BFI for 30fps Content on 120hz(+) Display?

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okaxihd
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Re: BFI for 30fps Content on 120hz(+) Display?

Post by okaxihd » 05 Sep 2022, 10:43

Guffman wrote:
05 Sep 2022, 02:55
okaxihd wrote:
03 Sep 2022, 18:35
RonsonPL wrote:
03 Sep 2022, 15:47
okaxihd wrote:
02 Sep 2022, 11:52
Hello, I wanted to ask a big question, do old CRT monitors (tube) run games at 30fps smooth? no ghosting? because 30fps on current monitors is terrible.
Thanks and sorry for my english.
Hi
Your English is fine, no worries. :)
Read this https://blurbusters.com/faq/motion-blur-reduction

In particular, this image explains why no display can ever display 30fps as acceptable, smooth and clear.

Code: Select all

[img]https://blurbusters.com/wp-content/uploads/2017/12/strobed-display-image-duplicates.png[/img]
30fps is simply not enough frames per second and unless you interpolate it, so artificially create frames in between the real frames, there's no way around it.
Got it, thank you very much for the quick response.
Yeah, your English is excellent. Wouldn't have even wondered had you not pointed it out yourself ;)

As an update to this idea, I'm trying to rig up one of the aforementioned "scanline generators" used for analog RGBHV to blank out every other frame instead of every other line for my own "Fake BFI". Would still require an ADC to be used with any monitor digital displays, but I suppose it won't matter anyway if I can't get it to work in analog, or if I find it's still too flickery and not worth pursuing anyway.
Please don't stop with this project ;) (120hz = 30fps bfi) because there are many people like me who need 30 fps to play their games on PC because they don't have the money to build a powerful pc and 30fps 1080p bfi would be a dream :P . Unfortunately companies create technologies for 60fps or more and forget about 30fps. :cry:

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Re: BFI for 30fps Content on 120hz(+) Display?

Post by Chief Blur Buster » 05 Sep 2022, 17:11

Guffman wrote:
20 Aug 2022, 19:15
I rigged up this very professional diagram^TM in Paint to hopefully illustrate how I feel like this would help. Since 30fps frames are doubled anyway to reach 60hz output, you're really not losing anything by blanking out half of your signal. Though you might not gain much either (as each frame will be quadrupled in a 120hz signal, then halved with BFI), but this would most likely help with 60fps games on 120hz display as well.

BFI Illustration.png

I forgot to mention I do use a now-old video processing device called the iScan DVDO VP50 from 2007 or so that can take a 60hz signal in and output 120hz via frame duplication. It doesn't use interpolation so you avoid the Soap Opera Effect, and it also works to eliminate 60hz flicker. So at least in my case I do have SOMETHING at my disposal to convert 60hz to 120hz output, but something more readily accessible and available would be welcome as well.
This is probably the hundredth(ish) time I've seen this.
It reduces flicker yes, but it introduces a duplicate image effect, so it isn't a Holy Grail.

For More Info And Animation Demos, See blurbusters.com/area51

Multi-strobe definitely creates duplicate images. This is confirmed:

Image

1 - Motion blur is proportional to pixel visibility time. For squarewave strobed framerate=Hz, motion blur=pulse width. For non0strobed, motion blur=frametime
Educational Animation Demo Link:
TestUFO Variable Persistence BFI
(*IMPORTANT: Not for strobed displays or CRTs; run this on a sample-and-hold display of 120Hz or higher. If you only have 60 Hz, it will be super-flickery)

2 - To avoid duplicate image artifacts, flicker must be contiguous for a unique frame, to avoid duplicate images.
Educational Animation Demo Link: TestUFO Black Frame Insertion With Duplicate Images

For More Info And Animation Demos, See blurbusters.com/area51

From the "Research" tab on the Blur Busters website, I have provided these two images as a reference how to get identical display motion blur on a strobed display versus impulsed display. (Important: CRTs impulse so briefly that no commercially available unstrobed sample-and-hold display can yet match the motion blur of CRT).

Image

Image

This is all confirmed and now known (for a decade) display motion blur science.

This is even demonstratable in software-based BFI, just click the links above. The more refresh rate the better, because BFI persistence can only be simulated in refresh cycle increments. So if your display is 144Hz, your BFI persistence control of software-based BFI can only occur in 1/144sec increments. So the TestUFO animations become more educational the higher the refresh rate you go

Blurfree 60fps absolutely has to unavoidably modulate light output (with a contguous light-output peak per unique image aka frame).
So because you're stuck with 60 light-output peaks (flickers) per second, you have to do various means of mitigation, as follows:

How Do You Fix 60 Hz Flicker As Much As Possible? (aka How To Simulate a CRT Better)

The main 60 Hz flicker workaround is
(A) Soften the leading edge and/or trailing edge. CRTs have phosphor decay so the motion blur trailing edge is softened slightly (less harsh flicker)
(B) make sure photons are continually hitting human eyes by using a rolling strobe (like a CRT) instead to soften the leading and trailing edges of the flicker, at the cost of a bit more blur/ghosting/phosphor-decay effects. That's why I'm a fan of future CRT simulators.

Be noted there are other factors (brightness, image size, viewing distance, ambient lighting, flicker sensitivities between humans, etc), but the above is what CRTs naturally did; a rolling flicker with a decay effect. This is what makes 60 Hz flicker a lot more tolerable than 60 Hz squarewave. Be noted the sensitivities vary a lot -- there are people who can't stand a 60 Hz CRT -- and on the opposite side of the spectrum, there are people who tolerate 60 Hz global strobing.

Some displays do (B) like LG OLED rolling BFI but that doesn't fix (A). So the current (2017-2022) LG OLED rolling strobe is a less flickery but has way more motion blur (over 10x more) than the best strobed LCDs. Many love the LG OLED (as do I) as a compromise, however. But it is not (yet) a Holy Grail.

That's why I am a big fan of future CRT electron beam simulators (rolling strobe with fadebehind), because once you have enough brute refresh rate, you can simulate in finer granularities. The higher the refresh rate, the shorter-persistence a CRT tube can be simulated (as persistence is in refreshtime increments). If only the LG OLEDs could do 1000Hz+....

Long-term, I'm interested in seeing an open-source Windows Indirect Display Driver exist (based on that Microsoft sample) to run various kinds of shader algorithms such as:
- software-based BFI (for 120Hz displays)
- rolling-scan simulators (for ultrahigh Hz displays, 240Hz+ OLED or 360Hz+ LCD)
- software simulated VRR (like testufo.com/vrr -- algorithm only works on sample and hold display; doesn't work on CRT)
- software-based LCD overdrive superior to manufacturer overdrive (e.g. allow in-between overdrive settings, and/or select different overdrive curves).
- etc.

An ADC isn't critical -- to omit a video processor box or ADC, you can just do a simple GPU shader running in a modified Microsoft-sample Windows Indirect Display Driver, and committed to github -- would do the job.

For More Info And Animation Demos, See blurbusters.com/area51
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Re: BFI for 30fps Content on 120hz(+) Display?

Post by Chief Blur Buster » 05 Sep 2022, 17:14

I have moved this to Display Engineering Forum (aka "Area 51") because this is a Display Engineering question.

If anyone has some Windows Indirect Display Driver programming knowledge, one can create a harness to experiment-with and execute these various algorithms.
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Re: BFI for 30fps Content on 120hz(+) Display?

Post by Guffman » 09 Sep 2022, 23:31

Thanks for getting back to me (and moving the topic for me as well). I saw your response to my other post first, but I appreciate you taking the time to reply to this one as well!

I bet it's probably a little annoying having to repeatedly explain the same stuff over and over again to people like me that don't really know what they're talking about :P

If interpolation really is the only solution then I suppose that's a different avenue I'd have to go down... Pretty unfortunate though given most interpolation I've seen introduces significant processing lag -- totally fine for video content but mostly unplayable for gaming.

Is there something possibly that can be done with interlacing video? In theory, each field of an original 30fps source is only on-screen for 16.66ms, right? So even though the original frames are still duplicated to reach 60hz output, only the odd or even lines of each frame will be displayed at a time. Obviously this would require a video processor to interlace the content and then a second video processor to de-interlace back into 60hz progressive, but combining this with a framedoubler for 120hz and adding BFI (please correct me if this terminology is wrong btw, since I mean the signal itself is 120hz but only 60 of those frames are black... is that 60hz BFI?) seems like an interesting idea... I would consider just leaving the signal interlaced, but the flicker drives me up a wall, and progressive displays generally deinterlace anyway (often lagfully), not to mention bob deinterlacing being about as flickery, if not more-so, than the original interlaced video was to begin with...

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Re: BFI for 30fps Content on 120hz(+) Display?

Post by Chief Blur Buster » 12 Sep 2022, 00:06

Guffman wrote:
09 Sep 2022, 23:31
If interpolation really is the only solution then I suppose that's a different avenue I'd have to go down... Pretty unfortunate though given most interpolation I've seen introduces significant processing lag -- totally fine for video content but mostly unplayable for gaming.
Good news.

Interpolation is not the only option, at least if we’re handling modern engines.

If you’ve ever played VR, they use a virtually lagless “add extra frames” technology called “reprojection”. Such as Oculus Asynchronous Warp (ASW).

PC games don’t generally do this, but VR games do it quite a lot. So the technology already exists, but requires access to additional data from the game engine (like high-Hz controller inputs and Z-buffer) to make it lagless and more artifact free.

You can read more about this in the Frame Rate Amplification Technology: Getting 1000fps For Cheap In Future.

As AI-based frame rate amplifiers become higher performance, they will eventually be capable of 10:1 frame rate amplification ratios, generating 1000fps output from 100fps feedstock in realtime.

We’re actually seeing elements of frame rate amplifiers borne itself out of research as we speak — in a left field area. DLSS is using neural network AI, as you already know — and AI is rapidly improving.

You’ve seen those AI art-engines (DALL-E, Midjourney, et al). DLSS 5.0 on steroids will probably be realtime inpainting those in-between frames. I heard a rumor that the top end of the RTX 4090 is capable of generating AI art in just 1-2 seconds, and DLSS is a much simpler operation than AI art. Soon, we can generate “AI-art-movies” at realtime framerates in a couple or more GPU generations later — I would predict.

Virtual-reality reprojection algorithms converts 45fps feedstock into 90fps view, eliminating stutters without adding interpolation latency. So the technology is here today, if you own a recent VR headset.

Now in the future …

GPU vendors can redirect some of the new ‘AI skills’ from AI-art-processing capability called “inpainting” (and similar algorithms) as a turbocharged DLSS with a 5:1 or 10:1 frame rate amplification ratio, possibly combined with temporally-dense raytracing algorithms too (NVIDIA cited my TestUFO in their research paper). This is all exciting developments.

Essentially, a merger between NVIDIA DLSS + Oculus ASW + subvariants of AI-art techniques like AI-based inpainting algorithms will make the 1000fps frame rate amplifier a reality within a decade or so — on a single commodity GPU.

That said, the silicon manufacturing shortage and geopoliticals (TSMC…) may set frame rate amplification back a few years. But UE5-quality 1000fps should become practical eventually.

A frame rate amplifying co-processor (or dedicated silicon) may be required, to keep the GPU workload down — given the power requirements of GPUs it may need to be done as a chiplet approach (bandwidth…), but as long as the AI engine has access to 1000Hz controller inputs as well as the Z-buffer to generate parallax-correct (artifact free) AI based frame rate amplification.
Guffman wrote:
09 Sep 2022, 23:31
Is there something possibly that can be done with interlacing video? In theory, each field of an original 30fps source is only on-screen for 16.66ms, right? So even though the original frames are still duplicated to reach 60hz output, only the odd or even lines of each frame will be displayed at a time.

Obviously this would require a video processor to interlace the content and then a second video processor to de-interlace back into 60hz progressive, but combining this with a framedoubler for 120hz and adding BFI (please correct me if this terminology is wrong btw, since I mean the signal itself is 120hz but only 60 of those frames are black... is that 60hz BFI?) seems like an interesting idea... I would consider just leaving the signal interlaced, but the flicker drives me up a wall, and progressive displays generally deinterlace anyway (often lagfully), not to mention bob deinterlacing being about as flickery, if not more-so, than the original interlaced video was to begin with...
A smart programmer would need to combine the video processor steps into a simultaneous step to avoid the serial latency-adding steps.

Perhaps even beam-race the video processing as much as possible (at least to keep it only 1/60sec latency, since you can only beam-race the second field with a resulting beam-raced progressive scan image.

Raster beam raced video processors/scalers are very rare (I think HDFury is one of them) because they use subframe buffering (rolling window of number of scanlines) spewing output concurrently with input, with only a few scanlines lagbehind.

Be noted that BFI is not necessarily a 50%:50% step, and sometimes BFI is a hardware operation (strobe backlight). BFI is often used as a synonym to strobing.

However, BFI at the software level, depends on the output refresh rate, so if you have 360Hz of output refresh rate, you can do BFI in 1/360sec increments. You can see variable-persistence BFI at www.testufo.com/blackframes#count=4&bonusufo=1 …. This version uses a 4-frame BFI per frame cycle, so best played at 240Hz for 60fps variable-persistence BFI (25% blur reduction, 50% blur reduction and 75% blur reduction). If you try to play this at 60Hz, it will flicker a lot at 15Hz, but it can still demonstrate the educational concept.

RetroArch is one of the only emulators that can do BFI at higher refresh rates (e.g. 180Hz, 240Hz, 300Hz, 360Hz) to produce less motion blur than 60Hz BFI.

The most lag-free scalers (e.g. HDFury) does not have built in BFI, but in theory software BFI won’t add more lag on top of the lag that a video processor generates, provided the visible frame is the first frame of the BFI sequence.

It’s more ideal if you use a progressive scan source, but a good beam-raced video processor should keep 30fps deinterlacing to only 1/60sec input lag (buffering the first field, and doing beam-raced deinterlacing during the second field). I don’t know if any video processors are that low latency in deinterlacing 30fps material.

This can be problematic for cadence-change events (e.g. when you’ve got a 1/60sec framedrop, so you’ve got one frame that has even-odd-even or odd-even-odd and subsequent frames having swapped odd-even versus even-odd cadence. All this stuff ideally needs lookahead, so buffering a few fields is more common.

I would expect that a theoretical future AI-assisted beam raced deinterlacer could keep latency pretty low, without generating artifacts, simply by the AI knowing what to expect from the engine during frame drops, etc.

If you are doing an emulator, beam racing is already possible (synchronization of real raster to emulator raster), I helped a few emulator authors achieve this (most particularly, WinUAE, but also is in CLK and an early-test version of GroovyMAME by Calamity).
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okaxihd
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Re: BFI for 30fps Content on 120hz(+) Display?

Post by okaxihd » 04 Jan 2023, 11:28

Hi guys, I would like to ask a favor if possible, would you be able to get the desktop BFI software and put in place of black, maybe a light gray just to make the blur smooth playing at 30fps? :| I don't care about the motion blur, the problem is that at 30fps it has a lot of flickering in several games, especially in very bright environments, I think that the light gray BFI would already solve this and with less flickering at 60hz monitor. I plan to do 60hz = 30fps. ;)

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