How to transfer video from USB camera to Decklink SDI?

Question

Video

There is a USB camera and a Blackmagic Decklink Duo I/O board.
How to transfer video from USB camera to Blackmagic card output?
I want to use ffmpeg or ffplay for this (compiled with the --enable-decklink option, of course).
I can get video from a USB camera with this command:
ffplay -f dshow -i video="Digital Camera"
Everything works fine.
How to transfer this video to Decklink (preferably with minimal delay or even better without it)? Already as soon as I did not try ...
If anyone knows, tell me.

Answer 1

On Windows XP, when installing a Decklink card, the so-called. extended display - working area with appropriate resolution. It is perfectly visible by connecting to the computer with radmin. The ffmpeg output window dragged there will go to SDI-out just fine. If you need sound, then you probably have to fiddle with virtual cables or do the same, but through vlc - redirect the sound input to Decklink Audio in the same place. On an OS higher than WinXP, the extended display was abandoned due to problems with the difference in color (I met this on their forum).