Video quality, and what cannot be recovered

Something looks worse than you expected and you want to know whether it can be fixed or whether it was lost at capture.

Resolution against bitrate, what upscaling really does, and the quality decisions that are made once and cannot be undone afterwards.

Guides

Worked through end to end. Start here if you want to understand the subject rather than fix one thing.

One question, one answer. Start here if you already know what you need.

The words this subject assumes you already know.

The same subject, specific to where your media came from.