RESOLVED: [Windows 2021.13610] Video Device Out TOP - Blackmagic Decklink 8K Pro - 10 bit output issue

Hi there!

I’m attempting to output two separate 3840x2160 @ 59.94 Hz video signals at 10-bit color depth via SDI out of our Blackmagic Decklink 8K Pro via a Video Device Out TOP, and our 12G SDI monitors we’re using to test output with recognize that it is a 4k 59.94 10-bit video signal, but the display output shows up black.

The Decklink 8K says it is rated to send 10 and even 12-bit color at any signal format, so to my knowledge this should technically work. Changing color depth to 8-bit allows us to send successfully at any signal format.

What’s really strange is that when we mess with the connector mapping settings in the Decklink setup utility so that software output #1 is mapped to every hardware SDI output (“SDI 1 to 4 In or Out”), the duplicated signal shows up on both of the monitors just fine at 4k59.94 10-bit. Also, when swapping our signal format to 4k30 10-bit or 4k59.94 8-bit we’re getting good signal for both.

Do you folks have any experience with this or have any recommendations for a good solve? I noticed in the Video Server Spec documentation on the site that the Decklink 8K Pro has been well-tested, so want to make sure I’m doing everything on my end correctly here. I also saw on this forum post: FIXED: [2021.11180] GPU Direct Not Function When Using Nvidia A6000 And Blackmagic Decklink 8k Pro - #4 by ivantsai21 that Derivative has the native Blackmagic library compiled against the 11.2 SDK, when we’re currently on 12.0.

Here are some machine and driver/firmware/software specs:
Windows 10
TD 099 2021.13610
Decklink firmware 12.0

I sincerely appreciate any support/advice on this! Thanks!

The driver version vs. the SKD version should be fine. I’ve been running 12.0 drivers on my machine without issue. If you are trying to send the 4K signal out over a single wire, you’ll want to set the device to be ‘SDI 1 In or Out’ (and the others should be ‘SDI 2 In or Out’ etc.). With the SDI 1 to 4 In or Out, you are trying to do a quad-link set where all 4 outputs are bound to a single device.
Let me know if that doesn’t help.

Confirmed that this is a bug currently. I have a branch build of 2021.10000 I can share with people that run into it. It’ll be also fixed in the 2021.30000 series.

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Just ran into this issue, has this change been merged into 2021.14360, or do we need to use a custom build? Thanks!

The change was too large to merge into the main 10K unfortunately.
Here is a link to the branch build though:

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Thank you for this build, Malcolm!

I ended up integrating this into a project with great success - a noticeable jump in quality for gradients and other subtle content.

Do you think this will be rolled into the next official release, or will this continue to need custom builds? Additionally, do you forsee any major issues with using 14357 vs 14360, if no new features from 14360 are being used?

This will be integrated into the 2021.30000 series of builds. There is no issues using the build though. If you need new features that come out in future 2021.10000 series releases, I can update this branch build so it has those, just let me know.

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Thanks, Malcolm - looking forward to trying out the 2021.30K builds.

Hi Malcolm, was the 10bit fix included in the official 15K branch? 2021.15020


Build series’ go by 2021.1xxxx, 2021.3xxxx, 2022.2xxxx, 2022.4xxxx etc. So 15020 is still part of the 2021.10000 Officials. This fix will be in the 2021.30000 releases. Here is a updated branch build that has the fix though:

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