If you turn an old Android phone into a security camera with no cloud and no subscription, every hour of video lands on the phone's own storage. Sooner or later you find a setting that promises to fit roughly twice as much footage in the same space: H.265 , also called HEVC , sometimes labelled "High efficiency video".

It is a fair promise, and it has a catch you only meet on the day you need the footage. This guide covers both sides, using what Android's compatibility rules, Mozilla's codec documentation and Microsoft's store listing actually say, so you can choose on purpose instead of by default.

The short answer

Choose H.264 (AVC) if footage needs to play on any PC, any browser, or be handed to someone else without fuss.…