I'm telling you their numbers don't make sense mathematically. It's what you call a triangle inequality.
That is, if I separate a 4K video stream into 4 1080p streams (just the 4 quadranges of the image rectangle), and encode each of those streams at 5mbps, I can put them together on the other end to have a 4K signal at 20mbps.
That being the dumb way to do it. Treating it as a single image would yield further advantages, so the number goes down from there.
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