Frame repeating for strobed monitor

[Intikhab]

My query here is that when we watch movies and play games there are limitations of what movies are made at fps wise and games being fps locked thus strobing with them can't be done directly to have no negative viewing experience as they are strobed at lower fps. I know movies can interpolated using smooth video project on pc's and benefit fully from strobing even at 144hz provided gpu is strong enough to render. But what to do when games are locked at 30 or 60 fps due to speed being directly linked to fps or other dev choice of locking it at 30 or 60 fps? Is there any way to repeat frames for games so that strobing effect can still be gained without low fps visual problems? I know it will still be responsive to 30 or 60fps 1/"x"fps or less depending on frame repeating overhead etc.

NOTE:If it is already asked I couldn't find it.

[spacediver]

Not sure I fully understand your question.

But just so we're on the same page, you understand that if you're strobing a 144 hz display, then it doesn't matter what fps the content is in, the display will still strobe 144 times a second, right?

[Falkentyne]

I don't understand what you're trying to ask, either.

Are you talking about BFI (Black Frame Insertion) or Double strobing?

Double strobing is when the backlight is strobed twice per refresh. The Eizo Foris FG2421 already does this.
Benq blur reduction (BBR Z series monitors before the XL2730Z freesync monitor) does this at lower than 100hz refresh rate, if single strobe is disabled in the service menu.
It single strobes at 100hz and higher.
Lightboost monitors can double strobe at 60hz with vertical totals higher than the 120hz lightboost trigger (> 1149; usually 1149 VT --the strobe signal activation for 120hz strobing--at 60hz is ignored deliberately, but higher Vertical totals that bypass this 'lock' may still unlock it); VG248QE will double strobe at 60hz at 1179 VT; Benq Z series monitors (and probably the T series before it) will double strobe at at 60hz at 1155 VT.

But I don't think this is what you're trying to ask.......?

black frame insertion allows you to get a clear motion blur free image on backlight strobing monitors when the framerate is half of the strobed refresh rate (e.g. 120hz strobing at 60 FPS). Usually 60 FPS at 120hz strobed refresh rate will cause a double image because the backlight isn't being strobed in sync with the framerate; black frame insertion will add an extra blanking which will help blank the double image, giving motion blur free eye tracking).

I'm sure Chief can explain this better, I'm probably not being very accurate.

it sounds a LOT like you're talking about Black Frame Insertion.

This usually is done with software. (there was a special MAME Version that was designed for 120hz lightboost and 60 FPS locked games that had black frame insertion built in). And it only works if you're playing back game or video content that is half of the current refresh rate and if the refresh rate is already backlight strobed. It is possible to do it through hardware, though, but if the framerate is not exactly half of the refresh rate if you try this, you aren't going to like what you see

[Intikhab]

thanks for replying. Let me be clear of what I am asking by example.
Example: lets say I have 2 games one is lord of the rings battle for middle earth(lotrbfme) rts frame locked at 30fps and another is shadow of mordor(som) not frame locked and can run at 120fps. If the monitor on which is to be run is g-sync monitor and I am using ulmb(g-sync is not being used I know) at 85 or 100 or 120hz how will games behave if they are not matching those hz for ulmb, if lotrbfme is running at 30fps at those 3 different hz what would the 3 possibilities be look like, if som is running at 60 or 75 or 80 or 90fps what would these fps at those different hz would look like?


Can they be still be easy on eyes to look at? do I have to do something about them to be better?
I am running 980 gtx and for now I have 60 hz 1080p monitor but will buy new 24 inch monitor ips 120hz 1920x1080 g-sync for ulmb or similar tech in it for clear motion, when it will become available for me in future years, they don't bring good stuff quickly here(plus 24 inch ips is not made yet XD)?

[Falkentyne]

30 FPS? Don't even bother.
60 FPS? 120hz ULMB with "Black frame insertion"

There's no other realistic way besides BFI and again you need an even divider of framerate/refresh rate, and a monitor capable of single strobing at the original refresh rate.

There is a directX program already capable of doing black frame insertion. It's used for Skyrim where uncapping the FPS beyond 60 causes physics problems. It's used for a few other games as well, but it's not a global solution for doing BFI at framerate half of refresh rate. You would have to ask someone to write a hook (like Fraps) that can do that.

As far as what they would look like natively..well....have you ever seen a CRT monitor? They used a scanning backlight by design, and were strobed by nature at all refresh rates at all times. So you could cap lock the framerate at a lower setting than the refresh rate and yes, it would stutter and not look too good. So things looked best at framerate=refresh rate, otherwise we usually turned off vsync to avoid double buffer FPS dropping in half or stuttering back then.

[Intikhab]

so if driver based BFI can be done could it be also possible to implement to repeat the last frame too? so 30fps or 60fps would be stretched out as 60-90-120 frames would be same slow game to play but easy to look at through strobing where it have 2-3-4 frames stretched out of single frame and still be 1/30 or 1/60 on gameplay level but it will not be bad looking at 120hz strobing level. I am being clear on my points?

[Intikhab]

Could someone point me in right direction where can I learn how to write programs for drivers for such purposes? I have done BSc. in computer science and good in programming so I might go fiddle with things and write something up. I did read the posts about the Skyrim after you told me about it Falkentyne. But that was BFI, where as I want to repeat frames for a game. BFI would benefit 120hz and strobeless monitors but repeating frames I think would still be good for strobing monitors to use.

[Falkentyne]

You should PM Chief Blur Buster. He's been busy but I'm sure he can point you in the right direction on this.

[Glide]

Could someone point me in right direction where can I learn how to write programs for drivers for such purposes? I have done BSc. in computer science and good in programming so I might go fiddle with things and write something up. I did read the posts about the Skyrim after you told me about it Falkentyne. But that was BFI, where as I want to repeat frames for a game. BFI would benefit 120hz and strobeless monitors but repeating frames I think would still be good for strobing monitors to use.

Frames will be repeated by default.
Repeating frames results in terrible double/triple/quadruple images and judder.

• 60 FPS at 60Hz
• 60 FPS at 120Hz

Your framerate must match the refresh rate when using an impulse-type display.

Dark frame insertion combined with strobing essentially keeps the refresh rate the same by extending the duration of the strobe.
If you have a 50% strobe and are displaying 60 FPS at 120Hz, using dark frame insertion would be equivalent to 60Hz with a strobe duration of 75% instead of repeating every frame.
Dark frame insertion is not as effective as strobing the backlight, because most LCDs don't switch off when displaying a black frame, and it places greater demands on the panel's response time.

The alternative is motion interpolation or reprojection.
Interpolation/reprojection creates new frames from the existing data instead of repeating them.
The problem is that it's very prone to creating artifacts, and interpolation adds a lot of latency which makes it unsuitable for gaming.