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Comment by shmerl | Hacker News Reader

May be it can change if USB 4 will sneak in and supplant HDMI in those devices, since it can route both HDMI and DP.

Is HDMI over USB even a thing that any real devices support? But yeah, demand for mobile phone support might force TV manufacturers to adopt DP over USB.

> Is HDMI over USB even a thing that any real devices support?

No. A spec for HDMI Alternate Mode was written, but almost nobody (possibly nobody at all?) implemented it, and it was eventually withdrawn.

https://arstechnica.com/gadgets/2023/01/hdmi-to-usb-c-spec-a...

It cannot route HDMI, partly because HDMI is built upon antiquated principles and doesn't really fit besides more modern protocol designs. USB4 would need to get entirely redesigned for tunneling native HDMI.

Having a DP to HDMI converter on one end though, that's easy.

> HDMI is built upon antiquated principles

I'm interested in learn more, in what way are they antiquated?

HDMI uses a digitalized form of the traditional TV signals. The format of the transmitted data still depends on the parameters that defined traditional TV signals, like video frame frequency, video line frequency, vertical and horizontal retrace intervals and so on. Such parameters are no longer essential for digital television and there is no longer any need to constrain the transmission of video signals with them.

DisplayPort uses a typical communication protocol that can carry arbitrary data packets, not much different from the protocols used on USB or Ethernet.

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