Duplicating and blending frames to simulate a "cinematic" feel

[23423451]

Hi, I'm mostly looking for advice on where to take my question or how to start finding answers, but direct answers to my question are welcome too. Thanks for anything you can provide! Going to start with preamble but I'll put a "skip to this part" below where I actually ask a question.

Goal: Make my favourite old 24p movie backup look as good as possible on my 120Hz display with regards to my taste in motion.

Premise:
120Hz fast response OLED "sample and hold" a frame nearly the entire length of time that frame is active in a video. At 24p this long hold time can look extra stuttering at times or to sensitive viewers. Slow response TV's don't have this problem as much because frames take time to fade in, or rather out (I think. My understanding is limited here). It's still 24fps with no interpolation so no soap opera effect, and maybe the reason this looks appealing to me is because movie theater projectors have done something similar. They show a frame 2 or 3 times with a 48Hz or 72 Hz shutter blinking in between. While not blending frames, they are preventing your brain from seeing the same constant frame for a full 1/24th of a second. In the past when they just did this shutter at the same framerate, 24Hz was slow enough that people could see the headache inducing flickering of darkness between frames.

Current workarounds:
My 120Hz OLED can flicker the LEDs off in between frames which darkens the picture (I can handle that) but also makes a visible flickering that gives me a headache (max flicker rate is 60Hz I think).
There's low levels of motion interpolation which start down the path towards soap opera effect and of artifacts on screen that stand out. So far this is my best option but it lacks that "feel" that theaters and some older panels produce where the content is only 24fps of information and the magic is between frames, not creating extra frames. (Older panels like LEDs with backlight can also faster flicker that backlight, dim backlight, or rolling shutter style it with local dimming. Fancy fixes an OLED with no separate backlight doesn't seem to have an answer to yet).

Future hope: maybe my tv would get a software update someday from the manufacturer that would give me the option to blend frames in a way that looks like the desired effect. It is Samsung though, and they don't seem to have a reputation for this sort of thing.

"SKIP TO THIS PART FOR MY QUESTION "

So can I fix this problem by encoding my video a certain way? It might be time consuming and resource intensive but I'd go that far for a beloved favourite film.

Ok so I have 24fps (or 23.976), and 120Hz. I could convert 24fps to 120 by duplicating each frame until I have 5 of each. This doesn't solve the problem but it gives me a canvas. Each proper frame now has 4 extra frames to work with to try and simulate that movie theater or older tv effect.

Possibilities of what to do with each of these frames include: leave as is, dim it, blacken it, blend it partially with the adjacent frame (simulate a frame wipe transition using up to 4 frames, or some kind of fade in/fade out combo).

I think this could be possible but I doubt I could conceive and program the algorithm from scratch so:

Can this be done using existing video encoding tools? Is there a good combination from the options above of what to do with those in between frames to keep the 24fps feel as well as the higher rate shutter or slow response frame transitions? Can I make my 24fps movie into a 120fps file that plays beautifully on a 120Hz screen with reduced stutter and no soap opera effect or out of place artifacts of interpolation? (Also without visible flickering of too much black frame insertion)

Thanks again! And sorry if I waste anyone's time with the long post and you end up thinking it a stupid question.

[poisondeathray]

It's not a stupid question. Different people have different perceptions.

You can try adding motion blur . That might satisfy some of the strobe sensitive viewers, but others will think picture looks smeary . You can't satisfy all viewers

Also, unless you have a time machine and can adjust the shutter speed - adding motion blur in post isn't 100% perfect either - you can sometimes have artifacts too

(Some people like the "soap opera effect", even if there was no artifacts. Others hate it)

[Bwaak]

Does the TV have special provisions for creating artificial frame flashes? Too funny. Maybe when they raise the flashing rate from 60 Hz to 72 Hz it will look better. Time to switch to 120 fps movies, I guess Sadly, I cannot suggest much. I hate interpolated "soap opera" look, and I cannot stand stutter. I am glad I have a good old plasma, which flickers just by itself.

[23423451]

It's not a stupid question. Different people have different perceptions.

You can try adding motion blur . That might satisfy some of the strobe sensitive viewers, but others will think picture looks smeary . You can't satisfy all viewers

Also, unless you have a time machine and can adjust the shutter speed - adding motion blur in post isn't 100% perfect either - you can sometimes have artifacts too

(Some people like the "soap opera effect", even if there was no artifacts. Others hate it)

I'm actually a fan of high frame-rate content depending on its use. 48fps hobbit in the theatre was excellent for panning shots of mountains, but resembled a live stage theatre performance rather than a fantasy movie. Good effect for shakespeare, but not for an established Peter Jackson Rings universe.

I read that Avatar 2 is doing something cool, for theatres with projectors that can handle it. They filmed at very high frame-rate and mastered the movie at 48fps. So for the wide panning shots it's 48fps, and for the close-ups and low motion shots it frame doubling every other frame to make it look like 24fps, maintaining the "cinematic feel" (since the projectors don't have variable refresh rates).

---

I think you might be right about adding motion blur, except instead of blurring all or every other frame it might look best to hold the correct frame and only have blurred frames 20-40% of the time.

24 fps: |1|-|2|-|3|-|4|-|5|
120 fps: |1||1||1||1||1|-|2||2||2||2||2|-|3||3||3||3||3|-|4||4||4||4||4|-|5||5||5||5||5|
then 120fps with blur on some:
|-/1||-/1||1||1||1|-|1/2||1/2||2||2||2|-|2/3||2/3||3||3||3|-|3/4||3/4|-|4||4||4|-|4/5||4/5||5||5||5|

Do you think it's possible to be this specific with video editing software? Maybe I'd have to x5 all the frames and export, then edit again with motion blur so that the motion only get applied to those edge frames and the inner 3 duplicate frames stay untouched.

[poisondeathray]

For motion blur - the magnitude of the blur is proportional to the amount of motion. It's dynamic, not a "dumb" blur. If it was a static scene, no blur would be added. A static background with moving foreground objects (e.g cars, actors) would be blurred more in the FG objects, none in the BG if the camera was still. There are plugins for editors, such as RE:Vision FX Reel Smart Motion Blur, a few others. There are some free options like avisynth mvtools2, or QTGMC has a shutter blur option . The artifacts of post production motion blur are generally "less bad" then framerate interpolation artifacts from optical flow or similar

You can also use "weighted blending" - it doesn't have to be a 50/50 mix of original frames for the blends . eg. If you have [A] [B] , you might chose [A] [0.7A,0.3B] [0.5A,0.5B] [0.3A,0.7B] [B] . Or any weighting or combination including repeats. One way to do this is avisynth or vapoursynth . It should be possible in an editor too, but it's probably easier programatically via scripts. One negative of 120FPS encoded at 120FPS - is it's more heavy on playback resources. 120FPS @ HD might be feasible, but 120FPS at UHD resolutions is much more difficult to playback ,depending on the hardware, profile, codec, etc... and if you get dropped frames because of insufficient resources - it will look a lot worse than the original

And it's possible to combine methods too as you wanted (apply motion blur or any filter/effect to specific frames only)

Experiment and see what you like better, or what ratios/combinations. Take a test clip (or few) and run some tests. If you need help with scripts, post and someone will help

Just remember, if you like it, there will be others that absolutely hate what you've done to it.

[Cornucopia]

Most 120Hz TVs do NOT allow for 120FPS direct input. Their max is usually 60FPS (perhaps 72).

Since you have a 120Hz OLED TV, there ought to be a feature that works specifically with 24FPS movie footage, allowing it to quintuple-flash without needing to do any pulldown. However, I contest that you say you can see the "flickering", as a 120Hz TV would AT WORST show interim black at 1/120sec for each frame (more likely 1/240sec), which is way shorter beyond the minimum level of perception for 99.999% of viewers.
My educated guess is that you are either noticing pulldown effects because the TV/player is NOT showing it optimally at a whole multiple of 24FPS, or it is showing whole multiples of 24 and you are noticing the normal effects of 24FPS shooting, which in this day and age should be considered LOW framerate.

Your TV should have a feature both for optimally showing 24FPS without frame/motion blending, and a feature WITH blending. All the (better than bargain basement) TVs I've seen in the last decade have had one or both of those options.

I do NOT recommend re-encoding your material just to accommodate this, in the hopes that it MIGHT be better than hardware blending, because you are still losing quality by re-encoding.

Scott

[Luke M]

There's a commercial tool that does what you want:

https://www.pixelworks.com/en/truecut

Personally I use the motion interpolation on my Sony TV (in "standard" mode, which preserves 24fps look). This tames the flicker.

Inserting black frames would work (if you have a 144hz display), but that cuts the screen brightness in half.