Need some help understanding Large Blanking Intervals

Ask about motion blur reduction in gaming monitors. Includes ULMB (Ultra Low Motion Blur), NVIDIA LightBoost, ASUS ELMB, BenQ/Zowie DyAc, Turbo240, ToastyX Strobelight, etc.
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liquidshadowfox
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Need some help understanding Large Blanking Intervals

Post by liquidshadowfox » 06 Aug 2021, 21:41

I read this article here: https://blurbusters.com/faq/advanced-st ... stalk-faq/

I am ideally trying to see if I can further improve the backlight strobing on my Asus XG27AQM with elmb sync. I found a way to edit the OD using the service menu (usually it's locked to OD 4 which is a little too high imo) and now I don't get any overshoot. When I play league of legends however and I pan my screen I notice a slight double imagining around the edges of rendered objects (to me it looks like crosstalk) and I've already tried capping the fps from 180 fps - 265 fps using RTSS but I haven't been able to get the crosstalk down. I notice the bottom part of the screen has less issues than the middle and the top is horrible. I'm hoping there's a way to improve this, Currently in the manual I see there's a line that says there's supposed to be a way to change the position of the strobe clarity + how much clarity but the option doesn't show up no matter if I use ELMB or ELMB sync.

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Re: Need some help understanding Large Blanking Intervals (Quick Frame Transport)

Post by Chief Blur Buster » 08 Aug 2021, 03:52

liquidshadowfox wrote:
06 Aug 2021, 21:41
I read this article here: https://blurbusters.com/faq/advanced-st ... stalk-faq/

I am ideally trying to see if I can further improve the backlight strobing on my Asus XG27AQM with elmb sync. I found a way to edit the OD using the service menu (usually it's locked to OD 4 which is a little too high imo) and now I don't get any overshoot. When I play league of legends however and I pan my screen I notice a slight double imagining around the edges of rendered objects (to me it looks like crosstalk) and I've already tried capping the fps from 180 fps - 265 fps using RTSS but I haven't been able to get the crosstalk down. I notice the bottom part of the screen has less issues than the middle and the top is horrible. I'm hoping there's a way to improve this, Currently in the manual I see there's a line that says there's supposed to be a way to change the position of the strobe clarity + how much clarity but the option doesn't show up no matter if I use ELMB or ELMB sync.
Hello, that FAQ is slightly old and I need to update it.

I heard that some implementations of ELMB-SYNC is not very Large-VT friendly because of the more complex algorithm it uses -- and I am not sure if your panel is fixed-horizontal-scanrate or variable-horizontal-scanrate (more large VT/QFT friendly). However, if you want to learn large vertical totals, please learn to do it on fixed-Hz ELMB first. Try doing it on 120Hz or 144Hz first.

First, study the following
1. Custom Resolution Utility Glossary
2. Quick Frame Transport (Large Vertical Totals)

The numbers in a Custom Resolution Utility is simply modifications to signal geometry including hidden pixels off the edges of the screen:

Image

To speed up frame delivery for a lower refresh rate (on a high Hz monitor), you ideally want a large blanking interval, which can be bigger than the active image. So you can have a 120Hz refresh cycle delivered in 1/240sec, or a 60Hz refresh cycle in 1/240sec.

Large Vertical Totals are also known as Quick Frame Transport aka QFT, because they speed up the delivery of the refresh cycle over the cable, e.g. a 120Hz refresh cycle in 1/240sec or 1/270sec.

Firstly, video cables transmit refresh cycles one pixel row at a time.
This is the basis of properly understanding those numbers in a Custom Resolution Utility.

The easiest steps are to use ToastyX and derive from a WORKING mode.

1. Start with working max-Hz mode

Image

2. Switch to Manual

Image

3. Put First Radio Button on "Total"
4. Put Second Radio Button on "Horizontal" (or "Pixel Clock")

Image

6. Double Vertical Total to Halve Hz (2x QFT at half Hz)
This will transmit the refresh cycle over the video cable at 2x its normal low-Hz velocity
Do not edit any other numbers, do not edit Hz, the refresh rate will be calculated automatically

Image

5. Quadruple Vertical Total to Quarter Hz (4x QFT at quarter Hz)
This will transmit the refresh cycle over the video cable at 4x its normal low-Hz velocity
Do not edit any other numbers, do not edit Hz, the refresh rate will be calculated automatically

Image

For intermediate refresh rates, calculate the vertical total using this formula:

Desired Vertical Total = (Original Vertical Total) x (Original Hz) / (Destination Hz)

Currently, this is the easiest way to create QFT modes at this time. We are still waiting for a monitor manufacturer to pre-program plug-n-play QFT EDIDs into the monitor that can be enabled/disabled via a "Quick Frame Transport: ON/OFF" setting.
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Re: Need some help understanding Large Blanking Intervals

Post by Chief Blur Buster » 08 Aug 2021, 04:39

Update: I made a new thread:

HOWTO: Quick Frame Transport (Large Vertical Totals)

This should make QFT tweaking a little bit easier.
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liquidshadowfox
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Re: Need some help understanding Large Blanking Intervals

Post by liquidshadowfox » 08 Aug 2021, 17:47

Thank you for the guide, it doesn't seem like this would be useful in the end then since elmb sync has to be using gsync (already using variable blanking intervals) and won't achieve the desired effect. ELMB without Gsync is better on this monitor than it's elmb sync equivalent but I don't want to play my games at a fixed refresh. I just wanted to cap every game at the lowest FPS I can get (.01 lows) and just play with elmb sync to reduce the motion blur.

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Re: Need some help understanding Large Blanking Intervals

Post by Chief Blur Buster » 09 Aug 2021, 02:28

liquidshadowfox wrote:
08 Aug 2021, 17:47
Thank you for the guide, it doesn't seem like this would be useful in the end then since elmb sync has to be using gsync (already using variable blanking intervals) and won't achieve the desired effect. ELMB without Gsync is better on this monitor than it's elmb sync equivalent but I don't want to play my games at a fixed refresh. I just wanted to cap every game at the lowest FPS I can get (.01 lows) and just play with elmb sync to reduce the motion blur.
Large vertical totals *may* have some use for ELMB SYNC since "Large Vertical Total + VRR" simply enforces the minimum-size VBI to use for VRR, which can be useful for certain purposes such as reducing VRR latency of lower-Hz VRR modes, as well as making sure strobe crosstalk doesn't worsen beyond a specific threshold (in theory). However, VRR strobing algorithms are a bit tricky and they may become better/worse with Large VT + VRR.
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liquidshadowfox
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Re: Need some help understanding Large Blanking Intervals

Post by liquidshadowfox » 09 Aug 2021, 06:27

So in theory I could get somewhat better strobing at lower hz because I am setting a minimal threshold to the LVT. My current asus can go up to 270 hz, I assume I could do a LVT that would emulate 270hz worth of blanking at 240hz? That could in theory reduce crosstalk at 240 hz or does it have to be strictly 1/2, 1/4, 1/3 of max refresh that I am able to set the LVT? This monitor is ALMOST there with elmb sync, it literally just needs a 10% push in the right direction.

liquidshadowfox
Posts: 143
Joined: 05 Nov 2020, 14:03

Re: Need some help understanding Large Blanking Intervals

Post by liquidshadowfox » 27 Jan 2022, 21:13

Chief Blur Buster wrote:
09 Aug 2021, 02:28
liquidshadowfox wrote:
08 Aug 2021, 17:47
Thank you for the guide, it doesn't seem like this would be useful in the end then since elmb sync has to be using gsync (already using variable blanking intervals) and won't achieve the desired effect. ELMB without Gsync is better on this monitor than it's elmb sync equivalent but I don't want to play my games at a fixed refresh. I just wanted to cap every game at the lowest FPS I can get (.01 lows) and just play with elmb sync to reduce the motion blur.
Large vertical totals *may* have some use for ELMB SYNC since "Large Vertical Total + VRR" simply enforces the minimum-size VBI to use for VRR, which can be useful for certain purposes such as reducing VRR latency of lower-Hz VRR modes, as well as making sure strobe crosstalk doesn't worsen beyond a specific threshold (in theory). However, VRR strobing algorithms are a bit tricky and they may become better/worse with Large VT + VRR.
Is there any way for me to test if the Large VT works with elmb sync? I think you mentioned that you didn't know if asus implemented the VT that plays nice with VRR, how would I find out?

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