Add support for STEMs

[JoergAtGithub]

Engine DJ devices can play stem prepared files, which can only be generated by the Engine DJ desktop application by now: https://support.denondj.com/en/support/solutions/articles/69000862383-engine-dj-stems-setup

Mixxx 2.6 will add support for STEMs, it would be great if the Engine export could convert them to Denons propritary stem format.

[mr-smidge]

This looks exciting - will see if I can do some analysis...

[jaygarcia]

IIRC, Stems in Engine OS uses a proprietary audio format. Would love to hear what you learn @mr-smidge !

(edit: Added Engine OS)

[JoergAtGithub]

Yes, there are multiple stem file formats, Mixxx 2.6 will use the "open" STEM file standard specified by Native Instruments, but EngineOS uses an own format.

[jaygarcia]

yes @JoergAtGithub . You are correct :D . I incorrectly did not include Engine OS in my comment. 🤦🏻‍♂️
That's what i meant by proprietary 😅 . Thank you for taking the time to help me elaborate.