Typed view of the mvhd Movie Header Box. Exposes timescale/duration
(and creation/modification times); all trailing fields (rate, volume, matrix,
next_track_ID, ...) are preserved verbatim in rest.
Summary
Types
@type t() :: %ISOMedia.Boxes.MovieHeader{ creation_time: non_neg_integer(), duration: non_neg_integer(), flags: <<_::24>>, modification_time: non_neg_integer(), rest: binary(), timescale: non_neg_integer(), version: non_neg_integer() }