MP4AddTrack - Add a user defined track
const char* type
hFile Specifies the mp4 file to which the operation applies.
type Specifies the type of track to be added.
Upon success, the track id of the new track. Upon an error,
MP4AddTrack adds a user defined track to the mp4 file. Care should be
taken to avoid any of the standardized track type names. A useful
convention is use only uppercase characters for user defined track
types. The string should be exactly four characters in length, e.g.
Note this should not be used to add any of the known track types
defined in the MP4 standard (ISO/IEC 14496-1:2001).