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I am trying to connect the HDMI of another device to my computer, but of course the graphic cards don't support HDMI input, so connecting HDMI to HDMI is out of the question.

Since USB-C to HDMI adapters are sold, is it possible to make USB C on my computer as an HDMI in port? (as USB-C is capable of transferring data both ways), and if so how can I do that?

To bring an example, lets say connect a gaming console HDMI port to my computer (like a Xbox or PS), and see it on my screen.

To sum it up, from the original device there would be HDMI, and the input that goes in on my device is USB-C

Or another alternative that would work for me is if it is possible to mirror the screen by connecting a USB C to USB C together.

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  • I think, either way, you're going to be looking for "USB video capture card" - whether there are many "USB-C" cards available just yet is going to need you to research.
    – Kinnectus
    Jun 13 '17 at 15:52
  • Yes, there are USB-C devices that output HDMI. This is a shopping request question though. Jun 13 '17 at 16:30
  • @music2myear No there is not. All those "capture cards" have a delay of around half a second which makes even Remote Desktop over LAN a more viable option then using capture cards.
    – Kirill2485
    Jun 13 '17 at 17:30
  • Laptops are generally not capable of serving their internal displays as usable screens for high speed graphics from a different source. I'm pretty sure that question had been asked before, but I'd have to search to find it. Jun 13 '17 at 17:56
  • @music2myear Again, thats only with USB 3.0, not USB-C. Have you heard of a device called the Razer Graphics Amplifier? It works with ANY laptop that has a USB-C port.
    – Kirill2485
    Jun 13 '17 at 18:04
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I am trying to connect the HDMI of another device to my computer, but of course the graphic cards don't support HDMI input, so connecting HDMI to HDMI is out of the question.

Correct. You either need:

  1. A device with graphics input (HDMI/DVI/DP/... in, possibly with an additional convertor).
  2. Or something which captures the input. Usually to a file or to a window of the capture program. If you maximize this then you are close to your goal.

Since USB-C to HDMI adapters are sold, is it possible to make USB C on my computer as an HDMI in port? (as USB-C is capable of transferring data both ways), and if so how can I do that?

No. First of all those adaptors are HDMI output. They work the wrong way around.

Secondly, USB-C does not carry video. USB-C is the physical form or a connector usually used for two things:

  • USB 3.1 gen 2, or
  • Thunderbolt 3.

Note that thunderbolt signals can be muxed with displayport video data. There are example where a TB port (with USB-C form factor) is used to attach a monitor. However you best consider it a graphics out with in an alternative connector.

Also note that most (all current?) TB3 connectors use an Intel chipset which can do both TB and/or USB on the same plug. in USB mode it does nothing special with graphics.

To bring an example, lets say connect a gaming console HDMI port to my computer (like a Xbox or PS), and see it on my screen. To sum it up, from the original device there would be HDMI, and the input that goes in on my device is USB-C

For that specific case you need a framegrabber/digitizer with HDMI input and with an USB-C connector to communicate with the computer. And I intentionally write 'communicate' rather than 'steam video in a regular format'.

Or another alternative that would work for me is if it is possible to mirror the screen by connecting a USB C to USB C together.

This would do nothing. And unless USB changed the master-slave setup it can not even work.

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  • Also, HDMI doesn't support 4k@60hz, while USB-C does. So USB-C is the superior display cable over HDMI.
    – Kirill2485
    Jun 14 '17 at 2:15
  • It would do nothing, that is correct, because of drivers. Wouldn't capturing RAW USB C data on the client device be able to capture the information to build a picture? Using wiki.wireshark.org/CaptureSetup/USB for example.
    – Kirill2485
    Jun 14 '17 at 2:27
  • We can't deal with theoretical solutions because they are theories, not yet existing. The USB protocol is fast, but raw speed isn't everything, and there has to be software and hardware to do this, and these do not yet exist outside the forms we have already mentioned to you. Jun 14 '17 at 4:50
  • Here's a different example: the computer mouse. It was first used over PS/2 ports and Microsoft had no role into making the new standard for mice to become USB. Logitech, with no help from Microsoft, invented the first USB Wheel Mouse. Before this it was not possible to use a PS/2 to USB adapter to capture mouse movements. But after a few years they also came out with PS/2 - USB adapters.
    – Kirill2485
    Jun 14 '17 at 6:06
  • I also got it to work on a hackintosh thanks to Reddit but I want it to work on Windows, but this is evidence that its possible and its 100% software based. support.apple.com/en-us/HT204592
    – Kirill2485
    Jun 14 '17 at 6:12
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Just to make certain I understand your question based on OP and the comments: You want your laptop display to act as a screen for an external video source, and the video connectors on your laptop are not capable of input.

If this is not the case, please clarify your question by editing it.

If the external graphics source is another laptop, there are programs that allow this function: Can I use my laptop as a second monitor?

If the external source is anything else, the answer is "no".

The ports on the laptop are only one part of the equation. The other part is that there is not a direct connection from the ports on your laptop to the screen on your laptop, and so any signal coming in through ANY of the ports must go through processing of some sort in order to be displayed on the laptop's screen. There is software and hardware that can do this (video capture), but it is unlikely to meet your needs.

Specifically regarding Remote Desktop, these are typically very optimized protocols and systems that usually do at least some of the processing of the graphical output on the client computer, allowing for near-realtime display of the remote screen contents.

I would recommend you look into video capture, and specifically capturing video for immediate display or playback. These will still not be realtime, but they may get close enough for certain use.

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  • All those "second monitor" programs do it over LAN, which is limited to 1gigabit due to Ethernet capabilities. On the otherhand, HDMI is 24gbps, while USB-C is 100gbps
    – Kirill2485
    Jun 14 '17 at 2:20
  • Those are the limitations you must deal with, and focusing on the raw specs isn't the correct perspective. How much bandwidth is needed to send a screens' worth of data? The LAN-based technologies are mature and work generally well and widely. The other techs are newer. There are different overheads. And when it comes down to it, your wanting something to exist does not make it exist. With your avaliable connectors you can go capture card or you can go home. That's what it comes down to. Jun 14 '17 at 2:33
  • Well HDMI 1.4a is maxed out at 2k display. 4k would have to be rendered at 30fps due to 30hz... so apparently 21gbps isn't enough to render a quality 4k picture, now imagine how much banndwith it would take to render a 1080p picture smoothly, probably around 10gbps, while Ethernet is 1gbps
    – Kirill2485
    Jun 14 '17 at 3:54
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    You still don't get it. The reason that works is because Apple designed the iMac to be able to do that. It is a combination of hardware that you don't see and software that you do. We've been telling you basically that exact thing for the past day. There is nothing similar built-in to Windows by default, and a computer manufacturer would have to explicitly design their computer to function in that way and would have to offer drivers that performed that function. Jun 14 '17 at 15:59
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    Note: USB 3.1 Gen 2 is 10gbps not 100gbps. That's what USB C has.
    – chx
    Jan 11 '18 at 9:24
-1

Here is a simple hdmi input to usb-c: https://sandberg.world/en-se/product/hdmi-capture-link-to-usb-c

Have not tried it

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