Get the OLED out
May 11, 2021 3:12 PM   Subscribe

Recently bought a new LG CX OLED TV (48") to replace my 10-year-old LCD model. It's lovely, but...

Last night I was watching Sherlock re-runs (sue me) streaming on BBC America, and I noticed a few times that when the character made an abrupt movement, that area of the screen basically degraded briefly into pixelation.

I'm familiar with motion blur from the LCD, which has not ever bothered me. However, this phenomenon, while brief, is far more noticeable. Maybe it's just the way the sources I've lighted upon choose to describe things, but so far in googling I don't see any descriptions that quite match this. I tried turning off TruMotion completely, but still saw it.

(My Internet connection is 400 MB/s so I don't think it's the streaming.)

What's going on? Is this "normal" for OLEDs? Is there anything I can do to minimize it?
posted by praemunire to Technology (13 answers total)
 
Best answer: That really sounds like a video compression artifact, not an OLED display artifact.

Can you reproduce the artifact by replaying the scene? (It could be poorly encoded video, if so, so don’t despair!)

Can you reproduce the artifact with rapid motion in other, similar scenes (ideally from an entirely different streaming provider, to get as different video encoding as possible)?
posted by Alterscape at 3:17 PM on May 11, 2021 [4 favorites]


Best answer: I have two LG OLED TVs (a CX and a C9) and I have never noticed that (I have noticed compression artifacts, but not this kind of effect unrelated to compression). Maybe I'm just not sensitive to it, but I think I would have noticed after all this time.

I would try the different picture modes (I think the one I use is called Cinema, but I'm not in front of it right now) to see if some processing setting is messing it up (there's more than just TruMotion).

Also, just because your connection is fast it doesn't mean that you're getting a good stream. BBC might just over-compress stuff, or throttle the connection, or something in between your house and their server is slow. I agree with Alterscape that I'd try some other sources.
posted by primethyme at 3:20 PM on May 11, 2021


My guess is that either (a) your old TV had some correction algorithm to minimize artifacts, (b) your old TV didn't have sufficient quality/brightness/contrast to see the artifacts, (c) the compression is bad (constant bit rate instead of variable, e.g.).
posted by supercres at 3:46 PM on May 11, 2021


Response by poster: OK, I'll see if I can find the show DVD and determine whether it happens at the same points. Also I think I still have some football recorded on the DVR, that probably has some rapid changes in direction.
posted by praemunire at 3:48 PM on May 11, 2021 [1 favorite]


Best answer: When you say "pixelation", do you mean blockiness? Like, the part of the picture with the sudden motion suddenly glitches up into a weird mass of squares? If so, that's a classic compression artifact (macroblocking) and it definitely suggests a problem with the BBC America stream, not your TV. Having a fast Internet connection doesn't necessarily mean you're in the clear -- you're still at the mercy of network congestion and latency, for one thing, which can affect BBCA's ability to get the stream to you, and then there's the BBCA itself and how aggressively they decide to compress their content to reduce the cost of delivering it to you.

If you're noticing the artifacts with the new TV, but you didn't when using the old TV with the same sources, then I think it's possible the LG (which is a great, great TV set) is revealing details in the picture or gradations in color that you were missing with your previous TV. It's also possible that your picture settings are making artifacts visible when they shouldn't be -- for instance, if you've cranked up the brightness too far (maybe because you're not yet accustomed to the glorious true black of OLED screens?) some macroblock artifacts will become starkly visible, and they'll literally disappear into the background if you turn the brightness down to the proper levels.

I'm curious, too, which picture mode you're using. If you're using the out-of-the-box "Vivid" or "Sports" settings or anything like that, I think the picture will be overly saturated and contrasty and as a result some compressed video streams may look really bad. I'd recommend setting it to "cinema" or experimenting with custom user settings and seeing if the problem is still apparent. Just throwing that out there in case it's a simple fix!
posted by Mothlight at 3:57 PM on May 11, 2021 [5 favorites]


Note that a DVD (if it's really a DVD) is pretty low resolution for a 4K TV, so that also might not look great. Blu Ray (the non-Ultra HD kind) is also not 4K, but my experience is that Blu Rays look great on the OLED.
posted by primethyme at 4:00 PM on May 11, 2021


Best answer: LCDs will sorta smear out blocky artifacts like that, an OLED will display them tack-sharp and then abruptly change to the next frame. So I am thinking you are just having an easier time noticing the blockiness that’s already there, because the TV can actually display it properly.
posted by doomsey at 4:01 PM on May 11, 2021


Best answer: I have that exact TV in the 55" size, am extremely sensitive to compression artifacts and visual glitches, and I have never noticed any problems. However, even with the "TruMotion" turned off, the picture is still being processed, especially with DVDs where you're asking it to improve the resolution by a factor of 4-5x. We basically have stopped watching DVDs, because there just is not enough resolution there to look good. Cartoony low-resolution sources look pretty good. Most 1080p sources are only doubling the resolution, and the smart upscaling seems to do a very good job with them, even though we are close enough that in theory we should be seeing almost the full benefit of a native 4K signal. (There was a change in nomenclature, 4K (aka 2160p) is roughly twice the resolution of 1080, which is roughly twice that of 480p (DVD)) I've considered trying to get the TV not to upscale to the full picture size but haven't figured that out yet.
posted by wnissen at 4:29 PM on May 11, 2021


Response by poster: OK, I found the old DVD, and while it doesn't look fantastic (as expected), it doesn't explode into a mass of blockiness at those spots, either. So it probably is just compression artifacts. My Internet speed tests indicate that I am getting more or less what I'm paying for, so I'll blame the BBC.

(I fiddled with the picture mode first thing--Vivid is downright creepy in its coloring.)

Thanks!
posted by praemunire at 4:29 PM on May 11, 2021


It's the streaming. I don't know if BBC can show streaming stats like Netflix can, but the streaming data rate tops out at far below the 400mbit of your internet service. For 1080p, its probably under 10mbit. Its typically 1/2 to 1/4 or less of the bluray disc bitrate. Which is generally fine for still scenes but anything action you will see the compression artifacts.

4k uhd streams from Amazon prime and Netflix (upcharge for 4k) will look better, although still have heavy compression, but there aren't a ton on either service.

For the best quality for your new tv you want 4k uhd blurays, and a 4k uhd player, but then you run into that many films, especially older ones don't have the resolution to match fancy new tvs and aren't any better than the 1080p hd blu-ray.
posted by TheAdamist at 5:24 PM on May 11, 2021


If you need to rule out encoding artifacts, you can download very high bitrate encodes of Tears of Steel. It's cheesy AF, but it's 4k HDR and the better encodes beat even UHD Blu-Ray in terms of bit rate, so it provides a good workout for the TV and media player.
posted by wierdo at 8:53 PM on May 11, 2021


I don't know what the steaming rate terms are with BBC America - but here in the UK the BBC have experimented with 1080p playback for a few people last year - before apparently getting cold feet about viewers breaking the internet with it during the 2020 lockdown. So, for now, the BBC are streaming a 1280 by 470 image steamed at between 1.5Mbps and 5Mbps. For comparison, a 1080p image is 1920 by 1080 and a 4K image is 3840 by 2160. So your 4K TV is getting only about 7% of the pixels that it needs to show a full resolution 4K image - and it is getting it on a stream that is only about 1-2% of the capacity you have between you and your ISP.

In the UK, the BBC are bound by the economics of running a public service - if they spend more money on streaming content to my fancy-arsed LG OLED TV - then there will be less cash for Benedict Cumberbatch. Which option does the nation really need? And if they scrimp and save on the bandwidth for a UK audience - then are they going to bother to provide anything better for foreign audiences?

In short: the BBC are not really good at catering for people wish 4K TVs and fast broadband. If you want to take advantage of that for an LG CX - then you would probably be better paying Netflix the UHD premium and waiting for BBC content to appear there.
posted by rongorongo at 4:08 AM on May 12, 2021 [1 favorite]


Response by poster: In the UK, the BBC are bound by the economics of running a public service

In the US, they are getting paid by the private market. I'm not free-riding on a VPN.
posted by praemunire at 7:32 AM on May 12, 2021


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