Unreal Engine 4 games flicker with gsync in dark areas

[y3nis]

I've got the same problem. So far as I understand, the flicker is not solvable; the gamma shift.

As Jorimt says, you want to achieve a steady framerate, but that's exactly the problem. I've used some games and the pendulum demo which all show the same problem.

Tested in pendulum (and AC odyssey and DMC5 and cyberpunk) with afterburner frametime overlay.
Gsync off: the frametime graph is flat at any framerate.(but only if I restart my tv after I've switched gsync off)
Gsync on: There are microstutters every few seconds, this happens at any framerate. The same stutters that can be seen in the framtime graphs posted in the videos in this topic.

I also think this problem happens only with LG tv's, I've got the C9 myself with a RTX3060ti. So far I haven't found a sollution, I Think there is none at the www atm. That's also why I joined this forum because this topic describes the exact problem that I also have. I hope a solution will be available soon.

I'll add a video soon

[tygeezy]

I think it’s just speculation whether or not it’s hardware that is the problem. Obviously it’s more ideal if tweaks to gamma through the entire vrr range will fix it, but I don’t think there is any confirmation outside of educated guesses.

[y3nis]

You just want a more steady framerate.
Here's what happens with my setup. This is recorded in pendulum but it happens in all games.
https://streamable.com/4pjk5r

When I disable gsync I'm able to achieve steady framerates, sometimes after restarting my tv.
Steps taken:
Gsync off:
steady framerate

Gsync on:
Drops shown as stutter in the motion test (these correlate to the spikes in the pendulum demo)

Gsync off:
still stutter
Restart tv
still stutter
Restart tv
Strangely the stutter is gone.

https://streamable.com/3v9y9t

[jorimt]

When I disable gsync I'm able to achieve steady framerates, sometimes after restarting my tv.

VRR being disabled on the LG isn't avoiding the issue directly because the frametime/framerate is better, it's avoiding the issue because it isn't dynamically adjusting the refresh rate of the display, thus the gamma curve remains the same regardless of frametime or framerate; you're system could be experiencing horrible frametime or framerate performance, and this flicker issue would not occur in fixed refresh rate mode.

However, when VRR is enabled on the LG, the refresh rate is dynamically adjusted, diverging from the fixed gamma curve, triggering visibility of the issue; the more sporadic the frametime = the faster/more abrupt the refresh rate change = the more apparent and severe the flicker/shift is.

Again, if I limit my framerate to a 100% achievable average in the given game with RTSS and frametime remains stable, I experience no flicker in gameplay with G-SYNC enabled.

Frametime performance and achievable framerate, however, is obviously heavily dependent on the given system capability mixed with the app/game being run, which is why some users say they don't notice it at all, and others say it's obvious.

What we're seeing is an OLED-specific reaction to fundamental VRR operation that LG didn't originally account for.

[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.

Typically store games do work like this yes. For me though the only way I get can gsync icon to pop is by telling that app to use gsync with window and full screen. Gear of war and for a horizon I get the notification without it.

[jorimt]

Typically store games do work like this yes. For me though the only way I get can gsync icon to pop is by telling that app to use gsync with window and full screen. Gear of war and for a horizon I get the notification without it.

You can't get SoT to work with VRR without setting G-SYNC to borderless/windowed? Hm, odd.

[tygeezy]

Typically store games do work like this yes. For me though the only way I get can gsync icon to pop is by telling that app to use gsync with window and full screen. Gear of war and for a horizon I get the notification without it.

You can't get SoT to work with VRR without setting G-SYNC to borderless/windowed? Hm, odd.

Yeah, it’s the only game I’ve tried from windows store that does this too.

[jorimt]

Yeah, it’s the only game I’ve tried from windows store that does this too.

Interesting, I can't replicate in SoT. I simply had G-SYNC set to "Enable for full screen mode" and in-game set to "Fullscreen," and VRR engaged on my CX. Do note, I did leave fullscreen optimization enabled for the exe as well.

[tygeezy]

Yeah, it’s the only game I’ve tried from windows store that does this too.

Interesting, I can't replicate in SoT. I simply had G-SYNC set to "Enable for full screen mode" and in-game set to "Fullscreen," and VRR engaged on my CX. Do note, I did leave fullscreen optimization enabled for the exe as well.

I don’t bother to disable full screen optimization for any game.