2020 iMac w/ 5700XT Stutters When Playing 4K HDR YouTube

[Takuro]

I just unboxed my new 2020 iMac that has a 5700XT. I know it doesn't support true HDR, but in Chrome, trying to play videos like the below completely causes my system to start freezing and stuttering whenever I select *any* HDR quality video.

You may need to manually open the above video in a Chrome window. Not sure if the embedded player supports it.

Is anyone else experiencing this?

 

[wilberforce]

I just unboxed my new 2020 iMac that has a 5700XT. I know it doesn't support true HDR, but in Chrome, trying to play videos like the below completely causes my system to start freezing and stuttering whenever I select *any* HDR quality video.

You may need to manually open the above video in a Chrome window. Not sure if the embedded player supports it.

Is anyone else experiencing this?

Works fine for me in Chrome, also in full screen. I confirmed it was in 4K HDR. But I have the 5500XT GPU, not the 5700XT.
btw, To avoid the blown highlights, I suggest disable the HDR by the following hidden option:

System Preferences
Option-click the Displays icon
Uncheck "allow extended dynamic range"
and refresh the Chrome web page

This will then also show a 5K option for that video, which also plays smoothly for me in full screen.

Hopefully this is not a 5700XT issue

 

[Takuro]

Just tested this with my 2019 MacBook Pro which has a Radeon Pro 555X. It behaves the exact same way.

Are you on Catalina like me or on Big Sur?

 

[LadyNinja]

Have the same machine, runs ok, but using brave

 

[wilberforce]

Just tested this with my 2019 MacBook Pro which has a Radeon Pro 555X. It behaves the exact same way.

Are you on Catalina like me or on Big Sur?

I am on Catalina.
Are you sure you don't have an internet or Wi-Fi connection issue, and the video is buffering?

 

[Takuro]

Yeah it's definitely an OS level hang. All graphics including the dock stutter very badly when mousing over icons (I have the magnification effect turned on). It lasts for about 10 full seconds even after force quitting Chrome. I installed Brave, and even though it's a virgin install, it behaves the same way.

All I can assume is I have some setting or app common to both machines that's impacting the ability to decode HDR. I might create a new user account and try to isolate what it is.

 

[Takuro]

So after creating a 2nd user account, copying some files from my primary account over to reproduce the issue, and using a very, very long process of elimination... it turns out it's this random old app I am using was causing it...

Displaperture

Round display corners.

manytricks.com

As soon as I quit that, my Mac's performance is way better and HDR is solid. Pretty wild...

Anyway, I filed a bug with the dev.