What a piece of fragmented MP4 opens with, read from the type of its first box (bytes 4 to 8): 'init' for ftyp, or for moov (an init segment sent without its ftyp), 'fragment' for moof or styp, and null for anything else, such as raw PCM audio.
'init'
ftyp
moov
'fragment'
moof
styp
null
The piece, as an ArrayBuffer or a view of one (a Uint8Array, a Node Buffer).
ArrayBuffer
Uint8Array
Buffer
What a piece of fragmented MP4 opens with, read from the type of its first box (bytes 4 to 8):
'init'forftyp, or formoov(an init segment sent without itsftyp),'fragment'formooforstyp, andnullfor anything else, such as raw PCM audio.