Amazon Prime, like many services, is a DRM hell. It won’t go to over 480p on Firefox on Linux at my end. However, instead of a rant, I am interested in why this is happening. Say, I rented the same film from YouTube Movies(Yes, such a service exists) and the quality can toggle all the upto 1080p but the same title on Prime Video is stuck at 480p. Is it because both services use two DIFFERENT kinds of DRM?
I think they’re using Widevine DRM. And with DRM they can enforce whatever arbitrary policies they like. They set special restrictions for Linux. I think Amazon set 480p as max, Netflix 720p and YouTube 4k or sth like that. AFAIK it has little to do with technology. It’s just a number that the specific company sets in their configuration.