Watching 4K YouTube videos on the 27" 5k iMac looks bad

[JustinThiel]

Hello! Just bought a 2015 27" iMac and everything about it I love, except for watching 4K videos. Any 4K video I open up and watch in full screen looks pixelated and mushy. I watched other people on YouTube videos testing out 4K YouTube videos in their new 5k iMac and could tell even through the video that their iMac was displaying the content far sharper than mine.

Even my 50" 1080p tv shows the same videos sharper through the Chromecast than on my new iMac. Something just doesn't seem right.. 4K videos should look amazing on this thing. Any video I've tried streaming looks bad. There was even a MacWorld article that has a video embedded that says to watch this video of the sun close-up in 4k, you'll be amazed at how it looks on your 5k iMac. It looked like 720p on my iMac.

 

[komiez]

Got this problem solved somehow? Just wondering
edit: saw the other thread.

 

[JustinThiel]

No, I learned that all videos after December 6th, 2016 can no longer be watched in 4k on Safari due to a new codec that is unsupported. Watching them on Chrome won't work either because the P3 wide color display over saturates everything in Chrome, especially YouTube videos.

 

[macmee]

This looks sharp to me on mine when I set it to 4k:

The only issue I have with this video is artifacting, which is a problem YouTube has in general with 4k video it would seem. I have a 1gbps internet connection (fast.com reporting it at 800mbps atm) and so buffering problems like this shouldn't be happening so it must be an issue on youtube's end.

Could this be the problem you're experiencing? Artifacts would make it seem like parts of the video are not in 4k.

 

[ryannel2003]

I have the same issue with that video. It looks incredible though.