x2/3/4 latency test using Frame Latency Meter

[Gizzmoe]

Just found this on Youtube.
https://www.youtube.com/watch?v=-20tF0CIMOk

Frame Latency Meter download:
https://gpuopen.com/flm/

How to use FLM:
https://www.youtube.com/watch?v=ybcUldLg_nw

[I Am Not Amused]

Spook님이 먼저 게시:

I do wonder how much of that can be chalked up to our brain associating a higher-FPS visual with a lower latency.

I haven't noticed it. You can simulate higher FPS with motion blur. Games that have a correct motion blur implementation that takes per pixel movement into account make 60FPS look more like 100FPS (the modern Doom games and System Shock Remake are examples that come to mind.) I don't feel like input lag changes at all even if my brain is fooled into thinking I'm seeing a higher frame rate.

The reverse is also true. There are games that have pretty much no lag at all even at 20FPS. Witcher 3 (next gen update) can be capped to 20FPS in the nvidia control panel and the latency feels exactly the same as 60. (RTSS doesn't work for this because for some reason, in this one game, its FPS limiter has much more input lag compared to Nvidia's.) I can clearly see it's 20FPS and therefore looks really choppy, but looking around with the mouse is extremely snappy and responsive.

As the difference between 60x2 and 60x4 should theoretically be a mere 4.17ms, or 1 frame at 240hz, if my thinking on this is correct. Which probably nears being unable to identify in a blind test.

Do you agree with the 4.17ms?

Yeah. The math works out that way. I think that it's easier to detect such a small difference with a mouse (if the mouse is fast enough that is, like 1000Hz polling rate or higher.) Mouse look in an FPS or a third-person view game feels just that little bit less floaty with x4. I don't think moving the mouse in such a game has anything to do with reaction times. We're not reacting to anything. But we can see and feel the difference.

It's kind of like playing a game (without FG at all) at 120FPS@120Hz (8.33ms frame time) and then going to 240FPS@240Hz (4.17ms frame time.) That's also a difference of just only 4.17ms, but the difference (at least to me) in how responsive mouse look feels is quite obvious, even if I use motion blur to make both look the same (as a test only, I never use motion blur at high frame rates.) And I think most people can as well. Probably.

So I'd say it's no wonder that 60x4, even though it's only a 4.17ms improvement, can be felt as better. I don't think it's placebo.

[Spook]

I Am Not Amused님이 먼저 게시:

Spook님이 먼저 게시:

I do wonder how much of that can be chalked up to our brain associating a higher-FPS visual with a lower latency.

I haven't noticed it. You can simulate higher FPS with motion blur. Games that have a correct motion blur implementation that takes per pixel movement into account make 60FPS look more like 100FPS [...]

So I'd say it's no wonder that 60x4, even though it's only a 4.17ms improvement, can be felt as better. I don't think it's placebo.

So i did some quick testing in TTP2 at 55 base-fps and Gsync on, and i agree that there is a perceived responsiveness difference between x2 and x4 and FLM also consistently measures about >75% of the theoretical 4.17ms difference (~25ms vs ~28ms). But when i turn on motion-blur to vastly reduce the difference in smoothness between x2 an x4, the perceived difference in responsiveness becomes way less. About 80% if i had to give it a number. So i'm not entirely convinced that latency is that only factor in the perceived-responsiveness equation. Though it's cool to see the theoretical difference measures just about like you expect and is indeed present.

*The difference may even be a bit bigger at a fixed refresh rate, on most displays. As Gsync eliminates the difference in scanout-speed between 60 and 240.

**I should also note that when i set Scanline-sync from 1 to 2060 @50hz(4k-monitor), which measures a difference of about 9ms, i perceive less of a difference in responsiveness than from LS going from x2 to x4 at the same base-fps.

[David Fifield]

I Am Not Amused님이 먼저 게시:

Spook님이 먼저 게시:

I do wonder how much of that can be chalked up to our brain associating a higher-FPS visual with a lower latency.

I haven't noticed it. You can simulate higher FPS with motion blur. Games that have a correct motion blur implementation that takes per pixel movement into account make 60FPS look more like 100FPS (the modern Doom games and System Shock Remake are examples that come to mind.) I don't feel like input lag changes at all even if my brain is fooled into thinking I'm seeing a higher frame rate.

The reverse is also true. There are games that have pretty much no lag at all even at 20FPS. Witcher 3 (next gen update) can be capped to 20FPS in the nvidia control panel and the latency feels exactly the same as 60. (RTSS doesn't work for this because for some reason, in this one game, its FPS limiter has much more input lag compared to Nvidia's.) I can clearly see it's 20FPS and therefore looks really choppy, but looking around with the mouse is extremely snappy and responsive.

As the difference between 60x2 and 60x4 should theoretically be a mere 4.17ms, or 1 frame at 240hz, if my thinking on this is correct. Which probably nears being unable to identify in a blind test.

Do you agree with the 4.17ms?

Yeah. The math works out that way. I think that it's easier to detect such a small difference with a mouse (if the mouse is fast enough that is, like 1000Hz polling rate or higher.) Mouse look in an FPS or a third-person view game feels just that little bit less floaty with x4. I don't think moving the mouse in such a game has anything to do with reaction times. We're not reacting to anything. But we can see and feel the difference.

It's kind of like playing a game (without FG at all) at 120FPS@120Hz (8.33ms frame time) and then going to 240FPS@240Hz (4.17ms frame time.) That's also a difference of just only 4.17ms, but the difference (at least to me) in how responsive mouse look feels is quite obvious, even if I use motion blur to make both look the same (as a test only, I never use motion blur at high frame rates.) And I think most people can as well. Probably.

So I'd say it's no wonder that 60x4, even though it's only a 4.17ms improvement, can be felt as better. I don't think it's placebo.

motion blur is terrible...makes it extremely hard to aim and gives a lot of people motion sickness. In reality there is no motion blur from moving your head.