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Discussion Starter · #1 · (Edited)
Now that the frame rate issues have finally been resolved with tvOS 14.5, I wanted to create a specific thread drawing attention to, and providing a discussion place for what I see as the two remaining biggest flaws with the Apple TV 4K, in the hopes that we can finally get Apple to fix them.

1) Raised Dolby Vision Black Levels (EDIT: Fixed on the 2021 model, still an issue on the 2017 model)
  • I've seen this reported on LG OLED TVs and and TCL TVs, it's definitely an Apple TV specific issue, not a tv-specific issue.
  • Only affects TV-Led Dolby Vision, as the Player-Led implementation of Dolby Vision on the Apple TV 4K is a little bit darker than the TV-Led implementation. This is why it does not affect Sony OLED TVs, as up until the X900H, Sony only supported the Player-Led Dolby Vision implementation.
  • Can be resolved in most content by setting the brightness to 49 on LG OLEDs, and fully resolved in all content by setting the brightness to 48, but either choice will result in crushed black levels and altered colors in content, so are not ideal
  • Does not seem to happen when outputting 4K DV content on a 2018 iPad Pro w/ the USB-C AV adapter
2) Near Black SDR Flickering
  • When playing back SDR content, there is very noticeable flickering in near black areas of the image. It's MUCH more noticeable when match frame rate is enabled with 24p/25p content (when output at 24Hz and 25Hz) then it is with 50p/60p content, my guess is because it is flickering less rapidly, and therefore more noticeable to the eyes.
  • This flickering is a video output issue, it happens even when a video is paused, and even is noticeable in the UI in certain circumstances, it is not just flickering in the content itself.
  • Switching the UI to 60Hz YCbCr 4:2:0 makes the issue pretty much completely disappear when in the UI, but when in YCbCr 4:4:4 60Hz, it is still there just nearly unnoticeable. However, even with match frame rate disabled, when content starts, the Apple TV switches to 4:4:4 60Hz, even if the UI is set to 4:2:0 60Hz.
  • Switching to RGB Low, or RGB High, reduces this issue quite a bit, but there is still some flickering
  • This issue is present no matter what output resolution is set, 720p, 1080p, 4K etc.
  • This issue is not limited to just the Apple TV 4K, it seems like all relatively recent Apple Silicon based devices have this issue, I've personally tested the Apple TV 4K, iPad Pro 2018 w/ USB-C AV Adapter, and a 2020 M1-Based MacBook Air, and it's there in the video output of all three of them
  • This issue is NOT present on the older 4th Gen Apple TV HD or older Intel-based Macs, both output a clean non-flickering image at low frame rates.
  • I only own LG OLEDs (currently a B7, C9, and CX), so I'm not sure if this is specific to them or not (I can't imagine it is though), and would like other users to test this for themselves, and let me know what you find
  • Here is a link where I attempt to show the issue, but it's kinda hard to capture (Ignore the fact that the video is in HDR, the Apple TV was outputting in SDR at the time I took the video):

I think both of these issues may be related, specifically to what @liberator72 talks about here with the variable video output issues on the Apple TV: 2020 LG OLED CX-GX Owner's Thread + FAQ (Posts 1-6)...

I've reported them to Apple, but would appreciate others doing the same, so we can get more traction behind them!
 

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Discussion Starter · #4 ·
Please also add that Apple TV 4K always sends fixed values for HDR metadata: [link]
While I would definitely like this to happen as well, unfortunately I think it may fall into a similar category as lossless audio passthrough. Correct HDR10 metadata is already being passed through for apps that use Apple’s built in video player api, but apps that implement their own custom video player like Plex and Infuse, can’t because Apple hasn’t provided the capability to do so. It just doesn’t seem like something Apple is gonna prioritize adding to me. I’ll definitely put in a request to see if they can add this though!


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Discussion Starter · #5 ·
Regarding the SDR flickering: “pulsing” may be a better word for it. If any of you have a chance, please try the following test and post your results:

1) Make sure match frame rate and match dynamic range are enabled on your ATV4K
2) Open Netflix and play back the movie “Before I Wake” and scrub with your remote to 1:21:53 in the movie.
3) Pause it when the actress is holding the cloth blue butterfly, as seen on the attached screenshot


4) Do you see noticeable pulsing/flickering in the darker portions of the screen? (Make sure to view in a dark room, to make it most noticeable)

I’m most curious to hear about peoples results with LCD or non-LG OLEDs, but the more people who test this the better, no matter the display!


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Unfortunately the movie you suggested to test this out, isn't available for me on Netflix (and it's not included with Prime for me), but I don't think the flickering/pulsing is an issue on my over 10-year old Full HD, SDR only Philips TV. ;)

But regarding the elevated blacks, and although I'm not affected by this, I'm curious to know:
Would those affected LG TVs, where ATV sends TV-led DV, also be able to handle player-led DV? Do you know what other devices are sending out to those TVs? For example Shield TV, Fire TVs or the new CCGTV? I mean, is there an external source device, that also sends TV-led DV in a RGB tunnel, where those elevated blacks don't appear?

If the ATV is the source for this issue, problems with the pre-processed player-led DV would appear more logical to me, because with the TV-led one, shouldn't the stream basically reach the TV "untouched"? So I wonder if there is a difference in the RGB tunnel coming in from ATV and other devices (BT.2020 flag or not?), that could be the reason for this?

And if those TVs could also accept player-led DV, could Apple "bypass" this by just forcing player-led DV in all cases? I've heard that Oppo offers a "Dolby Vision Processing" option on their UDP-203/205 Ultra Blu-ray Disc Players, so you can choose between TV-/player-led DV there. Could this also be an option on ATV and would there be any disadvantages of doing this?
 

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Unfortunately the movie you suggested to test this out, isn't available for me on Netflix (and it's not included with Prime for me), but I don't think the flickering/pulsing is an issue on my over 10-year old Full HD, SDR only Philips TV. ;)

But regarding the elevated blacks, and although I'm not affected by this, I'm curious to know:
Would those affected LG TVs, where ATV sends TV-led DV, also be able to handle player-led DV? Do you know what other devices are sending out to those TVs? For example Shield TV, Fire TVs or the new CCGTV? I mean, is there an external source device, that also sends TV-led DV in a RGB tunnel, where those elevated blacks don't appear?

If the ATV is the source for this issue, problems with the pre-processed player-led DV would appear more logical to me, because with the TV-led one, shouldn't the stream basically reach the TV "untouched"? So I wonder if there is a difference in the RGB tunnel coming in from ATV and other devices (BT.2020 flag or not?), that could be the reason for this?

And if those TVs could also accept player-led DV, could Apple "bypass" this by just forcing player-led DV in all cases? I've heard that Oppo offers a "Dolby Vision Processing" option on their UDP-203/205 Ultra Blu-ray Disc Players, so you can choose between TV-/player-led DV there. Could this also be an option on ATV and would there be any disadvantages of doing this?
ATV definitely needs a player or TV led option!

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Discussion Starter · #9 ·
Unfortunately the movie you suggested to test this out, isn't available for me on Netflix (and it's not included with Prime for me), but I don't think the flickering/pulsing is an issue on my over 10-year old Full HD, SDR only Philips TV. ;)

But regarding the elevated blacks, and although I'm not affected by this, I'm curious to know:
Would those affected LG TVs, where ATV sends TV-led DV, also be able to handle player-led DV? Do you know what other devices are sending out to those TVs? For example Shield TV, Fire TVs or the new CCGTV? I mean, is there an external source device, that also sends TV-led DV in a RGB tunnel, where those elevated blacks don't appear?

If the ATV is the source for this issue, problems with the pre-processed player-led DV would appear more logical to me, because with the TV-led one, shouldn't the stream basically reach the TV "untouched"? So I wonder if there is a difference in the RGB tunnel coming in from ATV and other devices (BT.2020 flag or not?), that could be the reason for this?

And if those TVs could also accept player-led DV, could Apple "bypass" this by just forcing player-led DV in all cases? I've heard that Oppo offers a "Dolby Vision Processing" option on their UDP-203/205 Ultra Blu-ray Disc Players, so you can choose between TV-/player-led DV there. Could this also be an option on ATV and would there be any disadvantages of doing this?
Yes, in fact, using an HDfury Vertex 2 (or similar other device from them) you can force an LLDV Sony EDID on an LG TV that is affected by this, and it solves the problem, and is a better solution than dropping your brightness to 49 (or 48), as it's much closer to reference levels than you get by dropping the brightness on TV-led dolby vision. But that shouldn't be necessary, nor should them really giving you a choice between the two, because it's clear the TV-led Dolby Vision has a flaw on the Apple TV 4K, and needs to be corrected, and if it worked as expected, than either output format would be just fine when automatically determined.
 

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But that shouldn't be necessary, nor should them really giving you a choice between the two, because it's clear the TV-led Dolby Vision has a flaw on the Apple TV 4K, and needs to be corrected, and if it worked as expected, than either output format would be just fine when automatically determined.
Yes ... I fully agree. But personally if the only choices would be to have TV-led DV with elevated blacks, where I would have to adjust brightness every time ATV sends DV, or getting the player-led DV, I think I would go for the second one. So having such an option on ATV, users could at least decide to “bypass” the problem. But unfortunately I think we won’t see such an option on ATV, nor Apple fixing it.

Does your IPad Pro, where those elevated blacks don’t occur, send tunneled TV-led DV? Are you able to spot any difference looking at the input signal information on your LG compared to the input on ATV?

Btw ... Have you already told AlanQuatermain about it? That’s the user on Reddit that is supposed to be a tvOS developer. ;)
 

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Discussion Starter · #13 ·
Yes ... I fully agree. But personally if the only choices would be to have TV-led DV with elevated blacks, where I would have to adjust brightness every time ATV sends DV, or getting the player-led DV, I think I would go for the second one. So having such an option on ATV, users could at least decide to “bypass” the problem. But unfortunately I think we won’t see such an option on ATV, nor Apple fixing it.

Does your IPad Pro, where those elevated blacks don’t occur, send tunneled TV-led DV? Are you able to spot any difference looking at the input signal information on your LG compared to the input on ATV?

Btw ... Have you already told AlanQuatermain about it? That’s the user on Reddit that is supposed to be a tvOS developer. ;)
The iPad Pro sends tunneled RGB TV-led Dolby vision. Comparing the input signal info in the HDMI debug menu on my C9 and info from my HDFury Vertex 2 yields no differences, the signals look identical from a format perspective. I haven’t contacted Alan Quartermain yet, but I know others have. I probably will be soon though, about the SDR flickering/pulsing in particular, since at least personally for me that’s a bigger issue, since I can workaround the DV issue with my current setup.


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While I would definitely like this to happen as well, unfortunately I think it may fall into a similar category as lossless audio passthrough. Correct HDR10 metadata is already being passed through for apps that use Apple’s built in video player api, but apps that implement their own custom video player like Plex and Infuse, can’t because Apple hasn’t provided the capability to do so. It just doesn’t seem like something Apple is gonna prioritize adding to me. I’ll definitely put in a request to see if they can add this though!


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Can you give an example? I tried with Pixels (2015) on iTunes, but the values are still 4000/1000.
 

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Discussion Starter · #15 ·
Can you give an example? I tried with Pixels (2015) on iTunes, but the values are still 4000/1000.
Here are Alien, The Greatest Showman, and Logan respectively, via iTunes.


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Seriously? First of all: LG CX has always had raised black in Dolby Vision and lowered black in HDR! Only latest firmware fixed it in DV while destroying gaming mode, that was later fixed too, while introducing overshoot. LG C9 has lowered black after 5.00.03! I have old LG C9 firmware, before this 💩 was introduced. You can read about here, with super good Netflix samples, 2020 LG OLED CX-GX Owner's Thread + FAQ (Posts 1-6)... Now.

@liberator72 is absolutely wrong here. First of all there is a know bug in the color picker capable monitor he used (1, 0, 1 fluctuating to 0, 0, 0 is total BS), second of all Calman measurements were done on broken LG CX (here I am not so sure), so there are two bugs on top of the other.
 

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@firecore Can you like fix that HDR wrong metadata issue? Or zero it out so that it will be "unknown" (see latest SMPTE ST 2086:2018)? Dunno. In that case it should recalculate them. Blu-ray spec says the values should be calculated from the video stream without the black borders... those 4000/1000 as all others on other videos should be precise to all digits.
 

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"but either choice will result in crushed black levels in content, so are not ideal"

Not only blacks. ALL COLOURS. You are too naive. You cannot change brightness (a.k.a black level, yeah, very confusing to some people) without changing all colors, and here I am not even talking about Superwhite stuff. And superblack (and there is a lot of superblack in videos) will now be shown, which may be not pleasant.
 

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HLG, or lack thereof, is a much bigger issue than these 2, at least in my opinion.
But HLG is not that popular. Only one HLG channel on Youtube. And anyway, it is even harder to present. And somehow everybody does not understand that HLG has SDR layer that should be presented on SDR displays and instead color manage HLG layer. Hillarious.
 
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