Re:MacBook Pro 14-inch and MacBook Pro 16-inch
by vetinari on Tuesday October 19, 2021 @04:34AM
(#28916034)
They composite everything at nearest higher integer scale, with correspondingly large framebuffer (just make a screenshot of entire screen and check the dimensions). Then, during scan out, it is scaled down by output encoder.
This method does not need GPU at all and also saves memory bandwidth; no need to save scaled down framebuffer and read it out again.
Windows on the other hand, does the theoretically correct thing but messes up the ecosystem (unsupported apps, multiple monitors)