With quad link SDI connections, there are two primary signal formats:
- Square Division Quad Split - each cable carries 1 quadrant of the image
- 2 Sample Interleave (2SI) - every 2-pixels alternate between different cables
With Square Division, each cable carries 1/4 of the image, so each signal can actually be viewed independently if desired. With 2SI, you kind of need to recombine all of the samples (de-interleave them) to construct a full frame of video.
Square Division is a little bit simpler to implement, but it does have some downsides, particularly in terms of latency. Since all of the quadrants really need to be clocked together so they can be displayed at the same time, you kind of have to wait until you get the full frame so that you can divide it up and start transmitting (or technically the delay is only 1/2 a frame because once you have the top two quadrants of a frame, you can process the lower two quadrants line by line in real time).
With 2SI, there's almost no latency, since every two pixels go out to a different cable, there's no waiting around for a big chunk of the frame to split up. There's some more background and tradeoffs of the different approaches here:
https://blog.rossvideo.com/how-to-go-uh ... -equipmentAnyhow, getting back to the Teranex Mini 8K, from the tech specs it looks like the Teranex Mini supports both Square Division and 2SI signal formats on its SDI inputs. However, I don't think there is any standard for HDMI video over 4 connectors.
My guess is that the Teranex probably uses the square division quad split approach on its HDMI outputs, with each cable carrying one quadrant of the image. This is based on the fact that in the product pages there is some reference to using quad split to build a video wall from 4 monitors.
In terms of 8K TV options, the Sharp LV-70X500E can handle 8K video over 4 HDMI 2.0 connectors, but it seems like it is only being sold in Europe. Pretty much all of the consumer-oriented 8K TVs being released in 2019 are using HDMI 2.1 to input 8K video over a single connector.
I'm doubtful we are going to see many 8K TVs with the quad HDMI input option moving forward. It seems like everything is going the HDMI 2.1 route now that HDMI 2.1 chips are becoming more available.
Hopefully, the Teranex Mini 8K is firmware upgradeable to add HDMI 2.1 support allowing 8K video over a single cable. Otherwise you are going to need multiple screens to monitor in 8K in most cases.
Incidentally, HDMI 2.1 adds a bunch of new stuff to the HDMI spec (as if there weren't enough in there already). For example, HDMI 2.1 adds Display Stream Compression (DSC 1.2, also used in DisplayPort) to enable 8K60 video at higher than 4:2:0 sub-sampling, but still fit it within the 48 Gbps bandwidth spec.