How to use a laptop with a HDMI to usb capture card as a screen for a thin client?

Last Updated on October 21, 2023 by pg@petergamma.org

Many of the remote desktop options how to control a Pi over a direct ethernet cable we discussed here are not very straightforward:

https://petergamma.org/category/singe-board-computer-displays/

Our is to use an Android phone as a Pi screen as shown in this video:

• Android phones have an excellent power management, but how to find a Pi screen with an excellent power management?
• Is not an Android phone over an usb capture card the best solution to solve this problem? It uses the HDMI connector but not the ethernet plug so we still have the wired ethernet plug to connect the Pi for instance to a router.

• We have connected an Android phone according to the above video instruction to a Pi 4.
• There are many usb capture cards on the market, we bought one of those and tested it.
• But the Android app we have choosen did not recognize the capture card no matter what we did.
• It is a complicated chain of connectors and adapters to connect a Pi in this way to an Android phone. Maybe a connector was faulty.

So we tried something else

• We started our next tests with a thin client and a laptop..
• We have connected the thin client over a HDMI cable to the usb capture card to the usb plug of a laptop.
• Then we have installed OSB studio on our laptop.
• There are numerous instructions available how to do this.
• We do not remember if it was exactly the following one:

• But it worked straight away.
• First we where able to see the thin client desktop in the upper windows of OBS studio.

But later on we sah only colorful stripes in OBC studio what is wrong is the usb capture card faulty?

• No, pressing the power button on our thin client solved this. problem.
• The colorful stripes are shown in OBS studio when the screen saver is running on the thin client.
• After pressing the power botton which was blinking on our thin client we could see the thin client desktop again on our laptop screen.

How to get full screen view on the Laptop with this setup?

• The follwoing instruction shows how to do this:

• We had to open a special window for the thin client desktop by a right click an maximize it.
• Now we have a full screen of our thin client desktop on our laptop screen.

• The borders are not perfect but it works.

W are able to control the thin client by keyboard and mouse with only the laptop as a screen.

• After the reboot OSB studio connected automatically again to the thin client connected over the usb capture cart to the old laptop and showed the desktop again, which is great.

This setup needs further testing and the connection seems to be a bit laggish but this test was successful. OSB studio offers tons of settings, it should be possible to get rid of the lag in the screen.