Fill and key randomly async over time

I have a problem that my fill and key of CasparCG is randomly async. It can happen at the beginning or after one hour. After another hour it can be in sync again.
I’m working with two Blackmagic DeckLink Mini Monitor 4K. Are the numbers maybe a problem? My config:


You will never get a stable fill & key with two individual cards.


Ah ok, that makes sense because I couldnt figure out why its so random. So I need a duo card?

That is a possibility, yes.

No, it may be the same with a Duo card. This is just 2 in one.
You need a card with external fill and key out like the Decklink Pro or Extreme series.

That is correct for the old Duo card, but not for the Duo 2. This has 4 outs and in the control panel applet you can set them up to 2 times fill and key.

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So a DeckLink Duo 2 DeckLink 8K Pro would be the solution for me? What would be the best choice in your opinion? And nothing else would help?

Yes, I think so.

The Duo 2 can only do HD. The 8K can also do 4K (I don’t know if it could do fill & key in 8K). So dependent on your jobs you can choose. If HD is ok, there is also the Duo 2 mini, that is a low profile card. You could also use the Extreme. It has a bunch of analog I/O, but it is more expensive and only a single fill & key.

In the end it is always better to have the fill & key coming from the hardware. Beside being more reliable you also gain performance, as Caspar only needs to output one stream of video instead of two.