A great rule I always follow for high quality is this formula. (1920x1080/600=3456). So around 3.5/4.0 mb for really solid 1080 VTC. Or if it's more around 720 (1280x720/600=1536). So 1.5/2.0 mb.
Does that make sense? Usually the standard I have heard lately is 4.0 up/down for good quality VTC.
Don't forget you need to add 20% for overheads.
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