LG CX OLED vs good pc monitor input lag?

High Hz on OLED produce excellent strobeless motion blur reduction with fast GtG pixel response. It is easier to tell apart 60Hz vs 120Hz vs 240Hz on OLED than LCD, and more visible to mainstream. Includes WOLED and QD-OLED displays.
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jorimt
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Re: LG CX OLED vs good pc monitor input lag?

Post by jorimt » 30 Jun 2020, 11:55

AddictFPS wrote:
30 Jun 2020, 10:02
Like 3dfan, i'm also interested to know if BFI work at more fixed frequencies. Excuse the insistence :oops:
Again, I'll see if I have some time this upcoming weekend to investigate further.
AddictFPS wrote:
30 Jun 2020, 10:02
phpBB [video]
Ironically, I bought this game a couple days ago and was testing it in that same hub with "High" BFI, which does seem well suited to locked 60Hz side-scrollers.
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Re: LG CX OLED vs good pc monitor input lag?

Post by deama » 30 Jun 2020, 12:33

So low and medium BFI isn't really worth it? Only High?

Also, in the video above, he mentioned input lag worsens with BFI, is that true or did I miss hear him?

On a side note: does 120hz with BFI look better than 240hz without BFI?

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Re: LG CX OLED vs good pc monitor input lag?

Post by jorimt » 30 Jun 2020, 12:56

deama wrote:
30 Jun 2020, 12:33
So low and medium BFI isn't really worth it? Only High?
For any meaningful reduction in motion blur caused by display persistence (aka MPRT), correct.
deama wrote:
30 Jun 2020, 12:33
Also, in the video above, he mentioned input lag worsens with BFI, is that true or did I miss hear him?
You didn't mishear him, BFI always has a slight input lag increase due to the black frame (on any display). In this case, non-BFI game mode at 60Hz is about 14ms. Add a half-refresh cycle to that, and you get roughly an added 4-5ms, so about 19-20ms input lag total (not the lowest some gaming monitors can get in similar circumstances, but still excellent for a gaming TV in BFI mode).
deama wrote:
30 Jun 2020, 12:33
On a side note: does 120hz with BFI look better than 240hz without BFI?
On this TV or in general? Because this TV doesn't have a 240Hz option, even on PC.
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Re: LG CX OLED vs good pc monitor input lag?

Post by deama » 30 Jun 2020, 13:39

jorimt wrote:
30 Jun 2020, 12:56
You didn't mishear him, BFI always has a slight input lag increase due to the black frame (on any display). In this case, non-BFI game mode at 60Hz is about 14ms. Add a half-refresh cycle to that, and you get roughly an added 4-5ms, so about 19-20ms input lag total (not the lowest some gaming monitors can get in similar circumstances, but still excellent for a gaming TV in BFI mode).
Oh ok, so BFI mode adds about half a refresh cycle of input lag? So at 120hz with BFI, it would add... 7ms + 2-3ms = 9-10ms total?
jorimt wrote:
30 Jun 2020, 12:56
On this TV or in general? Because this TV doesn't have a 240Hz option, even on PC.
Yeah I mean in general, say with a monitor that can push 240hz and has the ability to enable BFI, but only on 120hz or lower, which option would be best for overall motion clarity?
Also, assume brightness isn't an issue when BFI is enabled.

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Re: LG CX OLED vs good pc monitor input lag?

Post by jorimt » 30 Jun 2020, 14:28

deama wrote:
30 Jun 2020, 13:39
Oh ok, so BFI mode adds about half a refresh cycle of input lag? So at 120hz with BFI, it would add... 7ms + 2-3ms = 9-10ms total?
I think in the case of the LG CX, it's half a refresh cycle of 120Hz, so about 4ms additional (anyone feel free to correct this if wrong), regardless of 60Hz/120Hz operation. But again not 100% sure.

I specialize in VRR, not strobing/BFI, so my comments here have been casual and not fully thought through or tested, so grain of salt.
jorimt wrote:
30 Jun 2020, 12:56
Yeah I mean in general, say with a monitor that can push 240hz and has the ability to enable BFI, but only on 120hz or lower, which option would be best for overall motion clarity?
Also, assume brightness isn't an issue when BFI is enabled.
The Chief said earlier in this thread that "High" BFI on this TV should be comparable in motion clarity to non-BFI 240Hz, but with none of the overdrive artifacts or crosstalk an LCD display would typically have in a comparable BFI mode.

In my casual by-eye tests using TestUFO thus far, however, it seems a little clearer than non-BFI 240Hz, but that could be because of the fact that again, OLED doesn't need overdrive, so MPRT (aka display persistence) is virtually the only factor here.
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Re: LG CX OLED vs good pc monitor input lag?

Post by deama » 30 Jun 2020, 15:08

I just tested a desktop implementation of BFI mode on my 120hz monitor. Games at 120fps felt like playing at 60fps, so I thought it'd be best to cap them at 60fps.
It indeed felt smoother at 60fps with BFI mode at 120hz total, it kinda felt like I was playing at 70-75fps rather than 60.

Here's the software implementation for the curious:
viewtopic.php?f=22&t=5625&start=20
Unfortunately I can't really use this as at 120hz, bfi mode basically sets it to effective 60hz, which gives me some flickering, and after testing a game with it, causes a slight headache, I don't think the headache will be a problem at 100+ effective hz though, so not really worth it to actually use this unless you have a 240hz monitor.
Also, for some reason it screwed up my colours, it basically felt like I was playing at 6-bit? There was lots of dithering etc...

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Re: LG CX OLED vs good pc monitor input lag?

Post by Chief Blur Buster » 30 Jun 2020, 15:50

jorimt wrote:
30 Jun 2020, 12:56
You didn't mishear him, BFI always has a slight input lag increase due to the black frame (on any display).
While BFI does create minor lag on this specific display -- that's an Incorrect generalization (without knowing details), BFI doesn't mandatorily require input lag.

Actually, not necessarily. BFI can be lagless if it's rolling-scan based that is realtime scanout-following.

However, current OLED processing creates some trickiness, but if that is overcome, a lagless rolling-scan BFI is definitely indeed possible.

BFI does add input lag, but it's not a law-of-physics issue for a lagless rolling-window scanout. CRTs do that already, and BFI can already be a chasing rolling-scan.

Image

In this sense, *THIS* type of scanout can be made lagless. (i.e. no BFI lag penalty).

BFI isn't necessary a global frame, but can be rolling-based.

Also, see Sony Trimaster rolling-scan BFI in high speed video (7.5ms scan window):

phpBB [video]


Image

From an old OLED FAQ on Blur Busters, Why Does Some OLEDs Have Motion Blur?

Fixed that for you:
jorimt wrote:
30 Jun 2020, 12:56
You didn't mishear him, BFI on this specific display has a slight input lag increase due to the black frame processing (for this particular display).
The latency of hardware based strobing on LCDs is because of the time differential between cable's sequential scanout and global flash. However, strobing can be rolling-based.

The Blur Busters website was called "www.scanningbacklight.com" in Year 2012 before renaming to a more mainstream sounding "Blur Busters", so I have known this for a decade -- the concept of rolling-windows strobing.

It's problematic for backlights due to internal light diffusion (from the ON segments to the OFF segments), but OLED has no such problem, assuming that you can remove full-framebuffer-based processing delays from OLED.
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Re: LG CX OLED vs good pc monitor input lag?

Post by deama » 30 Jun 2020, 16:21

Chief Blur Buster wrote:
30 Jun 2020, 15:50
...
Is this rolling scan? The one on the left looks like it's global, so just an on and off, but the one on the right looks like it's rolling, but is that due to it going at effective 120hz whereas the left one is going at effective 60hz? Or are they both rolling scan?
phpBB [video]
Last edited by deama on 30 Jun 2020, 17:08, edited 1 time in total.

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Re: LG CX OLED vs good pc monitor input lag?

Post by jorimt » 30 Jun 2020, 16:26

Chief Blur Buster wrote:
30 Jun 2020, 15:50
Actually, not necessarily. BFI can be lagless if it's rolling-scan based that is realtime scanout-following.
Ah yes, that technique slipped my mind in the context of this particular conversation, as the most commonly implemented BFI method on most (but not all) mainstream gaming displays is currently global, not rolling.

Should have said "you didn't mishear him, global BFI typically has a slight input lag increase."
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Author: Blur Busters "G-SYNC 101" Series

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Re: LG CX OLED vs good pc monitor input lag?

Post by AddictFPS » 30 Jun 2020, 16:55

deama wrote:
30 Jun 2020, 12:33
On a side note: does 120hz with BFI look better than 240hz without BFI?
This is my assumption: From motion smoothness point of view, i think that 120Hz OLED Rolling Scan BFI is better that LCD 240Hz non strobed. Both run at 240Hz internaly, and have the same frame MPTR 4.16ms, but:

OLED: Loop [ 4.16ms game frame + 4.16ms black frame ]
LCD: Constant game frames at 4.16ms

Without black insertions, there are double "retina persistence" per second. LCD 240HZ strobing at 120Hz is the most accurate comparison. But actualy i not know any LCD monitor with these specs that are 100% free of these 3 issues at the same time: crosstalk, overshot and very low brightness.

Viewsonic XG270 show a bit of crosstalk at 120Hz strobed, and can be reduced with shorther MPTR but at cost of brightness. Is overshot free. BenQ XL2746S fix crosstalk and brightness at 120Hz, but there are a bit of overshot, because BenQ not optimize overdrive based on frequency, is "stuck" at Off-Default-Premium.

Now this OLED TV solve all 3 issues and future panels can also fix the added input lag. Hope soon LG build gaming monitor 27" Flat FHD OLED 240/360Hz BFI Adaptive Sync, without doubt, a serious rival for current eSports monitors. Burn-in is allways a stone in the shoe, but maybe can be controlled with a correct maintenance, just like this TV does with features "Pixel Refresh", periodicaly screen shift of static contents, auto-screensaver if detect completely full screen static more that X time, etc... can't be avoided completely but can be reduced the wear speed.

Also fix black and contrast issues of LCD, OLED is a very good overall panel. Response time is very good, with a setting to avoid full black, maybe can solve these ramp up "from black to..." 9ms spikes that show Rtings review, apart of these two spikes, all GtG changes under ms ;)

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