Sam WhitedI'm DJing for the local Lindy Hop social tonight, so naturally I spent half the day reverse engineering the Native Instruments stem file format and making a tool to convert them to OGG/FLAC files (mostly just a dumb wrapper around ffmpeg, it just ended up being its own tool because it turns out NI stores their metadata as a JSON blob that ffmpeg can't handle). Can anything actually play the stem part of these files? No (but the regular audio is backwards compatible and most media players can play them).
I wonder if it's worth actually trying to write up an actual open spec to standardize this (since the Native Instruments one is a bit sketchy as far as I can tell and requires lots of things with patents that could cause problems later):
https://codeberg.org/SamWhited/oggstem
Suggestions welcome, debating if I want to write up an RFC for this (what IETF working group would even handle this, or is Xiph a better place if I did?).
LEGAL VST
Ronnie / Rekkerd.org
Public Domain Image Archive
Jean-Louis Bouzou
Jessie Nabein 
Geetha
