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HDMI 2.1 on macs ,possible?
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Because the architecture design and software support of the M1 only allows for HDMI 2.0 :-/
exactly my question ,either i dont get people's obvious answer on that point ,or they dont get my(our) question...
After reading too many specification pages it becomes clear that USB4 requires Alt Mode DP which is at least DisplayPort 1.4a which is enough bandwidth to do 4K@120Hz 10bpc. From others posting here, it sounds like there is a bug in MacOS preventing the correct mode. Since all M1 SoCs are USB4 then logically all M1 Macs should be able to do 4K@120Hz unless Apple is breaking the spec which it seems like would prevent certification.
ok maybe im talking **** but the point isnt that tb4 doesnt have enough bandwith
the point is,whether or not,tb4 has to come with hdmi2.1 support
and yes to conccur to what youve said you can indeed run 4k120 via tb-to-dp adapter(dunno about 8k)
only tb to hdmi seems problematic,hence my question,whats preventing it to work ,what exactly is it that refuses to work
dont be so sure you wont use it lol,the day youll be willing to use a gorgeous TV as a monitor you'll regret today's sayings
but what i dont get again,in spite of what the other dude already said (that apple didnt license it ,which i havent found any sources on ) is
i get that the hdmi 2.0 port wont work.but because the providen hdmi -which ,needless to say,wasnt present in previous iterations of the mbp- is 2.0,it means that the whol IO of the PC is effectively locked at 2.0 ?? that doesnt make any sense does it ?
i mean how does a port using one TB lane affects what other TB lanes can provide ,given tb4 does have enough bandwidth to support 2.1
Probably not HDMI 2.1 48 Gbps support. But USB4 certification requires DP1.4a tunneling which is enough for a protocol converter to support 4K@120Hz 10bpc. Does a compatible DP to HDMI protocol converter exist? I have no idea and if macOS is buggy then the software needs to fixed as well. But if the hardware has to support DP1.4a then it seems that it should be possible to display 4K@120Hz.
Edit: It seems like it should be possible to test this if a DP connection on a 4K@120Hz display is available. That wouldn't need a protocol converter. This is HBR3 mode.
afaik dp is able to go this high in res because it has DSC ,display stream compression.
which is something that im not sure hdmi has as well
Have a look at DisplayPort Alt Mode. The Thunderbolt 4 ports will hopefully have the ability to switch to 80Gbit/s unidirectional.
Correct, all of the additional functionality in HDMI 2.1 relative to 2.0 is optional. A port, adapter, or cable labeled 2.1 may or may not support anything that isn't present in 2.0.
Yeah, this is probably the reason these adapters don't exist right now.
Just FYI, though, the earlier replies to your original post are incorrect, and you're right to be asking this question. Just because M1 Macs ship with *physical ports* that are HDMI 2.0 spec, that has absolutely *no bearing* on adapters connected to higher bandwidth ports. There's nothing in macOS that would prevent a TB4 -> HDMI 2.1 adapter if that were possible; it would just require the correct adapter, and plugin/firmware to enable that adapter on macOS. All the hooplah about this not being "electrically" possible are complete and utter nonsense.
But, as you noted, it appears that standard TB4 doesn't actually have the bandwidth needed to match HDMI 2.1.
thank you buddy .I'm not an expert but it also didn't make sense to me lol
you do trust that's the reason such adapters don't exist yet uh? what's weird is that I have found usb-c/tb3 to HDMI 2.1 adapters (albeit not tested )
tb3 !! so ofc it would work with tb4 . interestingly enough tho,the manufacturer says that 4k120/8k60 works ,BUT the res is limited to 4k60 on macs...which has me thinking it's a mac problem
still I don't see.how HDMI 2.1 would be possible ...unless maybe you can give HDMI 2.1 without full bandwidth?(hdmi2.1 is 48gb,4k120 and 8k60 both are 40gb I think...which is within tb4 abilities)
I bought and tested one of these - can’t even do 8k@30hz. Seems to be a macOS issue, hoping it gets fixed eventually. They actually clarified in the item description that macos won’t do 8k, but not until after I bought it. oops!
fortunatrly my work machine is a pc laptop so I can do 8k@60 hz with it. Hoping someday macOS will be updated and unlock the port for at least active adapters. Passive adapters might never be supported on current hardware.
its a tv you have isn't it ?
yep I was bashing on windows but it actually does so many things right lol
I would assume the LSPCON that Apple is using for the HDMI port only supports HDMI 2.0. Haven’t read a teardown yet that describes the actual chip, looking for that next.
The LSPCON that Apple used only support HDMI 2.0b, so the HDMI port is NEVER going to support HDMI 2.1 features.
Source: ifixit teardown and IRL for the DP to HDMI converter Apple uses - https://www.kinet-ic.com/mcdp2900/
4K 120Hz screens and 8K screens are not common at all, where are you coming up with that?
I never said the HDMI port might support HDMI 2.1, I said I hoped for HDMI 2.1 to be supported via the Thunderbolt 4 ports, which should be capable of doing this.
LG make a bunch of 4K 120Hz and 8K TV screens, that can be used as high performance monitors. Yes, they are expensive, but manageable.
What if it weighs 3 pounds
If someone implements it, it will be available on a Thunderbolt 4 dock in the future, it won’t simply be a cable. Parade is working on a DP 2.0 to HDMI 2.1 converter chip as of August 2021, which means it won’t be ready for shipping for a while. How many third party GPUs are supporting HDMI 2.1 at this point? Probably less than anyone wants to admit. In other words, don’t hold your breath.
Source: https://www.guru3d.com/news-story/new-converter-chip-can-convert-displayport-2-to-hdmi-2-1.html
Source: https://www.guru3d.com/news-story/new-converter-chip-can-convert-displayport-2-to-hdmi-2-1.html
Any DisplayPort 1.4 to HDMI 2.1 adapter will be limited to 25.92 Gbps but that's ok since DSC @ 8bpp can allow displays with pixel clocks up to 3240 MHz. 8K60 only requires pixel clock up to 2376MHz (HDMI timing).
Apple uses DSC @ 12 bpp which results in a max pixel clock of 2160MHz but that can do 8K60 if a CVT-RB timing is used instead of a HDMI timing. The 12bpp compression target can be overridden but I haven't tested that yet.
Anyway, since Macs supports DisplayPort 1.4 and DSC, the only reason things don't work is software (well maybe some GPUs can have pixel clock limits lower than what I stated). For example, there's no easy way to create custom display timings on M1 Macs. Macs in general don't allow the user to manually choose modes that reduce bpp to allow higher pixel clocks (such as DSC bpp target, chroma sub sampling modes 4:2:2 and 4:2:0, lower bpc such as 6 or 8 bpp) - you have to depend on macOS to choose the modes - and this is where it fails.
https://forums.macrumors.com/thread...-2-0-displays-on-mac-pro-yes-you-can.2309750/
Apple uses DSC @ 12 bpp which results in a max pixel clock of 2160MHz but that can do 8K60 if a CVT-RB timing is used instead of a HDMI timing. The 12bpp compression target can be overridden but I haven't tested that yet.
Anyway, since Macs supports DisplayPort 1.4 and DSC, the only reason things don't work is software (well maybe some GPUs can have pixel clock limits lower than what I stated). For example, there's no easy way to create custom display timings on M1 Macs. Macs in general don't allow the user to manually choose modes that reduce bpp to allow higher pixel clocks (such as DSC bpp target, chroma sub sampling modes 4:2:2 and 4:2:0, lower bpc such as 6 or 8 bpp) - you have to depend on macOS to choose the modes - and this is where it fails.
https://forums.macrumors.com/thread...-2-0-displays-on-mac-pro-yes-you-can.2309750/
Yup.
The USB standards marketing department (err... naming committee) appear to have infiltrated the HDMI spec committee.... it's a disgrace. Apple could call all the new machines HDMI 2.1 compliant and be correct. Happily they have not done that, but other PC vendors can/will.