05830: sms and clones [pstar] [captsilv] [shinobi] [kenseid]: Extra tones played along particular PSG musics

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
05830	Sound	Minor	Always	Jan 18, 2015, 18:45	Apr 9, 2016, 20:21

Tester	enik	View Status	Public	Platform	MESS (Self-compiled)
Assigned To		Resolution	Open	OS	Windows XP
Status [?]	Acknowledged			Driver	sega/sms.cpp
Version	0.157	Fixed in Version		Build	Normal
		Fixed in Git Commit		Github Pull Request #

Summary	05830: sms and clones [pstar] [captsilv] [shinobi] [kenseid]: Extra tones played along particular PSG musics
Description	Some tones, that don't seem to be part of the harmony, are played along particular PSG (not FM) background musics of the following scenes: - Intro sequence of Phantasy Star ( [pstar] and clones ); - End of the Scene Start screen and along first stage of Captain Silver ( [captsilv] and clones ). Updated the report (2015-05-24) to include: - 1st stage music of Shinobi ( [shinobi] and clones ); - 1st stage music of Kenseiden ( [kenseid] and clones ).
Steps To Reproduce	At the title screen of Captain Silver, press button 1 on controller 1 to start a new play session. Listen to the music of the Scene 1start screen and notice some extra tones played when it ends. Listen to the music of the first stage and notice the same tones playing soon after the music starts and repeated in other parts. Video reference, supposedly from original PAL hardware (skip to 1:04): At the title screen of Phantasy Star, press button 1 on controller 1 to start a new play session. Listen to the intro sequence music and notice some extra tones played along. Video references, supposedly from original hardware:
Additional Information	The old bug 1832 of MESS Bugzilla had a report of the issue with Captain Silver. When originally reported the issue, I discovered that extra tones are played only on the first channel. Then, I compared the sn76496 driver of MAME/MESS with the one by Maxim, of SMSPower. Maxim's driver has a predefined cut-off value, used to silence a PSG channel when the register has a lesser or equal value. I copied exactly the same line used to define the value and adapted the condition where it is used to the code of MAME/MESS sn76496 driver. The hack solved the problem and no problem was noticed with other games I tested. I'm attaching a newer version of the hack to this report, just for reference.
Github Commit

Flags
Regression Version
Affected Sets / Systems	sms and clones [pstar] [captsilv] [shinobi] [kenseid]

Attached Files	sn76496_capsilver.diff (745 bytes) Jan 18, 2015, 18:45 Uploaded by enik [Show Content]

No.11390 Tafoid Administrator Jan 19, 2015, 19:40	I compared emulation to the video (for Phantasy Star) and the most noticeable is the high pitched succession of notes at the beginning of the intro and every 7-8 seconds thereafter. I assume this is what you are referring to?
No.11393 enik Tester Jan 20, 2015, 02:34	Yes. The time interval for a PAL driver is about 7-8 seconds until the 5th succession of notes. After, the interval is doubled between 5th and 6th successions and between 6th and the 7th succession, that is the same as the 1st one because the music restarted at that point.
No.11677 enik Tester May 25, 2015, 01:24	Updated the report to include: - 1st stage music of Shinobi ( [shinobi] and clones ); - 1st stage music of Kenseiden ( [kenseid] and clones ).
No.12459 enik Tester Mar 12, 2016, 18:50 edited on: Mar 12, 2016, 21:37	Today while looking for other stuff, I found this reference in file /core/sound/sn76489.c of genplus-gx: 05/01/09 Eke-Eke (Genesis Plus GX) - Modified Cut-Off frequency ( according to Steve Snake: http://www.smspower.org/forums/viewtopic.php?t=1746 ) The SMSPower topic pointed by the URL refers to some problems that seem related to this bug report.
No.12461 hap Developer Mar 12, 2016, 22:30	Sound stream compression artifacts(aliasing) is a problem in the MAME core, not the device emulation itself. A rewrite of it is on Olivier Galibert's TODO.
No.12523 enik Tester Apr 9, 2016, 20:21	Just an update: I contacted Eke-Eke, he acknowledged that the cut-off value is a hack, we made some tests with his emulator, that also suffered from aliasing, and he found a way to get a correct sound without the hack, that will be committed to Genesis Plus GX probably along with some refactored code.