Hi there! One of the authors here (Prem). Thanks for reading, and for mentioning Spleeter! Spleeter is awesome. The idea behind this book is to give people the tools and code to train their own versions of Spleeter.
I was playing with spleeter a bit earlier in the year for drum practice and it was great. You can do drum covers (or whatever instrument) without the other (typically famous and amazing ) musician stepping all over your brilliant amateur playing !
Nice, I just tried Demucs on my go to track (Fleetwood Mac - Dreams, mainly because it happened to be on my computer and I thought I could hear it multiple times without going crazy, but also it does seem to be a reasonably good test as there are some effects which seem to make separating the voice non-trivial etc) and the end result was very impressive. Definitely much cleaner sounding (sharper and fewer FFT artefacts) than Spleeter, especially on the drums and vocal.
I also tried it on a dance track (BT - Mercury and Solace) and the results were much less impressive. I guess this maybe reflects what it was trained on?
There's also Spleeter Web [1], a self-hostable version of a Spleeter web app. A fun little project I've been working on! I'm thinking of supporting additional models such as Demucs [2], which seems to perform better than Spleeter.
Deezer does not offer an official hosted service but there are unofficial services like Acapella Extractor [4], melody ml [5] and moises [6].
[1] https://news.ycombinator.com/item?id=21431071
[2] https://news.ycombinator.com/item?id=23228539
[3] http://archives.ismir.net/ismir2019/latebreaking/000036.pdf
[4] https://www.acapella-extractor.com/
[5] https://melody.ml/
[6] https://moises.ai/