Decklink 8K Pro output delayed with 3-4 seconds

Hello! I have some major issues outputting from my Blackmagic Decklink 8K Pro. I’m sending key and fill to later be processes in Resolume but the video feed is delayed with between 3 to 4 seconds. If I disable the fill and only output one 8-bit channel the delay drops to 2-3 seconds which is still horrible. Everything updates in real-time in the editor as soon as I send my input.

I have tested sending NDI instead and that works perfectly with almost no delay. Same with outputting using Syphon Spout to OBS on the same machine. But due to reliability would I prefer to run the signal on SDI instead. And running an additional software like OBS to convert the Spout to SDI seems like an unnecessary step.

The machine is running an RTX A4000 with an i9-11900

UPDATE: This seems to be a bug introduced in version 2022.33910 released on 19 Jun, 2023. If I go back to any version before this everything works as intended.

Hi @Byberg

could you let us know which version of TouchDesigner you were experiencing this in?

cheers
Markus

Hello! I tested multiple versions to try to identify when the bug was introduced.

All versions I tested after 2022.32660 seem to have the bug. I think I specifically tested 2023.12000 and 2023.11510. And all version at and before works great.

Looking at the release notes I think this, from version 2022.33910, is the cause of the problem:

For now I will stay on 2022.32660 until it’s fixed

Thanks for the report. This issue isn’t widespread, and I can’t reproduce it myself. Can you tell us what signal format you are sending, and what settings you have the device setup as in the Blackmagic Desktop Video control panel? To really narrow this down, can you try out these two builds and see if the issue occurs in either of them?
https://www.dropbox.com/scl/fi/y6al67q5zc00fg96bgjyi/TouchDesigner.2022.32700.exe?rlkey=n1f6476kzr66d7fflu4atot4c&dl=0
https://www.dropbox.com/scl/fi/2nwwbrnmpl82ikmt9xdux/TouchDesigner.2022.32740.exe?rlkey=ee1b6p7u3hygw0y2gwf4se28m&dl=0

Thanks

Hi! I have done some more digging this morning and found it’s related to me outputting key and fill at a high resolution. If I just output a fill the problem is still there but a lot smaller.

I setup a light weight test scene to measure the time. Outputting a timecode that is looped back into the same card.

Here are the results:


2022.32660: 100ms delay. :white_check_mark:


2022.32700: 100ms delay :white_check_mark:


2022.32740: 500ms delay :warning:


2022.33910: 1363ms delay! :x:

Here are the settings I used on all tests:
settings

Thank you for looking into this issue