HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by RealNC » 30 Jan 2023, 02:24

roro13200 wrote:
29 Jan 2023, 20:03
hello for a qft mode must we have vsync on in the nvcp?
No. It's completely independent of any sync functionality (be it vsync, fast sync, or whatever.)
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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by roro13200 » 30 Jan 2023, 03:39

thank you for your answers .
the problem is that the game i play rtss does not work.

is there a way to know if our qft mode is functional?

when I activate a qft mode for a 60hz mode from 360hz (aw 2521h).

the indicator on the panel tells me 60hz, but in the osd it tells me 360hz.

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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by Chief Blur Buster » 01 Feb 2023, 03:53

roro13200 wrote:
30 Jan 2023, 03:39
thank you for your answers .
the problem is that the game i play rtss does not work.

is there a way to know if our qft mode is functional?

when I activate a qft mode for a 60hz mode from 360hz (aw 2521h).

the indicator on the panel tells me 60hz, but in the osd it tells me 360hz.
The divergence is usually because it's calculating based on the pixel clock, because your QFT 60Hz mode matches the monitor's 360Hz EDID's horizontal scanrate and pixel clock! While you will need tests to see if QFT lag reductions have been achieved, the divergence indirectly confirms your QFT is already functional.

That's a giant 6:1 QFT margin, reducing your refresh cycle delivery latency by 5/6ths (~83%).

Technically, if you've configured sync technologies correctly (including RTSS) and/or the panel is a fixed scanrate panel, then your maximum latency reduction is about ~13.9 milliseconds.
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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by Chief Blur Buster » 01 Feb 2023, 03:54

RealNC wrote:
30 Jan 2023, 02:24
roro13200 wrote:
29 Jan 2023, 20:03
hello for a qft mode must we have vsync on in the nvcp?
No. It's completely independent of any sync functionality (be it vsync, fast sync, or whatever.)
There is a difference between these two questions:
"Can we turn use VSYNC OFF with QFT" (Short answer: Yes)
"Can VSYNC OFF have latency reductions with QFT?" (Short answer: Depends. It can be Yes or No)

I was answering the latter question, while you're answering the former question.

Both equally valid answers, but a very important nuance that may decide worthiness of QFT depending on configured settings.

An indirect visual method of confirming a horizontal-scanrate multisync panel is to try www.testufo.com/scanskew with both QFT 60Hz and non-QFT 60Hz.

The non-QFT 60Hz will skew much more than the QFT 60Hz mode. This is a visual latency check, because the skew is because of the lag between top and bottom tips of the line. These panels typically have very low 60Hz VSYNC OFF latency out of the box. This type of panel will have no QFT benefit for unsynchronized VSYNC OFF (no RTSS, no scanline syncing, no strobing). This will require RTSS Scanline Sync or Special K Latent Sync to really have noticeable lag reduction benefits.
Example: Most 23.8" 240Hz panels is variable horizontal scanrate (e.g. ViewSonic XG2431)

If the scanskew is identical, then you've got a fixed-scanrate panel that is automatically buffering the input signal before displaying it. These panels typically have very high 60Hz VSYNC OFF latency out of the box. In this situation, QFT will benefit latency of the panel regardless of what sync technology that panel is using, and does not mandatorily require RTSS to have noticeable lag reductions (although RTSS will help even further, as a further a stacked latency-savings effect).
Example: Most 25" 240Hz panels seem to be fixed horizontal scanrate (e.g. Zowie XL2546)

Long term, if NVIDIA graphics drivers or Windows gains support beginning-of-refresh-cycle swapchain release (e.g. VSYNC ON Present() unblocks only right at the first scanline of a new refresh cycle and displays that presented frame directly at that refresh cycle), then RTSS Scanline Sync becomes unnecessary, and out-of-the-box graphics drivers will have maximally reduced VSYNC ON latency with QFT in both situations.

Now that being said, if you use strobing, then QFT will generally help to reduce lag of strobed modes regardless of whether your panel is scanrate multisync or not.
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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by roro13200 » 01 Feb 2023, 13:05

Thank you boss for your explanation.
I will try your test to find out what type of panel I have.

however I have games that don't support rtss and special k .

do you have an alternative to this thank you!

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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by sonicgenfan » 18 Feb 2023, 20:36

Chief Blur Buster wrote:
26 Oct 2022, 20:01
FlameOnion wrote:
25 Oct 2022, 08:06
Does increasing Vertical Total helps to reduce lag when converting from cvbs(retro console,nes) to hdmi or vga?
Unfortunately, this won't help because QFT is not supported in original retro consoles.
QFT needs to be done by a supported chip (e.g. NVIDIA, AMD)
FlameOnion wrote:
25 Oct 2022, 08:06
Increasing Vertical Total has the same effect on CRT?
It works on some CRTs but it has some severe side effects like very flat image size.
Large VBIs often create weird effects with CRT beam steering.
However, it would only work with a GPU (AMD/NVIDIA) capable of VGA output, or if you used a low-lag converter like a HDFury that converts digital output to analog.
FlameOnion wrote:
25 Oct 2022, 08:06
Increasing vertical Total works with this: scart(rgb) to vga (https://www.geocities.ws/podernixie/htp ... l#scartvga)
This cable lets you connect a DVD player, DTV receiver or any other device with RGB scart output to an Arcade or PC monitor.(nes composite>DVR scart rgb> vga xl2411 or crt)
This won't work because retro consoles don't have QFT support built into them.
You have to use an emulator from a PC to use QFT, and use QFT via the NVIDIA/AMD GPU, because the GPU generates the QFT.
Would it be possible to build a device to convert the HDMI signal of a 60fps console to a 60fps QFT (240fps output speed)?

I bought an xg2431 to play 60fps console games on and I was disappointed by the large crosstalk, without any way to get rid of it.

I am much more sensitive to motion blur/crosstalk than the 1 extra frame of input lag.

If there arent any devices (such as an fpga) that can convert the signal, are there any fixed-scanrate 240hz monitors that can strobe at 60hz with low/no crosstalk? The fixed-scanrate behaviour seems extremely desirable to me, as an exclusively console player. I would gladly sacrifice the extra frame of input lag for motion clarity closer to a crt,

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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by Chief Blur Buster » 19 Feb 2023, 06:11

sonicgenfan wrote:
18 Feb 2023, 20:36
Would it be possible to build a device to convert the HDMI signal of a 60fps console to a 60fps QFT (240fps output speed)?
Yes, in theory (would have lag), so would serve only as crosstalk reduction.

However, such a box would be unlikely to be created except out of DIY parts (e.g. a console connected to a video capture PCIe card, which is then being live-displayed through Windows with the QFT EDID, and recalibrated via ViewSonic STrobe Uti9lity) -- basic a roll-your-own video processor. It would be much more laggy than a dedicated box but you'd have the reduced strobe crosstalk. Perhaps an Elgato PCIe product maybe? (Untested) It would be high cost to do things this way.

For roughly the same price as a dedicated PC + basic NVIDIA product + Elgato card (to create your own DIY video signal processor/scaler), however, you can get an LG OLED TV with a BFI feature that reduces 60Hz motion blur by 50%. And would double as a gigantic 4K 120Hz VRR/FreeSync/GSYNC TV.

Twenty years ago, I used to work on PC-architecture-based video processors years ago, including dScaler app, the TAW ROCK, and the Key Digital Leeza (I also did some work for RUNCO Inc. but that wasn't PC-based architecture).
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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by elexor » 22 Feb 2023, 12:54

Chief Blur Buster wrote:
19 Feb 2023, 06:11
sonicgenfan wrote:
18 Feb 2023, 20:36
Would it be possible to build a device to convert the HDMI signal of a 60fps console to a 60fps QFT (240fps output speed)?
Yes, in theory (would have lag), so would serve only as crosstalk reduction.
my strobed vg279qm does this on the scaler with a pretty big latency penalty, I can tell because of the lack of crosstalk with nativescan 60hz inputs. just to be clear for sonicgenfan the vg79qm does not single strobe 60hz without hardware modifications.

chief do you know when they are going to start utilizing fald in a scanning backlight fashion i'd imagine a fast monitor like the xg2431 equipped with even a modest zone count fald backlight would be able to hide the 60hz nativescan crosstalk band fully, since the xg is already doing pretty well with a global flash backlight.

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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by Chief Blur Buster » 22 Feb 2023, 21:02

elexor wrote:
22 Feb 2023, 12:54
my strobed vg279qm does this on the scaler with a pretty big latency penalty, I can tell because of the lack of crosstalk with nativescan 60hz inputs. just to be clear for sonicgenfan the vg79qm does not single strobe 60hz without hardware modifications.

chief do you know when they are going to start utilizing fald in a scanning backlight fashion i'd imagine a fast monitor like the xg2431 equipped with even a modest zone count fald backlight would be able to hide the 60hz nativescan crosstalk band fully, since the xg is already doing pretty well with a global flash backlight.
Past scanning backlights were mediocre because of internal backlight diffusion (under 100:1 contrast ratio) creating more strobe crosstalk than global-flash. You need roughly a 500:1 contrast ratio between nearby segments to prevent even LCD black from looking like LCD gray (and showing any remnant LCD GtG's).

The good news is that multi-thousand count MicroLED arrays have much less light diffusion.

Now, a new problem is that low-cost MicroLED backlights aren't apparently yet timing-flexible enough (in row-column addressing) at the precision necessary to be controlled in sync with LCD scanout. It will take a bit more time.

Now, the new thing is that refresh rates of OLED is going up relatively fast at lower costs (with 240Hz available in some models for under $1000) and higher refresh rates are going to come by the 2030s. It may turn out to be cheaper to manufacture 1000Hz OLEDs (with capability for rolling scan) than manufacture diffusion-free scanning backlights.

So we're in a horse race between cheap MicroLED scanning backlights and cheap high-Hz OLEDs.

Time will tell!
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Re: HOWTO: Quick Frame Transport (QFT) - Large Vertical Totals (reduce lag, reduce crosstalk)

Post by elexor » 25 Feb 2023, 22:12

Chief Blur Buster wrote:
22 Feb 2023, 21:02
You make some good points about the viability of using scanning backlights for blur reduction with current FALD tech, thanks. will be waiting for some flexible bfi oleds.

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