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LightBoost, G-SYNC, Turbo240: 120Hz Strobe Backlight LCDs / No Motion Blur! - Page 165

post #1641 of 2929
Thread Starter 
Quote:
Originally Posted by PCM2 View Post

The initial DIY kit is only available for the VG248QE. Nobody knows which monitors will be moddable in the same way in the future. And I wouldn't start calling this low-persistence mode 'LightBoost 2.0' as it may cause confusion. Nvidia is unlikely to call it that seeing as it's not designed with 3D technology in mind. Perhaps G-Boost? Who knows. tongue.gif
Agreed. They probably have a brand name they will announce soon.
post #1642 of 2929
Thread Starter 
BTW, I have come up with a theory of why there's 768 MB of memory on G-SYNC.
And it's not what you think.
Quote:
The 768MB on G-SYNC was mentioned to be used for "color processing".
That's simplistic, but it's accurate scientifically.

Artifact-free response time acceleration. (keep colors from overshooting)
Artifact-free LCD inversion algorithms. (prevent checkerboard artifacts - demo animation - complaint example)
Artifact-free FRC algorithms. (improve colors further)
Artifact-free strobing (better Y-axis compensated RTC algorithms)

My math is that many gigaFLOPS is necessary if you do functions completely by math. To do the curves properly, you need multiple processing operations per pixel (probably a dozen or more), and there's a billion subpixel updates per second in 1920 x 1080 x (3 subpixels) x 144Hz. That'd require 10 GFLOPS for 10 operations per subpixel. Getting 10 gigabytes/sec memory throughput is cheaper than getting 10 GFLOPS, so I'm assuming they're not going to calculate the curves.

Also, isn't G-SYNC is a FPGA and not an ASIC at this time? Which, slightly limits processing power, but increases flexibility? I thought it was since ASIC's aren't flexible enough for G-SYNC requirements. From what I heard from John's talks and others, G-SYNC has a lot of programmable and upgradeable modes including variable-refresh rate modes, fixed-refresh modes, strobe modes (which requires a different Y-axis-compensated overdrive algorithm, for varying pixel freshnesses prior to the full-screen strobe). Other sources mentioned the firmware upgradeability, as well.

LightBoost doesn't even have enough bits of precision in its Y-axis compensated RTC -- the overdrive bands of Y-axis RTC show up on a LightBoost-enabled monitor during the Flicker Test - http://www.testufo.com/flicker (Height = Full Screen) -- during strobe backlight or 3D mode. I've determined these are rounding errors in Y-axis compensated RTC -- more bits of precision would make the overdrive zones disappear into a fully gradually blended Y-axis compensated RTC. So they'll probably need greater-than-8-bit precision during RTC, maybe even floating point RTC, and possibly might even have advanced temporal dithering in the RTC to try to blend out everything since 6-bit RTC cannot completely erase the previous refresh.

It's so incredibly involved to get pixels to settle nicely, it's mind boggling. If they're off by just even one 8-bit shade (1/256th), there's 0.3% brightness difference that can be human visible in some colors, you'll still see a faint sharp doubleghost (crosstalk, a problem for 3D too, and 2D motion). But TN's are often 6-bit and their RTC is probably only 6-bit as a result. The TestUFO Eiffel Tower Test on a strobe-backlight monitor demonstrates the crosstalk effect in 2D mode -- you see a razor-sharp ghost double image (non-blurred) a few pixels to the side of the eiffel tower as it scrolls sideways. Sometimes you also see 6-bit TN "noise" artifacts in the razor-sharp doubleghost (occurs more often on VG278H than my XL2411T, bottom edge of screen -- drag the TestUFO window near bottom edge); this instantly reveals the limited bits of the RTC.

Also, RTC and inversion has often nasty interference effects sometimes, see http://www.testufo.com/inversion (do this on TN 120Hz monitors)
This is greatly amplified with strobing, and has also created user complaints with 3D mode. LCD Inversion is well-explained at TechMind and Lagom.nl Tests, and I know traditional inversion patterns creates some issues with 3D modes / strobe modes.

(I've done lots of motion testing on LightBoost monitors, and it's amazing how much RTC secrets of a display, can be revealed)

Based on what I now know what's needed to cleanly fix RTC problems during strobing, I'm going to imagine that G-SYNC may need to include:
-- True floating point RTC.
-- True floating point framebuffers
-- Advanced LCD inversion algorithm
-- Advanced temporal dithering algorithm to convert the floating point framebuffer into a 6-bit image for the TN LCD.

We have to prevent interplay artifacts between FRC + inversion + RTC + strobing, there are so many opportunities for those to happen between merely even just any two of those (as we've seen from inversion+strobing at http://www.testufo.com/inversion when viewing it in LightBoost mode).

To simulate true floating point RTC without too many FLOPS, you'll probably need lots of pre-computed floating point lookup tables (created at monitor bootup) because the number of math operations per pixel becomes mind-boggling for fixing that last 1% of imperfectness in LCD pixel state. It's like going from 99% speed of light to closer to 100% speed of light. The work increases unimaginably gigantically on that last 1%, than going from 0%->99%

These aren't confirmable, but NVIDIA's reply of "color processing" is quite accurate, since that's a plain-english umbrella of keeping the pixel color values correct and as saturated as possible, without temporal/dynamic side effects (from variable refresh, from inversion, from strobing, from RTC).
post #1643 of 2929
Quote:
Originally Posted by mdrejhon View Post

All G-SYNC monitors include a mode that is a superior sequel to LightBoost.
There are multiple modes included in G-SYNC, that you can switch between:

1. G-SYNC Mode -- variable refresh rate with less stutters

2. Improved LightBoost mode -- fixed refresh rate but less blur

So for gaming, a G-SYNC monitor will beat my BenQ w/ Lightboost?
post #1644 of 2929
Thread Starter 
Quote:
Originally Posted by SightUp View Post

So for gaming, a G-SYNC monitor will beat my BenQ w/ Lightboost?
In other words, yes.
e.g. Like LightBoost, but with better colors, less ghosting, and even clearer motion than LightBoost=10%

The big question is whether the improvements might be marginal (e.g. smaller than the difference between VG278H and XL2411T) or it might be massive.
post #1645 of 2929
When will those G-Sync monitors come out? Any news about the pricing?
post #1646 of 2929
Quote:
Originally Posted by mdrejhon View Post

1. Make sure you're using recent GeForce or Radeon drivers.
2. Try plugging your monitor into the other DVI port of your graphics card.

Sometimes the graphics cards have two DVI ports, and only one of them is dual-link.

I will try this when i get home, but does anyone happen to have the driver for the monitor?
Edited by PainKiller89 - 10/23/13 at 12:53pm
post #1647 of 2929
Anyone here knows if g-sync will be applicable to my BenQ XL2411T? I bought this monitor a few months ago for the sake of lightboost, however, g-sync seems to be superior to lightboost thus that is what I want. If it isn't compatible I will sell the monitor right away, and the sooner I can sell it the more money I can get back.
    
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post #1648 of 2929
Thread Starter 
Quote:
Originally Posted by Hefner View Post

Anyone here knows if g-sync will be applicable to my BenQ XL2411T? I bought this monitor a few months ago for the sake of lightboost, however, g-sync seems to be superior to lightboost thus that is what I want. If it isn't compatible I will sell the monitor right away, and the sooner I can sell it the more money I can get back.
The XL2411T is so similar to the VG248QE, it might even use the same board. But ASUS uses different menus, so the board may very well need to be reprogrammed, or monitor firmware needs to be reflashed, etc. I guess time will tell if this is the case, or not.
post #1649 of 2929
Little typo on the NVIDIA G-SYNC datasheet. It says that the original VG248QE has VGA, HDMI, and DisplayPort. On mine, I have DVI, HDMI, and DisplayPort.

It also seems to state that, after inserting the G-SYNC module, you can only use DisplayPort--which is fine, but an interesting restriction.
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post #1650 of 2929
Thread Starter 
177Hz support? I posted on AnandTech but will bring the discussion over here, because this is very interesting.
Quote:
Originally Posted by Mark Rejhon 
Quote:
Originally Posted by BrightCandle;35628643 
Guru3d is reporting that monitors with gsync will come up to 177hz and 4k and timeframe was Q1 2014 (they said 2013 in their article but pretty clear that is a typo).
177Hz is exactly the maximum bandwidth of a single DP channel for 1920x1080.

1920 x 1080 x 24-bit x 177 (Hz) = 8.8 Gbits/sec
That's exactly half the DisplayPort 1.2 maximum bandwidth of 17.6 Gbits/sec.

Since they said 1Q2014, and the VG248QE during 1Q2014, plus the DisplayPort math above,
I suspect 177Hz non-strobed might even come to the ASUS VG248QE.
The panel in the VG248QE already can refresh its panel quicker than 144Hz, because it needs accelerated refreshes during LightBoost mode (source) to create blanking interval. The 1ms panel itself could theoretically be clocked to 240Hz, if using both DisplayPort channels, but that would go into overclocking territory. I wonder if the G-SYNC firmware theoretically allows the use of fixed-refresh-rate 960x1080 240Hz tiled mode. Color quality would be worse than 144Hz, but it would be fairly low-persistence (~4.1ms) without strobing. A bit more persistence than LightBoost=100% during 100Hz (~2.9ms persistence), but getting very close. Albiet you will need an insane GPU to run 240fps@240Hz non-strobed.

Not confirmed, of course.

-
Quote:
Originally Posted by Mark Rejhon 
Quote:
Originally Posted by BrightCandle;35643954 
16ms of scan out.
The scanout at 144Hz is 6.9ms. Since scanout remains constant during variable framerate delivery, you got 6.9ms scanout even at 60fps@60Hz, since the frame-delivery and scanout stays at the full 1/144sec speed (or 177Hz speed, 5.6ms frame delivery time) regardless of the current variable refresh rate (= rate of delivery of frames).

Now if you use DisplayPort 2.0, you could speed up delivery of 1920x1080p frames to just 2.3 milliseconds! The rate of delivery of frames doesn't necessarily have to match G-SYNC's maximum refresh rate. 1920x1080 354Hz is the theoretical maximum refresh rate of DisplayPort 2.0, but no panels can really support that today. You could even do it over DisplayPort 1.2 if you tiled two channels (960x1080 @ 354Hz side-by-side). Theoretically, of course.

However, that doesn't stop future graphics cards from using the maximum dotclock to speed up the delivery of individual refreshes to the monitor, even when the display can't refresh that fast. The monitor can buffer it while immediately beginning a slower scanout. Now you've got a 120Hz refresh with less input lag, because of a 1/240sec frame delivery time (or 1/354sec frame delivery time). In theory, of course.

The concept of decoupling frame-delivery time (over DP) from refresh time, even at fixed refresh rates, is probably going to be an interesting trend of G-SYNC moving forward for certain fixed-refresh-rate applications. G-SYNC will already reduce emulator input lag by about 10ms, even at a fixed refresh rate of 60fps@60Hz, since the 60Hz refresh can be delivered/scanned in only 1/144second (6.9ms versus 16.7ms)

This is getting mathematically interesting.

Edited by mdrejhon - 10/24/13 at 9:16am
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