iMac 5K watching 4K on YouTube?

Kurri

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Original poster
Mar 6, 2009
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Have a 27" iMac with 5K retina....SO.....I'm stumped. how can you watch 4K content on YouTube? Through safari I only see 1080p even when I click on a 4K video.

Now that I think of it, how about 4K through iTunes? is that possible?
 

ruslan120

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Jul 12, 2009
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Chrome. Safari doesn’t support 4K YouTube videos. You can even find a couple of 5K video of nature scenes.

warning - once you see 5K video nothing will look the same.
 
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Kurri

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Original poster
Mar 6, 2009
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Chrome. Safari doesn’t support 4K YouTube videos. You can even find a couple of 5K video of nature scenes.

warning - once you see 5K video nothing will look the same.
ahhh well that makes sense...well it makes no sense, but it makes sense why I was not getting the 4K option
 
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priitv8

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I assume he means playing back purchased iTunes movies in UHD. Which is not possible on an iMac as far as we can tell, as there is no model with a T2 chip. Although the statement from Apple on where it's supposed to work is very hard to parse into anything useful.
That is a completely different set of problems (DRM).
I just wanted to say, that technically there are no limitations, iTunes accepts UHD movies (both AVC and HEVC) into local library and QuickTime (Apple's generic media rendering engine) has no issues with playing them back, once de-drmmed.
On my 2019 27" iMac, I am only presented with HD versions of my purchases:
Screenshot 2020-01-22 at 19.50.18.png
 

mmomega

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Dec 30, 2009
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I assume he means playing back purchased iTunes movies in UHD. Which is not possible on an iMac as far as we can tell, as there is no model with a T2 chip. Although the statement from Apple on where it's supposed to work is very hard to parse into anything useful.
iMac Pro has a T2 and 5K display.

To OP:
Yes like someone mentioned. Safari and YouTube will not even show the option for 4K so all of my YouTube viewing is on Chrome exclusively.
MKBHD regularly uploads in 4K and recently uploaded an 8K video just for folks to check out.
And it shows up to 8K option on my iMac Pro.

I ran stats for nerds from during the stream and it only dropped 4 frames when i went from windowed mode to fullscreen, after that initial resizing it never dropped a frame.

Screen Shot 2020-01-23 at 11.33.10 AM.png
Screen Shot 2020-01-23 at 11.37.10 AM.png
 
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priitv8

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Safari and YouTube will not even show the option for 4K so all of my YouTube viewing is on Chrome exclusively.
MKBHD regularly uploads in 4K and recently uploaded an 8K video just for folks to check out.
And it shows up to 8K option on my iMac Pro.
YouTube won’t play in UHD because Alphabet Inc moved all UHD content from AVC to VP9 codec that Apple does not support.
I have no idea what is the actual issue there, licensing or something else.
On the other hand, I like Apple’s approach to keep the number of codecs at minimum. Who needs dozens of them?
 
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mmomega

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Apple states that it has to be a 2019 model, and there is no 2019 iMac Pro.

(Also there are multiple people I know who have tested the iMac Pro and it definitely doesn't work.)
I just did. And it definitely does.
Those screenshots are from the iMac Pro display.

I mean I can take you an uninterrupted phone video in a bit.

Not sure what Apple states that has to be a 2019 model. But the 2017 iMac Pro, has a T2 chip and a 5K display.
Link to Apple website about the T2 and all machines that have it. The iMac Pro was the first.
 

priitv8

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I just did. And it definitely does.
Those screenshots are from the iMac Pro display.

I mean I can take you an uninterrupted phone video in a bit.

Not sure what Apple states that has to be a 2019 model. But the 2017 iMac Pro, has a T2 chip and a 5K display.
I think the original question was about viewing your purchased iTunes movies on an iMac in UHD and/or HDR.
As far as I can tell, it is not possible on 2019 iMac (I’m still on Mojave, hence iTunes) because only HD versions are offered.
With my own content there is no issues playing UHD content, AVC or HEVC. Mojave does not handle HDR, though. Catalina seems to do proper tonemapping.
 

revmacian

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Oct 20, 2018
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YouTube won’t play in UHD because Alphabet Inc moved all UHD content from AVC to VP9 codec that Apple does not support.
I have no idea what is the actual issue there, licensing or something else.
On the other hand, I like Apple’s approach to keep the number of codecs at minimum. Who needs dozens of them?
A couple thoughts:
1. Does Chrome web browser on macOS allow blocking ads in YouTube videos?
2. Could it be that Google can more easily track users through Chrome than Safari?

Just trying to think of why Google (an advertising company) would make a move that it hopes Apple won't follow.
 

mmomega

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Other interesting note this morning. I decided to open activity monitor and GPU history while playing the same video.
iMac Pro 18Core

1080p on Safari = 25% CPU, no GPU utilization
4K Chrome = 159% CPU, 17% GPU rendering
1080p Chrome = 30-48% CPU, 5-33% GPU Rendering