The readme.txt file is out of sync in the dump, here’s how the stream works:

if the value is $01, then don’t write anything to the PSG.
if bit 0 is set, it’s a 1-byte lookup.
if bit 0 is clear, it’s a 2-byte lookup, low then high.
if the 2-byte lookup is $FFxx, then reset the stream.

The value for a “blank tick” used to be $00, not $01. Unfortunately, you can get values such as $0D00 of which the first byte read is… $00. D’oh!

And this is the thing  itself. Enjoy.