[willis936]

This reminds me of a task in my list that has been sitting there for nearly a decade:

  instrument FIR from song (justice - let there be light)

Here is the spectrogram of the sound I'm talking about:

https://imgur.com/kmtoMkd

It's pretty easy to filter out the drums since most of the energy is in other bands. Looking at the spectrum again I don't think a simple spectral replication will nail the sound right. It looks like there is some sort of beat phenomenon that isn't present at all center frequencies.

[not1ofU]

I dont think I understand what you mean, but, if I do, then you could look into using spleeter. It separates musical stems.

https://news.ycombinator.com/item?id=21431071

https://github.com/deezer/spleeter/wiki/2.-Getting-started#u...

[willis936]

The task I gave myself was to subtract out the drum beat (the song graciously gives the isolated loop before the instrument comes in), then mix/baseband the instrument to whatever frequency I wanted. If all went well I would make a complex FIR filter that I would pass tones into.

This model assumes the timbre is independent of the tone, but I can see now that this assumption is quite wrong and something more complicated (like this ML modeling) would be needed.

[malka]

https://www.steinberg.net/fr/spectralayers/

This might help you?

[squeaky-clean]

That synth is extremely distorted post summing of the voices. (That whole album has so much distortion, it's lovely).

So not only is timbre not independent of frequency, summing multiple notes is also non-linear. The "beating" this causes is most obvious on the second chord to play. This beating is not consistent as the notes change, it's based on the difference in frequencies between the two notes being played.

[pizza]

Maybe 2nd-order spectral relationships would get you a bit closer, e.g. bispectrum / bicepstrum