This is a really weird bug, but stat calls for pattern index, note index, and "number of ticks played" do not always sync up and sometimes one changes before the other. It was intermittent and hard to track down. In order to compensate for this, I had to write something to insulate myself from it:
function poll_songpos() local pat = stat(24) local n = stat(21) local ticks = stat(26) -- compensate for bug (!) where pattern sometimes changes before note if pat ~= songpos.pat and n ~= songpos.n then songpos.pat = pat songpos.n = n if songpos.prevticks > 0 and ticks >= songpos.prevticks then songpos.ticks = 0 songpos.waitingforticksync = true end elseif pat == songpos.pat and n ~= songpos.n then songpos.n = n end -- compensate for bug (!) where pattern sometimes changes before ticks if songpos.waitingforticksync then if ticks < songpos.prevticks then songpos.waitingforticksync = false end else songpos.ticks = ticks songpos.prevticks = ticks end end
(I then changed all other code to use songpos as the source of truth, rather than the stat calls)
However, this caused a big headache and was hard to track down and it would be great if this wrapper were not necessary. Also I'm not 100% sure this wrapper code is completely bulletproof; I simply wrote it out of necessity to get the issue out of the way from the specific cart I was working on.
Sorry I don't have a cart demonstrating the issue, but I will try to make one. I just wanted to get this reported sooner rather than later, in hopes that it might get addressed for the upcoming update :D
EDIT: as a reminder I also have another bug thread about stat(24) returning 0 instead of -1 which hasn't been fixed yet
Thanks again, @zep, for adding these sfx state-related stat calls a while back; it is super fun to get stuff to react to music/sfx, in a way that is not easily possible on most other platforms!
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