forghett wrote: ↑08 Jan 2020, 09:51
I can't understand how type of scaling (full screen, rescaled, noscaling ecc..) and way of scaling (gpu or display) can influence quality.
So my understanding is:
-Theoretically display scaling should be the one with less lag, even if modern gpus have barely noticiable scaling lag.
-What about scaling type ?
This is outdated information. In the past it was reliably true that displays had less scaling lag.
This is no longer reliably true for the last several years.
But very frequently GPU scaling has less lag nowadays on the fastest GPUs.
Much of the time, when both is lagless, there's no difference.
Fundamentally, there is scientifically no difference between display scaling and GPU scaling if implemented with the exactly same logic (practically lagless line-buffered scaling in a beam-raced manner). Even if line-buffered is not done, and full frame buffer is done instead, the fastest GPUs can scale a whole 1440p framebuffer in approximately 1/10,000th of a second -- all the 1000 and 2000 series NVIDIA GPUs do that in the -60 -70 and -80 classifications. The slower GPUs will still take less than 1/1000th a second. Now, some of them do real time line-buffered scaling at the GPU output level, so that is just exactly as lagless as display scaling.
If you've got 1060, 1070, 1080, 2070, 2080 or similarly fast GPU....
Best case scenario, lagless versus lagless.
Worst case, comparing unknown-lag display scaler versus predictably fast GPU scaling.
That's circa 2020 scenario, not outdated 2010 scenario.
The memory bandwidth and fillrate of the latest GPUs is so incredbly fast, that even full-framebuffer GPU scaling is darn near zero lag nowadays, but provides more predictability.
TL;DR: Modern GPU scaling at the high end GPU level, is more consistent guarantee. Monitors have more varying lag in GPU scaling (brand X versus Y can have hugely different scaling lag). But with GPU scaling, you get peace of mind of knowing lower scaling lag that is consistent regardless of what monitor you use, in scaled resolution being virtually identical in lag to original resolution.
Remember: This is not yesterday's slow GPU scaling.