automatically stretching and shrinking tracks in time to match them (I wrote a version of this myself). Sometimes it doesn’t work well anyway, because the tracks might have been processed differently or different instruments might be out of phase (this often happens with synthesizers and other virtual instruments, where both versions aren’t the same render to audio). In this case you can use even smarter software to try to subtract at the level of tones in the spectrum, instead of at the level of the raw audio.

Ultimately it’s all a bunch of compromises, and if you’re doing this by hand you’re probably going to be postprocessing stuff manually to cut out noise, EQ the result, etc. It’s not a one button push process.