Thanks for the pointers. My goal - I really didn't like the Erik Satie Gymnopedie #1 version I'd just bought, and wanted to generate a new version. With the recent Astra release, I wanted to see how it and Fable did on creating their own versions based upon a standard MIDI. The encoding was actually just to make the PianoDisc player work better. Their iPad app will actually play MIDI directly without encoding, but they feel like second class citizens in the app, and there's some weird Bluetooth audio and a second Bluetooth MIDI interface on the app. I was having problems with the MIDI one, but the mp3 encoded connection seemed to work reliably.
When Fable came back with the decoder, I knew something was off. The decoy notes... even more evidence of wonkiness. Mostly posted it to HN out of disbelief that Fable just hacked my piano and had I blindly pushed it to a public repo, I would likely have broken some law.
Btw, the version I like is performed by Pascal Roge back in the 1970s. The AIs don't quite match his performance, and I keep trying to figure out how to guide them. I don't think his version has a delay between the melody and the chords, while the AIs were both convinced that was desirable. They seem to be lacking some taste in that area, but overall I prefer their version to the one I bought.