Friday, July 07, 2006


Adding sound

I've been busy improving the Sega X-Board driver, and the most important improvement in the next version will be sound support in After Burner II!

Both the YM2151 and SegaPCM emulators have now simply been ported from existing and open C sources to java (preventing to reinvent the wheel).
Also the general sound system needed a small change, because it didn't support stereo sound yet.

Both sound chip emulators have been hooked up in the X-Board driver, and the Z80 emulation has been enabled. Thankfully, the performance impact is smaller than I expected and with everything enabled, I can still easily run it at full speed with great sound.

There's still some wrinkles to iron out, though. Most importantly, the music tempo is too low for some reason. Could be a bug in the interrupt timing or maybe there's a bug in the YM2151 timer function, not sure yet...
Also I still need to implement and test the option to disable sound in the driver (in case things run too slow).

Another (not sound related) thing I noticed is that maybe the 68K emulator is not at fault regarding the wrong refuelling sequences I mentioned in my last blog. For some reason, this behaviour seems to have improved in my latest build and I didn't change anything in the 68K emulation at all (as I didn't find any possible bug in it yet). I'm not sure I know what it was exactly that improved this behaviour.

Anyway, I hope to have ironed out the last issues regarding sound emulation soon so that I can release a new JEmu2 update this weekend.

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