Blur Busters Forums

Chief Blur Buster wrote: Buffer-and-accelerated-scanout.

Is real-time scanout a must for VRR mode?

KKNDT wrote:Is real-time scanout a must for VRR mode?

Not always, but it's very strongly recommended. At least for top-Hz mode.

Most VRR monitors behave as realtime scanout at their normal high-Hz VRR mode -- basically, 240Hz VRR monitors have 1/240sec scanout, no matter what the current refresh interval is (e.g. 48Hz, 100Hz, etc). The signal is constant scanrate, and constant pixel clock, just that the blanking interval (essentially a variable size Vertical Total -- but being done automatically between the graphics card and monitor) essentially varies in realtime to pad time between refresh cycles.

Some VRR monitors exhibit "partial-buffer-and-accelerated-scanout" behaviour when you use a lower-Hz lower-dotclock VRR signal from a computer (e.g. A 120Hz-max VRR signal instead of a 144Hz-max or 240Hz-max VRR signal). Basically the user might switch to a lower refresh rate, and that becomes the new max Hz.

Other VRR monitors will do realtime scanout (e.g. slow scanout velocity) for lower-max-Hz VRR modes.

I think it really depends on panel's capability and ease of engineering. But for PC eSports will only tolerate realtime scanout (for VSYNC OFF especially) -- otherwise the "feel" is odd. They're very sensitive to aimfeel problems. Fortunately, they will typically only use max-Hz, so many manufacturers can just get away with supporting realtime synchronous scanout (panel scanout fully in sync with signal scanout). And not all eSports enables VRR mode -- but if they do -- it has to be realtime scanout where possible.

Monitor manufacturers find it difficult to reprogram overdrive algorithms for a different panel scanout velocity, also refresh interval can affect the appearance of overdrive, and need adjustments for a different refresh interval (that's why variable-refresh overdrive is so difficult to engineer)

Note: Offtopic, but the EDID mode is the defined highest-Hz mode, except to lower the refresh rate during VRR operation, the interval between refresh cycles is lengthened (automatically by a graphics card) by adding lines to the vertical blanking interval -- down to the longest interval supported (e.g. say, 48Hz). The graphics card will often use LFC (Low Frame-rate Compensation) to repeat frames to keep things granular to VRR range -- e.g. 24fps will repeat a refresh cycle twice for (24fps = 48Hz monitor operation, 25fps = 50Hz monitor operation, etc). That's automatically done by the graphics card drivers, so the monitor doesn't handle LFC.

Note2: Also semi offtopic, but in the long term, consoles will probably gain support for the new Quick Frame Transport (QFT) specification (HDMI 2.1) which is roughly equivalent of Large Vertical Totals: Using a high pixel clock to deliver a 60Hz refresh cycle faster. A 240Hz monitor could later decide to support HDMI 2.1 Quick Frame Transport with perhaps a 4x frame delivery acceleration factor (imagine the use of ~VT4500 for 1080p -- about four times the usual VT1125 default -- resulting in four times the default Pixel Clock) -- And then the panel wouldn't have to slow down their scan velocity. A FreeSync-compatible 240Hz panel is very QFD-friendly anyway. Now they'd finally become realtime scanout (1/240sec scanout) without needing to buffer, because the 60Hz refresh cycle is finally being transmitted over the cable in 1/240sec (thanks to Quick Frame Transport specification of HDMI 2.1). But right now, consoles do not support that. Only PC's (via ToastyX Large Vertical Totals) can do an undocumented QFT-acceleration via manual Large Vertical Totals hacking in a Custom Resolution Utility. QFT, however, has biggest benefits VSYNC ON material (console eSports, since most console games have forced VSYNC ON) -- and is not necessarily always helpful for VSYNC OFF mechanics (PC eSports).

Regardless, the first 240Hz monitor that supports lagless realtime scanout at all refresh rates (including 60Hz for console), would finally be very good simultaneously for console eSports (60Hz PlayStation, XBox) and PC eSports (240Hz). No 240Hz monitor currently supports realtime scanout at 60Hz, and that's a problem for people who also wants to use it for top-notch console eSports.

Question -- Are you a casual gamer, or competition/eSports player, or a student, or a monitor engineer, or? Your questions match the pattern of questions coming from a 60Hz monitor engineer who's beginning to go into gaming monitor design for the first time, and trying to understand the complex needs of eSports game players of the worldwide market. Engineers are certainly welcome here, our forum advice is always free, we believe in "lifting all boats". (expression saying) I'm just curious what brings you to Blur Busters Forums? Cheers!

Chief Blur Buster wrote:
Most VRR monitors behave as realtime scanout at their normal high-Hz VRR mode -- basically, 240Hz VRR monitors have 1/240sec scanout, no matter what the current refresh interval is (e.g. 48Hz, 100Hz, etc). The signal is constant scanrate, and constant pixel clock, just that the blanking interval (essentially a variable size Vertical Total -- but being done automatically between the graphics card and monitor) essentially varies in realtime to pad time between refresh cycles.

Some VRR monitors exhibit "partial-buffer-and-accelerated-scanout" behaviour when you use a lower-Hz lower-dotclock VRR signal from a computer (e.g. A 120Hz-max VRR signal instead of a 144Hz-max or 240Hz-max VRR signal). Basically the user might switch to a lower refresh rate, and that becomes the new max Hz.

Other VRR monitors will do realtime scanout (e.g. slow scanout velocity) for lower-max-Hz VRR modes.

I think it really depends on panel's capability and ease of engineering. But for PC eSports will only tolerate realtime scanout (for VSYNC OFF especially) -- otherwise the "feel" is odd. They're very sensitive to aimfeel problems. Fortunately, they will typically only use max-Hz, so many manufacturers can just get away with supporting realtime synchronous scanout (panel scanout fully in sync with signal scanout). And not all eSports enables VRR mode -- but if they do -- it has to be realtime scanout where possible.

Monitor manufacturers find it difficult to reprogram overdrive algorithms for a different panel scanout velocity, also refresh interval can affect the appearance of overdrive, and need adjustments for a different refresh interval (that's why variable-refresh overdrive is so difficult to engineer)

Excellent explanation. Thank you very much!!!

Chief Blur Buster wrote: Question -- Are you a casual gamer, or competition/eSports player, or a student, or a monitor engineer, or? Your questions match the pattern of questions coming from a 60Hz monitor engineer who's beginning to go into gaming monitor design for the first time, and trying to understand the complex needs of eSports game players of the worldwide market. Engineers are certainly welcome here, our forum advice is always free, we believe in "lifting all boats". (expression saying) I'm just curious what brings you to Blur Busters Forums? Cheers!

Actully, my job is related to electrical and automation and has nothing to do with what we are talking about.

10 years ago, I was a competitive gamer, mainly focus on CounterStrike 1.6. During these days, I own a CRT which could work at 640x480@120HZ. I would never image a monitor could affact one's gaming experience until I replaced my CRT with a 60HZ LCD. What's lag(display-only)? What's blur??? They were so far away from me, but now has become the big enemy.

Sinece 1st hight refresh rate monitors came into being, more and more people like me pay more attantion to gaming monitors

- XL2410T--> maybe the 1st high refresh rate LCD, 2233RZ is too weak in G2G
- FG2421--> high refresh rate gaming monitor with better color and great contrast
- PG278Q--> VRR tech. into
- XB270HU--> 1st hight refresh rate IPS
- XL2540-->Finally, LCD beats CRT with it's tighter lag jitter
......

Now, I only spend less than 1 hour/day playing games. But I get very interested in everything better than 60HZ, and always keep an eye on how we are fighting against motion blur, latency, stutter...etc.

Blurblusters is a very famous site in this filed, which is a fact that I know many years ago. But I only used your online test and read your published articles. It's Jorimt's G-SYNC 101 test which brings me to this forums, and its your professtional posts caught my attraction and made me settled down. The real treasure lies in the forums.

Some sites only talk about things by feeling, such as <How do G-SYNC fix stutter?>. Blurblusters have the ability explan almost every things in theory, and can even translate something into mathematical formula. (Blurblusters' LAW)

What I have learnt here in the recent 2 months is almost doubled what I have learnt from other sites in the past 1 year!

KKNDT wrote:Blurblusters is a very famous site in this filed, which is a fact that I know many years ago. But I only used your online test and read your published articles. It's Jorimt's G-SYNC 101 test which brings me to this forums, and its your professtional posts caught my attraction and made me settled down. The real treasure lies in the forums.

Some sites only talk about things by feeling, such as <How do G-SYNC fix stutter?>. Blurblusters have the ability explan almost every things in theory, and can even translate something into mathematical formula. (Blurblusters' LAW)

What I have learnt here in the recent 2 months is almost doubled what I have learnt from other sites in the past 1 year!

Thanks for the compliment!

Yes, we are famous for being that "crazy high Hertz site".

Blur Busters is the only site in the world that really specializes in this!

We try our best to bridge the world of everyday PC gaming & advanced display research.

P.S. I notice you are using a Chinese email address... Blur Busters get visitors worldwide from almost every country in the world. The Blur Busters Laboratory is in Canada (where I am) with United States as the main audience, but we get more visitors from China than Canada. About 6.5% of Blur Busters web visitors come from China. Unexpectedly, two Chinese 240Hz monitor manufacturers recognized me when I walked into that CES 2018 tent. Y'all learn fast. I was surprised.

Oh.... and another thing.

I’d like to add an observation that my web statistics show that 9.6% of visitors to TestUFO are from China.

This is unusually big for one country, they are extremely interested in Blur Busters.

It seems Chinese manufacturers seem to use TestUFO for testing their domestically-manufactured gaming monitors.

Chief Blur Buster wrote:Oh.... and another thing.

I’d like to add an observation that my web statistics show that 9.6% of visitors to TestUFO are from China.

This is unusually big for one country, they are extremely interested in Blur Busters.

It seems Chinese manufacturers seem to use TestUFO for testing their domestically-manufactured gaming monitors.

That's very normal TestUFO has become a standard tool for motion test.

- Even a user without any knowledge of "fast monitor" will open the search engine and type "testufo" when he needs to know whether his new monitor is suitable for gaming.

- Most users will use your frame skipping test to ensure a sucessful display overclock.

- People sometimes do the very happy comparation with your "Moving photo test" with each other, even they do not know what they are really testing and what exactly makes the big difference.

- Advanced users will read your pubulished articles.

.....etc.

I think the next step for us is to learn how to use pursuit camera test. Till now, I see no local reviewers takes this into their monitor review.

I collect some lag numbers from RTINGS and Display Corner and made some simple calculation to see if the monitor uses asymmetry Scanout

KKNDT wrote:I collect some lag numbers from RTINGS and Display Corner and made some simple calculation to see if the monitor uses asymmetry Scanout

LAG Analyzation.png

A good (but incomplete) attempt.

The problem is asymmetric scanout may only happen at some refresh rates.

And not all testers disclose the refresh rate they test lag at.

Some only test lag of 60Hz.

Accurate disclosure is a big problem.

Here's another lag test result , 34UC89G



This makes me think that all the G-SYNC monitors do asymmetry scanout at (60HZ + HDMI at least).