Capture and playback of dual 4K60 12G

I have 2 cameras set up in a stereoscopic configuration, each outputting 12G-SDI @ 10 bit 4:2:2 in either UHD or DCI4K.

I'd like to be able to record and then immediately play back synchronized. I thought I could do that with a Hyperdeck 8K Extreme, but it does 2SI, not quads, and even then half the pixels are wasted.

So is there either:

1. A way to set the Hyperdeck 8K to square division?
2. A way to set the Hyperdeck 8K to record multiple single link 12G streams?
3. A converter from quad 12G square division to quad 12G 2SI?
4. Two 4K 12G recorders that can be slaved together for recording AND playback?

That's strange that the HyperDeck 8K Extreme does not accept square division quad split SDI input signals, since the Teranex SDI to HDMI 8K supports this format (in addition to 2SI).

Recording 4 independent video inputs is not supported on the HyperDeck 8K, although it has been requested by more than one person (of course, people requested the ability to record 4 HD streams on the HyperDeck Studio Pro too, but nothing ever came of that).

You might be able to accomplish what you want with two DeckLink 8K Pro cards in a single computer (one for recording and one for playback). I believe these cards do support quad split SDI inputs, although you may need a pretty fast machine to encode the video.

Another option would be to use 2 HyperDeck Studio 12G units. I believe if you genlock the HyperDecks to the same reference source and use a RS-422 remote controller with support for controlling multiple decks, you should be able to achieve synchronized playback (since both decks will start playing at the same time, and the frame timing will be determined by the reference source).

Yes, the Decklink 8K officially supports DCI 4K60 I/O on each of the 4 inputs, it was an update added after release. So you can record 3 cameras and output to the 4th or whatever. Very flexible.

I just want the same capabilities in a standalone unit.

Good tip on the HyperDeck Studio 12G, I forgot those existed. I'll see if they've been updated for DCI resolution, but I could probably get away with UHD if it works.