[Prezime]

Ne koristim "Amazon VOD" addon u Kodi-u, ali kako u UHD rade i Netflix addon i HBO_Max addon sa Atmos zvukom, pretpostavljam da bi i Amazon VOD radio.
Svakako procitaj za vise informacija: https://github.com/Sandmann79/xbmc i ovo:

"How can I play movies in HD/UHD?
Due to some limitations, we/IS.A are currently unable to play content with 4K or higher resolution. HD playback is only possible with a Widevine L1 secured device (mostly Android, e.g. Shield, MiBox), all other devices are limited to SD resolution.
On Android you can enable the use android app for 4K videos at settings. This starts the video in the official prime video app and works only for videos with "UHD", "Ultra HD" or "4K" in the video title."

Ako ti nudi samo HD rezolucije, onda trebas podesit i "inputstream.adaptive" prema objasnjenju na gornjim linkovima.