If a fragmented mp4 file is encountered this will container the box the parser encountered when it terminated the loop. We need to save this initial movie fragment, because the stream might not be seekable (e.g. HTTP stream). The 'moof' box is also not yet fully parsed, so the first thing the reader needs to do is finish parsing the box.

public MovieFragmentBox InitialFragmentBox

Public InitialFragmentBox As MovieFragmentBox

public:
MovieFragmentBox^ InitialFragmentBox

val mutable InitialFragmentBox: MovieFragmentBox