[PeterisP]

No, at the very least you also need to do the instrument separation, e.g. bass might match guitar chord root note at one moment, and do something entirely different half a second later, and of course in a coherent song all the different instruments will merge in the same frequency bins, either directly or with their overtones. Also, for certain instruments and effects on e.g. guitar amps the strongest peaks of Fourier transform for the instrument output may not necessarily match the notes that are actually being played.