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RetroArch fixes Input Lag
05-08-2018, 11:01 PM
Post: #2
RE: RetroArch fixes Input Lag
Well, what it's doing is basically using save states. It's easier to understand if you ignore internal game latency for a moment:

Let's say you have an input lag of 50ms. That means when you physically press a button it takes 3 frames before the game actually "sees" that button press. This might be caused by hardware, cables, drivers, monitor refresh rate latency, whatever.

So this feature basically takes a save state every single frame (kinda like rewind.) When a button press finally makes it through the hardware, it loads the save state from three frames backward, presses the button, and then skips frames back to where it was before. This way it's like it happened right when you pressed it.

It actually sounds like it's constantly rewinding to keep FPS stable (rather than only bad when you press buttons.)

This makes more sense when the game has internal latency, because then you skip the frames where it wasn't reacting (yet) to what you did.

The more Mhz and RAM a device has, the more the save state will cost. The PS1 had like 3MB of RAM, but the PSP has 32MB. Constantly saving and loading state would definitely be... hard on PPSSPP, mostly because of that RAM which is the slowest part of the save operation. It might even be worth it at that point to sacrifice some jit speed to track changed pages of RAM to reduce the sheer data of save states.

Interesting feature though, especially for old retro devices with tiny RAM.

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RetroArch fixes Input Lag - fivefeet8 - 05-07-2018, 04:24 PM
RE: RetroArch fixes Input Lag - [Unknown] - 05-08-2018 11:01 PM
RE: RetroArch fixes Input Lag - fivefeet8 - 05-09-2018, 05:03 AM

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