Viewing Issue Advanced Details
ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
07211 Sound Minor Always Jan 25, 2019, 03:53 Mar 16, 2021, 12:06
Tester Chamajid View Status Public Platform MAME (Official Binary)
Assigned To Resolution Open OS Windows 10 (64-bit)
Status [?] Acknowledged Driver midtunit.cpp
Version 0.205 Fixed in Version Build 64-bit
Fixed in Git Commit Github Pull Request #
Summary 07211: midtunit: MK music tempo slower then actual arcade
Description Hi

First of all, thankyou for fixing the extra drums on 0.193 for midtunit.cpp. Now the only imperfection remaining in the game sound is the tempo of the music. It sounds like the music is slower in mame then the arcade. I have included an mp3 of the one of the intro tracks.

There is also a youtube video which has same music running on arcade PCB but the video host is talking. You can definitely see the music speed is right speed there.

Steps To Reproduce you can hear it in the player intro or at the character screen. But this affects all music of the game.
Additional Information
Github Commit
Regression Version
Affected Sets / Systems midtunit
Attached Files
mp3 file icon 02 - In the Beginning.mp3 (2,178,949 bytes) Jan 25, 2019, 03:53 Uploaded by Chamajid
Mp3 from actual
There are no relationship linked to this issue.
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Jan 25, 2019, 21:48
edited on: Jan 25, 2019, 22:01
I took a look at this and the tempo is slower on mame. It could be a clock speed Yamaha YM2151 ADPCM sound board issue. I will take a look at the sound driver.
This could affect other games like NBA Jam, Total Carnage, and T2 as well.
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Jan 25, 2019, 22:20
Can you please tell me which file you will be looking at from the source? I tried to search but having no clue of how MAME works I couldnt guess. This will be educational.
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Jan 26, 2019, 14:17
To understand how MAME works I would refer to the documentation manual here.

There are multiple files for the game driver
src/mame/drivers/midtunit.c - main game driver MK, T2, NBA JAM etc.
There are references to the video and machine folders as well depends on the game.

src/mame/audio/williams.c - Most likely it would be here. This game uses a Yamaha YM2151 for FM, a DAC Chip, and OKI 6295 for ADPCM speech

Now is this an easy fix? No. This hardware is quite complicated. I have consulted with someone I know from the VGM music forums
that is an expert with sound drivers. The fix is either something with the timers, interrupts or the way the main pcb and the sound board updates for the emulation. Definitely a timing problem somewhere to make the sound tempo slower than the real machine but the pitch is correct.

.c file is source file
.h is header
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Jan 26, 2019, 17:12
Thanks vidpro1. I tried overclocking the adpcm sound cpu to 104% and it looks like that fixes it. Is there a way to save the overclock setting?
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Jan 27, 2019, 00:40
Hmmm. I always thought it was slower by design. I could've sworn the music speed up as the match went on similar to how the music behaves in the Megadrive version of Super Street Fighter 2 or the game and watch gallery series. Here's another pcb video for checking:
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Jan 27, 2019, 12:55
edited on: Jan 27, 2019, 16:34
Mortal Kombat's Arcade Music does not speed up when a player is about to be defeated as it uses a different sound call for that.
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Mar 5, 2020, 02:06
So its been more then year. Does some try looking into this?
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Mar 5, 2020, 07:05
edited on: Mar 5, 2020, 07:06
The oldest open bug registered here is from 2008. What's 1 year? ;)
Jokes aside, if you don't see the report changed to fixed, assume no one has worked on it.
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Mar 16, 2021, 02:47
Trying to set the clock speed from 100 to 114 percent speeds up the YM2151 synth but the pitch is going higher.
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Mar 16, 2021, 06:22
you gotta do something as no one has looked into it yet.
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Mar 16, 2021, 12:06
Being annoying is the easiest way to ensure no-one looks into it. If you keep this up, you’ll get demoted to viewer.