These rooms full of TVs are how Amazon gets Prime Video to look sharp on every device

A visit to Amazon's London headquarters provides an insight into how the retail-to-cloud-computing giant ensures that its Amazon Prime Video service works across thousands of different devices. And it involves lots and lots of TVs.

Amazon's London headquarters opened last year.

Amazon's video service can be accessed from thousands of different devices, so the company needs to make sure that there is a consistent service across them all.

In this room Amazon's engineers check the quality of the TV experience on different devices and the impact of new features like switching on High Dynamic Range (HDR) video to show more colour in the picture.

As the firmware in different TVs varies, Amazon has to understand and account for these differences.

This room aims to allow a consistent experience to be delivered across the fragmented set of devices. Around 5,500 different devices can run Amazon Prime Video, with that number growing every year as manufacturers add more models and device types.

There are 200 devices in this room, powered and online, and connected up to a service that allows remote access to Prime Video engineers. Previously, if they'd wanted to reproduce a problem they would have had to find the physical device and connect to it.

Using this fleet of devices, Amazon engineers can also automate the process of quality assurance against new devices rather than manually reproducing an issue and run it again many devices at once. The idea is to scale this up to a large fleet of devices.

But there's more. This is how Amazon is going to deal with scale: there are 400 smart TVs in this room with a library type system of movable shelves to allow access.

Remote access will to give engineers the ability to run tests from anywhere in the world.

Amazon's app depends on tight integration with the device firmware: if a manufacturer ships a firmware update, that can break the application. The idea is to catch issues like that before they reach customers' TV screens.

Because we hold onto our TVs longer than our cars, Amazon has to keep some pretty old devices around -- including a few CRTs like this old timer here.