code: public long getPlayingTime()
  	{
  		long datasize = (mp3File.length() * 8) - id3v2.getSize();
  		long bps = head.getBitRate() * 1000;
  		return datasize / bps;
  	}
docs: Returns the length (in seconds) of the playing time of this mp3.  This
  will not return an accurate value for VBR files.
  
  @return the playing time (in seconds) of this mp3