What are the solutions in the field of music analysis?

Question

Audio

There are old articles on Habré where the author describes his HOLO system for analyzing mp3 files ( https://habrahabr.ru/post/194724/). The main task is to create a playlist of very similar records for the selected songs.
In short, this system receives a list of characteristics for each file, by which it subsequently determines the similarity of compositions.
Please tell me more similar solutions or materials for studying on this topic. It is the analysis of the characteristics of audio files that are important for listening that is of interest.