(where XX = box size, ftyp = ASCII identifier)
To support live streaming and DASH (Dynamic Adaptive Streaming over HTTP), the standard was introduced. In fMP4, the moov box still exists at the start, but the mdat box is replaced by a series of moof (Movie Fragment) and mdat pairs. This structure allows the file to be written and read in small chunks, enabling live broadcast capabilities over HTTP protocols. nofile mp4