Sound Object position bytes

Hi All! I use Sound object http://help.adobe.com/en_US/AS3LCR/Flash_10.0/flash/media/Sound.html from my player. It method play get first param startTime in milliseconds. How i can get position in bytes by the time.

From stackoverflow

• var song:SoundChannel=new SoundChannel();
              var mp3:Sound=new Sound(new URLRequest("http://localhost/file.mp3"));
              var positionInBytes:int=0;
  
  
              song=mp3.play();
              positionInBytes=song.position/mp3.length*mp3.bytesTotal;