An HDMI Monitor From Your Phone

Digital video has proceeded to the point at which we have near-broadcast-quality HD production capabilities in the palm of our hand, and often for a surprisingly affordable price. One area in which the benefits haven’t quite made it to our wallets though is in the field of small HD monitors of the type you might place on top of a camera for filming. It’s a problem noted by [Neon Airship], who has come up with a solution allowing the use of an Android mobile phone as an HDMI monitor. Since many of us will now have a perfectly capable older phone gathering dust, it’s an attractive proposition with the potential to cost very little.

The secret isn’t the most elite of hacks in that it uses all off-the-shelf hardware, but sometimes that isn’t the only reason to be interested in a project such as this one. [Neon] is using an HDMI-to-USB capture card of the type that has recently become available from the usual sources for an astoundingly small sum. When paired with a suitable USB OTG cable, the adapter can be seen by the phone as just another webcam.

We see him try a few webcam viewer apps including one that rather worryingly demands a direct APK download, and the result is a very good quality HDMI monitor atop his camera that really didn’t break the bank. Sometimes the simplest of solutions deliver the most useful of results.

This is something of special interest to those of us who experiment with our own camera form factors.

46 thoughts on “An HDMI Monitor From Your Phone

  1. This is great! There are so many useful things you can do with an old cell phone!

    I use an old cellphone with a cracked screen to monitor 3D prints by snapping a picture every minute or so, or even on every layer change, and can use the resulting collection of still images to make time lapse movies, all with free software that has no advertising and requires no subscriptions.

  2. I think the value is that many people aren’t aware that this sort of device exists, and that it can be very useful for people who shoot a lot of video for vlogs, etc. You can buy small HDMI monitors, too, but this makes use of an old phone you probably have sitting in a drawer.

    1. We’ve had video conversion dongles for every format for so many decades, anybody who isn’t aware that they exist is a kid who never was allowed to touch the wires.

      If it really made an old phone into a small HDMI monitor, as you describe, it would be super-duper-awesome.

      But it doesn’t. It makes it into a USB monitor. Which it already was!

      The dongle doesn’t make the USB monitor into an HDMI monitor, it does the reverse; it makes an HDMI video output into a USB video output. The phone has nothing to do with it.

  3. I admit this is not something I am aware of. However, it is quite common that HDMI capture card does not work for HDCP content. This excludes a lot of premium contents. Also, could USB 2.0 keep up with HDMI?

    1. It’s streaming like a camera feed, maybe at a reduced resolution. And damn the drm content, I refuse to use any on principle and pirate it instead just out of spite. I’d happily pay if they didn’t abuse their users to get back at a tiny population of abusers.

    2. Nah the one he’s using strips HDCP. I’ve got the cheap Chinese HDMI Video Capture USB stick from eBay and it seems to strip it everytime. And it does indeed show up as a USB Mic and USB Webcam.

  4. Eh whatever, it’s a clever and not quite intended way to use it and I’m glad to learn about it. It’s not always about making something, sometimes it’s about effectively utilizing something.

    1. Same. I was just thinking about my little microscope camera that has USB and HDMI out. Would be neat to have a small phone screen attached to it. I’ve been looking at small monitors, but they seemed too expensive for the task, so i have this big old 24″ PC monitor on the desk for now. A smaller screen would help to free up some space on the workbench…
      My guess is that i would not even need the HDMI capture card when i can hook up the microscope directly over USB as a “webcam”, but maybe the external capture card would introduce less latency than going over the cameras USB output, depending on how the camera processes the signal internally?

    2. You’ll immediately get several frames of latency just from the camera itself. The dongle isn’t going to buffer very much, but the android app could add an arbitrary number of frames of delay – although the apps targetting FPV use are hopefully going to minimise it.

    3. Unfortunately even a few frames latency makes it unusable for many of the situations where a good monitor is most important. I played around with a number of things like this (camranger clone etc) before getting a real HD field monitor.
      Hurts that the beautiful screens on my tablets can’t do it, but their extra logic and processing capabilities all get in the way of having a simple direct feed to the screen, which is what a field monitor excels at.

    4. Depends on if the HDMI capture unit has a built-in H.264 encoder (usually good, but bad for an application like this), or does raw video over USB 3.0 – such as the Elgato Cam Links. Cam Links have very good latency due to not doing any compression.

  5. Both submission and video are missing links to the origin. To be fair video author mentions EposVox YT video daS5RHVAl2U from Jun 9
    Afaik this all started with this Jun 4 tweet by @Ascii211, a frickin NASA rocket surgeon :

    Inside is MacroSilicon MS2109. It goes up to 1920×1080@30 producing ~14.5Mbit mjpeg stream, or 640x480p@30 raw YUV. It DOES support HDCP handshake! Reportedly mere 20ms latency!?!
    Newest published information from MacroSilicon is for earlier MS2106 analog model, 8bit 8051 lives on :)
    Linux supports usb-audio as of 4 days ago, USB_DEVICE(0x534d, 0x2109), 48kHz stereo transferred as 96kHz mono with swapped channels and unaligned transfers.

    $15 USB 3.0 versions claiming 1080@60 are fake, just a blue plug with same guts inside, dont waste your money unless you can get full refund and free dongle by outscamming the scammers.
    $25-65 Wiistar USB 3.0 ones with integrated HDMI splitter are the real deal and do in fact capture up to 60Hz with less compression. They are older, less integrated design using different chips

    1. All of the links in the video are Amazon affiliate links so they’re going to get a nice chunk of money from this HaD article.

      HDCP doesn’t work on the two dongles I have which is strange. If it does have working HDCP then that is even better.

      Thanks for the link about the Wiistar. The integrated splitter would be helpful. I wonder if that also does HDCP?

  6. Agree on principle, but TIL that my old Android will support webcam and webcam like devices over USB OTG, so I was glad to read the article. Not sure where there’s another forum where this would reach the audience that would be interested to know that.

  7. All of these cheap HDMI to USB capture devices use a MacroSilicon MS2109 chip inside. The “USB 3.0” version is the same internally as the USB 2 one but with a blue USB 3 plug with none of the extra lines connected so save your money. It will accept up to 4K but the MS2109 encoder is limited to 1080p30 with MJPEG and 1080p5 if you want YUV. No HDCP support so you’ll need to strip that yourself.

    If you want one then search for “hdmi capture usb”. As usual, they’re significantly cheaper from China if you’re willing to wait.

  8. Well, I needed one of these, its a good solution to streaming an app over Zoom that displays on a secondary screen, I might even be able to do it from a laptop. I may use this as my ‘webcam’, or just share the screen, now I need a 2k hd screen. :/

    Thanks for another impulse buy hackaday, at least this should be more useful than the FPGA thin client I never did anything with

  9. I’ll admit, I just assumed it was some clever way to get HDMI into the phone through USB-C. Because USB supposedly has monitor functions now.

    Using a dongle, as intended… yeah. Complaining doesn’t get the time back, but it does provide the missing entertainment value.

  10. A few years ago, there were a bunch of $20 HDMI capture sticks that downscaled the video to 480p. Is there a sure way to check that the cheap capture sticks available nowadays uses the newer 1080p chipset before buying it?

  11. I have one of these adapters and the lag is significant. Using it to control another computer with a mouse requires a slow hand. I guess it could be okay for a camera monitor. I got mine for less than $9 on AliExpress. It’s amusing, if not completely practical.

  12. If I have two computers (a macbook pro and a windows desktop) and now have two monitors (both support displayport and HDMI) would it work to have this HUB connect to the mac via thunderbolt/usb-c and connect the monitors w DP and then use a KVI switch w USB 3.0 connected to keyboard and mouse and then connect the switch also to the windows PC and then use HDMI on the monitors for the PC?

  13. I’m so upset that this guy said he thought up this idea when all he did was copy my videos from my channel IMCE.

    I’ve done so many tests on canon M50, Eos-m magic lantern and bmpcc4k.

    There’s a lot of stuff he left out, a lot of questions unanswered and most of all the time I put in to make this happen. VEXED!

    1. Exactly! how dare he copy your video idea without attribution when You yourself clearly acknowledged and cited @Ascii211 as the source and inspirati… oh wait, you didnt? but somehow you didnt forget to put affiliate link to the fake USB 3.0 scam product. Good job sir! :)

  14. I bought a similar dongle from Ebay. It works. It’s Laggy. Anyone knows a good Android app that would work and give high res UVC video? I tried couple ones. Some doesn’t work, some gives low res. The person in the video said something about side loading an app to get good video resolution, but I don’t think I’ll go that route.


  15. I have several devices that I am using for other purposes. There are several tablets for home multimedia. There are also phones for shooting weather for the window, I make a small time-lapse when there is a downpour with thunderstorms, and so on. And there is an old PC that I use as a server, store family photos and videos on it. Very comfortably.

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