EXPLAINER: Why Does OLED Stutter More At Low Frame Rates? (Fast GtG Pixel Response)

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EXPLAINER: Why Does OLED Stutter More At Low Frame Rates? (Fast GtG Pixel Response)

Post by Chief Blur Buster » 21 Oct 2022, 03:19

Crosspost from a HardForum reply.
GoldenTiger, post: 1045482733, member: 96811 wrote: Its probably a combination of virtually no sample and hold blur on the oled and hardware gsync vs software, that makes it not look as good [USER=93712]Archaea[/USER]. This sounds like a question for [USER=304509]Chief Blur Buster[/USER] to me... Try either going to blurbusters forum or see if he shows up here since I tagged him :).
I need to unpack my reply into two technical sections to clear up confusion.

So the topic of this thread distracts from another additional cause: Fast pixel response makes stutters more visible too.

Firstly, gametime:photontime sync in G-SYNC Compatible and G-SYNC Native can sometimes be different (e.g. Compatible usually stutters slightly more than Native). That can be a factor, but since an OLED is involved, I would like to tell everyone why low frame rates on OLED seems to stutter more.

TL;DR version

LCD stops stuttering beyond about 50fps
OLED stops stuttering beyond about 75fps
(depends on human)


1. Don't confuse GtG and MPRT. Both can add blur that hides stutter.
2. OLED is sample and hold (MPRT is not zerod out)
3. OLED simply visibly stutters until a higher frame rate because of faster pixel response (GtG is near zero). Slow GtG helps mask stutters.

That's why you need higher frame rates to compensate for the increased visibility of stuttering made visible by pixel response being too fast. That's why OLED stutters more at the same frame rate as LCD, especially for framerates between 40fps-70fps territory. Above 100fps, the effect is not an issue, but is a consideration for people who hate stutter and have to play at low frame rates. One method is to upgrade your GPU and lower game settings. Another method is to add GPU motion blur to compensate, if you get headaches from stutter in low frame rate games (e.g. Cyberpunk 2077).

(Note: For more reading, you can view the "Research" button on Blur Busters website, which has my favourite well-vetted explainers (Also, I'm cited in over 25 research papers now)

1. OLED has no GtG blur, but it has MPRT blur (MPRT = sample and hold)

OLED always has sample-and-hold blur.
You're talking about lack of GtG blur, not MPRT blur.

There are two different pixel responses, GtG and MPRT.
  • GtG is linked to how fast a pixel changes color.
  • MPRT is linked to how long a pixel stays for.
  • MPRT = sample and hold = persistence
  • Both GtG and MPRT adds display motion blur
On your LG OLED, view www.testufo.com/eyetracking -- the top and bottom UFOs still looks different.

That's because of sample and hold. Your eyes are moving (analog) to track moving objects. As you track the moving UFO, your eyes are in different positions at the beginning of a refresh cycle and at the end of a refresh cycle. If a refresh cycle is on the screen continuously for 1/120sec (with no black period), you see display motion blur.

Mathematically, at GtG=0 and framerate=Hz
Sample-and-hold 120fps 240Hz has half the motion blur of 60fps 60Hz.
Sample-and-hold 240fps 240Hz has half the motion blur of 120fps 120Hz.
Sample-and-hold 480fps 480Hz has half the motion blur of 240fps 240Hz.
Eliminating motion blur without BFI (strobeless motion blur reduction) requires sheer frame rate at sheer Hz, while keeping GtG as low as possible (OLED FTW!)

MPRT100% is generally equal to frametime on sample-and-hold (when excluding GtG), which is why you need to geometrically upgrade displays, e.g. 60Hz -> 144Hz -> 360Hz -> 1000Hz.

Remember, for (display=nonstrobed AND GtG=0 AND framerate=Hz), display motion blur almost perfectly matches a camera shutter:

Image

OLED follows Blur Buster Law (MPRT100%) much more closely because GtG=0.
This is why 240Hz-vs-360Hz LCD is barely visible (1.1x) because GtG is visibly nonzero.
This is why 120Hz-vs-240Hz OLED is much more visible (2.0x) because GtG is zero.

Note: With brand new test variables, in an experimental laboratory (Viewpixx sells 1440Hz projectors commercially), we have found over 90% of people (even grandmas) can tell apart 240Hz vs 1000Hz in scrolling-text readability tests, but it's hard to tell apart 240Hz-vs-360Hz, you gotta geometrically upgrade frame rates and refresh rates for framerate-based motion blur reduction on sample-and-hold displays. We now recommend 1.5x-2x framerate+refreshrate upgrades for power users, and 2x-4x framerate+refreshrate upgrades for mainstream audiences. Just like some family members didn't instantly tell apart DVD-vs-HDTV, most can tell apart VHS-vs-4K. This is true with refresh rate and frame rate geometric upgrades. Increased resolutions also raises the retina refresh rate (aka refresh rate of no further human benefit). Retina refresh rate is actually linked to the human angular resolving resolution versus the pixels step per frame, because that's the guaranteed minimum persistence blur (MPRT) -- 8000 pixels/sec on an 8K 1000Hz 1000fps sample and hold display still generates 8 pixels of visible motion blur -- and we found retina refresh rate is projected to be beyond 20,000 Hz on 180-degree 16K VR displays if you want to 100% completely avoid strobing. Strobing eliminates the retina refresh rate problem, but real life doesn't strobe, so a perfect strobeless display that is also blurless, is by necessity a ultra high frame rate at ultra high refresh rate. Hard to believe? Remember, I'm now cited in several peer reviewed research papers now. Click the Research button at Blur Busters.

2. Stutter is Persistence Too! There's a Stutter-to-Blur Continuum (DEMO)

Did you know stutter and persistence motion blur is exactly the same thing?
Stutters is caused by persistence too.

*Here, I will talk about perfect frame paced stutter (e.g. regular stutter of low frame rates like testufo.com#count=8), I'm ignoring judder, harmonic/cyclic stutter, or erratic frame rates for the purpose of this explanation

Persistence = object staying in same position, regardless of low frame rate (stutter) or high frame rate (blur)
Stutter = slow vibration = like a slow vibrating music string (string looks shaky)
Blur = fast vibration = like a fast vibrating music string (string looks blurry)

Stutter-to-Blur Continuum Demo: See For Yourself! A second demo: The same effect can be seen in framerate-ramping animations in VRR like the demo at testufo.com/vrr



Now if you're someone who have both an LCD and an OLED:
1. Try this on LCD. Stutters blends to blur earlier (at a lower frame rate)
2. Try this on OLED. Stutter blends to blur later (at a higher frame rate)
Why? Faster pixel response (OLED) raises the flicker fusion threshold of the stutter-to-blur continuum.
  • LCD motion usually stop visibly stuttering at ~50-55fps* for most human eyes, which is why 60fps looks smooth (but still blurry)
  • OLED motion usually stop visibly stuttering at ~65-75fps* for most human eyes, which is why 60fps looks stuttery (hasn't fully blended to blur yet)
Different humans have different flicker fusion thresholds, so the ranges may be different for you.
But no matter what, slower and faster GtG moves the threshold of the stutter-to-blur continuum.

Notice that LCD stops stuttering just a tad below 60fps, and OLED stops stuttering just a tad above 60fps? Bingo.

Now, go to 120fps instead. That framerate is usually above most humans' flicker fusion threshold, so both has just blur from persistence.

Regardless, LCD 120fps and OLED 120fps still has too much motion blur to read the street name labels at TestUFO Moving Map Test because of sample and hold. Try it, you can't read the street name labels, because of the sample and hold effect (aka persistence, aka MPRT above zero)

Solution To Stutters Caused By (Fast Pixel Response AND Low Frame Rate)

Now you know why faster pixel response makes stutters more visible.

If you hate stutters more than blur:
1. Raise your frame rate and refresh rate.
2. Get a more powerful GPU.
3. Adjust game settings.
4. Failing that, Just Add GPU motion blur (yes, it's evil but it's a defacto assistive feature for some people).

GPU motion blur is a pick-poison. It helps masks stutters if you're playing at low "Hollywood Movie" style frame rates (e.g. 24fps-60fps) on OLED. So you're adding GPU motion blur to compensate for pixel response being too fast for low frame rates.

Now, that being said, once you're usually above 100fps, I advise most people to always disable GPU motion blur effects. But it's a wonderful band-aid for Hollywood frame rates when you hate amplified stroboscopics and amplified stutters (some people gets more headaches from stutters than blur).

Choose whatever ergonomic setting helps you the most, sometimes "GPU Motion Blur Is An Assistive Feature" (for easily-stutter-headached people), even though it's evil to us HFR folks...

Personally, I'd rather be armed with an RTX 4090 and call it a day, to spray brute framerate if you want strobeless motion blur reduction...

Main Fix: Keep Your Frame Rates High On OLED! Then It's Ergonomic.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter

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Re: EXPLAINER: Why Does OLED Stutter More At Low Frame Rates? (Fast GtG Pixel Response)

Post by Chief Blur Buster » 19 Dec 2023, 21:00

Updated with newer information.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter

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Forum Rules wrote:  1. Rule #1: Be Nice. This is published forum rule #1. Even To Newbies & People You Disagree With!
  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

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