Non-DP Alt Mode USB-C to HDMI Adapter

justdigi on 28/04/2025 - 20:01

My workplace recently purchased all new devices including mobile phones, tablets and laptops. They are all USB-C, however none of them support DisplayPort Alt-Mode for video out via the USB-C port. None of the devices have HDMI or DisplayPort ports either. I need a non-DP Alt Mode USB-C to HDMI adapter, so that we can show presentations and media on an external display or projector.

Doesn't even need to be a bargain, I literally cannot find the device I'm after searching via regular search engines or marketplaces, as keyword stuffing search optimising retailers have all bought the keywords and everything I can see requires DP Alt-Mode. I have asked at local retailers who either assure me that that type of device doesn't exist or have sold me a device that requires alt-mode when I clearly explained that it wouldn't work.

I know these exist, as there is one for AR glasses called a Rayneo Thunderbird Air Adapter (though I need C to HDMI, not C to C that this device is). Can anyone find me this device? And no, we can't return all our new devices, though I think the guy who procured them should be put on a PIP.

Find Me A Bargain HDMI Adapter

Comments

  • L0zBargain on 28/04/2025 - 20:20
    +1

    Ahh, the old corporate saving money trick!

  • askbargain on 28/04/2025 - 20:21

    /r/usbchardware

    if they don't support DP out, what makes you think it supports video?

    rayneo is video in not out

    • justdigi on 28/04/2025 - 21:45

      Because they are essentially an external video card. The devices even work on USB A, which never supported DisplayPort output. I know they exist, I just can’t find them and am obviously using the wrong keywords.

      • askbargain on 28/04/2025 - 21:49
        -3

        they are essentially an external video card

        ?? they?

        The devices even work on USB A, which never supported DisplayPort output

        what?

        Take pixel 7 for example. They have a usb-c port but you will never get video out. Any USB-C to HDMI cable you see converts the DP signal to HDMI.

        https://www.androidpolice.com/google-launches-usb-c-to-hdmi-…

        • justdigi on 28/04/2025 - 21:52

          Read below, @pinchies gave me the keyword DisplayLink. It does exactly what I asked for, outputs from devices without display out.

          I did not want a simple C to HDMI adapter, which is what JB/Officeworks tried to sell me, and which you seem to suggest too.

          Yes a DisplayLink adapter will work with a pixel 7, as long as the app/driver is installed.

          • askbargain on 28/04/2025 - 21:57
            -3

            @justdigi:

            outputs from devices without display out

            software solution to output video lol. can't wait for the 1 month update when you decide to just get new laptops.

            • eug on 28/04/2025 - 23:50
              +2

              @askbargain: DisplayLink docks have been around for over 15 years. They work fine for standard boring business applications.

              • justdigi on 29/04/2025 - 07:32

                @eug: Thank you. That’s exactly what it’s for, PowerPoint presentations, not 4K 120fps gaming. It just needs to work, not be high resolution or frame rate.

            • justdigi on 29/04/2025 - 07:33

              @askbargain: I don’t understand why you’re doubling down when two other posters have shown you that it’s not a software solution, it’s video out over a data line and the technology has been around for over a decade.

  • pinchies on 28/04/2025 - 21:44
    +1

    I think what you are asking for are "fake" display adapters, like those with proprietary DisplayLink Graphics technology. I wish you luck, even though they have gotten better, I still think they are horrible hacky kludges. Otherwise, what you are asking for does not exist.

    And a laptop without a external display output sounds very odd… so you might have something wrong there.

    • justdigi on 28/04/2025 - 21:49

      This is it! The keyword is DisplayLink. Needs drivers on Windows and Android, but is able to output from regular USB A, as well as C ports without DP ALT-mode. Not cheap, we’re looking at about $200, but will only need them in the conference rooms. Thank you.

    • eug on 28/04/2025 - 23:40
      +1

      The ones I've used worked fine for normal office use. Get a good brand like Plugable and it should be fine. Their founder worked at Microsoft as a developer and manager working on Bluetooth and USB drivers before becoming a VP at DisplayLink after which he started Plugable, so I'm not surprised their DisplayLink products worked well for me.

      • justdigi on 29/04/2025 - 16:18

        Thank you for the recommendation, I have a Plugable adapter on the way from Amazon and it was about $25 cheaper than what I was going to purchase. It arrives tomorrow, but I'm confident it should work.

  • GordonD on 29/04/2025 - 10:11
    -1

    I thought you could do this with any USB-C hub that has HDMI ports on it. None of them say the USB-C port you plug them into has to support alt mode. Are they failing to declare an essential requirement of them doing what they claim? You can get them for $10-$20.

    • justdigi on 29/04/2025 - 12:44

      No that’s not the case at all. Unfortunately it seems that’s a common belief, as the salesperson at JB HiFi also believed that.

      USB-C is a port, not the protocol that runs over it. There are different protocols, like USB 3.2, Thunderbolt, PCIe or DisplayPort. The device has to support those for it to work.

      • GordonD on 29/04/2025 - 15:44
        -1

        You are trying to tell me that there's thousands of USB-C hubs on the market with HDMI ports on them, the adverts for them and the salesmen selling them say they'll let you add extra HDMI screens, but they don't actually work, and no-one buying them is complaining that they don't work. This is a story I'm having a lot of trouble believing.

        • eug on 29/04/2025 - 16:03
          +1

          What are the hubs you've seen?

          I did a quick search on Amazon:

          This $20 UGreen says "Please make sure the USB-C port of your host device supports video output"

          This $18 Novoo says your PC or smartphone must support DP Alternate mode

          This $50 Wavlink asks you to confirm your Type C port supports video output.

          I didn't look any further, but as with all things the buyer really should be reading the product description fully before buying.

          • GordonD on 29/04/2025 - 16:24

            @eug: "Video output" as referred to in these adverts, and DP Alt Mode, are two different ways of doing the same thing.

            DP Alt Mode is hardware. It is using some of the spare pins in the USB-C connector to send a DP signal direct from the video circuitry in the host device to the DP or HDMI screen. And extracting it from those pins at the other end as if it came in on a DP or HDMI port. That's why there are DP Alt mode cables, because if its one of those it guarantees to implement those pins separately to the USB functionalty.

            Video output is software. It is the video in the host device being able to direct the DP or HDMI data stream to the device's USB controller where it is encapsulated in a USB protocol envelope and sent down the USB pins to something at the other end. It is having a driver that can recognise the thing that's at the end of the USB cable is a screen, and it wants a video data stream, and being able to direct one there.

            If this wasn't the case you couldn't have a USB-C hub that had more than one HDMI port on it. Because the DP Alt mode signal couldn't somehow be sent to both of the two HDMI ports on the hub.

            • eug on 29/04/2025 - 18:16

              @GordonD:

              Video output is software. It is the video in the host device being able to direct the DP or HDMI data stream to the device's USB controller where it is encapsulated in a USB protocol envelope and sent down the USB pins to something at the other end. It is having a driver that can recognise the thing that's at the end of the USB cable is a screen, and it wants a video data stream, and being able to direct one there.

              You've pretty much described DisplayLink - a software solution to send video over a standard USB port to a DisplayLink chip which is the "something at the other end" to decode the data and send it out over HDMI.

              Those cheap hubs don't support that - they require DP Alt. A typical consumer won't understand what DP Alt is, so it's easier to just call it "video output".

              If this wasn't the case you couldn't have a USB-C hub that had more than one HDMI port on it. Because the DP Alt mode signal couldn't somehow be sent to both of the two HDMI ports on the hub.

              USB hubs are annoyingly complicated. A brief summary:

              A Type C port has four high-speed lanes and a dedicated USB 2.0 lane. Some devices have the Type C port wired to the GPU - these are the devices that are able to send video over the Type C port (i.e. DP Alt) without needing something like DisplayLink.

              A Type C to DP/HDMI dongle can use all four lanes to give 4K60 with DP1.2.

              A low-cost USB hub/dock like the ones I linked to above will use one lane for USB 3 Tx, one lane for USB 3 Rx, and two lanes for DP. The bandwidth available to DP has halved which is why they can only do 4K30.

              As you go up in cost, more features are supported. DP 1.2 onwards has MST support which lets you split a single stream to multiple streams allowing for docks with two outputs. The supported resolutions depend on the available bandwidth which is why you have to carefully read the descriptions, e.g. this Wavlink has two ports but can only do 4K60 on one port and 4K30 on the other. Macs don't support MST so you get silly compatibility problems like this Wavlink hub supporting two separate outputs on PCs but Macs only being able to treat both ports as a mirrored pair.

              At the ~$200 price range, e.g. this Wavlink or this Plugable you can get 2x 4K60. They do this by either supporting DP 1.4 with DSC (Plugable) or going back to the software solution - a DisplayLink chip.

              Then there are Thunderbolt docks…

        • justdigi on 29/04/2025 - 16:16

          No not at all. You're making up a scenario that I never said, and getting angry about it.

          I'm saying that some devices do not have that compatibility and that is what my company purchased. I was speaking about a specific scenario (which I detailed in my post) and you generalised it to every USB-C device? My company purchased products made for another market (as they were significantly cheaper than Australian market products) and that market did not require display over USB-C functionality. I need the technology called DisplayLink, but didn't know what it was called. I know now and have an adapter on the way.

          The vast majority of Australian market products have USB-C display out functionality, so you would never see the difference. But USB-C isn't universally compatible. I have a budget mobile phone (CMF Phone 1) from JB HiFi that is USB-C charging only and doesn't output video. If I bought the adapter you're speaking of it wont work, but the salesman said it would. He was wrong. However I have a personal MacBook Air and a $10 USB-C to HDMI cable from Kmart works flawlessly. Both are Australian market products, so it pays to check.

          • GordonD on 29/04/2025 - 16:30

            @justdigi: And you are confusing the two things too. You are talking about the host devices not having DP Alt mode, when the reason they're not working is that they don't implement video output over USB. Either because the capability to send video data to the USB controller wasn't designed in, or there's no USB driver to recognise that whats on the other end of the USB is a screen that can accept video through its USB port.

    • justdigi on 29/04/2025 - 12:48

      It’s all explained in the Wikipedia Article. My devices are USB 2.0 only USB-C ports, and only support power and slow data.

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