7 ms·

Using a laptop as an HDMI monitor for an SBC

168 points by hasheddan 1y ago

kevmo314 1y ago
Since there’s monitors that work over USB-C, could one replace the capture card and somehow get the laptop to pull video like a USB-C monitor?
- detaro 1y ago
  not really. The video stuff needs explicit hardware support, so the laptop would need to include what's essentially a capture card already. It'd be awesome if vendors did that, but to my knowledge nobody does.
- numpad0 1y ago
  Those USB-C display outputs are real raw GPU output patched through electronically, not like image over USB protocol. They just use the connector, and they can't be captured as USB data.
05 1y ago
I'm thinking a better solution for console would be an SSH to serial bridge using just a spare ESP32 and something like ESP32SerialSSHProxy[0]. Haven't tried myself yet, and there is suspiciously few stars on that repo, but that would be a nice lights out-ish management system for some hidden away home automation server. [0] https://github.com/programminghoch10/ESP32SerialSSHProxy https://github.com/programminghoch10/ESP32SerialSSHProxy
- jonathanberi 1y ago
  That works sometimes. It can be flaky.
- hasheddan 1y ago
  You can also throw together a cheap software KVM switch[0] using an ESP32 or similar. [0] https://euer.krebsco.de/a-software-kvm-switch.html https://euer.krebsco.de/a-software-kvm-switch.html
- zoobab 1y ago
  I used 1eur esp8266 with jee-link firmware: http://www.zoobab.com/esp8266-serial2wifi-bridge http://www.zoobab.com/esp8266-serial2wifi-bridge
  - 05 1y ago
    Yeah but do you really want to give everyone on your LAN unauthenticated access to the server console? :)
- Saris 1y ago
  Does serial work for BIOS/UEFI access too?
thesandlord 1y ago
If you have an iPad with a USB-C port, you can use the free Orion app to do this too https://orion.tube/ https://orion.tube/
- rahimnathwani 1y ago
  My son uses the Genki Studio app on his iPad. It works well enough without payment. https://apps.apple.com/us/app/genki-studio/id6466343285 https://apps.apple.com/us/app/genki-studio/id6466343285 I don't know how Orion compares. The home page says the one-time IAP unlocks 'AI-powered 4k upscaling', which sounds useful.
  - dylan604 1y ago
    > The home page says the one-time IAP unlocks 'AI-powered 4k upscaling', which sounds useful. To what end? For displaying on a tablet only? Does it provide screen capture to save that 4k version?
    - rahimnathwani 1y ago
      iPads have high resolution screens. Cheap USB capture devices usually support a maximum of 1080p@60Hz output. If you buy a random '4k' USB capture device, it probably supports up to 4k input but then scales it down to 1080p for output. So perhaps 4k upscaling on the ipad will make the image look better.
      - morganw 1y ago
        There's also the issue of chroma subsampling, giving you YUV 4:2:0 or 4:2:2 instead of YUV or RGB 4:4:4 This page https://obsproject.com/forum/resources/capture-card-documentation-latency-decode-modes-formats-more.777/ https://obsproject.com/forum/resources/capture-card-document... warned me about it, but I haven't seen any updated info on the newer AVermedia or Magewell interfaces, for instance https://www.magewell.com/products/usb-capture-hdmi-4k-pro https://www.magewell.com/products/usb-capture-hdmi-4k-pro This gives 4k60 4:4:4 only on the loop-thru output, higher resolutions require 20GBps USB 3.? but my Mac only goes to 10. I'd need Thunderbolt capture which start around $1000 https://www.bhphotovideo.com/c/product/1500555-REG/blackmagic_design_bdlkulsdmini4k_ultrastudio_4k_mini_connector.html https://www.bhphotovideo.com/c/product/1500555-REG/blackmagi... I'm using an Elgato CamLink 4k at 1080p60 for now & I'm wondering if the awful mouse feel in Linux (with a Mac for display) is maybe due to delay. Going to get a cheap-ash monitor to simplify. I thought it would be nice to have my 6k Pro XDR display have windows from all computers, but it's just too messy.
CYR1X 1y ago
Yes, $5 USB HDMI capture cards exist?
- actionfromafar 1y ago
  Usually slow
  - gsich 1y ago
    In what regard? The common Macrosilicon chip MS2130 has <100ms.
    - actionfromafar 1y ago
      10 fps isn’t great, latency wise. Even typing or using a mouse is very clunky. I may have been unlucky, but I have seen even worse.
      - deleted 1y ago
        [deleted]
      - detaro 1y ago
        100ms latency, they do at least 30fps.
      - gsich 1y ago
        Latency, not FPS. Still suitable for using it as KVM.
- dlcarrier 1y ago
  There's off-the-shelf semiconductors that perform the conversion in hardware, so all the dongles need is a simple breakout board for the component.
- RamRodification 1y ago
  Crazy times
frankus 1y ago
This would have been super helpful like 20 years ago when I was on the data center floor trying to debug rack-mount (headless) Linux servers. The center had like one KVM "crash cart" that needed to be plugged into a spare outlet in the rack that wasn't always easy to come by. I'm sure we could have improved on that setup but we were an inexperienced skeleton crew on a shoestring budget and not the best management. I always thought it would be great to have a "laptop without a motherboard" to manage these, and this is close enough given the price of the redundant hardware now.
- bombcar 1y ago
  We actually HAD literally that - I don't recall which model it was, but someone found a laptop that internally had PS/2 and VGA I believe, and had rewired it to have cables hanging out of it. Advantage - battery still somewhat worked so you could get a few minutes (often all you needed) with just that.
- axiolite 1y ago
  > I always thought it would be great to have a "laptop without a motherboard" That's basically what a rack console is. At 1U it was skinnier than laptops from prior decades. They're not exactly a laptop form factor, but to get them smaller you would have had to accept a much lower screen resolution, which would risk some systems not being able to display (e.g. your server may have booted-up to 1280x1024 while your laptop could only do 800x600), or would have needed to be quite expensive to add an ultra-high DPI screen. Still, at various times there were briefly devices like that available for purchase at closeout prices... like the failed "Motorola ATRIX lapdock": https://www.cnet.com/reviews/motorola-laptop-dock-review/ https://www.cnet.com/reviews/motorola-laptop-dock-review/ https://www.amazon.com/AT-Laptop-Dock-Motorola-ATRIX/dp/B004M17D62 https://www.amazon.com/AT-Laptop-Dock-Motorola-ATRIX/dp/B004... I'd say the USB-HDMI capture card is a better solution all-around. I even prefer it to USB "crash carts" because you aren't dependent on the manufacturer keeping their proprietary software software updated for each subsequent Windows/Linux/Mac release.
Havoc 1y ago
You can do similar with an Android tablet and a usb adapter
hard_times 1y ago
is there no vendor offering HDMI-in or Display Port-in?
- rzzzt 1y ago
  Some Alienware laptops had an HDMI input: https://youtu.be/Otln0Ao2z6M?t=36 https://youtu.be/Otln0Ao2z6M?t=36
- EnigmaCurry 1y ago
  GPD Pocket 4
- jollyllama 1y ago
  It always used to baffle me that there wasn't support for this (or the historic equivalent) 20 years ago.
  - dylan604 1y ago
    20 years ago it would have been prohibitively expensive.
    - jasongill 1y ago
      20 years ago (well, 25) it was actually more common than it is now - many computers in the late 90's to early 2000's came with video capture cards built in. The Sony VIAO for example, or some "multimedia" machines. The Hauppage WinTV cards and similar knockoffs were popular as well. I remember working on the Linux kernel modules/drivers for these types of cards (I want to say that the project was called "Video4Linux" or similar). Being able to "watch TV" on your computer used to be a somewhat popular request from well-to-do consumers, and as DVD's came out, people started wanting to digitize their VHS tapes, and video capture cards (the same concept as what the article is doing) allowed that.
      - rkomorn 1y ago
        I had one! Watching TV on my desktop was great in the pre-streaming era.
belthesar 1y ago
For use cases like attaching to an SBC or really any other computer, I'm sure this is great, but there are also USB crash cart consoles that can be gotten pretty cheaply like the NanoKVM-USB[0] or Cytrence's KIWI[1]. This gets you both video, keyboard and mouse. [0] https://wiki.sipeed.com/hardware/en/kvm/NanoKVM_USB/introduction.html https://wiki.sipeed.com/hardware/en/kvm/NanoKVM_USB/introduc... [1] https://www.cytrence.com/product-page/cytrence-kiwi https://www.cytrence.com/product-page/cytrence-kiwi
- rahimnathwani 1y ago
  Is there anywhere I can buy a NanoKVM-USB? The page you linked has a 'preorder' page linked, but I'm not sure how long I'd have to wait and whether it's an actual product that people have successfully used.
  - galaxy_gas 1y ago
    GLI Comet is much better from my experience.
    - rahimnathwani 1y ago
      Can GLI Comet allow my laptop to control a device without needing a network connection? That seems to be what NanoKVM-USB does. But GLI Comet seems to be KVM-over-IP?
      - all2 1y ago
        You might be able to use something like usbipd to forward the USB port from your target machine?
      - galaxy_gas 1y ago
        I use Comet in remote field by plug the ethernet it expects to the laptop. Both will set up the link local IP and accessible in browser without internet
    - 1y ago
deleted 1y ago
[deleted]
jmmv 1y ago
> digging up an HDMI monitor, finding somewhere to put it, and connecting it to the device is an annoying process. Furthermore, if I’m on the go I almost certainly don’t have easy access to an external monitor. This has annoyed me many times as well with the headless computers I run... until recently, when I bought a USB-powered 7-inch HDMI monitor for an embedded project that didn't go anywhere. But now I have a spare little monitor that I can easily use in these situations and even carry it around if necessary.
- blensor 1y ago
  You may be interested in this then https://github.com/mgschwan/viture_virtual_display https://github.com/mgschwan/viture_virtual_display Or now that I think of it, just use the glasses with a regular hdmi adapter ( but no 3dof tracking then )
- bombcar 1y ago
  Those tiny HDMI monitors are soooooo useful in so many situations, especially if they do pass-through. I like https://feelworld.ltd/collections/5-6-inch-camera-monitor/products/feelworld-s55-5-5-inch-camera-dslr-field-monitor-video-assist-ips-1280x800-4k-hdmi-dc-out-tilt-arm https://feelworld.ltd/collections/5-6-inch-camera-monitor/pr... or similar, $100. I use it for projection - then I can run the projector as a second monitor through this thing (or similar) and not have to use binoculars to see what's on the screen from the back of the room. Larger ones can be used as portable second monitors, too.
- dgfitz 1y ago
  I was stuck in a very remote location trying to update vehicle software. I needed both a monitor and keyboard (long story, serial wasn't outputting, no ssh, partition table was hosed) and I had neither a keyboard nor a monitor. I now carry a little HDMI screen and not one but two portable keyboards with me for all work travel. One of the keyboards is a larger but rolls up, the other is tiny but also has a mouse built into a touchpad. These devices have saved my bacon more than a few times. Highly recommend.
- wzdd 1y ago
  Exactly. I do quite a bit of dev on larger SBCs and it's much easier and more reliable to plug in a small HDMI monitor (powered through the USB) than it is to faff around with HDMI capture dongles, let alone networked KVM. The one I bought (on eBay, nothing special) has a wrap-around vinyl case which works rather like an iPad case in that it can function as a stand or as a screen cover, so you can just chuck it in a bag. Admittedly, it cost more than a capture card (I think it was around $70 USD in eBay), but that's still sufficiently cheap that if it and when it breaks I will not be devastated. USB capture devices introduce latency, get surprisingly hot, can have frame rate issues, and streaming video from them seems much more CPU-intensive than, for example, playing an equivalent-sized h.264 video (I don't know why but presume it's because they encode using something basic like MJPEG). A portable display has none of these problems.
asplake 1y ago
Anyone using a Intel iMac as a monitor for their much faster Apple CPU MacBook Pro? Wishing “target display mode” was still a thing…
- mwpmaybe 1y ago
  You can modify the internal electronics to accomplish this. YouTuber Luke Miani did it a couple years ago. A quick google brings up a few guides including a couple user-contributed-but-ostensibly-QC'd guides on iFixit.
crumpled 1y ago
I saw a video of this guy (the github project author) using the Lilygo T-deck as a VNC console. It's a fun looking solution, but it requires wifi. https://github.com/moononournation/T-Deck/blob/main/ArduinoVNC/ArduinoVNC.ino https://github.com/moononournation/T-Deck/blob/main/ArduinoV...
jwr 1y ago
I use this approach with a long-throw HDMI microscope, cheap ones are available on Aliexpress. I put one over my desk, and I get the output with reasonably low latency through a HDMI capture adapter on my computer screen. Very useful for electronics work or taking a closer look at stuff.
suddenlybananas 1y ago
Now is there a way to use a laptop's keyboard as input as well?
- chazeon 1y ago
  you can just buy a nanokvm
datadrivenangel 1y ago
You can also get an HDMI driver to turn the laptop screen into an HDMI monitor... Janky if you glue the board to the back of the screen.
- whatever1 1y ago
  And you have to find a driver compatible with your laptops lcd panel. Not straightforward.
  - userbinator 1y ago
    Nearly all LVDS ones are close enough that there's only a few common configurations. eDP is even simpler.
netsharc 1y ago
Matthias Wandel demoed a "brainless laptop": a screen and keyboard that can be "mated" with a Raspberry Pi: https://www.youtube.com/watch?v=CFA7iAnYZMs https://www.youtube.com/watch?v=CFA7iAnYZMs
- ramses0 1y ago
  This is so close to perfect except that it doesn't charge over USB-C. I went down the rabbit hole a bit and found the UPerfect "Lapdock" which is just an incredible description of the concept. So many times I want to dork with a raspberry pi or start mucking with an old computer... the rpi400 is nearly useless "as is" because you generally require a mouse and then everything goes to hell as far as "single device" goes. The concept of a "mobile crash cart / workstation" in laptop form factor even makes this tempting as a "front end" for a Mac mini or something?!? Sooo many times I want to bring the K/V/M to the computer instead of the computer to the K/V/M.
Lerc 1y ago
I have been looking at things like this and wondered if there is scope for an open source project to design boards that provide power and data access to a variety of common old laptop panels (and keyboard+touchpads) along with a holder for a compute module. Then let people lay out the location of their USB ports etc. in the shape of the motherboard of their old laptop and get one run off by JLCPCB or PCBWay I have several old laptops that still have good screens and keyboards, It would be nice to repurpose some of them. They are certainly large enough to house a compute module with plenty of extras.
- fmj 1y ago
  I'd definitely be interested in a project like that, but I think customizing a PCB layout and sending it off for manufacturing would be too much for many people that would otherwise be interested in it. I think a project like that would gain more traction if it focused on designing high quality boards for a few popular laptop models (MacBooks or ThinkPads IMO) and making those available via on demand manufacturing and/or crowdsourcing a bulk run.
PaulHoule 1y ago
Reminds me years ago of having a Nintendo Gamecube but no actual TV and just playing it on a computer with a TV capture card.
- thesandlord 1y ago
  I played all of KOTOR2 on Xbox using a capture card without sound. Good times.
ius 1y ago
Note most (all?) video players introduce quite some playback latency by default due to buffering - which is _really_ annoying using them as a 'monitor'. You'll want to look up the flags/settings for low latency playback to make it more usable, e.g. for mpv: https://mpv.io/manual/stable/#low-latency-playback https://mpv.io/manual/stable/#low-latency-playback
GuB-42 1y ago
I wonder why it hadn't been a built-in feature on some laptops. No software, just a built-in hardware kvm exposing the screen, keyboard and pointing device to an external port. A niche thing, but it shouldn't be expensive to implement, and the ports are already here (usb-c, hdmi).
- axiolite 1y ago
  > A niche thing, but it shouldn't be expensive to implement, and the ports are already here (usb-c, hdmi). A Display Controller Board for driving a laptop screen from an external input is going to add at least $20 to the price of the laptop. Considerably more expensive than the $6 USB-HDMI capture devices which do the job (and have more utility). The HDMI output port on your laptop (if you even have one, many only offer miniDP) can't just be run in reverse. The board would need to be updated to allow switching it between output and input, at considerable extra cost.
- Cyykratahk 1y ago
  I owned an Alienware laptop (M17X R4) many years ago that had a dedicated HDMI input. It was a strange laptop. MXM socketed GPU, 120Hz screen that came with Nvidia 3DVision shutter glasses, and the worst battery life I've ever experienced.
- m463 1y ago
  I saw a kind-of-laptop that did that. I think this might be it? https://gpdstore.net/blog/gpd-pocket-4-kvm-module-explained/ https://gpdstore.net/blog/gpd-pocket-4-kvm-module-explained/ or there is a similar one. It was a tiny laptop, the kind that a devops/sysadmin would carry around in a server room.
- voidUpdate 1y ago
  I believe some alienware laptops used to do this https://youtu.be/Otln0Ao2z6M https://youtu.be/Otln0Ao2z6M (Cathode Ray Dude video)
password4321 1y ago
I mention https://www.aurga.com https://www.aurga.com every time this comes up. Wireless HDMI, keyboard, and mouse to their app/desktop client for $95. https://news.ycombinator.com/item?id=45317527#45318263 https://news.ycombinator.com/item?id=45317527#45318263 https://news.ycombinator.com/item?id=41138701#41140193 https://news.ycombinator.com/item?id=41138701#41140193
- jacquesm 1y ago
  That says Linux is supported but apparently only on the input side, not on the viewer side.
exasperaited 1y ago
I too own no external monitors and do my dev/CAD/photography stuff on one of three laptops (macOS, linux, windows 11) [0] depending on where I am, and as much of my writing/planning on my now quite old iPad Pro away from said devices as possible. So I use one of those cheap HDMI capture devices that flooded eBay about three months into the pandemic to watch Raspberry Pi boot logs or function as ad-hoc console monitor, either with my MBP or with the iPad Pro. The iPad Pro functions usefully as an occasional second monitor for the MBP more directly with USB-C/wifi, of course, so it all works out rather well. [0] mostly macOS, though I am finally building up a desktop linux escape strategy, 31 years after I first ran X on linux, which might get finally kicked up a notch depending on what happens with Affinity at the end of the month
geokon 1y ago
> However, sometimes direct physical access to the SBC with a monitor and keyboard is useful for initial configuration, maintenance operations, or workloads that have a visual component Shouldn't this be possible with a single direct ethernet link between laptop and device? I'm not actually sure on the specifics. Or would this require a router? I know you can forward graphical programs with X11 as well This is one of those rough edges that I wish a Linux distro got right. It's rare, but once in a blue moon you do want to hook up two laptop (say one broken and one working one) and control one from the other (without the ability to configure stuff)
Thev00d00 1y ago
I brought a portable screen, which is basically a laptop panel powered by usb, works well.
rupas 1y ago
I've used a few of these KVM products. Some quick thoughts: ipkvm, I really like my 2 JetKVMs. It works very well, physically feels substantial, and the ATX power add-on makes remote management as good as any IPMI solution. I also have a sipeed NanoKVM and that works well, but I don't use it much at this point, just use the JetKVMs instead. For usb KVM I'm trying to find something that works as a KVM so that I can use the nice display on my home computer but also control my work laptop. This is purely a convenience thing. I'm not trying to use the work laptop remotely or fool my employer. I just prefer my 4k oled display on my personal thinkpad over the crap 1080p dell display on the work laptop. So I've tried two usb USB kvms. Cytrence Kiwi - this is the one I settle on to use. The software works well and has had regular updates. It does keyboard capture which I never could get to work with the NanoKVM. The video quality is much better. Except for the inability to capture alt-tab is my only real complaint. :( However, they just (yesterday?) released a new software build that can map another set of keys to alt-tab. Maybe I can train my fingers to do windows-tab or something similar. NanoKVM-USB - This one has some good ideas. I like the form factor. I like the USB port you can easily switch between host and target to copy images or whatever. As a crash cart type thingie, this is probably just fine. However, as stated above. Trying to use it full time with my work laptop was simply too frustrating. Video quality and lack of keyboard capture (maybe I just couldn't find it) just made it impossible. So, in summary: JetKVM for ipkvm, cytrence kiwi for usbkvm.

168 points by hasheddan 1y ago

Since there’s monitors that work over USB-C, could one replace the capture card and somehow get the laptop to pull video like a USB-C monitor?

detaro 1y ago
not really. The video stuff needs explicit hardware support, so the laptop would need to include what's essentially a capture card already. It'd be awesome if vendors did that, but to my knowledge nobody does.
numpad0 1y ago
Those USB-C display outputs are real raw GPU output patched through electronically, not like image over USB protocol. They just use the connector, and they can't be captured as USB data.

05 1y ago

I'm thinking a better solution for console would be an SSH to serial bridge using just a spare ESP32 and something like ESP32SerialSSHProxy[0]. Haven't tried myself yet, and there is suspiciously few stars on that repo, but that would be a nice lights out-ish management system for some hidden away home automation server. [0] https://github.com/programminghoch10/ESP32SerialSSHProxy https://github.com/programminghoch10/ESP32SerialSSHProxy

jonathanberi 1y ago
That works sometimes. It can be flaky.
hasheddan 1y ago
You can also throw together a cheap software KVM switch[0] using an ESP32 or similar. [0] https://euer.krebsco.de/a-software-kvm-switch.html https://euer.krebsco.de/a-software-kvm-switch.html
zoobab 1y ago
I used 1eur esp8266 with jee-link firmware: http://www.zoobab.com/esp8266-serial2wifi-bridge http://www.zoobab.com/esp8266-serial2wifi-bridge
- 05 1y ago
  Yeah but do you really want to give everyone on your LAN unauthenticated access to the server console? :)
Saris 1y ago
Does serial work for BIOS/UEFI access too?

thesandlord 1y ago

If you have an iPad with a USB-C port, you can use the free Orion app to do this too https://orion.tube/ https://orion.tube/

rahimnathwani 1y ago
My son uses the Genki Studio app on his iPad. It works well enough without payment. https://apps.apple.com/us/app/genki-studio/id6466343285 https://apps.apple.com/us/app/genki-studio/id6466343285 I don't know how Orion compares. The home page says the one-time IAP unlocks 'AI-powered 4k upscaling', which sounds useful.
- dylan604 1y ago
  > The home page says the one-time IAP unlocks 'AI-powered 4k upscaling', which sounds useful. To what end? For displaying on a tablet only? Does it provide screen capture to save that 4k version?
  - rahimnathwani 1y ago
    iPads have high resolution screens. Cheap USB capture devices usually support a maximum of 1080p@60Hz output. If you buy a random '4k' USB capture device, it probably supports up to 4k input but then scales it down to 1080p for output. So perhaps 4k upscaling on the ipad will make the image look better.
    - morganw 1y ago
      There's also the issue of chroma subsampling, giving you YUV 4:2:0 or 4:2:2 instead of YUV or RGB 4:4:4 This page https://obsproject.com/forum/resources/capture-card-documentation-latency-decode-modes-formats-more.777/ https://obsproject.com/forum/resources/capture-card-document... warned me about it, but I haven't seen any updated info on the newer AVermedia or Magewell interfaces, for instance https://www.magewell.com/products/usb-capture-hdmi-4k-pro https://www.magewell.com/products/usb-capture-hdmi-4k-pro This gives 4k60 4:4:4 only on the loop-thru output, higher resolutions require 20GBps USB 3.? but my Mac only goes to 10. I'd need Thunderbolt capture which start around $1000 https://www.bhphotovideo.com/c/product/1500555-REG/blackmagic_design_bdlkulsdmini4k_ultrastudio_4k_mini_connector.html https://www.bhphotovideo.com/c/product/1500555-REG/blackmagi... I'm using an Elgato CamLink 4k at 1080p60 for now & I'm wondering if the awful mouse feel in Linux (with a Mac for display) is maybe due to delay. Going to get a cheap-ash monitor to simplify. I thought it would be nice to have my 6k Pro XDR display have windows from all computers, but it's just too messy.

CYR1X 1y ago

Yes, $5 USB HDMI capture cards exist?

actionfromafar 1y ago
Usually slow
- gsich 1y ago
  In what regard? The common Macrosilicon chip MS2130 has <100ms.
  - actionfromafar 1y ago
    10 fps isn’t great, latency wise. Even typing or using a mouse is very clunky. I may have been unlucky, but I have seen even worse.
    - deleted 1y ago
      [deleted]
    - detaro 1y ago
      100ms latency, they do at least 30fps.
    - gsich 1y ago
      Latency, not FPS. Still suitable for using it as KVM.
dlcarrier 1y ago
There's off-the-shelf semiconductors that perform the conversion in hardware, so all the dongles need is a simple breakout board for the component.
RamRodification 1y ago
Crazy times

frankus 1y ago

This would have been super helpful like 20 years ago when I was on the data center floor trying to debug rack-mount (headless) Linux servers. The center had like one KVM "crash cart" that needed to be plugged into a spare outlet in the rack that wasn't always easy to come by. I'm sure we could have improved on that setup but we were an inexperienced skeleton crew on a shoestring budget and not the best management. I always thought it would be great to have a "laptop without a motherboard" to manage these, and this is close enough given the price of the redundant hardware now.

bombcar 1y ago
We actually HAD literally that - I don't recall which model it was, but someone found a laptop that internally had PS/2 and VGA I believe, and had rewired it to have cables hanging out of it. Advantage - battery still somewhat worked so you could get a few minutes (often all you needed) with just that.
axiolite 1y ago
> I always thought it would be great to have a "laptop without a motherboard" That's basically what a rack console is. At 1U it was skinnier than laptops from prior decades. They're not exactly a laptop form factor, but to get them smaller you would have had to accept a much lower screen resolution, which would risk some systems not being able to display (e.g. your server may have booted-up to 1280x1024 while your laptop could only do 800x600), or would have needed to be quite expensive to add an ultra-high DPI screen. Still, at various times there were briefly devices like that available for purchase at closeout prices... like the failed "Motorola ATRIX lapdock": https://www.cnet.com/reviews/motorola-laptop-dock-review/ https://www.cnet.com/reviews/motorola-laptop-dock-review/ https://www.amazon.com/AT-Laptop-Dock-Motorola-ATRIX/dp/B004M17D62 https://www.amazon.com/AT-Laptop-Dock-Motorola-ATRIX/dp/B004... I'd say the USB-HDMI capture card is a better solution all-around. I even prefer it to USB "crash carts" because you aren't dependent on the manufacturer keeping their proprietary software software updated for each subsequent Windows/Linux/Mac release.

Havoc 1y ago

You can do similar with an Android tablet and a usb adapter

hard_times 1y ago

is there no vendor offering HDMI-in or Display Port-in?

rzzzt 1y ago
Some Alienware laptops had an HDMI input: https://youtu.be/Otln0Ao2z6M?t=36 https://youtu.be/Otln0Ao2z6M?t=36
EnigmaCurry 1y ago
GPD Pocket 4
jollyllama 1y ago
It always used to baffle me that there wasn't support for this (or the historic equivalent) 20 years ago.
- dylan604 1y ago
  20 years ago it would have been prohibitively expensive.
  - jasongill 1y ago
    20 years ago (well, 25) it was actually more common than it is now - many computers in the late 90's to early 2000's came with video capture cards built in. The Sony VIAO for example, or some "multimedia" machines. The Hauppage WinTV cards and similar knockoffs were popular as well. I remember working on the Linux kernel modules/drivers for these types of cards (I want to say that the project was called "Video4Linux" or similar). Being able to "watch TV" on your computer used to be a somewhat popular request from well-to-do consumers, and as DVD's came out, people started wanting to digitize their VHS tapes, and video capture cards (the same concept as what the article is doing) allowed that.
    - rkomorn 1y ago
      I had one! Watching TV on my desktop was great in the pre-streaming era.

belthesar 1y ago

For use cases like attaching to an SBC or really any other computer, I'm sure this is great, but there are also USB crash cart consoles that can be gotten pretty cheaply like the NanoKVM-USB[0] or Cytrence's KIWI[1]. This gets you both video, keyboard and mouse. [0] https://wiki.sipeed.com/hardware/en/kvm/NanoKVM_USB/introduction.html https://wiki.sipeed.com/hardware/en/kvm/NanoKVM_USB/introduc... [1] https://www.cytrence.com/product-page/cytrence-kiwi https://www.cytrence.com/product-page/cytrence-kiwi

rahimnathwani 1y ago
Is there anywhere I can buy a NanoKVM-USB? The page you linked has a 'preorder' page linked, but I'm not sure how long I'd have to wait and whether it's an actual product that people have successfully used.
- galaxy_gas 1y ago
  GLI Comet is much better from my experience.
  - rahimnathwani 1y ago
    Can GLI Comet allow my laptop to control a device without needing a network connection? That seems to be what NanoKVM-USB does. But GLI Comet seems to be KVM-over-IP?
    - all2 1y ago
      You might be able to use something like usbipd to forward the USB port from your target machine?
    - galaxy_gas 1y ago
      I use Comet in remote field by plug the ethernet it expects to the laptop. Both will set up the link local IP and accessible in browser without internet
  - 1y ago

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jmmv 1y ago

> digging up an HDMI monitor, finding somewhere to put it, and connecting it to the device is an annoying process. Furthermore, if I’m on the go I almost certainly don’t have easy access to an external monitor. This has annoyed me many times as well with the headless computers I run... until recently, when I bought a USB-powered 7-inch HDMI monitor for an embedded project that didn't go anywhere. But now I have a spare little monitor that I can easily use in these situations and even carry it around if necessary.

blensor 1y ago
You may be interested in this then https://github.com/mgschwan/viture_virtual_display https://github.com/mgschwan/viture_virtual_display Or now that I think of it, just use the glasses with a regular hdmi adapter ( but no 3dof tracking then )
bombcar 1y ago
Those tiny HDMI monitors are soooooo useful in so many situations, especially if they do pass-through. I like https://feelworld.ltd/collections/5-6-inch-camera-monitor/products/feelworld-s55-5-5-inch-camera-dslr-field-monitor-video-assist-ips-1280x800-4k-hdmi-dc-out-tilt-arm https://feelworld.ltd/collections/5-6-inch-camera-monitor/pr... or similar, $100. I use it for projection - then I can run the projector as a second monitor through this thing (or similar) and not have to use binoculars to see what's on the screen from the back of the room. Larger ones can be used as portable second monitors, too.
dgfitz 1y ago
I was stuck in a very remote location trying to update vehicle software. I needed both a monitor and keyboard (long story, serial wasn't outputting, no ssh, partition table was hosed) and I had neither a keyboard nor a monitor. I now carry a little HDMI screen and not one but two portable keyboards with me for all work travel. One of the keyboards is a larger but rolls up, the other is tiny but also has a mouse built into a touchpad. These devices have saved my bacon more than a few times. Highly recommend.
wzdd 1y ago
Exactly. I do quite a bit of dev on larger SBCs and it's much easier and more reliable to plug in a small HDMI monitor (powered through the USB) than it is to faff around with HDMI capture dongles, let alone networked KVM. The one I bought (on eBay, nothing special) has a wrap-around vinyl case which works rather like an iPad case in that it can function as a stand or as a screen cover, so you can just chuck it in a bag. Admittedly, it cost more than a capture card (I think it was around $70 USD in eBay), but that's still sufficiently cheap that if it and when it breaks I will not be devastated. USB capture devices introduce latency, get surprisingly hot, can have frame rate issues, and streaming video from them seems much more CPU-intensive than, for example, playing an equivalent-sized h.264 video (I don't know why but presume it's because they encode using something basic like MJPEG). A portable display has none of these problems.

asplake 1y ago

Anyone using a Intel iMac as a monitor for their much faster Apple CPU MacBook Pro? Wishing “target display mode” was still a thing…

mwpmaybe 1y ago
You can modify the internal electronics to accomplish this. YouTuber Luke Miani did it a couple years ago. A quick google brings up a few guides including a couple user-contributed-but-ostensibly-QC'd guides on iFixit.

crumpled 1y ago

I saw a video of this guy (the github project author) using the Lilygo T-deck as a VNC console. It's a fun looking solution, but it requires wifi. https://github.com/moononournation/T-Deck/blob/main/ArduinoVNC/ArduinoVNC.ino https://github.com/moononournation/T-Deck/blob/main/ArduinoV...

jwr 1y ago

I use this approach with a long-throw HDMI microscope, cheap ones are available on Aliexpress. I put one over my desk, and I get the output with reasonably low latency through a HDMI capture adapter on my computer screen. Very useful for electronics work or taking a closer look at stuff.

suddenlybananas 1y ago

Now is there a way to use a laptop's keyboard as input as well?

chazeon 1y ago
you can just buy a nanokvm

datadrivenangel 1y ago

You can also get an HDMI driver to turn the laptop screen into an HDMI monitor... Janky if you glue the board to the back of the screen.

whatever1 1y ago
And you have to find a driver compatible with your laptops lcd panel. Not straightforward.
- userbinator 1y ago
  Nearly all LVDS ones are close enough that there's only a few common configurations. eDP is even simpler.

netsharc 1y ago

Matthias Wandel demoed a "brainless laptop": a screen and keyboard that can be "mated" with a Raspberry Pi: https://www.youtube.com/watch?v=CFA7iAnYZMs https://www.youtube.com/watch?v=CFA7iAnYZMs

ramses0 1y ago
This is so close to perfect except that it doesn't charge over USB-C. I went down the rabbit hole a bit and found the UPerfect "Lapdock" which is just an incredible description of the concept. So many times I want to dork with a raspberry pi or start mucking with an old computer... the rpi400 is nearly useless "as is" because you generally require a mouse and then everything goes to hell as far as "single device" goes. The concept of a "mobile crash cart / workstation" in laptop form factor even makes this tempting as a "front end" for a Mac mini or something?!? Sooo many times I want to bring the K/V/M to the computer instead of the computer to the K/V/M.

Lerc 1y ago

I have been looking at things like this and wondered if there is scope for an open source project to design boards that provide power and data access to a variety of common old laptop panels (and keyboard+touchpads) along with a holder for a compute module. Then let people lay out the location of their USB ports etc. in the shape of the motherboard of their old laptop and get one run off by JLCPCB or PCBWay I have several old laptops that still have good screens and keyboards, It would be nice to repurpose some of them. They are certainly large enough to house a compute module with plenty of extras.

fmj 1y ago
I'd definitely be interested in a project like that, but I think customizing a PCB layout and sending it off for manufacturing would be too much for many people that would otherwise be interested in it. I think a project like that would gain more traction if it focused on designing high quality boards for a few popular laptop models (MacBooks or ThinkPads IMO) and making those available via on demand manufacturing and/or crowdsourcing a bulk run.

PaulHoule 1y ago

Reminds me years ago of having a Nintendo Gamecube but no actual TV and just playing it on a computer with a TV capture card.

thesandlord 1y ago
I played all of KOTOR2 on Xbox using a capture card without sound. Good times.

ius 1y ago

Note most (all?) video players introduce quite some playback latency by default due to buffering - which is _really_ annoying using them as a 'monitor'. You'll want to look up the flags/settings for low latency playback to make it more usable, e.g. for mpv: https://mpv.io/manual/stable/#low-latency-playback https://mpv.io/manual/stable/#low-latency-playback

GuB-42 1y ago

I wonder why it hadn't been a built-in feature on some laptops. No software, just a built-in hardware kvm exposing the screen, keyboard and pointing device to an external port. A niche thing, but it shouldn't be expensive to implement, and the ports are already here (usb-c, hdmi).

axiolite 1y ago
> A niche thing, but it shouldn't be expensive to implement, and the ports are already here (usb-c, hdmi). A Display Controller Board for driving a laptop screen from an external input is going to add at least $20 to the price of the laptop. Considerably more expensive than the $6 USB-HDMI capture devices which do the job (and have more utility). The HDMI output port on your laptop (if you even have one, many only offer miniDP) can't just be run in reverse. The board would need to be updated to allow switching it between output and input, at considerable extra cost.
Cyykratahk 1y ago
I owned an Alienware laptop (M17X R4) many years ago that had a dedicated HDMI input. It was a strange laptop. MXM socketed GPU, 120Hz screen that came with Nvidia 3DVision shutter glasses, and the worst battery life I've ever experienced.
m463 1y ago
I saw a kind-of-laptop that did that. I think this might be it? https://gpdstore.net/blog/gpd-pocket-4-kvm-module-explained/ https://gpdstore.net/blog/gpd-pocket-4-kvm-module-explained/ or there is a similar one. It was a tiny laptop, the kind that a devops/sysadmin would carry around in a server room.
voidUpdate 1y ago
I believe some alienware laptops used to do this https://youtu.be/Otln0Ao2z6M https://youtu.be/Otln0Ao2z6M (Cathode Ray Dude video)

password4321 1y ago

I mention https://www.aurga.com https://www.aurga.com every time this comes up. Wireless HDMI, keyboard, and mouse to their app/desktop client for $95. https://news.ycombinator.com/item?id=45317527#45318263 https://news.ycombinator.com/item?id=45317527#45318263 https://news.ycombinator.com/item?id=41138701#41140193 https://news.ycombinator.com/item?id=41138701#41140193

jacquesm 1y ago
That says Linux is supported but apparently only on the input side, not on the viewer side.

exasperaited 1y ago

I too own no external monitors and do my dev/CAD/photography stuff on one of three laptops (macOS, linux, windows 11) [0] depending on where I am, and as much of my writing/planning on my now quite old iPad Pro away from said devices as possible. So I use one of those cheap HDMI capture devices that flooded eBay about three months into the pandemic to watch Raspberry Pi boot logs or function as ad-hoc console monitor, either with my MBP or with the iPad Pro. The iPad Pro functions usefully as an occasional second monitor for the MBP more directly with USB-C/wifi, of course, so it all works out rather well. [0] mostly macOS, though I am finally building up a desktop linux escape strategy, 31 years after I first ran X on linux, which might get finally kicked up a notch depending on what happens with Affinity at the end of the month

geokon 1y ago

> However, sometimes direct physical access to the SBC with a monitor and keyboard is useful for initial configuration, maintenance operations, or workloads that have a visual component Shouldn't this be possible with a single direct ethernet link between laptop and device? I'm not actually sure on the specifics. Or would this require a router? I know you can forward graphical programs with X11 as well This is one of those rough edges that I wish a Linux distro got right. It's rare, but once in a blue moon you do want to hook up two laptop (say one broken and one working one) and control one from the other (without the ability to configure stuff)

Thev00d00 1y ago

I brought a portable screen, which is basically a laptop panel powered by usb, works well.

rupas 1y ago

I've used a few of these KVM products. Some quick thoughts: ipkvm, I really like my 2 JetKVMs. It works very well, physically feels substantial, and the ATX power add-on makes remote management as good as any IPMI solution. I also have a sipeed NanoKVM and that works well, but I don't use it much at this point, just use the JetKVMs instead. For usb KVM I'm trying to find something that works as a KVM so that I can use the nice display on my home computer but also control my work laptop. This is purely a convenience thing. I'm not trying to use the work laptop remotely or fool my employer. I just prefer my 4k oled display on my personal thinkpad over the crap 1080p dell display on the work laptop. So I've tried two usb USB kvms. Cytrence Kiwi - this is the one I settle on to use. The software works well and has had regular updates. It does keyboard capture which I never could get to work with the NanoKVM. The video quality is much better. Except for the inability to capture alt-tab is my only real complaint. :( However, they just (yesterday?) released a new software build that can map another set of keys to alt-tab. Maybe I can train my fingers to do windows-tab or something similar. NanoKVM-USB - This one has some good ideas. I like the form factor. I like the USB port you can easily switch between host and target to copy images or whatever. As a crash cart type thingie, this is probably just fine. However, as stated above. Trying to use it full time with my work laptop was simply too frustrating. Video quality and lack of keyboard capture (maybe I just couldn't find it) just made it impossible. So, in summary: JetKVM for ipkvm, cytrence kiwi for usbkvm.