Hoh-kayyyy.... Have looked at that shot in 1917. Characteristically long analysis coming!
I see what you're saying. Yep, looks pretty nasty in most people's "normal" mode on a C8 (that's with all the interpolation etc switched off, no sharpening, proper white balance etc). It's equally bad on both the UHD and the standard Blu Ray versions, so it's not anything to do with an HDR bug, or trouble handling the UHD data rate.
So I filmed the screen at high frame rate (240fps - best I can manage) and went thru it frame by frame to try and figure out what's going on. Far as I can make out, there are three things at work here (well, kind of two and a half, since two of the problems are related).
1) The good news is it's definitely displaying 24fps progressive as it should. The screen shows a new frame of film every 10 frames of 240fps. So there is 24fps judder. That's to be expected, and pans are of course the worst for showing it up.
2) However, exacerbating that 24fps judder is the fact that It appears to be shot at a fairly high shutter speed, so there's not much motion blur in each frame to help join one frame to the next. e.g. the thin bars in the windows of the building near the end of the pan are surprisingly clear while the pan is happening, and aren't much blurrier
during the pan than they are when the camera is stationary. Odd decision. Maybe they went for a high shutter speed to get crisp details in the characters' clothing etc. All the other movement in that scene is very slow and smooth, so perhaps they chose to sacrifice the pan smoothness for super-sharpness in the rest of the shot. I don't know. Ask the DoP!
3) This is the big revelation, and it was the first thing that leapt out at me when I saw the shot. The frame is tearing - you see the upper parts of the buildings sort of detach and flicker separately from the lower parts! Here's why (this should have occurred to me before, seems obvious now).
To update the OLED panel it is scanned from top to bottom. That is to say, the whole frame is not updated at the same time (like it would be in a film projector). When a new 24fps film frame arrives, the OLED updates the pixels at the top of the panel first, and works its way down to the bottom. It takes about 1/80th of a second to update the whole panel.
So, 1/80th of a second, that's pretty fast right? A lot faster than the 24fps frame rate. BUT it means that for about a third of the duration of the 1/24s frame, the bottom of the panel shows the image from the previous frame, and the top of the panel the image from the next frame. That produces tearing when the image moves horizontally, which makes the buildings look a bit bent - the upper parts of the buildings don't seem to line up with the lower parts - made worse I'm sure by the fact that they have bright white sky behind them.
The tearing can be almost totally fixed by switching the black frame insertion on (TruMotion "Motion Pro"). That means that you never see the top of one frame sitting right next to the bottom of the previous frame, and that flickery "bent" look to the buildings goes away.
However, it doesn't fix the 24fps judder, because there is still very little motion blur in the source frames. So it doesn't magically clear up the whole problem, it just addresses one aspect of it. Def better though.
The BFI introduces a small amount of flicker at 24fps, but you don't notice it once the disc starts playing. You do have to contend with a drop in picture brightness, and a bit of a loss of visual punch. Colours feel a little bit muted. If you're going to use TruMotion Pro, I'd suggest watching in a darkened room, and probably recalibrating the black and white points, OLED light, etc. For SDR material I have one user picture preset for bright room conditions, and one for dark room with the BFI switched on.
I would be fascinated to try a CX/GX with the improved BFI. On the C8 the BFI presents as a wide black bar that scans down the image every 1/60s. I don't know exactly how it has changed on the 2020 LGs, but I understand it's much more refined. I know the width of the bar can be adjusted, but does it scan faster too?
Anyhow... I look forward to seeing how the JVC handles that scene. I'm also going to try and come up with other scenes from movies that include similar pans, and figure out what's happening in those, because they don't always look as bad as that one in 1917. It is fairly horrible.
HTH. See what you think on your systems.
)
