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Apple TV 4K 2021 can only use HDMI 2.0 video output settings?! 🤬

J

JohnnieBBadde

macrumors regular
Original poster
Dec 11, 2014
119
103
Hi,

got my unit today (A2169), I was very eager for the new ATV 4K 2021 since I've been using HDMI 2.1 features since 2020 with LG CX TVs and PC GPUs.

All devices' firmwares are up-to-date, however the ATV GUI only shows HDMI output settings within HDMI 2.0 limitations, these are in (its best case) 2160p/60 Hz/4:2:2/HDR on.

Have tested multiple 48 Gbit/s-capable HDMI 2.1 cables that work fine with PCs and the same LG CX TV with 2160p/120 Hz/Full-range RGB/10 bpc color/HDR on, the ATV also says after its little tests that the used cable is "of good quality" (no sh*t, Sherlock!).

I know that refresh rates above 60 Hz are currently not supported but I was hoping for at least 2160p/60 Hz/Full-range RGB/10 bpc color/HDR on.

I want these features not for third-party content consumption but my own videos and photos that on a strictly technological note exceed the stuff that is streaming down the river of mediocrity.

Can other users confirm this? Am highly disappointed by this. Hope I'm only experiencing a somehow fixable handshake bug :(
 
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120hz is not supported yet. No reason give as to why, but it looks to be supported soon as mentions of it have been found in beta appletv updates.
 
I expected as such. No 4K120 video format options.

There is no requirement to implement all features of HDMI 2.1 to advertise it. I suspect the only HDMI 2.1 feature enabled is eARC connectivity to TVs.
 
I do not care about 120 Hz, I care about the higher-quality color settings for a given HDMI connection with 60 Hz, for example.

HDMI 2.1 no longer has any bandwith limitations that would require color subsampling (<- ugly) for 2160p (up to 120 Hz when using a 10 bpc color display).

HDMI 2.0 can only do this with 2160p up to 30 Hz (!), any refresh rate above that leads to some kind of image quality reduction depending on the chosen setting.
 
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Are you noticing if the Apple TV is utilizing the Quick Media Switching available with HDMI 2.1? Is there still a long black screen when switching between SDR and Dolby Vision?
 
Yes, the black screen is still there though I currently only tested video with different fps properties to test for VRR capability. Also a bummer but I am more upset about the stagnant low image quality (no difference to 2017 model as far as I know, I currently don't have one to A-B test with at hand).
 
JohnnieBBadde said:
I do not care about 120 Hz, I care about the higher quality color settings for a given HDMI connection with 60 Hz, for example.

HDMI 2.1 no longer has any bandwith limitations that would require color subsampling (<- ugly) for 2160p (up to 120 Hz when using a 10 bpc color display).

HDMI 2.0 can only do this with 2160p up to 30 Hz (!), any refresh rate above that leads to some kind of image quality reduction depending on the chosen setting.
Click to expand...
With video format set to 4K60 (59.94Hz) HDR the only chroma options are still 4:2:2 and 4:2:0.
 
cjake said:
With video format set to 4K60 (59.94Hz) HDR the only chroma options are still 4:2:2 and 4:2:0.
Click to expand...
Yes, that is called chroma subsampling, a compromise to be able to transfer an image/frame with its quality reduced over an interface (HDMI 2.0) that doesn't have sufficient bandwith for the original quality.

With HDMI 2.1 4:4:4 would be possible when staying with the YCbCr color space.
 
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If Apple were to implement support for it. Just like adding support for 4K120. Adding eARC was their claim for HDMI 2.1.
 
Yes, indeed. And this works fine with the same LG TVs (since 2019) and a PC and a current-gen dGPU (AMD RX 6000 series, NVIDIA RTX 30 series) with an HDMI 2.1 port.
 
whats the difference between these color modes? I have 2020 LG CX OLED. I usually watch Netflix and YouTube on the native app. does this mean that the new YouTube tv will look worse than built in quality?
 
The media files that are to be displayed via a visually lossless interface need to be stored in such a format. To save storage space video files from all streaming platforms are already using chroma subsampling for the image information within them.

It's not that your YouTube TV app is going to look worse via the Apple TV than the one built into the "Smart TV", it's that the OLED panel itself can display a higher quality image than you are used to seeing.

This is why for me personally HDMI 2.1 was and is such a huge deal since chroma subsampling is no longer automatically introduced into the viewing chain by the HDMI interface on "cheap" devices like OLED TVs that have reached an impressive level - even more so after an aftermarket display panel calibration.

Of course it would be much less of a pain-in-the-butt to use a display with DisplayPort 1.4 et al. but unfortunately TVs only use that goddamn HDMI interface since of course the industry is evil...

Chroma subsampling is especially ugly when the display is showing very fine details with high contrast, an extreme example for helping a lay person's imagination is small text on plain background.

Here's a wikipedia article with some sample images:

en.wikipedia.org

Chroma subsampling - Wikipedia

en.wikipedia.org en.wikipedia.org
 
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Oh ffs. Apple better not have screwed us by having an HDMI 2.0b port with eARC added in (therefore allowing the HDMI 2.1 name as eARC is a 2.1 feature). Not supporting QMS is an absolute amateur mistake in a device that does switch video modes a lot. That fact they are listing 60 FPS as high frame rate is also concerning. I need a new Apple TV, but will wait for WWDC to see if TVOS gets an update to unlock HDMI 2.1 bandwidth and features.
 
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cjake said:
With video format set to 4K60 (59.94Hz) HDR the only chroma options are still 4:2:2 and 4:2:0.
Click to expand...
What would be the point of supporting 4:4:4, given that there is no streaming service (or other consumer video format) that doesn't use chroma subsampling?
 
Maybe since there are also people that like looking at some kind of not moving images - can't think of a name for that technology at the moment... :rolleyes:

PS: I don't want YCBCr 4:4:4 but 0-255 RGB with 10 bits per channel color and HDR.
 
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Rigby said:
What would be the point of supporting 4:4:4, given that there is no streaming service (or other consumer video format) that doesn't use chroma subsampling?
Click to expand...
HDR games and applications benefit greatly from 10-bit RGB. Fine UI elements look terrible on YCbCr 4:2:2.

Even if the hardware was limited to lower bandwidth, tvOS could do HDR 8-bit RGB with dithering like Windows 10 can. This is visually indistinguishable from 10-bit when dithering at higher refresh rates (60 Hz) than the content (24 fps). Only the source content needs to be true 10-bit for HDR, not the signal to the display.
 
mnsportsgeek said:
Lame. HDMI 2.1 was supposed to improve that.
Click to expand...

It takes 1 sec on the CX. That delay is from HDMI handshake.

I dont know if QMS/VRR will fix that

I believe it will get rid of the black screen switching between different refresh rates not
SDR to HDR

Also eARC doesnt work very well with the CX

I get arc working perfectly but the minute i turn on earc i get disruption of sound each time the screen changes refresh rates like
Browsing music videos in the music app
 
forums.macrumors.com

Best HDMI 2.1 cable for the new Apple TV 4K?

The thing is that the 2nd gen ATV4K is not capable of any video modes that require HDMI 2.1. We know this because they used the same DP to HDMI 2.0 converter as in the 1st gen model. See step 7 in this teardown: https://www.ifixit.com/Teardown/Apple+TV+4K+2021+Teardown/142845 And step 6 here...
forums.macrumors.com forums.macrumors.com

It appears Apple is using the same DP to HDMI converter chip in the 2021 4K ATV as they did in the 2017 model. So the hardware is limited to HDMI 2.0.
 
diamond.g said:
It appears Apple is using the same DP to HDMI converter chip in the 2021 4K ATV as they did in the 2017 model. So the hardware is limited to HDMI 2.0.
Click to expand...
This is not entirely accurate since the 2021 model also added eARC through an add-on chip, and eARC is an HDMI 2.1 feature. So it's not wrong to call it HDMI 2.1. It is true though that it does not support any of the new HDMI 2.1 video modes, like 4K@120Hz or 8K.
 
Rigby said:
This is not entirely accurate since the 2021 model also added eARC through an add-on chip, and eARC is an HDMI 2.1 feature. So it's not wrong to call it HDMI 2.1. It is true though that it does not support any of the new HDMI 2.1 video modes, like 4K@120Hz or 8K.
Click to expand...
That is fair.
 
Dammit Apple! Sounds like they've trolled us by referring to HDMI 2.1 as a general feature of the device when actually they've only added a new (old) APU and eARC. This is clearly the design that was ready to be launched back around Easter 2020 and, as with the 4th gen, when the time came to actually release it after a delay, they didn't bother updating it so the device is essentially a year old already! Sadly, this probably also means that a true HDMI 2.1 Apply TV (with 120 Hz, VRR, QMS etc) likely won't arrive for years.
 
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