OBS Studio 28 breaks keyer in Decklink Output, performance in 4K extremely poor

[PhotoJoseph]

Operating System Info

macOS 12

Other OS

No response

OBS Studio Version

28.0.3

OBS Studio Version (Other)

No response

OBS Studio Log URL

https://obsproject.com/logs/Ysc4v8pJc2ksZueX

OBS Studio Crash Log URL

No response

Expected Behavior

Key and Fill on Blackmagic hardware output when Keyer is enabled

Current Behavior

On OBS 28, this no longer works. Same image (or close to the same image) is output both on key and fill channels. Reverting to OBS 27 resolves this.

Steps to Reproduce

1. Install Decklink or UltraStudio
2. Switch to Video Color Format: RGB in Advanced settings, per Decklink Output instructions
3. Enable Decklink output with a keyer enabled
4. view separate key and fill feeds; they are virtually identical.

Anything else we should know?

No response

[Fenrirthviti]

I have this device and in my testing it was broken in both 27 and 28. Can you give me as close to the exact steps for this as you can so I can test?

[PhotoJoseph]

Sure thing. I have the same result on an UltraStudio 4K Mini and Decklink 8K Pro PCIe card.

• OBS 27.2.4 Intel build works (key and fill are correct); OBS 28.0.3 does not (key and fill are the same)
• Mac is Intel Mac Pro on macOS Monterey 12.4
• I generated a graphic a few ways but the simplest was just a PNG dragged into the OBS canvas. Key and fill were nearly identical, but the key was slightly… off color? But not a B&W key for sure!
• BMD Desktop Video Setup is at v12.3. There is a 12.4 out but I think that was just an ARM processor update so I haven't installed
• OBS Settings > Advanced > Video > Color Format is set to RGB, per the instructions in the Decklink Output window (quite hidden, I must say… that critical little note should be at the top!).
• in Decklink Output, keyer is set to External and of course the framerate (mode) is set to match the OBS Video settings (in my case, 3840x2160 @ 29.97)

[sneaker333]

I had started a discussion in the forum which has some photos to illustrate the issue ... https://obsproject.com/forum/threads/decklink-keyer-output-broken-on-28-0.159096/

I have yet to test 28.0.3, but I'm not hopeful. The comments in that thread implied that the issue is not platform-specific.

[Fenrirthviti]

Thanks for the detailed steps, I should be able to hopefully get to some testing either this week or early next week.

[PhotoJoseph]

awesome, thanks @Fenrirthviti I can test pretty quickly once you have something up.

[DrEVILish]

Still broken in v28 v29 beta works as expected when switching back to v27

[Fenrirthviti]

We are aware of the issues, but no ETA on when they might be resolved.

[jpark37]

FWIW, #7786 and #7814 were recently merged. Along with #8501, those collectively should bring some perf relief and I did some basic keyer testing although I'll stop short of promising that it's completely fixed. The code paths are very different going forward, so bugs you were seeing before won't be the same at the very least.

[jpark37]

Also, pinging me is usually the best way to get your request reordered to the end of my backlog, but circumstances are a little different in this case. Please don't make it a habit.

[aaronpk]

I just tried updating to OBS 30, but this is still broken. I get the same image on the key and fill outputs of the Ultrastudio.

The first photo is from OBS 27. I created a scene in OBS with just a red rectangle. It shows as I expect, the fill channel has the red rectangle and the key channel has the white rectangle.

The second photo is from OBS 30. Both channels are outputting the red rectangle so the key fails.

I'm running:

• MacOS Ventura 13.3.1
• M1 Mac Mini
• UltraStudio 4K Mini

[aaronpk]

Update: I forgot to check the version of the Blackmagic Desktop Video software! I was previously using version 12.0, and I just updated it to the current 12.7 and now the key channel works properly in OBS 30.0.0!