This box specifies the characteristics of a single track. Exactly one Track Header Box is contained in a track.
In the absence of an edit list, the presentation of a track starts at the beginning of the overall presentation. An
empty edit is used to offset the start time of a track.
The default value of the track header flags for media tracks is 7 (track_enabled, track_in_movie,
track_in_preview). If in a presentation all tracks have neither track_in_movie nor track_in_preview set, then all
tracks shall be treated as if both flags were set on all tracks. Hint tracks should have the track header flags set
to 0, so that they are ignored for local playback and preview.