07967: genesis and clones [oozeju]: Missing notes in intro music of The Ooze

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
07967	Sound	Minor	Always	May 4, 2021, 14:55	May 11, 2021, 22:13

Tester	ICEknight	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Open	OS	Windows 10 (64-bit)
Status [?]	Acknowledged			Driver	sega/mdconsole.cpp
Version	0.231	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	07967: genesis and clones [oozeju]: Missing notes in intro music of The Ooze
Description	At some point during the intro, the main melody misses playing two simultaneous notes. Real hardware footage from a Genesis Nomad: Also tested on a Japanese Mega Drive and the music plays properly as well.
Steps To Reproduce	Just load the game with: mame.exe genesis -cart megadriv:oozeju:cart and wait for 40 seconds.
Additional Information	The missing notes in the intro is not a regression due to the recent YM changes, seems to have been happening for a while (always?). However, the same music track seems to only randomly fail when played on the game's Sound Test (example savestates of both failure and success attached).
Github Commit

Flags	Verified with Original
Regression Version
Affected Sets / Systems	genesis and clones [oozeju]

Attached Files	genesis_tmss oozeju.zip (83,080 bytes) May 8, 2021, 19:28 Uploaded by ICEknight Savestates in Sound Test
Attached Files	genesis_tmss oozeju 0.218.zip (40,913 bytes) May 9, 2021, 17:14 Uploaded by ICEknight Savestate in Sound Test (playing correctly in 0.218)

No.18803 ICEknight Tester May 4, 2021, 16:55	Footage from Japanese Mega Drive (model 1) where you can also hear the intended sounds playing:
No.18807 Haze Senior Tester May 4, 2021, 22:52	is this a new bug, or an old one that could be attributed to the less than perfect Genesis emulation?
No.18823 ICEknight Tester May 8, 2021, 19:29	The problem seems to happen in the sound test too, albeit randomly. I've uploaded two savestates, one in which the music plays normally and one where it has problems playing that part.
No.18824 Haze Senior Tester May 9, 2021, 16:24	again, is this a new bug, or an old bug?
No.18826 ICEknight Tester May 9, 2021, 17:13 edited on: May 9, 2021, 17:36	As I mentioned in "Additional information", this has been happening for a while (0.218 won't play the notes correctly on the intro). However... I've just noticed that I can't trigger the bug from the sound test in MAME 0.218, so that might actually be a regression (or perhaps the bug is just very random and difficult to pull)? I'm attaching a savestate for that version, where it plays correctly.
No.18827 Haze Senior Tester May 9, 2021, 19:16	Ah, I missed that update to the report. Maybe it's a timing thing then. I'm not going to be touching the Megadrive emulation code again however, so until somebody else does it won't be looked at.