What is h.265 (hevc)?
A newer codec that roughly halves file size versus H.264 at similar quality, at the cost of narrower playback support.
HEVC is what recent iPhones record in by default, usually inside a .mov or .mp4 container. The efficiency gain is real, but decoding support is less universal than H.264 - some Windows PCs, older Android phones and some upload pipelines handle it poorly or not at all, which is the usual cause of "this file won't play" complaints about recent iPhone footage.
Re-encoding an HEVC file to H.264 fixes most playback complaints at the cost of a somewhat larger file - a reasonable trade when a file needs to go somewhere you don't control.
Koldflux picks the right codec, container and bitrate for every platform automatically - this glossary exists because our own team had to get it right first.
Automate this in Koldflux