I have an audio file which for some reason reports incorrect bitrate. MPlayer shows audio length over two hours, the video it belongs to is only 1 h 42 min. Any clues how to modify AAC headers without recoding the file? I can use hex editor, but which byte(s) to edit?

Edit: I've learned ADTS headers are before each packet. So now the question is: is there a tool to modify these headers?