Which Video Format Is Actually Smallest? H.264 vs VP9 vs AV1, Measured

"Convert it to MP4 to save space" is advice you hear constantly, and it's mostly wrong. MP4 is a container — a box that holds video, audio and metadata — not a compression method. The thing that actually decides the file size is the codec inside it: H.264, VP9 or AV1. Rename a .webm to .mp4 and you've changed nothing about how big it is. So we...