Sub 1 Frame Lag


#1

Can anyone explain to me how the game actually handles/deals with sub 1 frame lag? I’ve heard some people say “it doesn’t affect anything.”

At the very least if you do an input in the last X milliseconds of a frame (where X is the input delay) it should at least be registered on the next frame, right?

I’ve also heard that the way its handled on a monitor is by splitting the frames unevenly, so certain frames get dropped?

All I know for sure is that monitors with sub-1 frame lag (obviously the evo monitor/Asus in particular) feel different to me, consistently. Can someone tell me what’s really going on here?


#2

There are lots of frames:
The frame currently on display.
Some number (possibly 0) frames buffered by the display
The frame that’s being sent out from the console
The frame that’s cued in the tripple buffer (possibly discarded)
The frame that’s being rendered.
The frame that’s being simulated by the game engine.

There’s also lag on the controller bus.

When people talk about sub 1-frame lag, they’re typically just talking about the time that the video takes to go from the console to show the display. Beacuse it takes 3-4 frames (~ 60 ms) for the console output to update in a way that reflects your input, you’re unlikely to notice more lag. It’s a rather crude measurement of timing, but things get kind of tricky if you want to get fancier anyway because video goes from dark to light and light to dark at different rates and so on.

It’s also worth pointing out that lag becomes much more noticable around 100 ms.


#3

If we rule everything but the display itself as a constant, how does a CRT compare to, say, the “EVO monitor” ASUS in terms of absolute input lag?

The ASUS is sub-1 frame in terms of input lag, but since that number is not zero, nor is it the same amount of input lag as a typical CRT, the question is: what is happening on the more technical side and on the more practical side, how does it affect the player(s)?


#4

I’m not sure. I haven’t seen any tests of both using the same methodology.


#5

bump