Mark Rejhon I have questions for you to answer!!!

[IamElonMusk]

So from what I understand Sony ships TVs that use the strobe backlight method to reduce motion blur. So say Sony decides to ship a TV with both strobe backlight and freesync 2, and I then take my xbox and start playing a 30fps game (that sometimes dips to 29 or 28fps), so this means my TV only refreshes 28-30 times per second and of course the strobe backlight is synchronized with the refresh rate. Also this hypothetical TV is a full array local dimming TV as well, but has strobe backlight ever been done before with a full array TV, is it possible?

I mean I would love to have the perfect CRT like motion clarity on my LCD, but is it possible to do at 30hz without people noticing flicker? Also the reason I mention full array local dimming is because its becoming more popular with TV makers these days, even samsung's flagship 2018 TVs are full array so it has to be taken into consideration, also I dont want to buy a TV without it.

Now since discovering your website you are the only person in the world who really understand what causes "motion blur" on TVs, swear to god you're a pioneer and one of a kind!

p.s. So on the rtings.com I was reading that Vizio TVs use a black frame insertion technique for their motion blur reduction and since I own a vizio I decided to turn the feature on and I could just barely notice screen flicker and also it didn't reduce motion blur at all, whats your opinion on BFI?

[RealNC]

Freesync cannot be used at the same time as strobing. It's one or the other.

Also, TVs don't do strobing below 100Hz. For 30FPS, you usually get 120Hz strobing. Same for BFI.

30Hz strobing or BFI is unusable. The flicker is extreme.

[IamElonMusk]

Freesync cannot be used at the same time as strobing. It's one or the other.

Also, TVs don't do strobing below 100Hz. For 30FPS, you usually get 120Hz strobing. Same for BFI.

30Hz strobing or BFI is unusable. The flicker is extreme.

But strobe backlight is used with g-sync correct? Also BFI is crap right from reading this website it seems there are only two ways to get CRT like motion clarity, strobe backlight or 1000hz, Mark never mentions BFI.

[RealNC]

But strobe backlight is used with g-sync correct?

Nope. Strobing and g-sync are mutually exclusive. On some monitors, you can enable both at the same time using a "hidden" mode, but the results are not that great. It works, but there's some major issues. There's a thread about it here:

viewtopic.php?f=4&t=2883

Also BFI is crap right from reading this website it seems there are only two ways to get CRT like motion clarity, strobe backlight or 1000hz, Mark never mentions BFI.

BFI is only useful when strobing isn't available. It's not a good solution.

[IamElonMusk]

But strobe backlight is used with g-sync correct?

Nope. Strobing and g-sync are mutually exclusive. On some monitors, you can enable both at the same time using a "hidden" mode, but the results are not that great. It works, but there's some major issues. There's a thread about it here:

viewtopic.php?f=4&t=2883

Also BFI is crap right from reading this website it seems there are only two ways to get CRT like motion clarity, strobe backlight or 1000hz, Mark never mentions BFI.

BFI is only useful when strobing isn't available. It's not a good solution.

How come in all the YouTube videos and articles I have read on g-sync this hasn't been mentioned till now? I'm dumbfounded you mean to tell me these Nvidia g-sync displays with ULMB, you can't use both at the same time? Please link me an article that confirms this?

[RealNC]

How come in all the YouTube videos and articles I have read on g-sync this hasn't been mentioned till now? I'm dumbfounded you mean to tell me these Nvidia g-sync displays with ULMB, you can't use both at the same time? Please link me an article that confirms this?

https://en.wikipedia.org/wiki/Display_m ... backlights

[IamElonMusk]

How come in all the YouTube videos and articles I have read on g-sync this hasn't been mentioned till now? I'm dumbfounded you mean to tell me these Nvidia g-sync displays with ULMB, you can't use both at the same time? Please link me an article that confirms this?

https://en.wikipedia.org/wiki/Display_m ... backlights

at the 13:00 mark Tim Sweeney says "You can read the text even when its moving" looking at a gsync monitor, this was taken back in 2013
https://www.youtube.com/watch?v=o1T-80prQ74&t=922s
to get an up close view of what Tim Sweeney was looking at go to the 29:00 mark, you will see that as the text is moving it becomes unreadable due to motion blur https://www.youtube.com/watch?v=KhLYYYvFp9A but I thought only the strobe backlight effect could do that???

Listen to me, so say you got the most powerful GPU there is which can play 120fps locked and you have a 120hz dispay, but this display is non gsync, would that text be readable at it moves? If not then how would gsync change that?

Of course the text shouldn't be legible at 120hz because theres 8ms persistence and plenty of blur at 120hz https://www.blurbusters.com/blur-buster ... -and-hold/ , yet Tim Sweeney was looking at that gsync screen and saying "You can read the text".

[Chief Blur Buster]

Also, TVs don't do strobing below 100Hz. For 30FPS, you usually get 120Hz strobing. Same for BFI.

Not entirely true. Some have 60Hz single-strobe!

RTINGS.com HDTV reviews tells you which TVs have 60Hz strobing.
Several 2015, 2016 and 2017 HDTV television screens provide a single-strobe option....but you must look for them by specific brands and specific models. Fortunately RTINGS mentions which HDTVs support single-strobe Game Mode, which is a great service that RTINGS does for motion blur nuts like us.

Some of them, in fact, even display a warning message about flicker. One of the Sony HDTVs I tried does that.

I wish BenQ/Zowie would do that -- to re-enable single-strobe for 60 Hertz. Let users decide if they don't mind the flicker. Display a warning message and call it a day, let users decide.

[Chief Blur Buster]

+1 for correctly spelling my last name.

to get an up close view of what Tim Sweeney was looking at go to the 29:00 mark, you will see that as the text is moving it becomes unreadable due to motion blur https://www.youtube.com/watch?v=KhLYYYvFp9A but I thought only the strobe backlight effect could do that???

Or ultra-high refresh rates.

Simply put, in display motion blur science -- display motion blur (persistence) is linearly proportional to individual frame visibility time. Whether strobed (strobe length time) or sample-and-hold (frame duration time). That's what the big industry titans say (under various terminology, like "persistence", "sample-and-hold", "display motion blur", "MPRT", "Moving Picture Response Time", etc). Being the world's first website to test a 480 Hz display, 2ms persistence can be achieved via 500fps@500Hz with motion blur equivalent to 2ms flashes of a strobe backlight, which you've already quoted. But quoting again for other Blur Busters readers who may not be familiar with this.

• 480 Hz monitor tests
• Blur Busters Law And The Amazing Journey To 1000 Hz Displays

Listen to me, so say you got the most powerful GPU there is which can play 120fps locked and you have a 120hz dispay, but this display is non gsync, would that text be readable at it moves? If not then how would gsync change that?

No, you still can't read the text either in GSYNC or non-GSYNC, unless you turn on ULMB strobe backlight.

At "only" 120Hz, it is not possible to read small fast moving text in the TestUFO Panning Map Test on a sample and hold display. That's 960 pixels per second horizontal scrolling motion -- permanently faster moving than the pendulum in the NVIDIA G-SYNC Demo.

Not to say, GSYNC does have other benefits like the magical ability to make random framerates look smooth, as seen in the TestUFO GSYNC Demo (simulated on fixed Hz displays via interpolation). Make sure you have a stutter-free web browser that continuously displays the green "READY" in TestUFO -- try both Chrome and FireFox -- and then try out Ramp Slow/Fast/Random/Struggle at Max -- that's the benefit of a variable refresh rate display. It smooths out stutters by keeping your display's random refresh rate perfectly in sync with a game's random framerate.

Of course the text shouldn't be legible at 120hz because theres 8ms persistence and plenty of blur at 120hz https://www.blurbusters.com/blur-buster ... -and-hold/ , yet Tim Sweeney was looking at that gsync screen and saying "You can read the text".

If the text is big enough or slow moving enough, then the de-stuttering of GSYNC can help improve readability of text, where the stutter being the weak link instead of motion blur being the weak link.

By default, GSYNC does not fix motion blur. Consistent 100fps at 100Hz GSYNC (on any GSYNC Monitor, 144Hz or 240Hz) pretty much simply looks like 100fps@100Hz perfect VSYNC ON. Same amount of sample-and-hold. Same amount of persistence motion blur.

The NVIDIA Pendulum demo is indeed slightly easier to read without stutters, since they intentionally made that demo to have stutters be the weak link in readability. The text is slow moving (so motion blur is not weak link) but the text is very stuttery (so stutter is the weak link).

Now on these monitors, they also have a ULMB mode, but that disables GSYNC. By default, you can't use both at the same time. However...

Now, the good news.... There's an unofficial hack for simultaneous GSYNC and ULMB. It does exactly what you want but with caveats. It works very well if you know how to use it, but it causes a lot of uncomfortable flickering effects many people do not like.

The problem is doing this raises the minimum comfortable framerate to roughly ~75 frames per second because anything below that flickers too uncomfortably. The highest framerate is the ULMB's max, which is 120Hz or 144Hz. So your comfortable strobed VRR range is very tight -- 75fps-to-120fps -- and so mainly benefits games that play "usually maxed out but comfortably and gradually fluctuates downwards now and then". You also need zero disk-read stutters, so you really want a fast SSD and lots of RAM, so disk-load stutters don't cause random flickers very often. A good M.2 SSD, preferably -- and ~32GB+ RAM -- this combo will help reduce a lot of variable-rate strobe flicker that is uncomfortable for many people's eyes.

Once smoothed out, GSYNC+ULMB hack de-stutters the framerate slowdowns, while keeping the strobed benefits of ULMB. Unfortunately, many games play at only 30 frames per second in things like main menus -- so entering/exiting a game can be downright uncomfortable with this unofficial hack.

(Aside: Long term tweaks.... I think this can improve with some good framepacing algorithms (maybe a modified RTSS optimized for variable-rate strobing) that automatically inserts double-strobes when it falls below a frmerate target such as 75fps. Stutters below 75fps is the lesser of evil compared to 30Hz flicker. I wish GSYNC monitors had a configurable repeat-refresh floor (E.g. raising the bottommost Hz to 75Hz instead of 30Hz) to help improve the comfort zone of variable-refresh-rate strobing... A FreeSync monitor has a hackable FreeSync range via ToastyX CRU though....and a FreeSync monitor can theoretically be backlight-hacked to have variable rate strobing, but their LCD overdrive lookup tables are not nearly as strobe-optimized as GSYNC monitors....but this could be further indie experiments of the future ala Zisworks style territory)

That said, if you can pay that price of admission, strobed ULMB+GSYNC is absolutely beautiful in some games that meets the framerate-fluctuation range criteria (e.g. fluctuations 100fps-144Hz look pretty lovely with the ULMB+GSYNC hack on a 240Hz monitor -- you're just losing 240Hz, and going with a very tight VRR range to gain the benefits of stutter-free variable-rate strobing. It does indeed work, with a few asteriks and caveats. The venn diagram is small -- only 25% of games look really amazing with the hack -- because of the pitfalls of variable-rate strobe flicker.

Thanks
Mark Rejhon
Founder, Blur Busters

[IamElonMusk]

Mark thank you for replying, why cant strobe backlight go to higher frequencies, wouldn't that be beneficial in regard to flicker? So strobing at 30hz will make flicker too unbearable then?