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.

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

Postby open » 16 Jul 2017, 12:14

knypol wrote:Why should I use Vsync ON with G-Sync? If i have capped 3 frames below my max refresh whats the purpose of VSYNC in Nvidia CP?


If you stay within the GSYNC range there isn't much affected by the setting. Its just sort of a fallback mode.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby RealNC » 16 Jul 2017, 14:33

knypol wrote:Why should I use Vsync ON with G-Sync? If i have capped 3 frames below my max refresh whats the purpose of VSYNC in Nvidia CP?

This thread assumes you have read the article. When you read it, you will find out that the vsync setting does not actually control vsync when you use g-sync. It controls a tearing prevention mechanism in the g-sync module, and it has nothing to do with vsync.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby knypol » 16 Jul 2017, 15:23

On pg258q i havent noticed any tearing with g-sync and vsync off and im very sensitive to it. Basically teraing was only reason i invested to g-sync. Maybe some games which i'm not playing have some problems...
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby RealNC » 16 Jul 2017, 16:33

If the only reason you invested in g-sync is tearing, then you need to make sure vsync is set to "on" in the nvidia panel.

There is no reason to disable vsync when using g-sync. Is there a reason you disable it?

All of this is explained in the article.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby open » 16 Jul 2017, 16:39

RealNC wrote:If the only reason you invested in g-sync is tearing, then you need to make sure vsync is set to "on" in the nvidia panel.

There is no reason to disable vsync when using g-sync. Is there a reason you disable it?

All of this is explained in the article. Did you read it?
knypol wrote:On pg258q i havent noticed any tearing with g-sync and vsync off and im very sensitive to it. Basically teraing was only reason i invested to g-sync. Maybe some games which i'm not playing have some problems...


I have the same monitor and I use gsync with vsync off with fps limit of 300 for overwatch. The tearing is hard to notice at 240 refreshes and 240+ fps. And when it goes lower gsync is very nice to keep it smooth. I don't really care alot about tearing. It wasn't even that bad at 144hz but the micro stutters were bad when framerates were in weird proportion to refresh.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby jorimt » 16 Jul 2017, 17:08

Regarding the recent conversation, the only problem I've ever had with G-SYNC + V-SYNC "Off" is 1, Nvidia's choice of labeling, and 2, the adjoining confusion by users that has followed.

G-SYNC + V-SYNC "Off" is adaptive G-SYNC, and will tear at some point, plain and simple. If the user understands this, and wants to use it anyway, go for it; that's the best of PC gaming, choice. Just don't use it and claim G-SYNC is broken when you see tearing, even inside the G-SYNC range.

@open, as for 240Hz G-SYNC + V-SYNC "Off," I agree that is a viable method. I have a 240Hz G-SYNC display myself, and its true that the difference between G-SYNC and V-SYNC OFF in the 238+ FPS range is there, but quite small.

As I stated in my article, while with framerates above the refresh rate tearing artifacts can effectively appear as microstutter, with a 4.2ms scanout, 240Hz in the same instance means even 1000 FPS would only see up to four tearlines on-screen at any given time, and for a very short period due to its sheer scanout speed. This translates to a much smoother V-SYNC OFF experience than at lower refresh rates.

If we ever hit 1000 FPS/1000Hz-capable displays, the gap between G-SYNC and V-SYNC OFF will be even smaller, though G-SYNC would still have the edge at much lower framerates.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby Chief Blur Buster » 17 Jul 2017, 10:56

open wrote:I have the same monitor and I use gsync with vsync off with fps limit of 300 for overwatch. The tearing is hard to notice at 240 refreshes and 240+ fps. And when it goes lower gsync is very nice to keep it smooth. I don't really care alot about tearing. It wasn't even that bad at 144hz but the micro stutters were bad when framerates were in weird proportion to refresh.

It's certainly true that "refresh-rate-mismatch" microstutters are worse at lower refresh rates.

Mathematically, the stutter amplitude is equal to the inverse of frame rate.

Just covering ground, just to be safe. Definitions of stutters somewhat vary, but stutter, judder, microstutters, generally is defined as us by.

regular stutter: What people see at low frame rates even at perfect frametimes. e.g. 20fps, 24fps, 30fps
micro stutter: Visible minor erraticness in motion (even at high framerates, still visible but faint at 240Hz)
a stutter / single stutter / frame drop: A single stutter, usually a single frame discontinuity (frame repeat, frame drop, frame skip). Easy to see during perfect motion (e.g. TestUFO), especially in blur-reduced mode.
judder: Often similar to a form of microstutter, I've usually used this term to define 3:2 pulldown (24fps played at 60Hz)

TestUFO Animations of comparing "regular stutter" of different framerates
At 960 pixels per second and 240 frames per second, the stutter amplitude is only 4 pixels -- that's your motion blurring thickness as seen at http://www.testufo.com (excluding GtG-added motion blurring -- that's above and beyond [url-http://www.testufo.com/eyetracking]eye-tracking motion blur[/url]) .... But it also happens to be the microstutter amplitude too (e.g. for harmonic microstutters -- e.g. 239fps/241fps at 240Hz -- will create up to a 4-pixel "apparent" microstutter relative to fluid eye tracking position)

High-frequency stutters blend into motion blur
A great demo of stutter amplitudes can be seen at TestUFO count=6 for http://www.testufo.com/framerates#count=6
At higher framerates, the "stutter" is so high frequency that it blends into human-perceived motion blur.

Motion Blur Reduction
The Black Frames animation configured to a large number of UFOs (for 240Hz users, for [url=[url=http://www.testufo.com/#count=4]120/144Hz users[/url], and for 60Hz users) is also extremely educational too, on the motion-blur-versus-stutter relationship, in the exercise of black frame insertion motion blur reduction technique in a software-based manner. (Hardware-based motion blur reduction techniques such as strobe backlights -- can do a far better job -- since they can reduce persistence to sub-frame cycles via backlight strobing)

GSYNC and VSYNC OFF
Now with variable refresh rate, like GSYNC (for non GSYNC/FreeSync users, see this stutter-elimination GSYNC animation simulation) you don't have to worry about erratic stutters/microstutter effects until you hit really high framerates (240fps+). By the time you begin exceeding GSYNC's maximum (240fps) and use VSYNC OFF, the microstutters are already extremely small and you can keep gaining lag reducing advantages. If doing things this way (GSYNC + VSYNC OFF), I'd suggest raising your framerate cap higher (e.g. >500) since our tests still show continued VSYNC OFF lag-improving advantages all the way to >1000fps. (That said, if CPU/GPU/mouse starts behaving weird at high framerates -- game engine limitations, CPU starvation -- then that's another story. It also helps if you adjust your multicore setting in Source Engine games).

While for most use cases, GSYNC + VSYNC OFF really isn't a super-big use for most gamers, and our testing concluded it has relatively little use -- I do think it's not useless. It is still useful in certain cases (A) It keeps microstutters away until you're already a really high framerate where the microstutters is now a very small amplitude, and (B) It lets you access the ultralow lag of ultra-high-framerate VSYNC OFF (e.g. fps_max 1000fps)
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby Chief Blur Buster » 17 Jul 2017, 11:23

jorimt wrote:Just don't use it and claim G-SYNC is broken when you see tearing, even inside the G-SYNC range.

This is completely normal. Tearing can still occur inside the GSYNC range.

This is because of frametime variances.

At 240Hz GSYNC and a framerate of 239fps, one frame might take 1/245th of a second, and the next frame takes 1/235th of a second.

The faster frame (1/245th sec) will interrupt the previous frame in mid-scanout (tearline!).

Even if you're running at 200fps on 240Hz GSYNC, a game engine with sufficiently highly variable frametimes, some frametimes might be faster than the refresh cycle. Those specific refresh cycles will likely have tearlines.

As long as you're OK with gradually increasing tearlines the closer to GSYNC max, and you're aiming for the "eSports-league" competitive benefits of ultra-high-framerate VSYNC OFF, it's a legitimate user choice. It does definitely keeps tearlines very low until you're already high framerates (where it's harder to see tearlines).

Most eSports players will not use VRR, but I also think that's partially because many of them aren't familiar with the specific VRR input lag gotchas and input lag eliminating solutions that we've discovered with VRR lag testing. So, if you are indeed a high-end competitive player (even if not quite eSports) -- that indeed wants to turn on VRR, and then raise fps_max to high values (e.g. exceeding twice your GSYNC max Hz -- such as 1000), there are still lag-reducing benefits. Albiet of heavily diminishing returns, as our graphs show -- often just a barebones millsecond or two in many cases for ultra-high-framerate VSYNC OFF.
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