Help Please: GH5, ATOMOS, MixPre HDMI Timecode and Control

I'm hoping that our community might be able to solve this together.

I've received the same question 4 times this week alone: How do I get timecode and Record Start/Stop controls to work with the GH5, ATOMOS (Ninja V, Sumo, Shogun, etc.), and the MixPre (3, 6, 10T) via HDMI?

I was NOT able to get all of them working by routing and HDMI cable from the GH5 to the Sumo, and from the Sumo to the MixPre. However, I confirmed with the same cables that it works when you use just the GH5 and MixPre or just the GH5 and ATOMOS recorder.

One hypothesis is that an HDMI splitter might solve the problem: Route an HDMI cable from the GH5 to an HDMI splitter, and from there, one of the splitter outputs to the ATOMOS and the other output to from the splitter to the MixPre.

Has anyone had success with this?

If this works, there's still the problem of how to power the HDMI splitter as most of them require power. But I believe there are some which are USB powered so that might work.

Thanks if anyone has information on whether the HDMI splitter approach or any other approach works. I'll create another video if we are able to find a solution.

I know that this is a bit of a Frankenstein type of rig. I don't usually shoot this way but I used to and many others still do for various reasons.

Thanks!

Copyright 2019 - Curtis Judd