Blur Buster's G-SYNC 101 Series Discussion

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag. List of G-SYNC Monitors.
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jorimt
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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by jorimt » 22 Jun 2017, 16:28

sekta wrote:Did you test ingame limiter with RTSS limiter active at the same time?
Would be interested to see when both are set to the same value, or ingame at Hz - 3 and RTSS at Hz - 2, or some other staggered set up depending on how much the ingame limiter fluctuates.
I did not.

That kind of testing goes far beyond the scope of the article, and I have a hard time wrapping my head around how I would even be able to measure such a difference with any useful conclusion, at least with my current equipment.

I mean, with Overwatch for instance, I suppose I could set both the in-game and RTSS limiter to 141 FPS at 144Hz at the same time, and compare them to the existing standalone in-game or RTSS reading, and see if they match one or the other, or are somewhere in between. I'm assuming it would be random, depending on the given run and how the system is responding during that test.

Honestly though, as long as you have frametime compensation enabled (V-SYNC "On") with G-SYNC, any advantage RTSS has in frametime stability over the in-game limiter is smoothed over by the aforementioned G-SYNC function, which is a moot point anyway, since RTSS adds up to 1 frame of delay where the in-game limiter does not.

This means while G-SYNC frametime compensation may be engaging more with the in-game limiter than it does with RTSS, the accumulative effect of those frametime adjustments with the in-game limiter active probably don't come close to the extra delay RTSS adds when it is the framerate's limiting factor.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by Sparky » 22 Jun 2017, 18:48

sekta wrote:Did you test ingame limiter with RTSS limiter active at the same time?
Would be interested to see when both are set to the same value, or ingame at Hz - 3 and RTSS at Hz - 2, or some other staggered set up depending on how much the ingame limiter fluctuates.
Well, only 1 thing is really limiting framerate at a time, and it's that that determines latency. Setting them to the same value means you don't get to decide which one is limiting framerate. Setting RTSS at -2 and in game at -3 can simplify things, so you can leave RTSS globally enabled, and just enable the in game cap for the games that have it. If the RTSS setting fixes the fluctuations from an in-game cap, it's still doing it by adding latency.

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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by sekta » 22 Jun 2017, 21:05

Sparky wrote:
sekta wrote:Did you test ingame limiter with RTSS limiter active at the same time?
Would be interested to see when both are set to the same value, or ingame at Hz - 3 and RTSS at Hz - 2, or some other staggered set up depending on how much the ingame limiter fluctuates.
Well, only 1 thing is really limiting framerate at a time, and it's that that determines latency. Setting them to the same value means you don't get to decide which one is limiting framerate. Setting RTSS at -2 and in game at -3 can simplify things, so you can leave RTSS globally enabled, and just enable the in game cap for the games that have it. If the RTSS setting fixes the fluctuations from an in-game cap, it's still doing it by adding latency.
That was the intention, to enable it globally. RTSS could still act as the last line of defense for games that do have an fps limiter and would have less latency than full blown vsync if the frame times were to fluctuate enough. Was wondering if it could smooth out the delivery at all without any noticeable input latency.

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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by jorimt » 22 Jun 2017, 21:37

The tests featured in my article show with just a -2 FPS in-game limit, that isn't at a risk of happening. In fact, if you have steady enough frametimes, just -1 FPS can nearly be enough in some cases.

What you should be more worried about is abrupt framerate drops (frametime spikes), not momentary framerate jumps (low frametimes) above the refresh rate; with an appropriate FPS limit, the G-SYNC frametime compensation mechanic will take care of those instances.

I see no benefit to stacking FPS limiters with G-SYNC enabled, and a single -3 FPS limit with either the in-game or RTSS limiter is already safe enough to avoid the G-SYNC ceiling at all times.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by Fixide » 23 Jun 2017, 05:16

On a 144Hz screen what is the best setting to adopt for gsync and dishnored 2 game? This is the only game where I really have bad results ...
My settings :
Nvidia panel : Vsync on + gsync on. Gsync full screen only.
In game : Vsync off. Frame rate limiter 90. Full screen on. Triple buffer off.

Thanks

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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by Glide » 23 Jun 2017, 07:56

Fixide wrote:On a 144Hz screen what is the best setting to adopt for gsync and dishnored 2 game? This is the only game where I really have bad results ...
My settings :
Nvidia panel : Vsync on + gsync on. Gsync full screen only.
In game : Vsync off. Frame rate limiter 90. Full screen on. Triple buffer off.
Thanks
The in-game limiter has to be set to 60 for smooth gameplay in Dishonored 2.
Something is broken in the engine.
jorimt wrote:I see no benefit to stacking FPS limiters with G-SYNC enabled, and a single -3 FPS limit with either the in-game or RTSS limiter is already safe enough to avoid the G-SYNC ceiling at all times.
I think the point is that you could leave RTSS enabled globally, if enabling an in-game framerate limiter would prevent RTSS from kicking in and adding up to 1 frame of lag.
That would be a lot more convenient than toggling RTSS frequently, or enabling it on a per-game basis.

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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by jorimt » 23 Jun 2017, 09:14

Sure, you could, I just can't guarantee the results, so I'd still recommend using a single limiter at a time until something that specific could be tested.

Obviously though, I'm not one to be inconvenienced by simple manual operations, so I have a hard time sympathizing with those that find adjusting RTSS per game "daunting."

I could understand those who are, however, and they, of course, may use whatever combinations of methods they wish; just use at your own risk is all.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by RealNC » 23 Jun 2017, 10:22

Glide wrote:I think the point is that you could leave RTSS enabled globally, if enabling an in-game framerate limiter would prevent RTSS from kicking in and adding up to 1 frame of lag.
The whole "up to 1 frame of lag" when it comes to RTSS is not exactly as it sounds. RTSS does not add lag. It does not REDUCE lag. There's a difference. An in-game limiter REDUCES lag. RTSS has AT MOST the same lag as uncapped framerate at that specific frame time. Usually lower. Example, if uncapped you get 130FPS, if you cap to 129FPS with RTSS, you get either the same latency or lower. Not higher. (Usually lower, due to pre-render buffers as posted earlier in this thread.)

I think it might be best if we switched from "up to 1 frame of latency" to "less than 1 frame of latency." This is more correct even, since for RTSS to add 1 frame of lag, the game must run at infinite FPS.

Right now, we just make RTSS sound like it adds latency, even though it does not:

Uncapped: latency = frame time
In-game limiter: reduces latency below frame time; latency < frame time
RTSS: does neither reduce nor add latency; latency = frame time

Many people do not realize that at all. It has to sink in a bit: At worst, RTSS has the same input lag as vsync off uncapped at any given frame rate.

RTSS will not increase input lag. Not by 1 frame, not by 1/2 frame, not by anything.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by jorimt » 23 Jun 2017, 11:10

I'd be happy to amend "up to" to "less than" both in my article and in future references when discussing RTSS, but even I'm having a hard time wrapping my head around the concept.

For instance, how would we explain why RTSS sees higher latency with V-SYNC OFF than is seen with V-SYNC OFF + the in-game limiter with the same framerate limit, especially if what you say is the case?

Image

The only way I could think to isolate and verify this is to run the game at settings that would force my system to sustain framerates below the given refresh rate, test, and then test RTSS at that same framerate.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Post by RealNC » 23 Jun 2017, 11:39

jorimt wrote:I'd be happy to amend "up to" to "less than" both in my article and in future references when discussing RTSS, but even I'm having a hard time wrapping my head around the concept.

For instance, how would we explain why RTSS sees higher latency with V-SYNC OFF than is seen with V-SYNC OFF + the in-game limiter with the same framerate limit, especially if what you say is the case?
Because the in-game limiter can reduce the impact of frame latency on total input lag. At 100FPS, frame latency is 10ms. That is part of the total input lag. An in-game limiter however can remove some of that 10ms from the total latency, if the game renders at higher FPS.

Case 1: If the game needs 1ms (1000FPS) to render a frame, a in-game limiter 100FPS cap can potentially decrease total input lag by up to 9ms.

Case 2: If the game renders a frame in 10ms (100FPS), then a 100FPS in-game cap cannot reduce latency further.

RTSS on the other hand, will always behave as if the second case is always true. Regardless of whether the game renders the frame in 1ms or in 10ms, you will get the 10ms frame latency of 100FPS added to the total input lag. That latency is the same as if the game was running uncapped at 100FPS.

If you think about how external, non-predictive frame limiting is done (as RTSS does), it makes sense. The algorithm is quite simple. If the frame time is less than the target frame time (cap), wait until we reached the target frame time. That means regardless of how much time it took to render a frame, the result will always be the same as if the frame took Nms to render, where N is our target frame time. Thus, input lag is the same as if the game was rendering at the target frame rate.

In other words, RTSS is perfectly "neutral." It does not reduce nor increase latency. The in-game limiter reduces latency. (And NVidia's limiter increases latency.)

And, again, that's only "in theory". In practice, RTSS reduces latency in many games due to the frame buffering issue.
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