03877: donpachi at least, possibly all MSM6295: [possible] Audio is too high quality

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
03877	Sound	Minor	N/A	Jun 11, 2010, 03:25	Jun 14, 2010, 03:29

Tester	trap15	View Status	Public	Platform
Assigned To		Resolution	Suspended	OS
Status [?]	Closed			Driver
Version	0.138u1	Fixed in Version		Build
		Fixed in Git Commit		Github Pull Request #

Summary	03877: donpachi at least, possibly all MSM6295: [possible] Audio is too high quality
Description	This bug is not confirmed, it has not been compared with a high-quality recording from a PCB. Donpachi uses 2 OKI MSM6295's, 1 for music, 1 for SFX. The music 6295 is clocked at 1.056MHz and the pin 7 is pulled high according to MAME (and this seems correct compared to the OST) and as such plays samples at 8kHz. When comparing output from MAME and the "[Original]" versions of the songs from the OST (which I presume are recordings from the PCB, since they have audible aliasing) it is apparent that MAME does not alias where the OST does. An artifact of the output not being actually 8kHz is shown in donpatch.png. The top graph is MAMEs output, and the bottom is MAMEs output reduced to 19kHz. There are a few other subtle differences, but the biggest difference is at the end. When comparing MAMEs original output to the OST, you also see a difference. In the donpachi.png the top is MAME, and the bottom is the OST.
Steps To Reproduce
Additional Information
Github Commit

Flags	Possible
Regression Version
Affected Sets / Systems	donpachi at least, possibly all MSM6295

Attached Files	donpatch.png (318,199 bytes) Jun 11, 2010, 03:25
Attached Files	donpachi.png (323,372 bytes) Jun 11, 2010, 03:45

No.06241 Fujix Administrator Jun 11, 2010, 14:02	The only available soundtrack contains both original version and PCB version. The former is made with the original raw PCM sounds, and the latter one is from PCB allegedly. But usually (99.9%) those sounds are filtered in various forms when mastering the CD, if we go over things like this, we need real direct recordings from PCB as well as technical details of the OKI6295 chip and its implementation.
No.06242 trap15 Senior Tester Jun 11, 2010, 14:07	Yeah, the one I'm referencing is the one "from the PCB." Like I said, this may or may not actually be a problem, depending on how well the PCB was recorded. I'll try to find someone with the PCB that can get a high quality recording and if/when I do, I'll compare them.
No.06246 Fujix Administrator Jun 14, 2010, 03:28	Please let us know when you get new information to reopen this entry. Thanks.