We have just purchased a TouchDesigner Pro license in order to test the new “sync outputs” option with our 2 blackmagic decklink 8K Pro cards.
I have upgraded TouchDesigner to the lastest version (2025.31740) and the drivers of the decklink cards are now also at the lastest version (14.4). (operating system = Windows)
Therefore i’m now able to activate the “Sync outputs” as long as the 5th output on the second decklink card is not getting synced in the same “sync group index”
So i’m noticing that i’m only able to sync 4 outputs on a single card.
Hey, I just tried this with two 8K cards and it works for me. Can you open the Blackmagic Desktop Video control panel and confirm both cards are showing the correct reference input there?
The other thing to test is try only using Sync Group with a single output, and then 2 outputs, from that second card (without using the first card). Does that work?
On the second card (without using the first card) i can succesfully use “sync outputs” + “sync group index=0”, both on a single output, or 2 outputs or 3 outputs or 4 outputs without an issue.
The error only arises when activating the same “sync group index” on outputs on both cards.
Regarding the reference/genlock:
We measuremened and tested the genlock of the Blackmagic Decklink 8K Pro cards. It originally had Tri-Level Sync on it, measured with an oscilloscope, and it looked good. However, the blackmagic software doesn’t seem to recognize it. Then I also tried with Blackburst, which also looked good on the oscilloscope, but it’s still not recognized in the software. I suspect it’s a specific problem related to the fact that it’s a 12G SDI card. BMD (Blackmagic Design)'s architecture for their DeckLink cards has always been strange when using every SDI connection as an individual output… And from what I read online, it might have to do with the internal resolution of the signal in the card and the properties of the genlock you provide it… Currently, I cannot solve it with our company house sync.
Could you give me some more details on your setup and if you had to do anything special to get the reference signal recognised on your cards?
Thanks for the investigation. There is nothing we can do from the software side to fix this. If the card isn’t recognizing the genlock in the Blackmagic Desktop Video app, then that is the issue.
The Blackmagic cards are able to do Synchronized Output withing a single card without a genlock source, which is why you can see it working with only one card. With multiple cards they require a genlock source though. We output an error if the cards report that they don’t have a genlock source.
You’ll need to reach out to Blackmagic support for help with this issue at this stage, until the genlock source is recognized by their utility.
OK makes sense, thanks for claifying. Will try to reach out to black Magic or try to get the reference signal to get recognised somehow. Will update here if we found a fix.
Think we’ll also test some deltacast cards soon that are also capable of doing sync output so hope they are a bit more robuust.
Could you please still let me know the exact video output format and the reference input format you were using on your side that allowed you to sync both decklink 8k pro cards, so I can also check if there is some kind of format mismatch on our side.
Just to let you know that we’ve managed to detect the sync on our blackmagic decklink 8k pro cards by using a (TLS) 720/p50 reference from a separate Rostec sync generator. After doing so, both the decklink video app and touchdesigner are capable of detecting the sync signal.
Now i’m also able to activate the “sync outputs“ option for the same “sync group index” on all 5 SDI outputs (2160p50).
Will still do a longer content sync test on our 17712x2048 ledwall to see if everything stays nice and synchronised.
(Next week we’ll also start testing the same but with DeltaCast)
