Writes a song file as one HTML page, which plays the song's render and shows each part's notes on a timeline.
mix mx.page song.exs
mix mx.page song.exs --out song.html --title "A song" --seconds 60The page is written beside the song with the extension .html unless --out names it, and --force writes over a file that exists.
--seconds is how long to render a song whose music does not end.
The song's sound is encoded with ffmpeg, which has to be installed.