These days, even phone-class CPUs can decode 4k video at playback rate, but they use a lot of power doing it. Not reasonable for battery-powered devices. For AC-powered devices, the problem might be heat dissipation, particularly for little streaming boxes with only passive cooling.
I'm using an Elgato CamLink 4k at 1080p60 for now & I'm wondering if the awful mouse feel in Linux (with a Mac for display) is maybe due to delay. Going to get a cheap-ash monitor to simplify. I thought it would be nice to have my 6k Pro XDR display have windows from all computers, but it's just too messy.
Worked on DEC Alpha, AMD K7 & K8, Broadcom, P.A. Semi, was in turn purchased by Apple. Jim spent four years at Apple before first returning to AMD, then on to Tesla, Intel and finally Tenstorrent.
