Audio Timing

[njz3]

Over the past week, I spent some time figuring out why the timers were so off on games like Scud Race and others. Many of the timer functions were set to use only one SCSP chip, where Model 3 is supposed to use two. I ported a handful of code from MAME and Audio Overload as well (like EG fixes), which has fixed many musical keyoff problems.

Also I removed a lot of code that seemed useless, like the REVERB_DIF stuff and functions such as TimersAddTicks2. The music in most games should now play close to what is heard on real arcade hardware! Unfortunately, there is still the one issue with VF3 where there's too much reverb on some songs, and apparently the intro in L.A. Machineguns doesn't quite play quite in sync with the intro (but I haven't tested that game yet). Here's my current modified code in the attached zip (haven't really done much with the DSP file yet):

Hi ConversusVans,
I tested your patch on last r793, and it actually make music play way too fast on Le mans and Scud Race compared to the real hardware.
I also tried to change the SysFPS to some other values to tune the music tempo (57.6, 60, even 10 or 90), as I did before, and it has no more effects on the music tempo.
I belive something is broken ?
Benjamin

[Conversus W. Vans]

Hey Benjamin,

I tried that new config option with the r795 build from Emu-France, and there is some improvement with the slow tempo for sure! It seems to not only make samples of SCSP music sound just like real hardware, but improves latency as well. I patched it to my build of SVN r793 with the MAME core that I integrated and tweaks I did for FM mixing, so that may explain why the config option became "broken". But great work!

I could also knock the values of the timing registers down to make songs play close to the real deal by not having pre-rendered guitars play too off-sync (this happens to be most noticeable in Fighting Vipers 2).

By the way, the patch you saw was most likely from December - there are many other changes made to the SCSP in my current build.

Thanks for that update.