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HDMI Alt Mode for USB Type-C Connector

hdmi.org

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Re: HDMI Alt Mode for USB Type-C Connector

#4
not a lot of details in this but I'm curious how the AC-coupled USB-C interface works with the DC-coupled HDMI. typically there would be a DP-to-HDMI convertor in the cable plug and just use DP alt-mode but this specifically says:

"This allows native HDMI features and capabilities to be utilized in a source device and to be directly connected to any HDMI display. Other Alt Mode solutions do not enable HDMI-specific features and also require converters and connector adapters to connect to HDMI-enabled displays. A simple HDMI to USB Type-C cable can be used to connect USB Type-C devices to native HDMI displays."

Re: HDMI Alt Mode for USB Type-C Connector

#5
It's alas unlikely but oh how grand it would be to not need HDMI.

USB4 ports mandatorily have DisplayPort output, on each port. HDMI is not going to catch up. It is an expensive proprietary system & won't ever match the availability.

Re: HDMI Alt Mode for USB Type-C Connector

#6

How is this relevant considering DisplayPort alt mode has been a thing for a while?

It's relevant because the display just needs an HDMI port. You can plug a HDMI-to-USC-C cable into a computer and a TV or projector and it'll work using this. If your device doesn't do displayport then displayport support is moot.

Re: HDMI Alt Mode for USB Type-C Connector

#7
post #4

not a lot of details in this but I'm curious how the AC-coupled USB-C interface works with the DC-coupled HDMI. typically there would be a DP-to-HDMI convertor in the cable plug and just use DP alt-mode but this specifically says: "This allows native HDMI features and capabilities to be utilized in a source device and to be directly connected to any HDMI display. Other Alt Mode solutions do not enable HDMI-specific f…

I'd suspect "simple" is doing a lot of work here.

Re: HDMI Alt Mode for USB Type-C Connector

#8
HDMI Alt Mode was basically dead on arrival.

The computer world pretty much standardized on DisplayPort already, so USB-C devices would already have to support DisplayPort Alt Mode anyways. Why add support for yet another Alt Mode when DP-to-HDMI converter chips are dirt cheap, and pretty much all USB-C-to-HDMI cables will be using those anyways due to the aforementioned DP ubiquity.

One thing which really bothers me is that all those Alt Mode specifications are proprietary. USB-C itself is a completely open spec and anyone can download the PDFs from their website - but the Alt Modes require you to join the VESA / HDMI consortium, with an associated member fee and NDA.

Re: HDMI Alt Mode for USB Type-C Connector

#9

How is this relevant considering DisplayPort alt mode has been a thing for a while?

It's relevant because the display just needs an HDMI port. You can plug a HDMI-to-USC-C cable into a computer and a TV or projector and it'll work using this. If your device doesn't do displayport then displayport support is moot.

Virtually all USB-C-to-HDMI cables use DisplayPort Alt Mode and internally convert from DP to HDMI.

Re: HDMI Alt Mode for USB Type-C Connector

#10
post #3

Is there anything interesting here or is this just the spec that we have been using on laptops for ages now?

You probably haven't been using it for ages, because virtually nobody bothered to implement it. Everyone is using DisplayPort Alt Mode instead - even for C-to-HDMI adapters.
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