MP4GetTrackEditDuration - Get the duration of a track edit segment
hFile Specifies the mp4 file to which the operation applies.
Specifies the track to which the operation applies.
editId Specifies the edit segment for which the duration is desired.
The duration of the edit segment in track time scale units of the track
in the mp4 file.
MP4GetTrackEditDuration returns the duration of the specified track
Caveat: The value is in units of the track time scale.