Flickering in dark areas of picture when displaying 4:4:4 signal from an Apple TV 4K on a 2016 LG B6 OLED

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Flickering in dark areas of picture when displaying 4:4:4 signal from an Apple TV 4K on a 2016 LG B6 OLED

Hey everyone! So I've noticed an issue with my 4K Apple TV, when connected to my LG 2016 OLED65B6P television, and I was wondering if you guys had any ideas. I've found that whenever the Apple TV outputs a signal with 4:4:4 chroma, there is some flickering in dark parts of the image.

I've found that if I change the input icon on my TV for the corresponding hdmi input, to the PC icon, which from my understanding is what enables the TV to truly accept a 4:4:4 input, the flickering goes away, but this unfortunately prevents me from turning on Real Cinema mode for proper display of 24p content. I would probably be fine with this for just the one input, but I want to run my Apple TV through my receiver, so I am not limited to just 5.1 DD over ARC, which would mean I would have to be fine with getting rid of Real Cinema on my Oppo 203 as well, which I also run through my receiver, and that is something I would really not like to have to do.

Furthermore, when the Apple TV outputs a 4:2:0 signal, there is no flickering, so I tried leaving it at that as the default SDR setting, but if I turn on auto frame rate switching, it ends up switching to 4:4:4 when displaying 24p content, even if the main setting is 4K SDR 60 4:2:0.

Right now I have the apple tv set to only match dynamic range, and leave the frame rate at 60fps, which seems to be the best compromise I have found so far, to eliminate the flickering while still running the apple tv through the receiver. However, this means I lose proper display of 24p and DV, unless I manually switch to that format in settings, since the 2016 OLEDs can't receive 60Hz Dolby Vision.

I have a 2017 55" B7A OLED in another room, and it does not exhibit any of the same flickering with an Apple TV 4k and 4:4:4 content, even without switching the input logo to PC.

Any ideas about what I could do to solve this and still be able to keep frame rate switching and running it through my receiver?

The ideal solution would be for Apple to fix the fact that it switches to 4:4:4 chroma when displaying 24p content with frame rate matching turned on, even with the chroma set to 4:2:0 in the settings.

Thanks!

Apple TV 4K, iOS 11.3.1

Posted on May 14, 2018 6:21 AM

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Answer 1

May 14, 2018 6:38 AM in response to JWort93

Streaming video content is 4:2:0, so a setting of 4:4:4 or 4:2:2 won’t improve your video picture, it just produces (4×) more data describing the same quality. Small text in a generated (non-video-encoded) menu might look a bit crisper in 4:4:4, but that’s about it. Therefore 4:4:4 is best suited for tv-as-computer-monitor and tv-as-game-monitor.

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Answer 2

JWort93 Author

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May 14, 2018 6:40 AM in response to Urquhart1244

I am aware of this, my issue is even with the main video setting at 4:2:0 in the apple tv, with Frame Rate Switching enabled, the apple tv for some reason automatically switches to 4:4:4 mode for 24p content, even if the content itself is 4:2:0. This is causing the flickering, and there doesn't seem to be anything I can do about it, if I want auto frame rate switching enabled.

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Answer 3

JWort93 Author

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May 14, 2018 7:15 AM in response to Urquhart1244

I've since found out that 4:2:0 is not a valid output format for 24p content according to the HDMI 2.0 specification, which is why the apple tv outputs 4:4:4 for 24p content. I've also heard that using HDMI port 3 or 4 on my TV may solve my issue, instead of using HDMI 1 or 2, so I am gonna give that a shot when I get home tonight.

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Answer 4

May 14, 2018 8:08 AM in response to JWort93

I've since found out that 4:2:0 is not a valid output format for 24p content according to the HDMI 2.0 specification,

I think the reverse is true: HDMI 2.0 allows the passthrough of 4:2:0 that previous standards didn’t allow (only 4:4:4 and 4:2:2). A data-saving technique that allows a push for more data in other areas (resolution, bit depth).

As far as I could tell for reading online, all HDMI ports on the 2016 LG B6 OLED are the same?

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Answer 5

JWort93 Author

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May 14, 2018 8:06 AM in response to Urquhart1244

I got my info from that same FAQ, where there is a chart which clearly shows only 4:4:4 supported for 4K 24Hz content: HDMI :: Manufacturer :: HDMI 2.0 :: FAQ for HDMI 2.0, with only the bold ones being new, which makes me think 4K 24Hz 4:2:0 is not valid for HDMI 1.x either.

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Answer 6

JWort93 Author

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May 14, 2018 8:08 AM in response to Urquhart1244

All the ports are HDMI2.0/HDCP2.2 4K UHD 60 capable, which makes me think that isn't the issue, but I found someone who suggested that I try using port 3 or 4, instead of 1 or 2, so I am going to give that a shot.

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Answer 7

JWort93 Author

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May 16, 2018 5:31 AM in response to Urquhart1244

Switching to HDMI 3 or 4 unfortunately did not solve the issue. I also determined that the flicker with 4:4:4 video from the Apple TV 4K is also actually present on the 2017 B7 OLED TV, contrary to what I originally thought, it is just much less obvious. There is definitely a flaw with the way the Apple TV 4K processes/outputs a 4:4:4 signal, because playing back the same file I was testing on my Apple TV, on my Oppo UDP-203 at 4:4:4, produces a completely stable, flicker-free picture. I tried multiple HDMI 18gbps premium certified cables, including the one I use with my Oppo 203, and none of them resolved the issue, so I know it's not a cable issue as well.

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Answer 8

May 27, 2018 8:47 PM in response to JWort93

I have a possible solution for you to try - you're going to be skeptical, and I can't promise it'll fix it, but please do try it and let me know. This works for me for movies that flicker.

On the LG (I have a 2016 E6, so this might be slightly different), go to Settings (Gear) -> More Settings -> Picture -> Picture Mode Settings Submenu -> Picture Options Submenu. Set Noise Reduction to Low. (I turned mine off when setting up the TV.) As soon as I do that, for me, the flickering in dark areas stops.

Hope this helps - figured it's worth a try since you've exhausted other options. As far as I can tell, the Low Noise Reduction isn't hurting the picture quality any.

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Flickering in dark areas of picture when displaying 4:4:4 signal from an Apple TV 4K on a 2016 LG B6 OLED

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