I did this for my graduate capstone (https://www.deepjams.com/ https://www.deepjams.com/) We extracted chord progressions from existing music you would upload a

I did this for my graduate capstone (https://www.deepjams.com/ https://www.deepjams.com/) We extracted chord progressions from existing music you would upload and then riffed based on those chords. there are open source libraries for this.