Recommended hardware for 4-8K video input to 5x1080p VPs with configurable mapping

Hardware
1

Hi there,

I’m trying to find (or build) a solution for real-time multi-videoprojectors mapping.
I’m fairly new to video equipment and bottlenecks, so I apologize in advance for any misconceptions I may have. Any tips or expertise is appreciated.

Specifications:

  • The device I’m looking for should be able to capture 1 video stream (at least 4K@30Hz) and share its stream between 5 VPs (1080p each). The mapping correction and layout can vary and should be remotely control (cropping, keystone). So if I go for a PC-based solution, I would need a 6th video output to get a monitoring screen.
  • The video latency from the capture to the playback should be as short as possible because it’s for audiovisual shows.
  • I wonder if I can find a hardware solution to run this task within a pretty small budget <2000€.

I’ve seen some standalone cards such as the Matrox QuadHead2Go. However they does not seem to have keystone control. They also only have 4 video outputs and I would have to double the price to chain 2 of them to get my 5 outputs.
I’ve also seen some low cost ones such as the OREI Wall Controller Processor Display. Besides the price, what are the differences with the more expensive ones? Do they induce more latency?
Any idea of a standalone cards that can do keystone for multiple outputs?

Alternatively, I’m looking for a PC-based solution that could handle this. For that I was thinking of using:

I think I have some misunderstandings about how video outputs from GPU work. For instance on a 4090 the specs from NVIDIA says “Multi Monitor → up to 4”.
Does that mean that If I want a 5th monitor, I would necessarily need a secondary graphic card or video device like I mentioned above?
Or can I just use a MST (Multiple Streams Transport) hub such as this one to extend one of the DP ports to 2 HDMI outputs and get 5 monitor displays in total?
For the last case, what I’ve seen from the forums is that I would need to have a GPU able to handle more than 4 outputs (e.g. 6 for the AMD W6800). And even if there are only 4 physical outputs an MST hub can be used in this case. But I’m not sure I understood it correctly.

I’ve also seen the Matrox C680 video card which has 6 physical outputs which seems to be perfect for my case. But it is a bit old and rare. And I don’t know if it would be sufficient by itself for my task? or if I would need a more powerful primary GPU.

Above all these questions, I wonder what computing power and memory specifications to choose for the PC. Since its only task would be to capture the input video stream, map it and broadcast it on the 5 VPs I don’t think it would require a high end GPU neither CPU. But I don’t know much more about it.
What GPU, CPU, RAM specs would you recommend for this kind of task?
What kind of motherboard would be suited to handle 1 video capture card, one primary GPU and a secondary one?

Thanks in advance.
Adrien