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CES 2023 | The demise of HDMI over USB-C (Alt Mode) and more power in cables

Never made it to the market: HDMI adapter that only exists in theory. (Source: HDMI LA)
Never made it to the market: HDMI adapter that only exists in theory. (Source: HDMI LA)
True USB-C to HDMI adapters are no longer going to be a thing. The HDMI Alt Mode is more or less history, and DisplayPort has won. Notebookcheck spoke to HDMI LA and the USB-IF about it. Furthermore, there is hope that more devices can be powered directly over HDMI in future.

There aren't going to be any HDMI adapters that deliver HDMI signals from a USB-C port in Alt Mode, as they don't make sense any more. The HDMI Licensing Administration (LA) revealed this in a conversation with Notebookcheck at CES.

According to HDMI LA, there are simply no more uses for Alt Mode. One of the reasons is that companies like Apple have begun putting HDMI ports on their products again. HDMI Alt Mode also no longer offers any advantages. As a result, the specification will not receive any further updates. This means an HDMI output has to come from somewhere else on a laptop.

Besides the standard and mini sockets, DisplayPort is typically used in Alt Mode via a USB-C port. Eventually, the signal is converted to HDMI output. As HDMI LA mentioned at CES, there are people currently working on a logo program for labelling certified HDMI adapters to help consumers be sure that a USB-C to HDMI adapter will work properly. Right now, such a program only exists for cables. Whilst USB to HDMI adapters with DisplayPort undergo base certification, this is not something that is apparent in retail shops.

HDMI Alt Mode has never managed to win over manufacturers. HDMI LA said that it doesn't know of a single adapter that has ever been produced. Similarly, at the USB Implementers Forum (USB-IF), people who are familiar with the certification process have yet to see a true USB-C to HDMI adapter.

This is good news for consumers because there is no longer any risk that an HDMI adapter on the market won't work with conventional USB-C ports that support DisplayPort.

HDMI Cable Power will be updated

At CES, HDMI LA cautiously announced to Notebookcheck that HDMI Cable Power will receive another update. There are currently two ways to deliver power via the HDMI interface: the usual minimum power (which is practically consumed for HDMI itself and doesn't have a name) as well as what has been known for some time as HDMI Cable Power (see Notebookcheck's background article published in 2021: "HDMI: A standard with a lot of untapped potential").

At just 0.3A@5V, HDMI Cable Power is at most able to drive a cable over longer distances. The specification was announced back at CES 2021 but only officially introduced in mid 2022.

There are now plans to further increase the amount of power provided. This means it may be possible in future to power streaming devices (e.g. Fire TV Sticks) directly over an HDMI port. At the moment, you usually still have to use USB to power such devices.

However, HDMI LA was very careful about this announcement and emphasised that the upcoming standard is still in the discussion phase. So it's up in the air how much power will ultimately be provided and when the update will arrive.

Though one thing for sure: as with industry standards, this is going take a few more years. The announcement of HDMI Cable Power quite clearly demonstrates this. Right now, there is a lack of cables that support this feature. The upgrade could solve this problem as the potential grows. Long HDMI cables have rather specific use cases, such as for presentations or in home theatre installations. Most HDMI cables are fairly short by contrast.


HDMI LA and USB IF at CES 2023

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> Expert Reviews and News on Laptops, Smartphones and Tech Innovations > Reviews > The demise of HDMI over USB-C (Alt Mode) and more power in cables
Andreas Sebayang, 2023-01-11 (Update: 2023-01-11)