Licensing 

Pardon me, but MP3 is already public domain.  It is a file format.  You cannot patent a file format as far as i know.  that would be like Adobe saying they have a patent on PDF or Microsoft saying they have a patent on WMA or DOC files.  You simply cannot patent or copyright or in any other way protect your idea if it involves a format of storing data.  Just as you cannot patent things like NTFS or FAT or HFS, you cannot patent MP3.