We are putting together a sub-set of musicbrainz which mimics the (now basically defunct sigh) Echo Nest in terms of schema & data structure. One thing we where hoping you could help with is the calculation for the valence & energy properties. As far as we can tell these are based on segment duration & loudness with valance using energy as a factor. Anyone have any ideas about the calculation/algo that the ECN guys used in the context of the available AcousticBrainz data?
Our plan is to open up this work as both an open source project (with the generation tools for creating the set and importing it to MongoDB & ElasticSearch) and as a publicly available API (with a clean, human-readable JSON response type).
Any help would be greatly appreciated.