Some info on the issue: When you start any of the Genesis games, the audio slowly gets out of sync until around 6 minutes in it starts to corrupt for about 20 seconds, then it resyncs, and the issue repeats faster each time. This is avoided if you bring up the in-game emu menu (pressing Z).
I first experienced this issue on a real Wii via the Devolution loader, wanting to fix it I tried nintendont, but the issue was identical. Why? It doesn't seem right, I played this loads on the old Cube and never encountered this problem.
So I went back and tested on a real GameCube, and I remembered right, there were no audio issues. Next I tested the Wii's GC mode using the official MIOS, no issues either, I tested a loader called DML, no issues, I suspected the CPU difference was the culprit, so I loaded the MIOS in Wii mode, despite some glitches there was no delay in the audio at all.
A few days ago I was allowed to test SMC on Dolphin 5.0-5139 on a capable PC, and was surprised to find that the aforementioned issue is present. I tried several settings, even messed with the overclocking option, and there was no change.
I had written a patch that helps a lot, but does not actually fix the problem. With the patch there is still a minor delay but instead of the corrupted sound there's a very faint skip. I played through the entirety of Sonic 2 and was quite pleased with the result.
Still I would like to know why it happens, why it's identical to devolution/nintendont, and how it can really be fixed.
Because of that I wanted to share it here, in hopes that someone might understand the problem better.
A video showcasing the issue.
I first experienced this issue on a real Wii via the Devolution loader, wanting to fix it I tried nintendont, but the issue was identical. Why? It doesn't seem right, I played this loads on the old Cube and never encountered this problem.
So I went back and tested on a real GameCube, and I remembered right, there were no audio issues. Next I tested the Wii's GC mode using the official MIOS, no issues either, I tested a loader called DML, no issues, I suspected the CPU difference was the culprit, so I loaded the MIOS in Wii mode, despite some glitches there was no delay in the audio at all.
A few days ago I was allowed to test SMC on Dolphin 5.0-5139 on a capable PC, and was surprised to find that the aforementioned issue is present. I tried several settings, even messed with the overclocking option, and there was no change.
I had written a patch that helps a lot, but does not actually fix the problem. With the patch there is still a minor delay but instead of the corrupted sound there's a very faint skip. I played through the entirety of Sonic 2 and was quite pleased with the result.
Still I would like to know why it happens, why it's identical to devolution/nintendont, and how it can really be fixed.
Because of that I wanted to share it here, in hopes that someone might understand the problem better.
Code:
NTSC-U
Audio Patch (SS)
202AA2F9 000005BE
042AA2F9 00000B7B
E0000000 00000000
PAL (60Hz mode only)
Audio Patch (SS)
202C8619 000005BE
042C8619 00000B7B
E0000000 00000000
NTSC-J
Audio Patch (SS)
202ABD11 000005BE
042ABD11 00000B7B
E0000000 00000000
A video showcasing the issue.