On Fri, Oct 14, 2022 at 02:27:38PM -0400, D. Hugh Redelmeier via talk wrote:

The USB standardization committee has created layers of naming confusion. Horrible.

Now I find out that that is the case for HDMI too.

See <https://tftcentral.co.uk/articles/when-hdmi-2-1-isnt-hdmi-2-1>

HDMI 2.0 no longer exists, and devices should not claim compliance to v2.0 as it is not referenced any more

The features of HDMI 2.0 are now a sub-set of 2.1

All the new capabilities and features associated with HDMI 2.1 are optional (this includes FRL, the higher bandwidths, VRR, ALLM and everything else)

If a device claims compliance to 2.1 then they need to also state which features the device supports so there is “no confusion” (hmmmm)

Here's a list of the interesting new stuff in HDMI 2.1:

Support for much higher bandwidths than older generations, allowing

Support for higher resolutions – including 4K and even up to 8K

Support for the combination of 4K and 120Hz high refresh rate (including at 10-bit, HDR and without colour compression)

Variable Refresh Rate (VRR) support

ALLM (Auto Low Latency Mode) support

Well each new version always includes the features of the previous version. 2.1 added new features like very other version before it, and they were all optional. I don't think this is anything new. Any device tested for compliance with the standard now is HDMI 2.1 no matter what features it supports as long as the features it lists as supported pass the tests. Not sure what naming system they could use that would make it clear really. After all you could have a device with support for 48Gbps bandwidth, or one with support for 32Gbps or 40Gbps, or one with support for eARC or ALLM or QMS or VRR. Many of those features make no sense for certain devices (why would a bluray player have VRR support or ALLM? Why would a game console support eARC?). A proper list of supported features really does seem like the only way to be clear about the capabilities of a device. -- Len Sorensen