This is a 100% javascript Soundsmith Player. Soundsmith was a music program released in the late 80s for the Apple IIgs. Many games and demos used Soundsmith for their music. I've included some examples with the player.
Earlier FTA software didn't use Soundsmith. I've built a specialized player specifically for them.
I have included some quick-and-dirty command-line tools to extract music from FTA demos and other sources inside the extract/ folder.
I have documented how I used those tools to reverse engineer demo organization and extract music in the docs/ folder. In particular, the Modulae demo, the Xmas demo, and the Nucleus demo.
I have also documented how the Apple IIgs Ensoniq DOC works, as well as pseudocode on how the Soundsmith player works. You can read about it here.
Finally, you can check out this project on GitHub.