SFML2 Audio format seperating audio by instrument

[Intrexa]

I googled each of the file formats that SFML supports, I just want to make sure I'm not missing something obvious.

What I want is for a song to have several instruments in it, and to be able to dynamically remove or add a single instrument from it. So say a song has drums, guitar, and piano, I want to be able to stop the piano dynamically at 40 seconds in, and start it again 80 seconds in.

Obviously I can simply have a different file for each instrument, but this seems rather inefficent and obtouse. I am new completly new to everything audio, so I really have no knowledge on audio files or the way it is playedback, so any advice is very much welcomed.

Which format/method would allow me to produce my desired effect, without taking up unreasonable amounts of disk space and ram?

[Laurent]

Maybe the MIDI format would be the best for you. But it requires specific audio libraries, and not all of them can provide enough control to do what you want.

And, MIDI requires to have an instruments bank available, which can take more than 100 MB for good quality.