New emulation method to eliminate input lag

Darksavior

@mediamogul I'm not enabling the second core. Is there a difference?

mediamogul

@darksavior said in New emulation method to eliminate input lag:

Is there a difference?

Definitely. Without it being active, I get a drop of 20-30 FPS past a 2 frame run-ahead in both lr-fceumm and lr-snes2010 (The only two cores I've tested). I'm actually able to get a steady 60 FPS with no stutter in lr-fceumm with 5 frames of run-ahead and rewind enabled, which of course is a decent hit to the processor in and of itself.

Darksavior

@mediamogul Ah ok, that helps a bit. Unfortunately, even with the crt-pi shader off, I still notice and feel the jerkyness when set to 3 or 4 (really noticeable at 4) on fceumm/genesis gx so I'll leave both instances enabled at 2. I have the overclock setting on for NES which it's really needed in megaman 3 and probably tons of others.

It also doesn't help when I enable the fix slowdown hack in snes9x2010, which I'll need to turn off and actually look into what games actually need it. So far it's just super rtype.

mediamogul

@darksavior

Interesting. Results with run-ahead on the Pi may end up varying greatly with users, depending on a number of factors. Fortunately for you specifically, if you do plan to continue using it, 1-2 frames generally seems to be all that is needed in most cases.

Keltron3030

Are these input lag settings available on 1.7.1?

dankcushions

@keltron3030 no

Keltron3030

Shouldn't updating retroarch from source get me to 1.7.3? It still shows 1.7.1 on the GUI. Sorry for a likely dumb question.

dankcushions

@keltron3030 you have to update your retropie-setup script first.

Keltron3030

@dankcushions

Oh, got it thanks. Now I'm on 1.7.3 and I see latency settings; thanks. Now my hot keys don't work, dammit! 🤪

mediamogul

In trying to read as much as I can to understand run-ahead better, I found where the developer of the feature (Dwedit) has stated that a setting of 1 frame of run-ahead "should almost always be safe" in games that have inherent latency. This likely only excludes Atari 2600 titles, as there is no inherent latency for those games, by nature of how they were programmed, so naturally run-ahead would have no benefit there.

Keltron3030

@dankcushions

Oh, it's awesome. Totally fixed Contra and MegaMan 2 for me. Thanks guys for pointing this out.

mediamogul

@keltron3030 said in New emulation method to eliminate input lag:

Totally fixed Contra and MegaMan 2 for me.

Last night I held my own and survived all three rounds against Mike Tyson for my first time ever. Of course he won by decision, but my next goal is to "git gud" and send him to the mat with a second round TKO.

pjft

@mediamogul Thank you for the detailed response. I was hoping there'd be a stable "default-ish" setup that would work for the majority of cases in each system, and then I'd adjust the ones for which it didn't work.

From reading your developments, I believe 2 might hopefully be the right value for nes, genesis, and potentially snes as you're describing - with the 2nd core, of course.

I'll dig into that in the coming week, many thanks all!

mediamogul

@pjft said in New emulation method to eliminate input lag:

I was hoping there'd be a stable "default-ish" setup that would work for the majority of cases in each system

A setting of '1' should actually be stable across the board, barring 2600 games. Anything more in many games will alter your timing in the opposite direction as latency and even create artifacts, such as single-frame 'game over' screens and sprite interactions that shouldn't carry over from your actual input. Still, a setting of '2' is only adding one more frame and it's possible that artifacting would rarely be noticed.

I'll dig into that in the coming week

Let us know how it goes.

Keltron3030

Hey guys how to I enable the latency features for just some emulators. Do I need to setup custom emulator config files or is there an easier way to do this through the gui.

mediamogul

@keltron3030

You could enable it for individual systems by adding

run_ahead_enabled = "true"
run_ahead_frames = "1"
run_ahead_secondary_instance = "true"

to /opt/retropie/configs/chosen-system/retroarch.cfg above the #include line

Keltron3030

@mediamogul

Excellent, thanks a lot.