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Displays Hardware

HDMI Alt Mode Is Dead (notebookcheck.net) 62

Posted by BeauHD from the good-news-for-consumers dept.
According to the HDMI Licensing Administrator (LA), the HDMI Alt Mode feature is dead. Notebookcheck reports: 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. The HDMI Licensing Administrator may have given up on Alt Mode, but it's still working on improving power delivery. "At just 0.3A@5V, HDMI Cable Power is at most able to drive a cable over longer distances," reports Notebookcheck. "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."

That said, HDMI LA cautioned that the upcoming standard is still in the discussion phase and there's no date for when the update will arrive.
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HDMI Alt Mode Is Dead More

HDMI Alt Mode Is Dead

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  • Bad summary technique (Score:5, Insightful)

    by Mononymous ( 6156676 ) on Thursday January 12, 2023 @08:49PM (#63204528)

    This story is about HDMI Alt Mode. It's the subject of the headline, and repeated a bunch of times in TFS.
    No definition given. Wake up, BeauHD!

    • This story is about HDMI Alt Mode. It's the subject of the headline, and repeated a bunch of times in TFS.
      No definition given. Wake up, BeauHD!

      Had to look it up. Apparently it's usb-c to hdmi [makeuseof.com].

      • That is no help at all. It also mentions HDMI Alt Mode several times but never tells you what it is.

      • I have quite a collection of devices with USB-C to connect to a device, a USB-C port for power, and HDMI plus a few to plenty of other ports as extension ports. I got my first during home office times two years ago because my company was too cheap to get me another docking station. Now that we're moving to Samsung phones in my family, I've loaded up, and I think all those devices actually use DP alt mode and then convert to HDMI. Your link includes the info that HDMI alt mode is limited to 4k@30Hz, and even

        • Re:Bad summary technique (Score:5, Informative)

          by Zuriel ( 1760072 ) on Friday January 13, 2023 @02:42AM (#63205042)
          IIRC, DisplayPort Alt Mode only uses one set of high speed pins in a type-C port, where HDMI Alt Mode uses both sets. Basically everything does DP Alt Mode and then converts to HDMI using a converter chip, because then you can still do USB 3.0 on the other pins. That's also why you can get type-C hubs with DisplayPort output for dirt cheap, they don't have the converter chip and won't work if you try to use an adapter to plug them into a HDMI-only display. One of the main reasons they're killing HDMI Alt Mode is because hardly anything actually implemented it.
          • Thanks a lot! Interesting, although my hubs with display port out aren't cheaper than the ones with HDMI... Either can be found under 20 bucks at AliExpress if you don't want other ports (with 2 USB ports plus ethernet and a card reader it's closer to 30 bucks). The cheapest one I have that does 4k@60Hz was 12 bucks including shipping. Only one USB 3 port, so it requires a USB hub {3 bucks) for keyboard and mouse if you use non Bluetooth devices...

      • Re: (Score:3)

        by AmiMoJo ( 196126 )

        HDMI is the same data format as DisplayPort, so adapters that convert DisplayPort to HDMI are fairly simple devices. As such there isn't much real need for HDMI Alt Mode, you can just use a cheap USB-C DisplayPort to HDMI adapter.

    • You must not frequent this site. Dupes and poor editing go back two decades now.

    • Re:Bad summary technique (Score:5, Funny)

      by Waffle Iron ( 339739 ) on Thursday January 12, 2023 @10:20PM (#63204682)

      This story is about HDMI Alt Mode. It's the subject of the headline, and repeated a bunch of times in TFS.
      No definition given. Wake up, BeauHD!

      TL;DR: HDMI is dropping Alt Mode in favor of the more powerful Windows Key Mode.

      • Meanwhile EMACs users are lording it up with their superior Escape-Meta-Alt-Ctrl-Shift Mode.

        Vi users never left the home row.

    • Re: (Score:2)

      by Rhipf ( 525263 )

      I guess a link to the explanation right in the summary isn't enough of an explanation of what HDMI Alt Mode is?

      • No, that's not how you write a summary.

        • Re: (Score:2)

          by mrex ( 25183 )

          To summarize: the Alt-Right Arrow HDMI LA knows where it is at all times, because it knows where it isn't.

          It's also still working on improved power delivery(!?)

        • That's literally the definition of a summary; a brief statement or account of the main points of something.

          It's supposed to leave out detail like the technical definition of HDMI alt mode and cover only the main points.

          • Of course the technical definition goes in the proper standard.
            TFS should have started with something like, "HDMI Alt Mode is the standard that covers sending an HDMI signal over USB-C." (Or whatever; I still haven't bothered to look it up).

    • Re: (Score:2)

      by gweihir ( 88907 )

      Indeed. Came here to ask the same thing: WTF is this story about?

    • I'll try to explain it based on what I know:
      We all know USB-C.
      ALT modes enable various "non-usb" types of packets to travel over the USB wire. (don't know if packets are encapsulated, or if they get their own wires...) There are currently a few alt modes specified:
      Displayport, HDMI, Thunderbolt, MHL. The limitations for these modes compared to their native cables come from USB physical limitations.

      What this article says is that no adapter has ever been produced implementing the HDMI alt mode, and thus it is

      • Why mention apple including an HDMI port? No idea.

        Having a "real" HDMI port that uses a real HDMI to HDMI cable makes USB ALT-HDMI mode completely pointless. Why plug an expensive USB-C to HDMI cable into a USB-C port when you can just plug a cheap HDMI cable into an HDMI port? Unless you have two HDMI monitors.

      • Why mention apple including an HDMI port? No idea.

        Because its an example. Firstly Apple is a prime example because for several years they didn't offer a single product with a HDMI port, whereas now all Macbook Pros do include HDMI. But they are far from the only ones. TFS didn't specifical call out Apple, they called out "companies like Apple". My previous Dell Inspiron work machine had no HDMI port. My current one does again. Same trend by other companies.

    • There's a link to a website explaining exactly what HDMI Alt-Mode is. Basically, you have a cable that is USB-C on one end and HDMI on the other end, and if your graphics card supports HDMI Alt-Mode then it sends output to the USB-C port which goes through this cable and arrives as HDMI at your monitor.

      Since no computer supporting HDMI Alt-Mode has ever been shipped, we should not call it "dead" but "stillborn".

    • Sorry but this is Slashdot, minimum knowledge is expected. Who here doesn't know what USB-C Alt-Mode is, we've discussed it here a LOT of times" Even if you didn't know there was a HDMI alt-mode one could figure that out very quickly from the words "HDMI alt-mode". The summary even talks about it in the context of Display Port Alt Mode.

  • Article was written in ALT mode (Score:5, Insightful)

    by Tony Isaac ( 1301187 ) on Thursday January 12, 2023 @08:50PM (#63204530) Homepage

    One sentence leads to another sentence that has nothing to do with the previous one.

    One of the reasons is that companies like Apple have begun putting HDMI ports on their products again

    And how does Apple's decision to include HDMI ports lead to canceling ALT mode, whatever that is?

    This means an HDMI output has to come from somewhere else on a laptop

    Somewhere else than what, exactly?

    And what does DisplayPort have to do with HDMI Alt Mode?

    Maybe somebody smarter than me can explain what all this means, to those of us who haven't actually read the HDMI spec.

    • I think HDMI Alt Mode must mean carrying an HDMI signal over USB, then converting it back. That's the only thing that would make sense in this article. And it sounds like the existing connectors that _look_ like HDMI over USB are actually using DisplayPort over a USB -C cable (but not USB signal), then converting that to HDMI.

    • Re: (Score:3)

      by Rhipf ( 525263 )

      And how does Apple's decision to include HDMI ports lead to canceling ALT mode, whatever that is?

      It really shouldn't be that hard to see that if there is an HDMI port on a device you don't really need HDMI Alt Mode on that device.
      "But what is HDMI Alt Mode?" you ask. Maybe if you click on the nice link provided it you could see what HDMI Alt Mode is. It is simply an HDMI signal that can be sent out over a USB-C connection on one end to an actual HDMI connector on the other end. This is the same as DisplayPort Alt Mode.

      Somewhere else than what, exactly?

      And what does DisplayPort have to do with HDMI Alt Mode?

      If the HDMI signal isn't coming out of the device via a USB-C port (using HDMI Alt Mo

      • Re:Article was written in ALT mode (Score:4, Insightful)

        by Tony Isaac ( 1301187 ) on Thursday January 12, 2023 @10:47PM (#63204724) Homepage

        You realize this is Slashdot, right? I'm proud of myself for having actually clicked to view the linked article. Having to click a link in the linked article, is one step too far!

        • The point of a summary is to summarize. It should absolutely tell you what the hell is the point of the article and why you should bother reading it, so hopefully you won't waste time reading clickbait behind a paywall or something.

          Editors not doing their job? Yeah, this is Slashdot, all right.

      • That actually helps me understand the craptastic video over USB situation. I am the proud owner of an expensive Apple USB-C display that works with nothing - it doesnt work with any of my Apple, Windows or Linux computers. It is purely ornamental.
      • Thank you for doing the "editor's" job.

    • And how does Apple's decision to include HDMI ports lead to canceling ALT mode, whatever that is?

      Not Apple's. Companies like Apple's. Also how do you not know what Alt mode is? It comes up in literally every discussion we have about USB and Thunderbolt. It's the ability for a USB port to act like something ... alternate.

      What it means is we no longer need a standard to push HDMI out over USB since there's already HDMI ports on the machines themselves.

      Somewhere else than what, exactly?

      Didn't you just quote a piece of text that says companies are including HDMI ports? I get short attention span but this is something else entirely!

      And what does DisplayPort have to do with HDMI Alt Mode?

      Literall

      • I know you think I don't read carefully, but lots of moderators apparently agree with my post, so I'm not that clueless.

        Perhaps it's because I live in the Windows world, where "alt" mode isn't discussed, laptops and computers have never "lost" their HDMI ports, we don't need special USB adapters to connect ordinary equipment, and few computers have DisplayPort or Thunderbolt.

        • but lots of moderators apparently agree with my post, so I'm not that clueless.

          Moderation points are random, and there are some serious moderators showing brain damage in their moderation. All your mods show it that you have 3 people agree with you (out of over 10million slashdot accounts), and one of them appears to think you may have been joking since one of your mods is funny.

          Perhaps it's because I live in the Windows world, where "alt" mode isn't discussed

          Alt mode isn't a windows or non-windows thing. It's a feature of USB. We've discussed alt mode many times on Slashdot. Displayport is the most famous, but there's also Thunderbolt (you've heard of that right?)

          • You seem to be fixated on the exceptions to the rule. Sure there were some Dell laptops that didn't have HDMI, but the vast majority did. It has been primarily Apple that seems fixated on removing useful plugs from their equipment. Heck, my Motorola Android phone still has a headphone jack!

            And when I say that Windows laptops don't have Thunderbolt or DisplayPort, I'm referring to the physical plugs for those specs. Sure, they might support Thunderbolt and DisplayPort via USB Alt mode, but they don't typical

    • Maybe somebody smarter than me can explain what all this means, to those of us who haven't actually read the HDMI spec.

      Using USB-C to drive HDMI displays is dead, because A) DisplayPort displaced HDMI for that use case and B) devices that want to advertise driving HDMI screens are simply including HDMI ports.

      Unmentioned is that this is really about the audio. HDMI supports audio channels. That's why there was an USB-C -> HDMI mode. However, that only matters if you're driving a TV. Otherwise, there is no problem with having DisplayPort for the video, and regular audio outputs as normal for whatever the device is. But in

      • Thanks, your response was a lot more helpful than the article itself.

        I doubt that USB-C to HDMI is dead, because even in the Windows world (where computers and laptops never lost their HDMI ports) these types of adapters are sometimes used to drive a second monitor. These are widely available on Amazon and other retailers.

    • Somewhere else than what, exactly?

      And what does DisplayPort have to do with HDMI Alt Mode?

      Maybe somebody smarter than me can explain what all this means, to those of us who haven't actually read the HDMI spec.

      USB-C adds a feature called alternate mode [wikipedia.org] that creates a standardized method for both sides of the USB-C cable to negotiate using the USB-C cable to carry a completely different signal than USB. The USB-C connector has a dedicated pin for a new low speed sideband connection called USB PD (Power Delivery) the main use of USB PD is to negotiate a higher Vbus voltage between a computer and a USB-C charger. But the other big use case of USB PD is to negotiate alternate modes. With DisplayPort alternate mode, a

      • Great writeup, you just provided far more informative and interesting information than the original author. Thank you!

  • Is there a DVI Alt mode? SCSI Atl mode? MIDI Alt mode? Parallel Port Alt mode?

  • Yeah I'm using Alt Mode. But it's probably DP Alt mode with an HDMI conversion chip in the dock. Since HDMI Alt mode never really worked that well nor was as widely support as DP.

    • This is literally how many HDMI - USB-C adapters are implemented as well. Not just some docks.

      • Yea, I've used the conversion chips before. They're kind of power hogs. Not important if you use them in a dock. But a real pain if you're like me and you had to put them in a tablet and an accessory for a handheld game console.

  • Don't Nintendo Switches use alt mode? They have only a USB-C port, but connect to TVs and monitors by HDMI. Is one of the worlds best selling game systems really "no use case has been found"?

    • Re: (Score:3)

      by Dwedit ( 232252 )

      A website site claims that "The Switch uses DP Alt Mode for video output. It is essentially USB-C DisplayPort. The dock uses HDMI output as it is more common on TVs than DisplayPort. The dock handles the DP Alt Mode to HDMI conversion."

    • Don't Nintendo Switches use alt mode?

      Yes but not HDMI alt-mode. They use DisplayPort alt-mode. Displayport is nicely convertible to HDMI (it was designed to be compatible with just a minor change in signalling).

      Most HDMI adapters on the market and most laptop docks, the Switch included use DisplayPort alt mode and active conversion afterwards.

  • When someone here wants to get a laptop that has usb-c, I make sure they get a travel dock too. One of those aluminum ones with a mix of usb-a, gig ethernet, sd card readers, AND HDMI. Because so often they'll be somewhere they need to connect to a projector and need either vga or hdmi out. Basically it takes the place of having to carry a bag full of different usb-c adapters. For the purposes of hdmi, it works as an adapter, so I hope this issue doesn't mean they're going to break functionality on thes

    • One of those aluminum ones with a mix of usb-a, gig ethernet, sd card readers, AND HDMI.

      What this article is saying is that HDMI isn't native in those docks. Those docks almost always use DisplayPort alt mode and convert DP to HDMI. This is how most adapters work as well.

      I'll admit though, I've never seen a usb-c to hdmi adapter.

      There's countless out there. I have one for my work laptop, and the official Microsoft one for my Surface Pro at home. Both use display port alt mode and convert to HDMI.

  • > 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.

    Adapters? The whole point of alt mode [hdmi.org] was to "deliver HDMI signals and features over a simple cable without the need for protocol and connector adapters or dongles." So, why would anyone think a claim that no adapters have been produced is in any way meaningful?

    • You are being pedantic over the word "adapter". Anyone who looks at the action of plugging a HDMI device into a USB port considers that an "adapter" whether or not there's native alt-mode used underneath is irrelevant.

  • ... oh, one of _those_

    I do actually have a USB-C to HDMI cable, can't even remember when I used it last or why I bought it.

    ALT Mode? - I wasn't even aware it existed.
    I guess, at the time I bought that cable, I had a macBook with only USB-C - but it was short lived, because I got a USB-C to displayPort instead.
    Still using that, because I have 4 computers connected to my monitor.
    Two macs, one Linux PC and a Windows gaming rig - yeah, I'm an agnostic - whatever works :shrug:

    I'm more concerned, to be honest, ab

  • https://arstechnica.com/gadget... [arstechnica.com] "If you're using a USB-C port to connect a computer to a display, you're most likely using DisplayPort Alternate Mode (Alt Mode), and due to non-existent adoption, we can pretty much guarantee you're not using HDMI Alt Mode."

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