What is a MP4 file?
MP4 (MPEG‑4 Part 14) is the dominant container for online video. Based on QuickTime atoms, it can hold H.264/AVC, HEVC, AV1, AAC, AC‑3, timed text, and fragmented segments for adaptive streaming. Finalised in 2001 and revised in 2003 (ISO/IEC 14496‑14), MP4 became the hand‑off format of choice thanks to the iPod Video and PlayStation Portable. The arrival of HLS and DASH further entrenched MP4, which supports ‘moov’ boxes at either head or tail for progressive download or live streams.


