Hi There,
This is my first post. But I am very happy with this setup, so I thought it was too good, not share with everyone.
USE-CASE: As part of my Job I normally have multiple device setup that all output via HDMI, This could be WindowsPCs, Raspberry PIs or just anything with an HDMI Output.
I used a 4 input HDMI switcher that allowed multiple devices to display simultaneously. As seen in Fig1, the HDMI switcher allows you to view all 4 input simultaneously in a couple of formats. This worked great and for a long time, I was using a USB to HDMI capture to stream these feeds live to anyone I was having a virtual meeting with as well as being able to record the HDMI output at 60fps 1080p. 
However, this was only good for when I was at home. I wanted a way to be able to view the output of the switcher remotely and control the inputs and output of the switcher too. So I added a second USB capture card to raspberry pi and installed MotionEye to it. WHALA! A nice way of viewing the stream. Then I connected my Synology to the HDMI Switcher via an RS232 cable and worked out how to change the input and output via RS232 
FIG 1:
KIT LIST:
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Eazy2hD HDMI 4x1
https://www.amazon.co.uk/gp/product/B01HTDD6W4/
NOTES: Currently not available but there are alternatives) -
Magewell USB 3.0 HDMI Full HD Video Capture Device 1080p
https://www.amazon.co.uk/gp/product/B00I16VQOY
NOTES: This device is quite expensive and there are cheaper alternatives. I would recommend testing with your Operating System to, This one only worked on macOS for me) -
Mirabox USB 3.0 HDMI Game Capture Card 1080P 60FPS:
https://www.amazon.co.uk/gp/product/B07G84G7VF
NOTES: It took me a few tries to find an HDMI capture device that works well with MotionOS. This one is working well so far (3 weeks in)
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Synology NAS, Not going to go into detail here but I run HassIO in a VM. This is quite a new transition as before I was running in Docker.
-
Monitor: LG Widescreen helps me with multitasking and a separate 16:9 HD screen (Dual Monitor setup)
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Raspberry Pi3 Running MotionEye (HTTP Stream, would like to move to RTSP in the future)
Screen Shot from HA:
If you click the stream thumbnail it takes you to the Live stream from MotionEye,
In addition to this, I have most of the input device powered over PoE with UniFi integrated into HA so I am able to power up and power down devices as needed.
Side Note: The input into my Macbook is using the Magewell device, just shows up as a camera input and is great fun when combined with CamTwist (Free software). OBS has only got a virtual camera driver for windows currently 
Future Improvements: I Want to integrate this into Chromecast features to stream to any TV or Chromecast enabled device. Hens wanting to use an RTSP stream instead of HTTP Stream
This is my first post so be kind with your feedback. But very happy to know if you think I can improve this in any way?