Black screen on Elgato Cam Link 4K and generic HDMI to UVC adapter

[jeremyherbert]

Hi,

Thanks for sharing this project! I'm currently running it on the Tang Nano 9k and it works great on my HDMI LCD monitor, but I can't get it to show anything on HDMI capture devices. I have tried with an Elgato Cam Link 4K, as well as a generic HDMI to UVC adapter: https://www.adafruit.com/product/4669 (these are all over ebay/aliexpress too)

On the Cam Link is an LED which indicates that it is capturing, and when I connect the Tang Nano the LED remains off. Also, when I connect the device to a HDMI switcher, it doesn't detect that a video input has been connected. On the generic UVC adapter, it seems like I just get a black screen, though I am unsure exactly if it can detect the video stream or it just outputs a black screen by default.

Have you tested this on any HDMI capture devices? I haven't modified the project at all, I just followed the instructions in the readme, then built and flashed it with the gowin IDE and openFPGAloader. FWIW, I also flashed the picotiny example which comes with the Tang Nano 9k, and it also fails to capture.

[Martoni]

Hi @jeremyherbert,
Have you tryied the project with a standard HDMI screen ?
I never tested it with a HDMI capture devices, but it's an interesting test.
If I can found this device I will test.

[jeremyherbert]

Yes, I have, my HDMI monitor works fine. I was just hoping to tinker with HDMI but without giving up a whole screen :)

You can find them for quite cheap on Aliexpress by searching for "HDMI capture USB", for example: here.