c/techsupport · by akunohana@piefed.blahaj.zone · 10d

Why are dark parts flickering?

I'm using mpv to play some FHD Bluray Remuxes on a 4K TV with all "smart" enchantments turned off (smoothing and whatever). Any darker colors flicker. Let me know if the uploaded video doesn't clearly show what I mean. Is there a fix for this?

4 points · 11 comments · view on lemmy.world

11 Comments

tal@lemmy.today · 5 pts · 10d (1 reply)

It looks like patches. Maybe if the TV has...what do you call it, local lighting? The brightness is just right to trip those?

searches

Local dimming.

I wouldn't think that it'd be so visible, but it sounds like it's at least possible to produce similar artifacts on some televisions.

https://eu.community.samsung.com/t5/tv/2019-qled-local-dimming-unsable-on-hdr-content-brightness/td-p/5236850

2019 QLED - Local Dimming unsable on HDR content - Brightness flickering in gray/dark scenes

This is not limited to HDR I believe but more pronounced while watching HDR content. The issue is that the local dimming seems to be unsure what brightness to use causing the brightness to flicker. This happens especially on grey or darker background walls in movies and so on. The biggest issue is, that it causes multiple areas on the screen to flicker. It's a bit difficult to film, because scenes change fast and the camera is masking this problem a bit. But I could "simulate" this issue in this video. Watch the dark horizontal band starting from the middle of the screen to move up after the top timer bar disappears. The bar disappears in less than 1 second yet it affects half the screen for a whole ~3 seconds. It's like a shadow or ghosting effect.

https://www.youtube.com/watch?v=Kym5aHsYaEU

Now imagine this happening in every dark scene when there is something moving and the whole area left and right is affected by it. It's a constant flicker in those areas. It's not limited to the light source changing, meaning this isn't like blooming when you use subtitles. This stops when I pause the movie or when there is absolutely no movement/change in the scene or when I enable Game Mode, meaning when Local Dimming is turned off.

It's so distracting that I can't really watch anything anymore without looking for it. I noticed this a few times after buying this TV but I rarely noticed it after that. Now it's suddenly so extreme that I can not watch darker movies because it's constantly flickering.

Everything from ECO mode to Intelligent Mode, Auto Brightness etc is OFF!

If your TV has local dimming, maybe try disabling it?

akunohana@piefed.blahaj.zone · 1 pts · 10d

Thanks so much for looking that up! It doesn't quite look like "my" flickerings and my TV doesn't have such a setting.

CameronDev@programming.dev · 2 pts · 10d (8 replies)

I was going to guess compression, but if that is a blueray quality rip then maybe not. Does it happen with any other players, or is it just MPV?

akunohana@piefed.blahaj.zone · 1 pts · 10d (7 replies)

Haven't tried. I'll try VLC and update! Meanwhile, here are the exact file details, because I'm really bad with video meta data: 1080p, BluRay, Remux, AVC, DTS-HD, MA5.1

CameronDev@programming.dev · 2 pts · 10d (6 replies)

Bitrate? I'm guessing its been upscaled or something anyway, because the office was never filmed in 1080p.

akunohana@piefed.blahaj.zone · 1 pts · 10d (5 replies)

mediainfo says variable bit rate, overall bit rate 32.6 Mb/s, bit rate 27.6 Mb/s and maximum bit rate 38.2 Mb/s. Variable bit rate? That cannot be how it was recorded, right? Some conversion thing to save space? That's insanely valuable knowledge regardless, knowing 1080p isn't the original resolution. How do you know? 😊

CameronDev@programming.dev · 1 pts · 10d (4 replies)

It was filmed for TV 20 years ago, it would have been NTSC, which is 720x480. HD for TV came a bit later.

Doesnt help you with your problem though :(

akunohana@piefed.blahaj.zone · 3 pts · 10d (2 replies)

So, interestingly, the flickering was reduced but still visible with the H.265 encoding. A common denominator is that the flickering is most visible when/where there are horizontal and/or vertical lines, say, like a fence (for instance some of Michael's suits, in keeping with The Office). So maybe it isn't a color, color depth or toning problem at all?

CameronDev@programming.dev · 2 pts · 10d (1 reply)

Maybe its this then:

https://tvtropes.org/pmwiki/pmwiki.php/Main/Strobing

Artefact of the upscaling perhaps?

akunohana@piefed.blahaj.zone · 2 pts · 6d

Thanks and sorry for the late reply! Yes, it could be. I still have to check some hardware stuff first though: I have two other HDMI ports on this TV and a few different configurations on the picture.

akunohana@piefed.blahaj.zone · 2 pts · 10d

I still appreciate the info though, because I am looking into obtaining more and more "authentic" stuff, if you get my drift. Maybe it's my age. XD

Before I try VLC, I'm going to try another encoding (h265), also from Blu-ray, also in 1080p though... to see if that does anything.