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macrumors 65816
Original poster
Jul 7, 2011
I’m seeing really bad blocking / low res patches when watching HDR content.

It’s native HDR in Netflix

My ATV4K is set to SDR 4k @ 60hz (uk) but with range and frame match content set to on

When watching a HDR show with a bright scene (like a white sky with a gradient) I get terrible blocking / low res patches with some colour banding

Watch exactly the same scene via the Samsung TVs inbuilt app also in HDR, everything is fine.

So that rules out the panel and picture settings.

My HDMI input is set to UHD colour and the only other thing is the cable. I don’t have any new cables. All the ones I have at 2-3+ years old. But they do say high speed with Ethernet.

Any ideas what it could be?


macrumors 601
Jan 13, 2011
I would also start with HDMI cable (must at least be able to put through 18Gb/s. 48Gb/s HDMI 2.1 would be even future-proof for some time to come), then check every HDMI port on the TV. They may not all be created equal.


macrumors 6502
Feb 20, 2012
Treviso, Italy
In my experience pixelation is caused by a low bitrate. I'd check with Speedtest (there is the app in the App Store) if you're getting the right bandwidth (and latency/ping) with your connection. Also if the ATV is wired I'd tried via WiFi (just for testing). And vice-versa. Unfortunately I don't know the way to check what's the current bitrate in Netflix while streaming on the ATV 4K, if there is any.

Then it would help to know which Netflix show(s) is causing the issue (unless it is all shows/movies you tried). I mean, just to check if we get the same issue ourselves.


macrumors 65816
Original poster
Jul 7, 2011
Thanks, I will double check the bandwidth, but i'm very confident all that is fine.

I run 5ghz wifi with no interference and i have a fibre connect at around 70Mbps with a throughput of at least 60Mbps at all times.

I ran a netflix bandwidth test too, in the account/support settings via the app and the speed came out fine.

It maybe the cable so i've ordered a newer HDMI cable from amazon. Fingers crossed!
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