Dolby Vision plays back in BT709 not BT2020 in Apple TV 4K

Hello Bruiserfox,

If you need help with your Apple TV, we'd recommend checking out the steps in this article: About 4K, HDR, and Dolby Vision on your Apple TV 4K

This should help to clear this up for you.

Take care!

My understanding of the Dolby Vision technology is superficial, but a primary benefit of mastering content in Dolby Vision is the ability to dynamically render it accurately to various cinema Target Displays. While the default Mastering Display is bt.2020, apparently the default Target Display is bt.709.

I'm not sure why your ATV4K is using this default Target Display definition for your TV, but I would like to think it's the result of some sort of handshake/configuration dialogue taking place (correctly) over HDMI. Is it possible that your TV has some sort of optional HDMI deep color switch that needs to be enabled for the port your ATV4K is connected to? I would expect the fact that the TV's reporting Dolby Vision support to the ATV4K would imply deep color capabilities, but the two capabilities could operate independently.

I'm afraid my cheaper 2020 LG doesn't support Dolby Vision and my ATV4K's video Format is set to 4K HDR@60 with Match Content off... the TV always reports bt.2020 output from the ATV4K (which makes sense). Perhaps someone geeky enough to be reading this with a brand new Dolby Vision-enabled TV can report what they're seeing out of their ATV4K :-).

Bruiserfox wrote:

[...]

I have Format set at SDR at 60 htz with Content and Frame Rate matching, ( as advised by Vincent Teoh from HDTV TEST as well as other YouTubers. ) Forcing Enable Dolby Vision makes no difference.

While I suspect that @Vincent_Teoh has forgotten more about home theater electronics than I'll ever know, and I don't know the context or date of this advice, I dislike this particular recommendation on my setup. In general, I prefer to configure my home theater equipment with factory default settings using recommended setup procedures while enabling beneficial advanced capabilities as needed/where possible. From there, I'll cheerfully tweak settings to address issues or make observable improvements.

When I do this with my TV (factory video settings + enable HDMI CEC + ultra deep color + etc.), then reset video settings on the ATV4K, the ATV4K lands on 4K HDR@60 with Match Content = Off. I then enable the improved chroma settings and do the color calibration process, and things look pretty dern good! The majority of streaming content I watch is sourced with 4K HDR or better, and the older HD (1080p SDR, etc.) content I watch looks just great after passing through the ATV4K's upsampling to 4K HDR, and I don't need to watch my TV go blank for a few seconds as it adapts to lesser color ranges or frame rates.

I've read 2 year-old posts advocating the same ATV4K settings you've landed on, and I understand the attraction of watching content in its original color range at its original frame rate, so I've experimented... older SDR bt.709 content delivered to my TV at its original color range looks different but not better than the ATV4K's rendering to HDR. I've seen complaints of visible issues in the ATV4Ks rendering SDR content to HDR, but have never seen any on my setup. As for viewing the content at its original 24 or 30 fps, I can't really see the difference and I've never noticed flaws in the ATV4K's rendering/interpolating the content to 60fps. Perhaps the once visible issues that inspired setting the ATV4K to a lesser default color range and enabling Match Content range/framerate = On have been addressed in ATV and/or TV firmware updates.

[...]

Just thought I'd let you know that I just changed Format to 4K HDR at 60Htz and just like your experience it rendered in BT2020

Is this true of Dolby Vision content you're watching that was previously observed in bt.709? If so, I suspect that by setting your (default) VIDEO Format to 4k SDR, you were essentially telling the ATV4K that your TV prefers SDR. Since Dolby Vision can adapt to an SDR target display, that's what you saw. Be careful what you ask for :-).

Bruiserfox wrote:

[...]

It seems DV plays back in HDR BT2020 When in that setting.

This is interesting... It sounds like all of those folks who've accepted the 'ATV4K-should-be-set-to-4K-SDR+Match-Content=On' advice of various experts may be experiencing a reduced/limited color gamut while watching modern Dolby Vision content. Perhaps this is why some say Dolby Vision content looks better/brighter using their TV's native apps vs. Apple TV 4K.

Hey, here's me from another thread. I can't seem to check the color space of the HDMI in my Sony TV, btw as per bgmeek

suggestion, if I set the 2021ATV4K to always Dolby Vision, the signal is actually different, it's not "dim" as when the ATV is set to SDR and match dynamic range. Weird. Only problem is that always Dolby Vision makes the dashboard washed out, it's so much better in SDR. And there's little tweaking of the dolby vision bright or dolby vision dark presets to my TV switches to with DV always on. Looks like there's no ideal solution to this, but interesting find

Well I actually ended the message that abrupt way XD anyway I did update the firmware of my TV and now the image looks the same from ATV4K and internal apps. It was probably a bug of some sorts, or maybe it was because the TV now accept full DV signal and not low latency DV signal as before. I sadly can't check which color space the ATV outputs, when in DV mode the TV doesn't let me see it. I tried the "always DV" mode but I don't know, I still don't like the ATV menus in HDR.

Glad to hear you're able to enjoy Dolby Vision content through the ATV4K on your Sony now. By all means, if you prefer the 4K SDR mode for bouncing around the ATV screens, use it. If the setting indeed causes the ATV4K to output Dolby Vision content in the bt.709 color space for an SDR display, as @Bruiserfox has observed, you probably won't notice the difference anyway. After all, @Bruiserfox also observed that things look good regardless (DVision is all about rendering content correctly to whatever the Target Display is).

You might try setting the default video format to 4K HDR (rather than 4K Dolby Vision) with Match Content Range=On, then fiddle with your Sony's various HDR display modes; and see if using the ATV4K's iPhone-based calibration process yields results that you like, etc. Chances are you can find settings that you like in this mode. You'll also know that Dolby Vision content will be delivered in the (likely) source bt.2020 color space and that SDR content will be delivered in SDR/bt.709 to satisfy your inner video purist :-).