Can the Mi Box S play high bitrate 4K HDR movies (say 60 mbps hvec) smoothly through a HDD connected to the USB port? My Samsung TV can't play DTS audio and I don't feel like converting all the movies I have in DTS. Would the Mi Box S be good for that purpose?
The AMLogic S905X chipset in the Mi Box can easily handle 4K Bluray Rips - IF - you can get the data into it properly.
And as stated below, even USB2 has plenty of data bandwidth for that purpose.
I personally use an AMLogic chipset device running CoreELEC Kodi for local high bitrate video playback:
Should be fine, check this. https://youtu.be/mHMeN-M9xSE
Though problem you might have later on is with DTS as mibox suppose to be dts 2.0 only and needs Passthrough to get 5.1 on receiver. Kodi used to be the one that was working fine but since 9.0 (mibox 3) any player that support dts should work by changing audio settings.. for me selecting spdif did the trick.
You need to keep in mind that the port on the Mibox is USB 2.0, so the theoretical maximum transfer speed is 480Mb/s. On my PC, using a SATA SSD on a UASP enclosure, I get about 38MB/s transfer connecting it to USB 2.0 port, while I get 10 times that (380MB/s) on a USB 3.0 port