Fbaneo latest and run-ahead

[Hari-82]

Yesterday I finally updated my Fbneo romset, so I decided to unlock update the core as well. The thing is that now run-ahead doesn’t work properly with some games, the first time I noticed was with dodonpachi, during patterns of the first boss, then I tried r-type and it seems to work fine, then Galaga (the parent namco version) also freaks out (the background sky “moves” at every press of the fire button). I tried to disable second instance and it seems to solve the problem, but I don’t think that keeping it off is a great idea… I tested with my config and also with a fresh install, I used vulkan and gl core, and different video sync settings same results… I tested the old backed up core (I think aug 2021) and it works perfectly. So I think is something in the new core.

Can someone have a little test? I suggest galaga because is easier to notice the problem.

[hunterk]

I believe this is a result of improvements in the core and runahead. Evidently, second instance is only supposed to be used as a fallback with cores that get broken audio without it. So, disabling second instance is the correct move in this situation.

[Hari-82]

oh well, thanks for the answer!

so I guess tomorrow I’ll go “back to the future”, with the updated core, and test some games disabling second instance and see if there are any problems, to be fair when I tried turning second instance off I don’t recall getting any audio crackling…

[Cyber]

@Hari-82

to be fair when I tried turning second instance off I don’t recall getting any audio crackling…

Don’t worry, you won’t lose anything by disabling Second Instance with the FB Neo Core. It isn’t even officially supported but single instance is, just like in standalone FB Neo.

FBNEO fast forward; rewind throws off sound and video synchronization

Single instance runahead is the mode we officially support because it’s the only mode also available in standalone FBNeo. Any issue about it will be fixed as long as it’s reported. I can’t guarantee the same for second instance. Dwedit (author of the runahead implementation) made some interesting statement about single vs second instance here and there. Some people have indeed been using second instance because they think it’s faster, but actually it seems to be a placebo effect only happening…

[Hari-82]

I played some games with varying run-ahead setting up to 4 frames (strikers 1945) and all is working well! Turning second instance Off did indeed solved the problems and didn’t add any…

There might be a case to disable the option in the core option menu? or maybe few words to say that second Instance is not supported by the core and will most likely cause problems?

[BarbuDreadMon]

Note that it’s recommended to use latest retroarch nightlies, because they allow the core to differentiate between single and second instance, so that the core can properly tune the savestates for the requested mode.