19 ms·

mouse switch for my two 4k monitors

458 points by car 6y ago

joshu 6y ago
I use the IOGear switch between windows/pc and like 1/5 times it doesn't switch correctly (it'll end up holding the option key down or something.) are there any keyboard switches that emulate a keyboard correctly instead of just unplugging and replugging the usb connection?
- zerkten 6y ago
  I've given up finding a KVM that has this support for emulation. I've got a Kinesis Freestyle Edge RGB and even for the better ConnectPRO KVMs, there are just too many USB endpoints. I found that X-Keys make a range of keypads that are specifically designed for KVMs. I have it setup for KVM switching and the remaining keys have other macros. I'm glad I got it, but it's expensive compared to DIY kits.
- duskwuff 6y ago
  > are there any keyboard switches that emulate a keyboard correctly instead of just unplugging and replugging the usb connection? StarTech's KVMs have a rather robust USB stack which handles this situation very well.
  - joshu 6y ago
    thank you! any particular products you have experience with?
AntiRush 6y ago
This is awesome! I've often dreamed about doing this with a keyboard shortcut ala switching layouts in a tiling WM (or 'real' kvm switches from the CRT + ps2 era). Is there a good usb hub that supports switching outputs via software?
- bertjk 6y ago
  Some of the IOGear KVMs do provide hotkey functionality.
vaillancourtmax 6y ago
Neat! I use a similar setup where I literally have a single USB cable that gives me access to everything: monitor, keyboard, mouse, lighting, camera, microphone. I just need to plug the cable in the computer I want to use. However, I do need to change the input on the monitor as one of the them is connected via HDMI.
- harikb 6y ago
  You must in the USBC world!
- bluGill 6y ago
  USB connectors have a terrible plug/unplug lifespan.. I have a few computers where the USB ports can't be used because they have been unplugged too often. Might just be USB-A, I haven't looked at the other specs
D13Fd 6y ago
I like it! Thank you for sharing the code! By the way, I have that same USB switch. I have tried a number of them, and that is the fastest I've found. The only major flaw is the status lights -- they are too hard to see from far away. To fix that issue, I drilled a hole in the top of the case, over the lights, about the same size as the adjacent power button. I put a small piece of foam inside to separate the two lights, and covered it with tape. It works perfectly now and it's so much easier to see the status from a typical usage angle. The whole modification took maybe 15 minutes, and I didn't even bother disassembling it first.
- haimgel 6y ago
  This is an interesting hack, thanks for sharing! I agree the status lights are hard to see...
Havoc 6y ago
> I wrote some software. And my heart sank. Zero chance of getting that past corporate laptops that are way too locked down for actual code anything beyond VBA
- smabie 6y ago
  Then just have corporate buy you a real KVM switch?
mercora 6y ago
ive done the same on Linux using udev rules and a simple usb switch. i use it for a VM with a physical GPU attached and it worked great ever since.
- zwayhowder 6y ago
  To paraphrase the internet. Sample configs or it didn't happen! Seriously, I'd love to see this. I have had mixed results with udev and no idea where to start to send an input switch command to my monitor.
  - mercora 6y ago
    sure, i used this[0] for the hotpluging part and these[1] are the udev rules :) in order to switch inputs you should take a look at ddcutil... [0] https://github.com/olavmrk/usb-libvirt-hotplug/blob/master/usb-libvirt-hotplug.sh https://github.com/olavmrk/usb-libvirt-hotplug/blob/master/u... [1] https://gist.github.com/4ab23675ab69162934ce75b52bd1d290 https://gist.github.com/4ab23675ab69162934ce75b52bd1d290
    - zwayhowder 6y ago
      Thank you.
mandeepj 6y ago
I was searching for it couple weeks ago. The cheapest KVM for two monitors at ebay starts from $80. So, good job.
mmsimanga 6y ago
I have similar setup without the software to automatically switch inputs. I use the physical buttons on the monitor to switch input. Not efficient but I get a better resolution than pushing display through a cheap KVM switch. Will be trying software in article. Anyone know of software that runs on Linux to switch display the input? OP lists Windows and Mac OS support.
- pedrocr 6y ago
  In Linux you can probably do it with a script that calls ddcutil: http://www.ddcutil.com/ http://www.ddcutil.com/
haram_masala 6y ago
https://www.amazon.com/gp/aw/d/B0817YFJKW https://www.amazon.com/gp/aw/d/B0817YFJKW $60 shipped.
- vxNsr 6y ago
  that's one monitor
- jen20 6y ago
  This fails at two criteria presented in the second paragraph: - it only supports one 4K monitor, not two, - it doesn't support USB-C.
- D13Fd 6y ago
  That's USB 2 and one monitor. He is looking for USB 3. Also, I can tell you it's harder than you'd think to find good hardware in this area, so I don't think the software effort is wasted.
- hbcondo714 6y ago
  Interesting image descriptions. The 6th one says "Suport operate system" with a Windows 7, 8 and Vista icons.
m0shen 6y ago
This is great! I did something very similar using AutoHotKey and Synergy : https://moshen.net/posts/virtual_kvm/ https://moshen.net/posts/virtual_kvm/
- D13Fd 6y ago
  That looks nice! But there are two downsides: - Your solution requires Synergy. In my experience, Synergy has been buggy--or at least extremely finicky--every time I've tried it since release circa 2001. When it comes to input devices, I want things to be basically flawless. So I like this very simple fix better. - The posted solution is cross-platform between Mac and Windows, which is a common use case. Yours relies on Autohotkey, which is awesome on Windows but, last I checked, terrible on Mac OS.
  - m0shen 6y ago
    Yeah, fair points. Every now and then I have to stop/start Synergy for it to work. Since my mouse/keyboard remain connected to my Windows machine, it can act as the "server" and issue the DCC to the monitor to switch when my key combo is hit. So I only ever run it on the Windows box.
  - kitsunesoba 6y ago
    The other thing about Synergy is that it's a bit of a question mark in terms of security, even with encryption enabled (at least that I've seen — would be happy to be corrected!)
- nly 6y ago
  Please support Barrier[0] (FOSS) or, perhaps, just buy ShareMouse[1] or download Input Director[2] (free but closed source) rather than supporting Synergy. I worked for Symless for 2 years and I can tell you first hand that the owner had little interest in fixing or improving the core functionality, the code for which has remained largely unchanged for 12-15 years. Most of the input bugs in the software are a decade old, and unless a community patch comes along that can be merged, the owner only has interest in keeping it working on new OS versions, and tarting up the UI/UX to support Symless as a lifestyle business. In the 2 years since I left I've seen exactly 3 bugfix releases, one of which broke TLS, and none of which seemed to contain any significant original work. Supposedly Synergy 3 is in the works, after Synergy 2 (which I worked on) was scrapped, but this will almost certainly only be a proprietary Electron UI for the FOSS CLI instead of a Qt/QML UI for the FOSS CLI (as v2 was). Major versions of Input Director (v2.0) and ShareMouse (v5.0) have been announced in the last few months, and it looks like significant work has taken place on both projects. Both of these products need better marketing. Unfortunately none of the alternatives to Barrier/Synergy seem to want to support Linux, which remains its moat. The days for that are numbered due to Wayland though (Synergy uses the X11 XTest extension to inject input). [0] https://github.com/debauchee/barrier https://github.com/debauchee/barrier [1] https://www.sharemouse.com/ https://www.sharemouse.com/ [2] https://www.inputdirector.com https://www.inputdirector.com
dkersten 6y ago
Hah, I use a low tech solution: I have a HDMI extension cable that reaches the front of the monitor that I just plug the device I want active into (and a usb splitter similar to what he uses for keyboard and mouse). It’s not quite as seamless as the solution described here but it took no time to set up.
- evanweaver 6y ago
  You can get a physical HDMI button so you don't even have to unplug anything: https://www.amazon.com/gp/product/B01L8LLP2G/ https://www.amazon.com/gp/product/B01L8LLP2G/
  - pstrateman 6y ago
    "4Kx2K@30hz resolution" The issue is 4k@60.
  - dkersten 6y ago
    Yeah, I did use a switcher before I upgraded my resolution.
  - andechs 6y ago
    Does something like this exist for USB-C devices? I have to plug and unplug a certain device to change it between machines. Not full emulation and remaining "connected" - just the ability to press a button and change what the device is plugged into.
    - kingosticks 6y ago
      Would the one in the article work for you? https://www.amazon.ca/gp/product/B01N6GD9JO https://www.amazon.ca/gp/product/B01N6GD9JO
      - dkersten 6y ago
        That doesn’t look like USB-C
TehCorwiz 6y ago
This would probably work great for running VMs with a hardware pass-through GPU. Can't wait to try this out.
deleted 6y ago
[deleted]
justaguy88 6y ago
for those who have less time than money, https://store.level1techs.com/?category=Hardware https://store.level1techs.com/?category=Hardware
- D13Fd 6y ago
  Both of the KVMs meeting his criteria on that page are sold out (and one is a pre-order as well as being sold out).
- stoobs 6y ago
  Another option is the Aten CS1944DP - 4 input dual 4K60 USB3 KVM switch - I have it and it's rather wonderful given I now have my work laptop here due to covid - not cheap, but it's really, really good.
  - wasmitnetzen 6y ago
    Not cheap is quite the understatement. I could easily just get another screen for less money.
    - stoobs 6y ago
      Depends on your use-case - I already have two screens but I need them switching between multiple computers - there are very few options for dual display multiple input KVMs which can support 4K60 and USB3
zachrose 6y ago
Would somebody like to help me understand why KVM switches are so sophisticated? A DisplayPort cable has 20 pins, so why can't it just be a 20 pole switch? (Or 30 pole for two USBs and a headphone jack, etc.)
- bravo22 6y ago
  Signal integrity. High speed signals degrade with even slightest mismatch in trace length or stubs. For high-speed signals you use a chip which is essentially an electrical repeater to redirect the output to port A or B.
- adrianpike 6y ago
  It can be, eBay has HDMI physical switches for like $8. Your computers will see it as a monitor unplug, though, and do fun things with adjusting windows/icons/resolutions, and then have to re-handshake on every switch. Not a blocker, just a pain. I'm also not 100% sure if it'll freak HDCP out.
  - 8ytecoder 6y ago
    I bought a HDMI switch and a USB switch. Total cost was under $30. I now have to press two buttons instead of one but that's about it. However, I don't know how to scale that for two monitors. I prefer a single monitor setup so it works for me.
  - fock 6y ago
    iirc most of this switches (and cheap chinese capture cards) work around this problem by "breaking" HDCP. Problem solved.
- myself248 6y ago
  At the multi-gigabit speeds of a modern video signal, the components of a normal mechanical switch are antennas.
  - modeless 6y ago
    So are the pins in cable connectors, but cables are (relatively) cheap and switching signals by replugging connectors works just fine.
renewiltord 6y ago
Haha, this is clever and I like it. You turned what is usually solved on the physical layer to something solved on the logical layer - which is almost always better because you can express conceptual changes much better when you don't need hardware. It's a small taste of the stuff that software-defined networks have added to networking.
dasloop 6y ago
I have an MX Keys keyboard that can connect to up to three devices (with three special keys). Unfortunately, the operating system does not see the key pressed. But if it was, I could activate the display input switching using your app (thanks!). I have filled a support request at Logitech, maybe one day...
- OJFord 6y ago
  Are other keys (e.g. Fn) mappable to the special keys? Maybe you could work around it by setting e.g. F1-3 to F1-3 + Special1-3, and then input switching on F1-3.
  - wasmitnetzen 6y ago
    Or the other way around? Map the special keys to F13 or something. (Normal keyboard only have up to F12, but I believe the standard allows up to F24.)
NKosmatos 6y ago
Reminds me of a similar post in HN in order to switch inputs on a single monitor, between mac and PC, via software only. Ideally a shortcut on the mac desktop in order to switch to HDMI and another shortcut on the PC desktop to switch to DisplayPort. For sure I’m going to give a go at the code of this soft/hard KVM.
Splendor 6y ago
Very cool. Will this only work over HDMI?
- moolcool 6y ago
  I imagine it will work on any input your display supports
salex89 6y ago
I hoped for the actual switch schematics :) . Offtopic: I wanted to buy this USB switch, but it's hard to get on the current market in my country (or available for an absurd price). So I started trying to build my own... which was fun, but then I understood I need a some USB/MAX chips that are also hard to find, and started to cause me frustration instead of fun, because I'm not really that good with low-level electronics, university was a long time ago. And I was still without my switch/hub. So at the end I just chose a 3-pole double-throw toggle switch and a couple of USB connectors and wired them up. I only need to switch my keyboard, because my mouse is multi-device. If I need more, I'll just wire a hub to it. Work is in progress, but it can't get simpler than that. If you're wondering what got complicated, well as far as I read and understood, actually breaking a USB connection with solid state logic is kind of a pain in the neck if you want to stay within the USB parameters, at least for an inexperienced designer like me. And you need to build the power supply for the circuit, and I didn't want to introduce an external power supply, I wanted to piggyback of the USB source. Something this ugreen product does not do. So I left this project for another time, when I freshen up on my perished knowledge. A mechanical switch just switches the lines and that's it.
- deorder 6y ago
  I opened the same ugreen switch up and plan to attach some wires from the button pins to my RaspberryPI. This way I will be able to use my RaspberryPI to switch between the two USB hosts and use the RaspberryPI's built-in CEC support to switch between video inputs. What the board looks like: https://imgur.com/lX1uZ7Q https://imgur.com/lX1uZ7Q
yfiapo 6y ago
That's cool. As another alternative, this is the one I bought at start of lockdown which does everything but the USB-C: https://smile.amazon.com/gp/product/B0851CMHP2/ https://smile.amazon.com/gp/product/B0851CMHP2/ Not particularly cheap but at least no longer back-ordered. I've been pretty happy with it switching 2x4K monitors, keyboard and mouse between a Mac and a PC laptop. Both corporate laptops where custom software is more difficult.
- Bedon292 6y ago
  You like this one? I have been looking for a while, but didn't find one I felt was trustworthy in that price range. For instances 11 reviews on this one.
nkrisc 6y ago
This is perfect. The software competent is exactly what I was missing from my setup. I use a USB switch to switch my peripherals but I've been manually changing the input on my monitor like a caveman.
- Freak_NL 6y ago
  I'll have to have a go at this DDC/CI stuff as well. I too have a USB switch that just works (click button, two seconds later other computer has keyboard and mouse, and whatever else is on it, click again, back to the other one). It's simple, it's foolproof, and I can do it with my eyes closed if I so wanted to. Now, switching the monitor however… This involves clicking the six buttons on the rear of the monitor in an arcane sequence (your fingers sort of curl around the side, the buttons have labels on the front of the monitor on the right-side bezel, and yes, that works as well as you can imagine). Which then switches the monitor: * Button 1: activate menu * 1 again: select input * 2: move down list of three inputs * 2: move down list of three inputs * 3: select mini display port A somewhat similar sequence exists for going back to its HDMI input. But hold on! It gets better if you turn off the computer you have live at the moment. The monitor then goes blank, and until it throws its 'no signal found' message, it won't respond to anything. If you are lucky, you can switch inputs before the current computer is shut down completely and the monitor blanks itself. I do feel like a caveman.
  - narrowtux 6y ago
    The software on modern displays is often abysmal, with the exception of Dell's in my experience.
    - Freak_NL 6y ago
      It really is. All I want is one button that just cycles to the next active port connected.
  - nkrisc 6y ago
    Unfortunately it looks like my monitor does support DDC but does not support VPC Code 96 (0x60) meaning I can't programmatically change the input. What a bummer. Monitor is ASUS PG348Q.
doctorhandshake 6y ago
There was a comment here yesterday[1] about DDC/CI writes being finite on some hardware — is that a concern with this approach? [1] top comment - https://news.ycombinator.com/item?id=24344045 https://news.ycombinator.com/item?id=24344045
- jwalton 6y ago
  100K switches is switching your input 4 times a day for 68 years. You'll probably want a new fancy 32K monitor by then anyways. ;) Also, if your monitor stores the current input in EEPROM, changing it via the OSD will also write to EEPROM, so it's not like you're saving the EEPROM by doing it manually (buying a real KVM is another story, obviously).
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bijant 6y ago
The Headline hit me right in the stomach because it was just yesterday that I was pondering whether to build or to order a USB Switch. With much to do currently, I wussed out and just ordered it. I didnt pay 38$ though: https://de.aliexpress.com/item/1005001274095928.html https://de.aliexpress.com/item/1005001274095928.html USB 2 is more than enough for mouse and keyboard and it has the additional advantage of having an extension button to switch.
- hnick 6y ago
  I don't always trust tech from Aliexpress but sometimes it's worth a gamble. I had a look at that brand and they also do a KVM (HDMI, 2 USB ports for K/M) for USD $16. That seems way too cheap but I don't really understand the tech enough to know for sure.
aloer 6y ago
I recently bought a Philips 346b1c (34" UWQHD with built-in USB C hub + KVM) and the use of DDC/CI to tell the monitor what input to switch to could come in super handy here. The display is very good at automatically switching KVM based on the selected input, but the selection still has to be done with the little buttons underneath the screen
dugmartin 6y ago
I use a combination of a cheap USB switch and the remote for my 4K monitor (really a 43" TV) to switch inputs. Not as nice as one button press but much cheaper than a high end KVM.
- Polylactic_acid 6y ago
  The KVM I got is actually even simpler than a button press. It detects the active input and uses that so when I turn off my work laptop and turn on my desktop it switches. Its totally seamless.
brian_herman 6y ago
https://store.level1techs.com/products/kvm-switch-dual-monitor-model https://store.level1techs.com/products/kvm-switch-dual-monit... A little more expensive. But gets the job done!
ElCapitanMarkla 6y ago
I know this isn’t the same but if you don’t need to switch the monitor inputs and only need mouse / keyboard support. I’ve been using https://github.com/debauchee/barrier https://github.com/debauchee/barrier for the last few years. It works surprisingly well, no noticeable lag even when gaming.
- exhilaration 6y ago
  You still need some kind of a hub to connect the keyboard and mouse to both machines, right?
  - paranoidrobot 6y ago
    It says it's a fork of Synergy[0]. So the idea is you have PC A + Monitor A, and PC B + Monitor B. You install the software on both machines (they talk over a local network), and configure PC A to be left of PC B, and PC B to be right of PC A. Attach a keyboard+mouse to one machine. When your mouse goes 'off screen right' on PC A, it knows that PC B is over there, so it redirects keyboard/mouse input to PC B. I used Synergy for a while, and it was pretty great. The only issue is when you need to do control keys that the OS takes over (like CTRL-ALT-DEL on Windows), that wouldn't transfer over, and you'd be looking at Monitor B wondering why keyboard/mouse wasn't working... then look over at Monitor A and see it's at the lock screen. [0] https://symless.com/synergy https://symless.com/synergy
  - abiogenesis 6y ago
    I guess it's a mouse/keyboard emulator over TCP.
  - rainbowzootsuit 6y ago
    There's a server machine where you connect the keyboard and mouse and client machines that just have a monitor connection. You arrange the geometry in the software to make the mouse move between machines in an intuitive manner. Whichever machine has the mouse has the keyboard input as well. So you do need a dedicated monitor per machine from my experience.
- 6y ago
cellular 6y ago
There are full software solutions that just show the screen over the network and relay your mouse/keyboard to whichever machine is on focus. It worked well enough that I'd forget which pc the kvm s were actually connected to. But I was only programming, not gaming, so maybe the 60Hz would be a problem. no hurt to try. It was free and there were a couple software solutions.
- Polylactic_acid 6y ago
  The latency would probably make it a shitty experience. I got a displayport switch when I started working from home this year and the thing works so well I forget it exists. There is no latency at all and it automatically switches inputs based on which one is active so I never have to touch the thing.
  - TylerE 6y ago
    Why? At 60dps that is one frame every 16.7ms. Sub-ms latency is easy on a local network. Heck I can get a few states away and back in 16ms.
    - mercora 6y ago
      its not really about network latency at that level. you need to acquire screen contents and render them too. if you try to send signals uncompressed bandwidth (pps) could be a problem too in that time frame. if you compress it you introduce additional latency on capture and rendering times... i have yet to see this working over an ethernet network...
    - vmednis 6y ago
      There's encode and decode latency as well, but I've been able to get the total latency to a data center about 200km from me to around 30ms or so with some solutions. Was good enough for some non-competitive gaming for me.
- Bedon292 6y ago
  There are many keyboard mouse solutions like this, but I have not found a software including video. If you remember, can you point me at them?
milofeynman 6y ago
I have been using a KM switch and manually switching the monitor for the last few months. I was wishing there were a way to programmatically change the input, and apparently there is! But I assume this is only supported by some monitors. I will try it out tonight. Thank you
crisopolis 6y ago
Wow, I use this same USB switch and also use two monitors for everything. Right now I manually switch my main monitor and just gave up on switching the monitor above it. But this is friggin awesome.
fizzled 6y ago
The easiest way to do this is to skip KVM because the latency and disconnect is awful, and the tangle of wires is un unnecessary mess. Instead, use microsoft remote desktop or VNC. Caveat: I've only ever gotten dual monitor + VNC to work on Ubuntu.
zargon 6y ago
The disadvantage of this arrangement, which may not be obvious until you try it, is the delay in switching time. You have to wait for the monitor to re-sync on the new signal and for the USB to enumerate on the new host. I guess most people can tolerate this? For me that delay is intolerable. Quality KVMs (ConnectPRO is the one I remember off the top of my head) maintain both connections at all times and switching is instantaneous.
- jwalton 6y ago
  I bet it's a lot shorter than the delay involved in me using the touch sensitive not-buttons on the front of my monitor to switch inputs, which is what I do now. :P
  - milofeynman 6y ago
    I'm using it and I can confirm. it's significantly better than using that stupid monitor button.
  - IshKebab 6y ago
    But not as good as an actual KVM switch. I use this one: https://www.amazon.co.uk/gp/product/B07F8NVMH7 https://www.amazon.co.uk/gp/product/B07F8NVMH7 It also does 4K at 60 Hz. You can switch via the keyboard (uses scroll lock as a shortcut). It has worked flawlessly for me and is only £86. The only real downside is that it is yet more wires, and it can only switch one video signal. If I had two monitors I'd probably go with this guys solution.
    - driverdan 6y ago
      Also it's only USB 2, not USB 3. So it's fine for a keyboard and mouse but nothing with a decent data rate.
      - IshKebab 6y ago
        I suspect a USB 3 KVM switch does not exist. His solution also doesn't help if you want to switch a USB 3 device between computers. So that isn't really a con.
ohazi 6y ago
Okay, let's talk about that USB switch [1], because I was looking for one a few days ago and discovered something ghastly about the majority of the ones available on Amazon: Most of them use a USB Type-A to Type-A cable for the link between the switch and PC. This cable violates the USB spec, and is the moral equivalent of an electrical cord with prongs on both ends. It should never, ever be made or used, because plugging one of the ends into the wrong receptacle can destroy both USB ports. The correct cable to use here would be a standard Type-A to Type-B or Type-A to Micro-B cable, but for some reason a very small minority of these switches do that [2]. WTF is going on here? [1] https://www.amazon.com/gp/product/B01N6GD9JO/ https://www.amazon.com/gp/product/B01N6GD9JO/ [2] https://www.amazon.com/gp/product/B083JKDNRJ/ https://www.amazon.com/gp/product/B083JKDNRJ/
- jtl999 6y ago
  I have a keyboard from Cooler Master with one of those ghastly A to A cables :|
- adamhearn 6y ago
  It’s always about the money. USB A ports are either really cheap, or manufacturing the enclosure with the same port on both sides is cheaper. Could also be that the enclosure is a reused enclosure...
  - ohazi 6y ago
    It's not just the receptacles, it's also 2-4 custom cables per device, with sleeves and overmolds and all that, because it's a non-standard, spec-violating monstrosity that necessarily needs to be included with the cursed switch. I don't understand how that's cheaper than the alternative of paying a few cents more for the correct receptacles and then not even including cables, because the customer can use literally any standard off-the-shelf cable.
    - numpad0 6y ago
      Could very well be mistaken on this, but if I’m right, at some point some USB host port conformance test specified such A-A rollover cable. And also in more recent years, Intel DCI uses A-A 3.0 cable for CPU debugging on tablet PCs. Lesser known but Intel defines USB host controller spec. So not allowed in spec for public use, but not custom cables per se.
voltagex_ 6y ago
DDC/CI seems like an absolute crapshoot - I've got some 10 year old Dell monitors that don't seem to support it at all, but someone with the same monitors reported brightness control. I just checked my 2019 Acer XB27HU, which reports brightness control but it doesn't seem to work - it then got stuck in Factory Test mode. It doesn't support input selection and doesn't do any kind of hotplug detection. I've never seen a monitor review mention these kind of features, either.
- bohuim 6y ago
  Agreed, I was also looking into DDC/CI for input switching my 2017 XB271HU, and mine works for brightness but definitely not input switching. Meanwhile my 2019 HP Z27 supports the full protocol, so I had to drop the idea
- X-Cubed 6y ago
  It seems to also depend on the graphics card and possibly the monitor input used. DDC works fine from my desktop over DisplayPort from an nvidia GPU, but I can't seem to get it working from my laptop over HDMI from an Intel GPU.
desdiv 6y ago
While we're on the subject on KVMs, what do you guys do about audio? Currently I have one computer connected to the AV receiver via TOSLINK (optical audio). The other computer is connected to the receiver via coaxial S/PDIF. When I switch computers I have to physically go to the receiver and switch between the two input channels. This presents two problems: P1: Manual action required P2: Only one computer can play sound at any given time Ideally, I would want a S/PDIF mixer that can decode the two S/PDIF streams, add each constituent channel together, and then output that as a single S/PDIF stream to the receiver. But I can't seem to find this anywhere. Most mixers I've found are: 1. Analog mixers 2. Pro audio mixing consoles that have a dozen input channels and 50 dials on it, with a price tag to match
- Bedon292 6y ago
  I have played with Voicemeter for this. You can stream the audio back and forth between machines. And one of them is always connected to the speakers. And you can mix between the two as well. https://www.vb-audio.com/Voicemeeter/vban.htm https://www.vb-audio.com/Voicemeeter/vban.htm
  - desdiv 6y ago
    Thank you! This is great.
- ben-schaaf 6y ago
  I bought a cheap audio switch but it was terribly built and introduced a bunch of noise. Now I just use a USB dac and let a USB switch handle the switching. If I wanted to have both computers play audio at the same time I'd set up pulseaudio to do that.
- driverdan 6y ago
  Get a USB DAC that's connected to the same switched USB as your keyboard and mouse.
j45 6y ago
It would be great if it was possible to extend this into a kvm over ip.
c0smic 6y ago
Big fan of the Level 1 Tech KVMs, both the hardware and support are quite good. You're way more likely to run into issues with docks/monitors/usb devices etc than something actually wrong with the KVM itself.
keithnz 6y ago
depending what you are doing, I find remote desktop solutions to be pretty good. However, multi monitor can be problematic.
- Bedon292 6y ago
  I experimented with Windows Remote Desktop for a couple days, it worked fine for coding, even with multi monitor. It was definitely a noticeable lag but didn't bug me too much. But I probably should have remoted into the desktop from the laptop instead of the other way around.
- rcarmo 6y ago
  I work all day on Windows machines and remote to them from a Mac with three monitors attached. zero issues — what is your experience?
car 6y ago
The author of this project is on HN. I hope he reads this and makes a top-level post, in case anyone has a question, suggestion or thanks for him. https://news.ycombinator.com/user?id=haimgel https://news.ycombinator.com/user?id=haimgel
Fannon 6y ago
The Dell U3219Q monitor has a (rather rare) feature that gets rid of the need for a KVM switch for me entirely. It has both an USB-C input and an USB3 upstream that can be combined with either DisplayPort or HDMI. It also has signal auto detection. When I'm starting up my PC, it will use the USB connection from my PC via USB3 upstream. When I power up my work laptop, it will take USB from its USB-C connection. That even eliminates the need to push a button to switch. I'm really happy with this setup.
- Jaruzel 6y ago
  BenQ PD3200Q (my current monitor) also has this feature, and comes with a puck style remote for quick switching. Added bonus, it's quite a good monitor!
- oblio 6y ago
  What do you do if both are turned on? Or does it figure it out?
thefz 6y ago
> for my two 4k monitors Weird flex, but okay.
PiMaker 6y ago
Did something similar a while back in C#. Registers itself as a system service so it can even switch displays when no user is logged in (i.e. you're on the Windows login screen). Also has a web GUI for configuration. https://github.com/PiMaker/DDCKVM https://github.com/PiMaker/DDCKVM
globular-toast 6y ago
Since working from home I've had the exact same use case. I thought a KVM would be perfect, but was really surprised that they are incredibly expensive and don't really seem very good anyway. It's odd because switching the keyboard/mouse seems easy, while switching the monitor inputs is something that is done by AVR receivers which can be found for less than a KVM. I've resorted to having both machines plugged into my monitors and switching inputs using the monitor front panel. Not ideal. For the keyboard/mouse I currently just have two of each on my desk. Also not ideal, although I must admit it provides some semblance of work/life separation. I'm going to look into one of the software solutions for switching the keyboard/mouse.
trissylegs 6y ago
Thanks for this. I was thinking about doing something like this. Because: 1. I have 4k 144hz monitor. Not many devices or even display protocals can handle that (I won't be able to even fully utilize it until I upgrade my desktops graphics card). 2. The amount of cambes I have for my current KVM swicth (for my second, 1080p, monitor). Is getting unweildy.
narrowtux 6y ago
I had the same problem, and one of my displays is insanely picky when it comes to switching sources. It seems like it will only attempt a handshake once, and when the source is not ready for it, it will switch back. I bought HDMI/DisplayPort switches which are capable of 4k60 and are very cheap. Only these combined KVMs have outrageous prices, but if you're fine with using multiple switches it can be achieved quite cheaply.

458 points by car 6y ago

I use the IOGear switch between windows/pc and like 1/5 times it doesn't switch correctly (it'll end up holding the option key down or something.) are there any keyboard switches that emulate a keyboard correctly instead of just unplugging and replugging the usb connection?

zerkten 6y ago
I've given up finding a KVM that has this support for emulation. I've got a Kinesis Freestyle Edge RGB and even for the better ConnectPRO KVMs, there are just too many USB endpoints. I found that X-Keys make a range of keypads that are specifically designed for KVMs. I have it setup for KVM switching and the remaining keys have other macros. I'm glad I got it, but it's expensive compared to DIY kits.
duskwuff 6y ago
> are there any keyboard switches that emulate a keyboard correctly instead of just unplugging and replugging the usb connection? StarTech's KVMs have a rather robust USB stack which handles this situation very well.
- joshu 6y ago
  thank you! any particular products you have experience with?

AntiRush 6y ago

This is awesome! I've often dreamed about doing this with a keyboard shortcut ala switching layouts in a tiling WM (or 'real' kvm switches from the CRT + ps2 era). Is there a good usb hub that supports switching outputs via software?

bertjk 6y ago
Some of the IOGear KVMs do provide hotkey functionality.

vaillancourtmax 6y ago

Neat! I use a similar setup where I literally have a single USB cable that gives me access to everything: monitor, keyboard, mouse, lighting, camera, microphone. I just need to plug the cable in the computer I want to use. However, I do need to change the input on the monitor as one of the them is connected via HDMI.

harikb 6y ago
You must in the USBC world!
bluGill 6y ago
USB connectors have a terrible plug/unplug lifespan.. I have a few computers where the USB ports can't be used because they have been unplugged too often. Might just be USB-A, I haven't looked at the other specs

D13Fd 6y ago

I like it! Thank you for sharing the code! By the way, I have that same USB switch. I have tried a number of them, and that is the fastest I've found. The only major flaw is the status lights -- they are too hard to see from far away. To fix that issue, I drilled a hole in the top of the case, over the lights, about the same size as the adjacent power button. I put a small piece of foam inside to separate the two lights, and covered it with tape. It works perfectly now and it's so much easier to see the status from a typical usage angle. The whole modification took maybe 15 minutes, and I didn't even bother disassembling it first.

haimgel 6y ago
This is an interesting hack, thanks for sharing! I agree the status lights are hard to see...

Havoc 6y ago

> I wrote some software. And my heart sank. Zero chance of getting that past corporate laptops that are way too locked down for actual code anything beyond VBA

smabie 6y ago
Then just have corporate buy you a real KVM switch?

mercora 6y ago

ive done the same on Linux using udev rules and a simple usb switch. i use it for a VM with a physical GPU attached and it worked great ever since.

zwayhowder 6y ago
To paraphrase the internet. Sample configs or it didn't happen! Seriously, I'd love to see this. I have had mixed results with udev and no idea where to start to send an input switch command to my monitor.
- mercora 6y ago
  sure, i used this[0] for the hotpluging part and these[1] are the udev rules :) in order to switch inputs you should take a look at ddcutil... [0] https://github.com/olavmrk/usb-libvirt-hotplug/blob/master/usb-libvirt-hotplug.sh https://github.com/olavmrk/usb-libvirt-hotplug/blob/master/u... [1] https://gist.github.com/4ab23675ab69162934ce75b52bd1d290 https://gist.github.com/4ab23675ab69162934ce75b52bd1d290
  - zwayhowder 6y ago
    Thank you.

mandeepj 6y ago

I was searching for it couple weeks ago. The cheapest KVM for two monitors at ebay starts from $80. So, good job.

mmsimanga 6y ago

I have similar setup without the software to automatically switch inputs. I use the physical buttons on the monitor to switch input. Not efficient but I get a better resolution than pushing display through a cheap KVM switch. Will be trying software in article. Anyone know of software that runs on Linux to switch display the input? OP lists Windows and Mac OS support.

pedrocr 6y ago
In Linux you can probably do it with a script that calls ddcutil: http://www.ddcutil.com/ http://www.ddcutil.com/

haram_masala 6y ago

https://www.amazon.com/gp/aw/d/B0817YFJKW https://www.amazon.com/gp/aw/d/B0817YFJKW $60 shipped.

vxNsr 6y ago
that's one monitor
jen20 6y ago
This fails at two criteria presented in the second paragraph: - it only supports one 4K monitor, not two, - it doesn't support USB-C.
D13Fd 6y ago
That's USB 2 and one monitor. He is looking for USB 3. Also, I can tell you it's harder than you'd think to find good hardware in this area, so I don't think the software effort is wasted.
hbcondo714 6y ago
Interesting image descriptions. The 6th one says "Suport operate system" with a Windows 7, 8 and Vista icons.

m0shen 6y ago

This is great! I did something very similar using AutoHotKey and Synergy : https://moshen.net/posts/virtual_kvm/ https://moshen.net/posts/virtual_kvm/

D13Fd 6y ago
That looks nice! But there are two downsides: - Your solution requires Synergy. In my experience, Synergy has been buggy--or at least extremely finicky--every time I've tried it since release circa 2001. When it comes to input devices, I want things to be basically flawless. So I like this very simple fix better. - The posted solution is cross-platform between Mac and Windows, which is a common use case. Yours relies on Autohotkey, which is awesome on Windows but, last I checked, terrible on Mac OS.
- m0shen 6y ago
  Yeah, fair points. Every now and then I have to stop/start Synergy for it to work. Since my mouse/keyboard remain connected to my Windows machine, it can act as the "server" and issue the DCC to the monitor to switch when my key combo is hit. So I only ever run it on the Windows box.
- kitsunesoba 6y ago
  The other thing about Synergy is that it's a bit of a question mark in terms of security, even with encryption enabled (at least that I've seen — would be happy to be corrected!)
nly 6y ago
Please support Barrier[0] (FOSS) or, perhaps, just buy ShareMouse[1] or download Input Director[2] (free but closed source) rather than supporting Synergy. I worked for Symless for 2 years and I can tell you first hand that the owner had little interest in fixing or improving the core functionality, the code for which has remained largely unchanged for 12-15 years. Most of the input bugs in the software are a decade old, and unless a community patch comes along that can be merged, the owner only has interest in keeping it working on new OS versions, and tarting up the UI/UX to support Symless as a lifestyle business. In the 2 years since I left I've seen exactly 3 bugfix releases, one of which broke TLS, and none of which seemed to contain any significant original work. Supposedly Synergy 3 is in the works, after Synergy 2 (which I worked on) was scrapped, but this will almost certainly only be a proprietary Electron UI for the FOSS CLI instead of a Qt/QML UI for the FOSS CLI (as v2 was). Major versions of Input Director (v2.0) and ShareMouse (v5.0) have been announced in the last few months, and it looks like significant work has taken place on both projects. Both of these products need better marketing. Unfortunately none of the alternatives to Barrier/Synergy seem to want to support Linux, which remains its moat. The days for that are numbered due to Wayland though (Synergy uses the X11 XTest extension to inject input). [0] https://github.com/debauchee/barrier https://github.com/debauchee/barrier [1] https://www.sharemouse.com/ https://www.sharemouse.com/ [2] https://www.inputdirector.com https://www.inputdirector.com

dkersten 6y ago

Hah, I use a low tech solution: I have a HDMI extension cable that reaches the front of the monitor that I just plug the device I want active into (and a usb splitter similar to what he uses for keyboard and mouse). It’s not quite as seamless as the solution described here but it took no time to set up.

evanweaver 6y ago
You can get a physical HDMI button so you don't even have to unplug anything: https://www.amazon.com/gp/product/B01L8LLP2G/ https://www.amazon.com/gp/product/B01L8LLP2G/
- pstrateman 6y ago
  "4Kx2K@30hz resolution" The issue is 4k@60.
- dkersten 6y ago
  Yeah, I did use a switcher before I upgraded my resolution.
- andechs 6y ago
  Does something like this exist for USB-C devices? I have to plug and unplug a certain device to change it between machines. Not full emulation and remaining "connected" - just the ability to press a button and change what the device is plugged into.
  - kingosticks 6y ago
    Would the one in the article work for you? https://www.amazon.ca/gp/product/B01N6GD9JO https://www.amazon.ca/gp/product/B01N6GD9JO
    - dkersten 6y ago
      That doesn’t look like USB-C

TehCorwiz 6y ago

This would probably work great for running VMs with a hardware pass-through GPU. Can't wait to try this out.

deleted 6y ago

[deleted]

justaguy88 6y ago

for those who have less time than money, https://store.level1techs.com/?category=Hardware https://store.level1techs.com/?category=Hardware

D13Fd 6y ago
Both of the KVMs meeting his criteria on that page are sold out (and one is a pre-order as well as being sold out).
stoobs 6y ago
Another option is the Aten CS1944DP - 4 input dual 4K60 USB3 KVM switch - I have it and it's rather wonderful given I now have my work laptop here due to covid - not cheap, but it's really, really good.
- wasmitnetzen 6y ago
  Not cheap is quite the understatement. I could easily just get another screen for less money.
  - stoobs 6y ago
    Depends on your use-case - I already have two screens but I need them switching between multiple computers - there are very few options for dual display multiple input KVMs which can support 4K60 and USB3

zachrose 6y ago

Would somebody like to help me understand why KVM switches are so sophisticated? A DisplayPort cable has 20 pins, so why can't it just be a 20 pole switch? (Or 30 pole for two USBs and a headphone jack, etc.)

bravo22 6y ago
Signal integrity. High speed signals degrade with even slightest mismatch in trace length or stubs. For high-speed signals you use a chip which is essentially an electrical repeater to redirect the output to port A or B.
adrianpike 6y ago
It can be, eBay has HDMI physical switches for like $8. Your computers will see it as a monitor unplug, though, and do fun things with adjusting windows/icons/resolutions, and then have to re-handshake on every switch. Not a blocker, just a pain. I'm also not 100% sure if it'll freak HDCP out.
- 8ytecoder 6y ago
  I bought a HDMI switch and a USB switch. Total cost was under $30. I now have to press two buttons instead of one but that's about it. However, I don't know how to scale that for two monitors. I prefer a single monitor setup so it works for me.
- fock 6y ago
  iirc most of this switches (and cheap chinese capture cards) work around this problem by "breaking" HDCP. Problem solved.
myself248 6y ago
At the multi-gigabit speeds of a modern video signal, the components of a normal mechanical switch are antennas.
- modeless 6y ago
  So are the pins in cable connectors, but cables are (relatively) cheap and switching signals by replugging connectors works just fine.

renewiltord 6y ago

Haha, this is clever and I like it. You turned what is usually solved on the physical layer to something solved on the logical layer - which is almost always better because you can express conceptual changes much better when you don't need hardware. It's a small taste of the stuff that software-defined networks have added to networking.

dasloop 6y ago

I have an MX Keys keyboard that can connect to up to three devices (with three special keys). Unfortunately, the operating system does not see the key pressed. But if it was, I could activate the display input switching using your app (thanks!). I have filled a support request at Logitech, maybe one day...

OJFord 6y ago
Are other keys (e.g. Fn) mappable to the special keys? Maybe you could work around it by setting e.g. F1-3 to F1-3 + Special1-3, and then input switching on F1-3.
- wasmitnetzen 6y ago
  Or the other way around? Map the special keys to F13 or something. (Normal keyboard only have up to F12, but I believe the standard allows up to F24.)

NKosmatos 6y ago

Reminds me of a similar post in HN in order to switch inputs on a single monitor, between mac and PC, via software only. Ideally a shortcut on the mac desktop in order to switch to HDMI and another shortcut on the PC desktop to switch to DisplayPort. For sure I’m going to give a go at the code of this soft/hard KVM.

Splendor 6y ago

Very cool. Will this only work over HDMI?

moolcool 6y ago
I imagine it will work on any input your display supports

salex89 6y ago

I hoped for the actual switch schematics :) . Offtopic: I wanted to buy this USB switch, but it's hard to get on the current market in my country (or available for an absurd price). So I started trying to build my own... which was fun, but then I understood I need a some USB/MAX chips that are also hard to find, and started to cause me frustration instead of fun, because I'm not really that good with low-level electronics, university was a long time ago. And I was still without my switch/hub. So at the end I just chose a 3-pole double-throw toggle switch and a couple of USB connectors and wired them up. I only need to switch my keyboard, because my mouse is multi-device. If I need more, I'll just wire a hub to it. Work is in progress, but it can't get simpler than that. If you're wondering what got complicated, well as far as I read and understood, actually breaking a USB connection with solid state logic is kind of a pain in the neck if you want to stay within the USB parameters, at least for an inexperienced designer like me. And you need to build the power supply for the circuit, and I didn't want to introduce an external power supply, I wanted to piggyback of the USB source. Something this ugreen product does not do. So I left this project for another time, when I freshen up on my perished knowledge. A mechanical switch just switches the lines and that's it.

deorder 6y ago
I opened the same ugreen switch up and plan to attach some wires from the button pins to my RaspberryPI. This way I will be able to use my RaspberryPI to switch between the two USB hosts and use the RaspberryPI's built-in CEC support to switch between video inputs. What the board looks like: https://imgur.com/lX1uZ7Q https://imgur.com/lX1uZ7Q

yfiapo 6y ago

That's cool. As another alternative, this is the one I bought at start of lockdown which does everything but the USB-C: https://smile.amazon.com/gp/product/B0851CMHP2/ https://smile.amazon.com/gp/product/B0851CMHP2/ Not particularly cheap but at least no longer back-ordered. I've been pretty happy with it switching 2x4K monitors, keyboard and mouse between a Mac and a PC laptop. Both corporate laptops where custom software is more difficult.

Bedon292 6y ago
You like this one? I have been looking for a while, but didn't find one I felt was trustworthy in that price range. For instances 11 reviews on this one.

nkrisc 6y ago

This is perfect. The software competent is exactly what I was missing from my setup. I use a USB switch to switch my peripherals but I've been manually changing the input on my monitor like a caveman.

Freak_NL 6y ago
I'll have to have a go at this DDC/CI stuff as well. I too have a USB switch that just works (click button, two seconds later other computer has keyboard and mouse, and whatever else is on it, click again, back to the other one). It's simple, it's foolproof, and I can do it with my eyes closed if I so wanted to. Now, switching the monitor however… This involves clicking the six buttons on the rear of the monitor in an arcane sequence (your fingers sort of curl around the side, the buttons have labels on the front of the monitor on the right-side bezel, and yes, that works as well as you can imagine). Which then switches the monitor: * Button 1: activate menu * 1 again: select input * 2: move down list of three inputs * 2: move down list of three inputs * 3: select mini display port A somewhat similar sequence exists for going back to its HDMI input. But hold on! It gets better if you turn off the computer you have live at the moment. The monitor then goes blank, and until it throws its 'no signal found' message, it won't respond to anything. If you are lucky, you can switch inputs before the current computer is shut down completely and the monitor blanks itself. I do feel like a caveman.
- narrowtux 6y ago
  The software on modern displays is often abysmal, with the exception of Dell's in my experience.
  - Freak_NL 6y ago
    It really is. All I want is one button that just cycles to the next active port connected.
- nkrisc 6y ago
  Unfortunately it looks like my monitor does support DDC but does not support VPC Code 96 (0x60) meaning I can't programmatically change the input. What a bummer. Monitor is ASUS PG348Q.

doctorhandshake 6y ago

There was a comment here yesterday[1] about DDC/CI writes being finite on some hardware — is that a concern with this approach? [1] top comment - https://news.ycombinator.com/item?id=24344045 https://news.ycombinator.com/item?id=24344045

jwalton 6y ago
100K switches is switching your input 4 times a day for 68 years. You'll probably want a new fancy 32K monitor by then anyways. ;) Also, if your monitor stores the current input in EEPROM, changing it via the OSD will also write to EEPROM, so it's not like you're saving the EEPROM by doing it manually (buying a real KVM is another story, obviously).

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bijant 6y ago

The Headline hit me right in the stomach because it was just yesterday that I was pondering whether to build or to order a USB Switch. With much to do currently, I wussed out and just ordered it. I didnt pay 38$ though: https://de.aliexpress.com/item/1005001274095928.html https://de.aliexpress.com/item/1005001274095928.html USB 2 is more than enough for mouse and keyboard and it has the additional advantage of having an extension button to switch.

hnick 6y ago
I don't always trust tech from Aliexpress but sometimes it's worth a gamble. I had a look at that brand and they also do a KVM (HDMI, 2 USB ports for K/M) for USD $16. That seems way too cheap but I don't really understand the tech enough to know for sure.

aloer 6y ago

I recently bought a Philips 346b1c (34" UWQHD with built-in USB C hub + KVM) and the use of DDC/CI to tell the monitor what input to switch to could come in super handy here. The display is very good at automatically switching KVM based on the selected input, but the selection still has to be done with the little buttons underneath the screen

dugmartin 6y ago

I use a combination of a cheap USB switch and the remote for my 4K monitor (really a 43" TV) to switch inputs. Not as nice as one button press but much cheaper than a high end KVM.

Polylactic_acid 6y ago
The KVM I got is actually even simpler than a button press. It detects the active input and uses that so when I turn off my work laptop and turn on my desktop it switches. Its totally seamless.

brian_herman 6y ago

https://store.level1techs.com/products/kvm-switch-dual-monitor-model https://store.level1techs.com/products/kvm-switch-dual-monit... A little more expensive. But gets the job done!

ElCapitanMarkla 6y ago

I know this isn’t the same but if you don’t need to switch the monitor inputs and only need mouse / keyboard support. I’ve been using https://github.com/debauchee/barrier https://github.com/debauchee/barrier for the last few years. It works surprisingly well, no noticeable lag even when gaming.

exhilaration 6y ago
You still need some kind of a hub to connect the keyboard and mouse to both machines, right?
- paranoidrobot 6y ago
  It says it's a fork of Synergy[0]. So the idea is you have PC A + Monitor A, and PC B + Monitor B. You install the software on both machines (they talk over a local network), and configure PC A to be left of PC B, and PC B to be right of PC A. Attach a keyboard+mouse to one machine. When your mouse goes 'off screen right' on PC A, it knows that PC B is over there, so it redirects keyboard/mouse input to PC B. I used Synergy for a while, and it was pretty great. The only issue is when you need to do control keys that the OS takes over (like CTRL-ALT-DEL on Windows), that wouldn't transfer over, and you'd be looking at Monitor B wondering why keyboard/mouse wasn't working... then look over at Monitor A and see it's at the lock screen. [0] https://symless.com/synergy https://symless.com/synergy
- abiogenesis 6y ago
  I guess it's a mouse/keyboard emulator over TCP.
- rainbowzootsuit 6y ago
  There's a server machine where you connect the keyboard and mouse and client machines that just have a monitor connection. You arrange the geometry in the software to make the mouse move between machines in an intuitive manner. Whichever machine has the mouse has the keyboard input as well. So you do need a dedicated monitor per machine from my experience.
6y ago

cellular 6y ago

There are full software solutions that just show the screen over the network and relay your mouse/keyboard to whichever machine is on focus. It worked well enough that I'd forget which pc the kvm s were actually connected to. But I was only programming, not gaming, so maybe the 60Hz would be a problem. no hurt to try. It was free and there were a couple software solutions.

Polylactic_acid 6y ago
The latency would probably make it a shitty experience. I got a displayport switch when I started working from home this year and the thing works so well I forget it exists. There is no latency at all and it automatically switches inputs based on which one is active so I never have to touch the thing.
- TylerE 6y ago
  Why? At 60dps that is one frame every 16.7ms. Sub-ms latency is easy on a local network. Heck I can get a few states away and back in 16ms.
  - mercora 6y ago
    its not really about network latency at that level. you need to acquire screen contents and render them too. if you try to send signals uncompressed bandwidth (pps) could be a problem too in that time frame. if you compress it you introduce additional latency on capture and rendering times... i have yet to see this working over an ethernet network...
  - vmednis 6y ago
    There's encode and decode latency as well, but I've been able to get the total latency to a data center about 200km from me to around 30ms or so with some solutions. Was good enough for some non-competitive gaming for me.
Bedon292 6y ago
There are many keyboard mouse solutions like this, but I have not found a software including video. If you remember, can you point me at them?

milofeynman 6y ago

I have been using a KM switch and manually switching the monitor for the last few months. I was wishing there were a way to programmatically change the input, and apparently there is! But I assume this is only supported by some monitors. I will try it out tonight. Thank you

crisopolis 6y ago

Wow, I use this same USB switch and also use two monitors for everything. Right now I manually switch my main monitor and just gave up on switching the monitor above it. But this is friggin awesome.

fizzled 6y ago

The easiest way to do this is to skip KVM because the latency and disconnect is awful, and the tangle of wires is un unnecessary mess. Instead, use microsoft remote desktop or VNC. Caveat: I've only ever gotten dual monitor + VNC to work on Ubuntu.

zargon 6y ago

The disadvantage of this arrangement, which may not be obvious until you try it, is the delay in switching time. You have to wait for the monitor to re-sync on the new signal and for the USB to enumerate on the new host. I guess most people can tolerate this? For me that delay is intolerable. Quality KVMs (ConnectPRO is the one I remember off the top of my head) maintain both connections at all times and switching is instantaneous.

jwalton 6y ago
I bet it's a lot shorter than the delay involved in me using the touch sensitive not-buttons on the front of my monitor to switch inputs, which is what I do now. :P
- milofeynman 6y ago
  I'm using it and I can confirm. it's significantly better than using that stupid monitor button.
- IshKebab 6y ago
  But not as good as an actual KVM switch. I use this one: https://www.amazon.co.uk/gp/product/B07F8NVMH7 https://www.amazon.co.uk/gp/product/B07F8NVMH7 It also does 4K at 60 Hz. You can switch via the keyboard (uses scroll lock as a shortcut). It has worked flawlessly for me and is only £86. The only real downside is that it is yet more wires, and it can only switch one video signal. If I had two monitors I'd probably go with this guys solution.
  - driverdan 6y ago
    Also it's only USB 2, not USB 3. So it's fine for a keyboard and mouse but nothing with a decent data rate.
    - IshKebab 6y ago
      I suspect a USB 3 KVM switch does not exist. His solution also doesn't help if you want to switch a USB 3 device between computers. So that isn't really a con.

ohazi 6y ago

Okay, let's talk about that USB switch [1], because I was looking for one a few days ago and discovered something ghastly about the majority of the ones available on Amazon: Most of them use a USB Type-A to Type-A cable for the link between the switch and PC. This cable violates the USB spec, and is the moral equivalent of an electrical cord with prongs on both ends. It should never, ever be made or used, because plugging one of the ends into the wrong receptacle can destroy both USB ports. The correct cable to use here would be a standard Type-A to Type-B or Type-A to Micro-B cable, but for some reason a very small minority of these switches do that [2]. WTF is going on here? [1] https://www.amazon.com/gp/product/B01N6GD9JO/ https://www.amazon.com/gp/product/B01N6GD9JO/ [2] https://www.amazon.com/gp/product/B083JKDNRJ/ https://www.amazon.com/gp/product/B083JKDNRJ/

jtl999 6y ago
I have a keyboard from Cooler Master with one of those ghastly A to A cables :|
adamhearn 6y ago
It’s always about the money. USB A ports are either really cheap, or manufacturing the enclosure with the same port on both sides is cheaper. Could also be that the enclosure is a reused enclosure...
- ohazi 6y ago
  It's not just the receptacles, it's also 2-4 custom cables per device, with sleeves and overmolds and all that, because it's a non-standard, spec-violating monstrosity that necessarily needs to be included with the cursed switch. I don't understand how that's cheaper than the alternative of paying a few cents more for the correct receptacles and then not even including cables, because the customer can use literally any standard off-the-shelf cable.
  - numpad0 6y ago
    Could very well be mistaken on this, but if I’m right, at some point some USB host port conformance test specified such A-A rollover cable. And also in more recent years, Intel DCI uses A-A 3.0 cable for CPU debugging on tablet PCs. Lesser known but Intel defines USB host controller spec. So not allowed in spec for public use, but not custom cables per se.

voltagex_ 6y ago

DDC/CI seems like an absolute crapshoot - I've got some 10 year old Dell monitors that don't seem to support it at all, but someone with the same monitors reported brightness control. I just checked my 2019 Acer XB27HU, which reports brightness control but it doesn't seem to work - it then got stuck in Factory Test mode. It doesn't support input selection and doesn't do any kind of hotplug detection. I've never seen a monitor review mention these kind of features, either.

bohuim 6y ago
Agreed, I was also looking into DDC/CI for input switching my 2017 XB271HU, and mine works for brightness but definitely not input switching. Meanwhile my 2019 HP Z27 supports the full protocol, so I had to drop the idea
X-Cubed 6y ago
It seems to also depend on the graphics card and possibly the monitor input used. DDC works fine from my desktop over DisplayPort from an nvidia GPU, but I can't seem to get it working from my laptop over HDMI from an Intel GPU.

desdiv 6y ago

While we're on the subject on KVMs, what do you guys do about audio? Currently I have one computer connected to the AV receiver via TOSLINK (optical audio). The other computer is connected to the receiver via coaxial S/PDIF. When I switch computers I have to physically go to the receiver and switch between the two input channels. This presents two problems: P1: Manual action required P2: Only one computer can play sound at any given time Ideally, I would want a S/PDIF mixer that can decode the two S/PDIF streams, add each constituent channel together, and then output that as a single S/PDIF stream to the receiver. But I can't seem to find this anywhere. Most mixers I've found are: 1. Analog mixers 2. Pro audio mixing consoles that have a dozen input channels and 50 dials on it, with a price tag to match

Bedon292 6y ago
I have played with Voicemeter for this. You can stream the audio back and forth between machines. And one of them is always connected to the speakers. And you can mix between the two as well. https://www.vb-audio.com/Voicemeeter/vban.htm https://www.vb-audio.com/Voicemeeter/vban.htm
- desdiv 6y ago
  Thank you! This is great.
ben-schaaf 6y ago
I bought a cheap audio switch but it was terribly built and introduced a bunch of noise. Now I just use a USB dac and let a USB switch handle the switching. If I wanted to have both computers play audio at the same time I'd set up pulseaudio to do that.
driverdan 6y ago
Get a USB DAC that's connected to the same switched USB as your keyboard and mouse.

j45 6y ago

It would be great if it was possible to extend this into a kvm over ip.

c0smic 6y ago

Big fan of the Level 1 Tech KVMs, both the hardware and support are quite good. You're way more likely to run into issues with docks/monitors/usb devices etc than something actually wrong with the KVM itself.

keithnz 6y ago

depending what you are doing, I find remote desktop solutions to be pretty good. However, multi monitor can be problematic.

Bedon292 6y ago
I experimented with Windows Remote Desktop for a couple days, it worked fine for coding, even with multi monitor. It was definitely a noticeable lag but didn't bug me too much. But I probably should have remoted into the desktop from the laptop instead of the other way around.
rcarmo 6y ago
I work all day on Windows machines and remote to them from a Mac with three monitors attached. zero issues — what is your experience?

car 6y ago

The author of this project is on HN. I hope he reads this and makes a top-level post, in case anyone has a question, suggestion or thanks for him. https://news.ycombinator.com/user?id=haimgel https://news.ycombinator.com/user?id=haimgel

Fannon 6y ago

The Dell U3219Q monitor has a (rather rare) feature that gets rid of the need for a KVM switch for me entirely. It has both an USB-C input and an USB3 upstream that can be combined with either DisplayPort or HDMI. It also has signal auto detection. When I'm starting up my PC, it will use the USB connection from my PC via USB3 upstream. When I power up my work laptop, it will take USB from its USB-C connection. That even eliminates the need to push a button to switch. I'm really happy with this setup.

Jaruzel 6y ago
BenQ PD3200Q (my current monitor) also has this feature, and comes with a puck style remote for quick switching. Added bonus, it's quite a good monitor!
oblio 6y ago
What do you do if both are turned on? Or does it figure it out?

thefz 6y ago

> for my two 4k monitors Weird flex, but okay.

PiMaker 6y ago

Did something similar a while back in C#. Registers itself as a system service so it can even switch displays when no user is logged in (i.e. you're on the Windows login screen). Also has a web GUI for configuration. https://github.com/PiMaker/DDCKVM https://github.com/PiMaker/DDCKVM

globular-toast 6y ago

Since working from home I've had the exact same use case. I thought a KVM would be perfect, but was really surprised that they are incredibly expensive and don't really seem very good anyway. It's odd because switching the keyboard/mouse seems easy, while switching the monitor inputs is something that is done by AVR receivers which can be found for less than a KVM. I've resorted to having both machines plugged into my monitors and switching inputs using the monitor front panel. Not ideal. For the keyboard/mouse I currently just have two of each on my desk. Also not ideal, although I must admit it provides some semblance of work/life separation. I'm going to look into one of the software solutions for switching the keyboard/mouse.

trissylegs 6y ago

Thanks for this. I was thinking about doing something like this. Because: 1. I have 4k 144hz monitor. Not many devices or even display protocals can handle that (I won't be able to even fully utilize it until I upgrade my desktops graphics card). 2. The amount of cambes I have for my current KVM swicth (for my second, 1080p, monitor). Is getting unweildy.

narrowtux 6y ago

I had the same problem, and one of my displays is insanely picky when it comes to switching sources. It seems like it will only attempt a handshake once, and when the source is not ready for it, it will switch back. I bought HDMI/DisplayPort switches which are capable of 4k60 and are very cheap. Only these combined KVMs have outrageous prices, but if you're fine with using multiple switches it can be achieved quite cheaply.