Unreal Engine 4 games flicker with gsync in dark areas

[tygeezy]

These spikes I dont think are large enough to drop it below the vrr floor.

They don't have to drop it below the VRR floor to cause this.

For instance, even on a G-SYNC module, with G-SYNC on + V-SYNC off, a frametime spike can cause a tear within the G-SYNC range. It just needs to be an abrupt enough jump from a higher to lower framerate or visa-versa.

Once I have a VRR (OLED) capable card, it will be interesting to see if the CX has this same issue.

Yeah I think these abrupt changes is what causes it and maybe why a game like modern warfare its not noticeable in game, but it is when you bring up the very dark menu.

Modern warfare doesnt have very stable frametimes, its kind of a wavy graph, but you dont see these large abrupt changes unless its loading shaders, in which case it will show in game.

[tygeezy]

These spikes I dont think are large enough to drop it below the vrr floor.

They don't have to drop it below the VRR floor to cause this.

For instance, even on a G-SYNC module, with G-SYNC on + V-SYNC off, a frametime spike can cause a tear within the G-SYNC range. It just needs to be an abrupt enough jump from a higher to lower framerate or visa-versa.

Once I have a VRR (OLED) capable card, it will be interesting to see if the CX has this same issue.

Okay, now that I know you picked up a 3080 do you still have sea of thieves installed? You can easily induce this pulsating light flicker by going to the lower deck of your ship and postioning your camera into the wall.

I think ultra engine 4 games tend to have a lot of micro stutters which causes these issues. I’m unable to trigger it in smoother engines such as frostbite or whatever they’re using for call of duty modern warfare.

[jorimt]

Okay, now that I know you picked up a 3080 do you still have sea of thieves installed?

I do, but on a secondary gaming drive that has since been de-synced from my current Windows re-install, so I'd have to install it again. And I would do that tonight, but I just happened to have ordered a 1TB 970 EVO Plus to replace my 3 year old 500GB 960 EVO, which I will be swapping out next week, so it will have to wait until then, else I'll have to reinstall SoT twice with how badly Window app installs are managed.

Once I get that done, I'll test that game and report back here though.

[tygeezy]

Okay, now that I know you picked up a 3080 do you still have sea of thieves installed?

I do, but on a secondary gaming drive that has since been de-synced from my current Windows re-install, so I'd have to install it again. And I would do that tonight, but I just happened to have ordered a 1TB 970 EVO Plus to replace my 3 year old 500GB 960 EVO, which I will be swapping out next week, so it will have to wait until then, else I'll have to reinstall SoT twice with how badly Window app installs are managed.

Once I get that done, I'll test that game and report back here though.

Awesome, thanks! I’m still hunting to get a 3080 myself. Are you using the windows store version of sea of thieves or steam version? I noticed the steam version with full screen exclusive mode has less vrr flicker.

Also, what tools did you use to calibrate your display?

[jorimt]

Awesome, thanks! I’m still hunting to get a 3080 myself. Are you using the windows store version of sea of thieves or steam version? I noticed the steam version with full screen exclusive mode has less vrr flicker.

Also, what tools did you use to calibrate your display?

Yeah, I "lucked" out by signing up for EVGA store notifications of the card, which later turned out to be a queue system. Still took two months for them to reach my place in the queue though, as I signed up in the evening on launch day.

My SoT is the Microsoft Store version.

I used ColourSpace HTL + an i1Display Pro (RevB) to calibrate my CX with a 3D LUT. It's involved, but gets the best results on these displays.

[jorimt]

You can easily induce this pulsating light flicker by going to the lower deck of your ship and postioning your camera into the wall.

Alright, I finally managed to test this; beyond the soft undulation of the lantern light, I'm not getting the flicker in this game, but I am in CoD Cold War:
https://www.avsforum.com/threads/2020-l ... t-60294485

It's entirely related to frametime performance, which in the case of Cold War and my specs specifically, appears to be triggered, in part, by CPU-limitation.

[tygeezy]

You can easily induce this pulsating light flicker by going to the lower deck of your ship and postioning your camera into the wall.

Alright, I finally managed to test this; beyond the soft undulation of the lantern light, I'm not getting the flicker in this game, but I am in CoD Cold War:
https://www.avsforum.com/threads/2020-l ... t-60294485

It's entirely related to frametime performance, which in the case of Cold War and my specs specifically, appears to be triggered, in part, by CPU-limitation.

Keep in mind if you’re playing the windows store version you need to make sure that gsync is enabled for windowed mode since full screen exclusive isn’t available for that version of the game.

Yes oled vrr seems even more sensitive to frame time variance flicker than lcd. Perhaps it’s because of its ultra fast response time?

[jorimt]

Keep in mind if you’re playing the windows store version you need to make sure that gsync is enabled for windowed mode since full screen exclusive isn’t available for that version of the game.

Yes oled vrr seems even more sensitive to frame time variance flicker than lcd. Perhaps it’s because of its ultra fast response time?

Microsoft Store games use Windows 10's FSO-style borderless/fullscreen hybrid mode that G-SYNC considers exclusive fullscreen, so the borderless/window G-SYNC mode need not be engaged for G-SYNC to work in that game.

I just checked again, and I experienced no flicker in that scenario, as my frametimes were steady enough with my specs in this particular game to avoid it in that instance. I also confirmed it was in VRR mode with the hidden CX menu.

As for why OLED does this, according to LG, the gamma curve is set for a fixed refresh of 120Hz, and when it deviates during VRR operation, the gamma fluctuates, creating flicker:
https://www.oled-a.org/lgersquos-48rdqu ... _9620.html

Gamma for OLED is optimized and fixed for 120Hz by establishing a fixed charging time for OLED sub-pixels. VRR is used when the frame rate is less than 120 Hz. When the OLED TV uses framerates less than 120Hz, the gamma curve is inconsistent with the frame rate. For example, a 40Hz frame rate is longer than 120Hz frame rate. Therefore, the lower frame rates results in sub pixels that are overcharged, causing flickering of dark gray images, which is noticeable for dark images rather than bright ones, because human eyes are more sensitive to low gray colors. LGD will likely solve this problem establishing multiple gamma curves optimized for lower frame rates.

Basically, while OLED doesn't need variable overdrive like an LCD does during VRR operation to reduce overdrive artifacts, it apparently needs something very similar, that being variable gamma adjustments per Hz to avoid flicker near black.

[tygeezy]

Keep in mind if you’re playing the windows store version you need to make sure that gsync is enabled for windowed mode since full screen exclusive isn’t available for that version of the game.

Yes oled vrr seems even more sensitive to frame time variance flicker than lcd. Perhaps it’s because of its ultra fast response time?

Microsoft Store games use Windows 10's FSO-style borderless/fullscreen hybrid mode that G-SYNC considers exclusive fullscreen, so the borderless/window G-SYNC mode need not be engaged for G-SYNC to work in that game.

I just checked again, and I experienced no flicker in that scenario, as my frametimes were steady enough with my specs in this particular game to avoid it in that instance. I also confirmed it was in VRR mode with the hidden CX menu.

As for why OLED does this, according to LG, the gamma curve is set for a fixed refresh of 120Hz, and when it deviates during VRR operation, the gamma fluctuates, creating flicker:
https://www.oled-a.org/lgersquos-48rdqu ... _9620.html

Gamma for OLED is optimized and fixed for 120Hz by establishing a fixed charging time for OLED sub-pixels. VRR is used when the frame rate is less than 120 Hz. When the OLED TV uses framerates less than 120Hz, the gamma curve is inconsistent with the frame rate. For example, a 40Hz frame rate is longer than 120Hz frame rate. Therefore, the lower frame rates results in sub pixels that are overcharged, causing flickering of dark gray images, which is noticeable for dark images rather than bright ones, because human eyes are more sensitive to low gray colors. LGD will likely solve this problem establishing multiple gamma curves optimized for lower frame rates.

Basically, while OLED doesn't need variable overdrive like an LCD does during VRR operation to reduce overdrive artifacts, it apparently needs something very similar, that being variable gamma adjustments per Hz to avoid flicker near black.

Hopefully they can have a software implementation where they can use the same game throughout the vrr range. Most of the time it isn’t noticeable.

[jorimt]

Hopefully they can have a software implementation where they can use the same game throughout the vrr range.

Some sort of partial software mitigation may be possible, but a complete solution is unlikely until it is addressed at the hardware level (separate of firmware) for future panels.

For now, the only way to avoid it in gameplay is to ensure steady frametime. For PC, this is easily controllable by lowering graphical effects and/or setting an FPS limit, for consoles, not so much.