btw this is true if you upsample all 3 levels. I have found in practise that you are fine upsampling 2 levels and then using a DAW to "clean up"/"remaster" [0]... again will work for certain sounds better than others.
The last upsampling step is by far the most expensive. so cutting that down cuts total time by 75%
[0] simple hacks such as using a low-pass filter
there are various models that do this [0]... just doesn't have the same power to generate waveform music that jukebox does.
Jukebox effectively is a 2 step model a) a 3 layer VQ-VAE compresses the music (so think of this as the MIDI equivalent) and b) a transfomer then learns/generates sequences.
The compression is the expensive part of the model.
[0] https://towardsdatascience.com/how-to-generate-music-using-a...
OpenAI already did this with Jukebox! I'm just surprised more people have not used it as an "instrument" vs as a novelty.
shameless plug: https://soundcloud.com/songshtr/sets/2106-ep