camera video stuttering in Tracked_Unreal_AR



I got potential customer who wants AR in his studio with Aximmetry Unreal.

I have a test place with below condition and I did some Unreal AR test but has camera video stuttering issue.

- 1080p59.94 camera on Jimmy jib.

- Redspy(Stype) camera tracker

- Broadcast DE

- Unreal AR sample(simple desk)


- AR moving is OK.(no stuttering)

- only camera video stuttering during jib moving(camera moving)

- GPU load less than 50%

- Input/output/rendering setup all to 1080p59.94

Do you know what may causes this stuttering issue?

I didn't do tracking delay or camera delay as I think it may not related this stuttering issue.

Hope to have any suggestion to solve this.

Thanks in advance.



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I just realize that it needs REF signal to stop stuttering.

And I still can say it's not like original camera signal...

Any comment to make it better?


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 feel like something is not right after 21.3.0 build. And I'm using 21.3.1 now

I didn't recognized video input stuttering at all before which will be 21.2.2 build, and now I also can see camera video stuttering even direct video input to output like below.

I use decklink duo2 and another one 8k pro. Both shows same symptom.

Should I try other vendor capture card?

Hope someone let me have a clue.


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You need to sync your BM cards and the camera  with genlock provided by an external Sync Generator.

And use the checkbox Sync on your Output.

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I don’t think you necessarily need to genlock the BM cards. We don’t do that with our Decklink 8K Pro and get absolutely no stuttering. The Sync checkbox is to automatically set the Aximmetry project frame rate to the same frame rate you have your output set to and doesn’t have anything to do with genlock.

A wild guess, but I think this could be a PsF signal issue, where a progressive video is sent in a interlaced signal. Sony and Canon use this format for some reason in many of their cameras. 

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I can only guess as well. I am not sure what screen do you use to check it back, but isn't it possible that it can handle only 60fps? (and not 59.94) 

Best Regards

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Without genlock, my system definitely is stuttering.

All genlocking for PC, camera and redspy makes perfect.

Thanks for you guys concerning.