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Barrier looks great, but does anyone know why KVM switches with DisplayPort or HDMI are so outrageously expensive? It should just be a switch, no complex electr

Barrier looks great, but does anyone know why KVM switches with DisplayPort or HDMI are so outrageously expensive? It should just be a switch, no complex electronics, so I truly can't figure out why any KVM should cost more than say $30-50 US. I suspect DRM or patents for rent seekers are involved somehow. Or maybe they're playing on the naivety of the business community towards this stuff. I'd sure like to know, and also if there are any low-cost or open source KVMs available.

wyager 5y ago
> It should just be a switch, no complex electronics For any high-bandwidth thing like HDMI, you need to do clock recovery and copy over the bitstream at the very least. You can't just use relays or whatever. Doing this at 10gbps+ is going to cost a bit.
- wlesieutre 5y ago
  How many plugs and unplugs is HDMI rated for? At the prices we're talking it would be cheaper for me to build a robot that physically swaps cables at the back of my computer. Of course then Windows gets confused by the lack of monitor and rearranges all the windows, so it's not a perfect solution.
- spicybright 5y ago
  I don't see that much of a reason you can't do a relay to "disconnect" one hdmi and plug in another. The computers would see the HDMI cable/USB cords unplugging and re-plugging. Obviously this can be problematic, but I can't see it being that expensive.
  - bartvk 5y ago
    As soon as there's enough volume for someone to design a specialized IC (and reference PCB), and it gets produced by VIA or TI or whatever, sure, then it's neither a problem nor expensive.
  - Nextgrid 5y ago
    Shielding might be a problem. You need your switching circuitry (which is most likely going to be solid state rather than individual relays for each line) to be equivalent to a good cable in terms of interference, crosstalk, etc.
  - wyager 5y ago
    Because mechanical relays have high impedance at HDMI frequencies.
    - TaylorAlexander 5y ago
      Yup. A quick search suggests HDMI runs at clock speeds of 25MHz to 340MHz. Not running that over a relay! Also HDMI is many pins, so you would need a low impedance high pole count relay even if it was possible, and such a relay plus the device wrapped around it plus some profit margin means you're not making it any cheaper.
  - mikepurvis 5y ago
    Even outside of impedence issues, you can't just use relays because then every switch is basically an unplug/replug, meaning that: a) the display will flip out and spend multiple seconds re-syncing itself, and b) the sources may take actions such as resizing the desktop, switching to the internal display, pausing the game, whatever. Part of the point of a hardware KVM is that it negotiates its own connection to all of the devices involved, and only changes which signals are passed through at any given moment, resulting in instantaneous switchovers. Now, a multi-input monitor can also do this, but then you have to deal with whatever compat issues are involved in commanding it to switch over DDC (see for example https://github.com/haimgel/display-switch https://github.com/haimgel/display-switch), and it typically also won't be as fast as a hardware solution since input switching speed isn't a metric most people care about when monitor shopping.
  - loxias 5y ago
    Spend just 5 minutes on the Wikipedia page for HDMI and you'll see how much of a folly this would be. :) It has like... 4? different physical layers running at different speeds and all sorts of other weirdness.
- makomk 5y ago
  There are really cheap commodity ICs that can switch HDMI, and they're generally purely analog devices that don't bother trying to reclock the signal. The real reason is that KVMs are specialised devices with a niche market. (Though there does seem to have been a bit of a push to integrate limited KVM functionality into some monitors lately.)
parentheses 5y ago
IMO KVM Switches with display support are luxury items. Who has 2 computers? People who can afford them.
- dividedbyzero 5y ago
  I didn't pay for my second computer, work did.
  - sokoloff 5y ago
    Work paid for my DP/USB KVM as well… That fits the same pattern that GP implies.
ridgered4 5y ago
It's pretty hard to beat a monitor with multiple inputs combined with a cheap USB switch when it comes to price and reliability. If you look up the prices of stand alone hdmi switches on amazon though I think the most likely explanation is these are now niche products so the price has gone up. Logically a decent vga USB KVM + an HDMI switch shouldn't require more cost than those two devices prices together.
banana_giraffe 5y ago
So, I might be missing something, but there are a couple of no-name HDMI/USB KVMs on Amazon in your price range (i.e., https://www.amazon.com/dp/B08NVKHRRT https://www.amazon.com/dp/B08NVKHRRT ) Some of the reviews suggest it acts as a pretty brain dead switch, which may cause problems with the OS. I know for a while I had a Windows 10 PC's monitor on a remote switch for silly reasons. I had to make sure to lock the PC before the monitor would turn off, otherwise some combination of driver/os/whatever would treat the disappearance of the monitor as a resolution change, and all my windows would get squished into 640x480. I could see KVMs like this triggering the same sort of madness.
- alar44 5y ago
  In addition to what you said, these things will shit out in a couple years. Button breaks, cord goes bad, etc. You pay for the quality.
Aeolun 5y ago
My first KVM switch was in the price range you mentioned, but switching caused the screen to go black for a while due to some HDMI stuff. The more expensive one I have now keeps both connections open at the same time, and switching takes a second or so. I dunno, I started thinking of it like switching from one game server to another, if you (somehow) do it in the middle of a game, stuff is bound to explode.
bradknowles 5y ago
You should ask the guys at Level1 Techs. They supposedly make the best DisplayPort KVMs in the business.
antifa 5y ago
I'd love a USB-only KVM style product, unfortunately newegg has decided to infringe on amazon's patent for "user must wade through endless ocean of unrelated garbage if sorting by lowest price". Logitech has a keyboard that perfectly connects to 3 devices (unifying and/or BT) but they don't have a mouse that follows the keyboard and their mouse oriented work-arounds for that are garbage.

wyager 5y ago

> It should just be a switch, no complex electronics For any high-bandwidth thing like HDMI, you need to do clock recovery and copy over the bitstream at the very least. You can't just use relays or whatever. Doing this at 10gbps+ is going to cost a bit.

wlesieutre 5y ago
How many plugs and unplugs is HDMI rated for? At the prices we're talking it would be cheaper for me to build a robot that physically swaps cables at the back of my computer. Of course then Windows gets confused by the lack of monitor and rearranges all the windows, so it's not a perfect solution.
spicybright 5y ago
I don't see that much of a reason you can't do a relay to "disconnect" one hdmi and plug in another. The computers would see the HDMI cable/USB cords unplugging and re-plugging. Obviously this can be problematic, but I can't see it being that expensive.
- bartvk 5y ago
  As soon as there's enough volume for someone to design a specialized IC (and reference PCB), and it gets produced by VIA or TI or whatever, sure, then it's neither a problem nor expensive.
- Nextgrid 5y ago
  Shielding might be a problem. You need your switching circuitry (which is most likely going to be solid state rather than individual relays for each line) to be equivalent to a good cable in terms of interference, crosstalk, etc.
- wyager 5y ago
  Because mechanical relays have high impedance at HDMI frequencies.
  - TaylorAlexander 5y ago
    Yup. A quick search suggests HDMI runs at clock speeds of 25MHz to 340MHz. Not running that over a relay! Also HDMI is many pins, so you would need a low impedance high pole count relay even if it was possible, and such a relay plus the device wrapped around it plus some profit margin means you're not making it any cheaper.
- mikepurvis 5y ago
  Even outside of impedence issues, you can't just use relays because then every switch is basically an unplug/replug, meaning that: a) the display will flip out and spend multiple seconds re-syncing itself, and b) the sources may take actions such as resizing the desktop, switching to the internal display, pausing the game, whatever. Part of the point of a hardware KVM is that it negotiates its own connection to all of the devices involved, and only changes which signals are passed through at any given moment, resulting in instantaneous switchovers. Now, a multi-input monitor can also do this, but then you have to deal with whatever compat issues are involved in commanding it to switch over DDC (see for example https://github.com/haimgel/display-switch https://github.com/haimgel/display-switch), and it typically also won't be as fast as a hardware solution since input switching speed isn't a metric most people care about when monitor shopping.
- loxias 5y ago
  Spend just 5 minutes on the Wikipedia page for HDMI and you'll see how much of a folly this would be. :) It has like... 4? different physical layers running at different speeds and all sorts of other weirdness.
makomk 5y ago
There are really cheap commodity ICs that can switch HDMI, and they're generally purely analog devices that don't bother trying to reclock the signal. The real reason is that KVMs are specialised devices with a niche market. (Though there does seem to have been a bit of a push to integrate limited KVM functionality into some monitors lately.)

parentheses 5y ago

IMO KVM Switches with display support are luxury items. Who has 2 computers? People who can afford them.

dividedbyzero 5y ago
I didn't pay for my second computer, work did.
- sokoloff 5y ago
  Work paid for my DP/USB KVM as well… That fits the same pattern that GP implies.

ridgered4 5y ago

It's pretty hard to beat a monitor with multiple inputs combined with a cheap USB switch when it comes to price and reliability. If you look up the prices of stand alone hdmi switches on amazon though I think the most likely explanation is these are now niche products so the price has gone up. Logically a decent vga USB KVM + an HDMI switch shouldn't require more cost than those two devices prices together.

banana_giraffe 5y ago

So, I might be missing something, but there are a couple of no-name HDMI/USB KVMs on Amazon in your price range (i.e., https://www.amazon.com/dp/B08NVKHRRT https://www.amazon.com/dp/B08NVKHRRT ) Some of the reviews suggest it acts as a pretty brain dead switch, which may cause problems with the OS. I know for a while I had a Windows 10 PC's monitor on a remote switch for silly reasons. I had to make sure to lock the PC before the monitor would turn off, otherwise some combination of driver/os/whatever would treat the disappearance of the monitor as a resolution change, and all my windows would get squished into 640x480. I could see KVMs like this triggering the same sort of madness.

alar44 5y ago
In addition to what you said, these things will shit out in a couple years. Button breaks, cord goes bad, etc. You pay for the quality.

Aeolun 5y ago

My first KVM switch was in the price range you mentioned, but switching caused the screen to go black for a while due to some HDMI stuff. The more expensive one I have now keeps both connections open at the same time, and switching takes a second or so. I dunno, I started thinking of it like switching from one game server to another, if you (somehow) do it in the middle of a game, stuff is bound to explode.

bradknowles 5y ago

You should ask the guys at Level1 Techs. They supposedly make the best DisplayPort KVMs in the business.

antifa 5y ago

I'd love a USB-only KVM style product, unfortunately newegg has decided to infringe on amazon's patent for "user must wade through endless ocean of unrelated garbage if sorting by lowest price". Logitech has a keyboard that perfectly connects to 3 devices (unifying and/or BT) but they don't have a mouse that follows the keyboard and their mouse oriented work-arounds for that are garbage.