this post was submitted on 29 Feb 2024
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853
The HDMI Forum rejected AMD's open source HDMI 2.1 implementation (www.gamingonlinux.com)
submitted 8 months ago by [email protected] to c/[email protected]
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[–] [email protected] 6 points 8 months ago (1 children)

There's some really high bandwidth stuff that USB-C isn't rated for. You have to really press the limits, though. Something like 4k + 240Hz + HDR.

[–] [email protected] 1 points 8 months ago (2 children)

That doesn't even seem so unreasonable. Is that the limit though? My cable puts a gigabyte a second down it so I wouldn't imagine that would hit the limit.

[–] [email protected] 2 points 8 months ago

USB-C with Thunderbolt currently had a limit of 40Gbit/sec. Wikipedia has a table of what DisplayPort can do at that bandwidth:

https://en.wikipedia.org/wiki/DisplayPort

See the section "Resolution and refresh frequency limits". The table there shows it'd be able to do 4k/144hz/10bpp just fine, but can't keep above 60hz for 8k.

Its an uncompressed video signal, and that takes a lot of bandwidth. Though there is a simple lossless compression mode.

[–] [email protected] 2 points 8 months ago (2 children)

It is trivial arithmetic: 4.52403840*2160 ≈ 9 GB/ s. Not even close. Even worse, that cable will struggle to get ordinary 60hz 4k delivered.

[–] [email protected] 3 points 8 months ago* (last edited 8 months ago)

4.5 × 240 × 3840 × 2160 ≈ 9 GB/s

It seems markdown formatting ruined your numbers because of the asterisks. Whatever is written between two of those turns italic, so they're not ideal for multiplication symbols here on Lemmy (or any other place that implements markdown formatting).

[–] [email protected] 1 points 8 months ago (1 children)

I think the maths got a bit funky there. I don't think a cable capable of such speeds would struggled to do 60Hz at 4K, it surely doesn't need close to a gigabyte a second?

[–] [email protected] 2 points 8 months ago

It surely does. Check pirates post for clean math formatting