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No 4K, Dolby Vision, HDR support on iMac Pro

g0ren said:
I'm honestly really confused even after reading every page in this topic. I've got an 2019 iMac with an i9 and Vega48 and the TV app doesn't have a dedicated section for 4K HDR. The little logos do show up when you click into the video page but it's still really confusing.

As has been pointed out, the iMac Pro can apparently do HDR, but the 2019 iMac isn't on there.

Play HDR video on Mac - Apple Support

Support for high dynamic range (HDR) video, such as HDR movies and TV shows from Apple or other providers, requires the latest version of macOS, a compatible Mac model, and an HDR10-compatible display, TV, or projector.
support.apple.com support.apple.com

Yet, at the same time, the 2019 iMac can drive the Pro Display XDR in 6K HDR but the iMac Pro can't?
support.apple.com

Set up and use Apple Pro Display XDR - Apple Support

Learn about Pro Display XDR and how to set up and use it with your Mac.
support.apple.com support.apple.com

How does any of that make sense? Why wouldn't the 2019 iMac be on the first page?
Click to expand...

I don’t know/understand why the 2019 iMac cannot support HDR. Consensus seems to be that Apple has not configured the AMD dGPU drivers in the regular iMacs to support HDR. Although @priitv8 seems to have got it working?

Regarding 6K support for the XDR, I think a machine needs to have at least one of the following:
  • Intel 10th gen iGPU + TB3
  • dGPU + Titan Ridge TB3 controller
  • dGPU that supports DSC (Display Stream Compression). This can output over DP, USB-C or TB3.
  • Apple Silicon(?)
The iMac Pro has none of the four criteria above, hence only native 5K support for the XDR.
 
BeatCrazy said:
I don’t know/understand why the 2019 iMac cannot support HDR. Consensus seems to be that Apple has not configured the AMD dGPU drivers in the regular iMacs to support HDR. Although @priitv8 seems to have got it working?
Click to expand...

I feel like it does work with apps like IINA, Quicktime, VLC, and Final Cut Pro, but the TV app is the odd one out. I think Apple has got to look at this documentation and be a lot more clear. I'm getting ready to just hook the thing up to my HDR TV in the living room in the hopes I'll get a confirmation of HDR signal.
 
g0ren said:
I feel like it does work with apps like IINA, Quicktime, VLC, and Final Cut Pro, but the TV app is the odd one out. I think Apple has got to look at this documentation and be a lot more clear. I'm getting ready to just hook the thing up to my HDR TV in the living room in the hopes I'll get a confirmation of HDR signal.
Click to expand...

Go for it! If it works, you should get an option for it to use HDR (radio button) for your TV in Display settings. See my post https://forums.macrumors.com/thread...ro.2183921/page-6?post=28451907#post-28451907
 
g0ren said:
I feel like it does work with apps like IINA, Quicktime, VLC, and Final Cut Pro, but the TV app is the odd one out.
Click to expand...
That is correct. Now I see the correct handling of PQ gamma, also from the OS (ie QuickTime). In Mojave only IINA did it correctly, OS itself still used the 2.2gamma rendering.
With the TV app on Catalina, it is hard to tell what do I exactly see, as there is no stream info visible anywhere. But it does look like SDR to me.
And that does not mean the iMac 2019 screen shines with HDR performance. Its just that the PQ is now rendered/tonemapped correctly on screen.
I also connected my old MBP with nVidia 960GT (on Catalina) to my TV to see if I can get HDR from HDMI out. Nothing to see there.
 
g0ren said:
Not in the TV app. I think Final Cut Pro, IINA, VLC and even Quicktime do though.
Click to expand...
IINA for sure does not count, as it does its own tonemapping, internally.
FCP and QT use macOS graphics engine and indeed tonemap HDR10 now correctly.
That does not change the fact, that iMac display is not a HDR-grade device.
Ultimately, it leaves me impression, that TV+ app simply does not send HDR stream to iMac, the receiving side is fully capable of rendering it.
 
Last edited:
It's a mess on the iMac Pro. HDR content works for me well on Netflix in Safari despite the HDR setting MISSING from the System Preferences.
 
Running latest version of Mac OS Ventura here (13.3.1), iMac Pro 2017 - 3.2 GHz 9 Core Intel Xeon W with a discrete GPU Radeon Pro Vega 56 8 GB, and YouTube plays HDR video with no issues. No, I do not see any setting in system preferences related to HDR, but it works just fine.
 
rferreira.dba said:
Running latest version of Mac OS Ventura here (13.3.1), iMac Pro 2017 - 3.2 GHz 9 Core Intel Xeon W with a discrete GPU Radeon Pro Vega 56 8 GB, and YouTube plays HDR video with no issues. No, I do not see any setting in system preferences related to HDR, but it works just fine.
Click to expand...
Interesting. How can one check if HDR is really played and not a downgraded version? I tried a short movie like this on iMac 2019, 3.7 GHz, 6-Core i5. It plays correctly displaying 2160p60, HDR 4K in the settings button of YouTube, the image is stunningly sharp and rich in colour. But I am not sure if I see the real thing. If I remember well the display in this iMac is not really HDR, but the difference was very noticeable compared to FHD from Blu-ray disk.

By the way, and with other processes in the background, when playing this video through Brave, CPU hovers around 23-37% and GPU (Radeon Pro Vega 48) around 5-15%. Safari seems better optimised, with 12-17% and 2-5% respectively for CPU and GPU. The Intel HD Graphics CFL is also fully used.
 
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