Synology Camera Integration: how does the "camera orientation" setting work?

I have a couple of very cheap TP-Link Tapo cams connected via Synology Surveillance Station to give me continuous local recording, and then via the Synology_DSM integration to HA to give me a quick accessible live view from my home dashboard. I get best coverage of my driveway if one cam is mounted at 90degrees from normal horizontal. Unfortunately, neither the native Tapo app nor Synology Surveillance Station allow me to rotate the image 90 degrees, even though its an option for some cameras. However, under settings for the camera entity exposed in HA I came across a “camera orientation” property and can rotate the stream 90 degrees.

My question is how the integration works with the camera stream to achieve the rotation so “easily”, where neither TP-Link or Synology could? I assume some stream magic on my HA client or Synology/Camera is going on but I’d be interested to know exactly how as its not appreciably added any extra load that I can detect.

Having done that rotation, I’d like to crop the top and bottom of the video in the picture-entity that displays the live view - anyone have a suggestion if/how that might possible with some css wizardry and card-mod?