G-Sync and Cloned Displays

[Sparky]

e.g. 60fps suddenly changes to 45fps next frame, you're getting a GPU rendertime change of 1/45th of 1/60 = only about a 370 microsecond change in GPU rendertime during a single-frame sudden change from 60fps down to 45fps. GSYNC is perfectly capable of smoothing that stutter out, so reasonable sudden changes in framerates can still noticeably look much more stutterfree.

Sorry for going back off topic, but wouldn't the first frame at 45fps be 1/45 - 1/60, or 5.5milliseconds late relative to the animation interval? still a hell of a lot better than being 16ms late, but probably noticeable when compared to a constant 45fps.

[Chief Blur Buster]

e.g. 60fps suddenly changes to 45fps next frame, you're getting a GPU rendertime change of 1/45th of 1/60 = only about a 370 microsecond change in GPU rendertime during a single-frame sudden change from 60fps down to 45fps. GSYNC is perfectly capable of smoothing that stutter out, so reasonable sudden changes in framerates can still noticeably look much more stutterfree.

Sorry for going back off topic, but wouldn't the first frame at 45fps be 1/45 - 1/60, or 5.5milliseconds late relative to the animation interval? still a hell of a lot better than being 16ms late, but probably noticeable when compared to a constant 45fps.

I don't know if the best game engines do this that inaccurately, but it certainly doesn't look like a 5.5ms microstutter during a well-executed 45fps->60fps or 60fps->45fps transition in the best game engines.

BTW -- I would clearly see single a 5.5ms microstutter suddenly inserted in a stutterfree stream. It is nearly as big as a single framedrop during 143fps@144Hz during TestUFO tests; which I do notice (1/144sec = 6.9ms disjoint). GSYNC in the best games, don't create any stutters that noticeable during frame rate changes. It's game engine dependant, of course.

One good example is the GSYNC pendulum demo (now publicly available), which has a mode where the framerate randomizes between 40fps and 60fps at single frame intervals, but you never see a single microstutter caused by the random(40 thru 60) effect. But the fact that it's happening every single frame, may also have something to do with it: Averaged out, it looks smooth. Or that the GSYNC pendulum demo is displaying frames relative to start of rendertimes, rather than end of rendertimes. There is more to it going on, than it appears.

[GhostOrange]

I assume the frame pacing in SLI is currently done by adjusting backpressure, rather than buffering frames.

NVIDIA has been having occasional problems with combining GSYNC and SLI (getting better with new drivers), so I imagine they're trying to tweak the SLI framepacing to be more GSYNC compatible as we speak. I wonder if there are opportunities to combine GSYNC timing information with SLI frame pacing, to reduce SLI microstutters even further.

Yeah, framepacing is problematic from an input lag perspective (even SLI has more input lag than non-SLI), so it's simplest for GSYNC currently presents relative to end of GPU rendertimes.

I am creating a new thread for this issue (as my first thread on the BB forums!!) but I wanted to post here, too, because I think it's relevant.

Prior to installing G-Sync, I was running 2x SLI GTX 770 4GB and was getting around 145-150FPS in BF4. I was able to run Shadowplay and record on High with ~5FPS drop when it was running.

Now that I've installed G-Sync on the *exact* same system, when Shadowplay is enabled (note: NOT even running) it cuts my FPS down to 80FPS. This is a massive hit.

Since there are many users on this thread using similar setups I'm wondering if anyone else has experienced this?

Note that I have tried 5 different drivers, GF Experience 1.8, 1.8.1 and 1.8.2 with the exact same results. I have also tried OBS, which works well, but still takes about a 30FPS hit. I've seen similar issues in other games, too, though not cutting FPS in half.

The odd thing to me is that w/out Shadowplay I'm actually getting around 10-15FPS higher avg FPS w/G-Sync than without.

[HeLLoWorld]

Maybe for gsync sli it would be worth to try something else than afr again.
It scales less well, but maybe a 1.5 factor without sli lag and microstutter would be visually superior to 2x with drawbacks.
The pixel shader part at least could maybe be split without too much effort, the rest is another story. Maybe two half viewports would turn out well if the engine can eject geometry early, would be elegant. Pray for no artifacts in the middle.

And yes, giving timestamp of simulation to driver and having it prevent abrupt deceleration of lag to preserve spatiotemporal coherence and user input feedback temporal smoothness crossed my mind, though even if superior I don't hold my breath because it means less average fps in benchs.
For abrupt increase of frametime I guess there's not much to do cause doing the same would mean adding permanently adding a security margin lag. Don't know if I'm clear.

[Boildown]

Looks like its time to bump this thread. We've had 7 months of driver updates since my OP, and now the monitor I'd like to buy has been released.

Is it yet possible to clone the G-Synced DisplayPort to the Dual-link DVI port for my capture card? (I upgraded to a Datapath DVI-DL version a while ago.)

If not, is this feature coming? (This is probably a ManuelG question.)

If cloning the display isn't available or not possible, has anyone used OBS game capture while doing G-Sync on the ROG Swift at 120 or 144Hz? Did everything work normally?

Does Nvidia still plan to get G-Sync working on other ports than DisplayPort? I.e. DVI or HDMI? This was mentioned as being possible to do when G-Sync was first being revealed.

Thanks!

[ManuelG_NVIDIA]

Looks like its time to bump this thread. We've had 7 months of driver updates since my OP, and now the monitor I'd like to buy has been released.

Is it yet possible to clone the G-Synced DisplayPort to the Dual-link DVI port for my capture card? (I upgraded to a Datapath DVI-DL version a while ago.)

If not, is this feature coming? (This is probably a ManuelG question.)

If cloning the display isn't available or not possible, has anyone used OBS game capture while doing G-Sync on the ROG Swift at 120 or 144Hz? Did everything work normally?

Does Nvidia still plan to get G-Sync working on other ports than DisplayPort? I.e. DVI or HDMI? This was mentioned as being possible to do when G-Sync was first being revealed.

Thanks!

We will have more information on this later on. Stay tuned.

[Boildown]

We will have more information on this later on. Stay tuned.

Thanks!

[Cinder]

Hey Boildown, have you gotten anywhere with a G-Sync display and the Datapath DVI-DL?

[Boildown]

Hey Boildown, have you gotten anywhere with a G-Sync display and the Datapath DVI-DL?

I've yet to buy a G-Sync display because to my knowledge the drivers still won't let you clone a screen while the main screen is in G-Sync mode. I pinged Manuel_G on Twitter and he said he would check again, but never got back to me. I do have a GTX 980 now though, so if it would require the latest hardware to work, I've got it.

[Cinder]

I have a 980 and the Asus PG278Q G-Sync monitor. I have to lower my resolution to 1080p to clone my display over to the Avermedia card I have and G-Sync seems to work with cloning. At least my FPS in Battlefield 4 stays ~144, as it does without cloning the display and the game still feels smooth.

Apparently capture card options are pretty limited when you have a G-Sync display Only option I can think of is the Datapath DVI-DL and cloning the G-Sync display over to it...

I'm waiting on the next gen Nvidia cards, be it 980Ti or Titan or whatever they decide to call it and get two of those. I read somewhere that you can't clone displays when using SLI, so that might be show stopper for the only capture card option.