A GRUB_INIT_TUNE uses the following format: tempo [freq duration] [freq duration]…
- tempo: is the base for all note durations in beats per minute, 60 gives a second base (60s/60 = 1s), 120 gives a half-second base, etc.
- freq: is the frequency (in hertz) of the sound (set 0 to produce a rest)
- duration: is the duration of the sound in beats
You can preview the tunes below with the standalone index.html included in this gist.