Full description not available yet.
  
  Ok, multipass doesn't come from 5th Element, but it describes the best quality audio or video encoding method known at the moment.
  
  Using multipass technique when encoding video into another format means basically that the video encoder analyzes the video many (multi :-) times from the beginning to the end before the actual encoding process. While scanning the file, encoder writes information about the original video to its own logfile and uses that log to determine the best possible way to fit the video within the bitrate limits user has set for the encoding process -- this is why multi-pass encoding is only used in VBR encoding (the CBR encoding doesn't offer any flexibility for the encoder to determine the bitrate for each frame). Best way to understand why this is used is to think of a movie -- when there are shots that are totally, absolutely black, like scene changes, normal 1-pass CBR encoding uses the exact same amount of data to that part as it uses for complex action scene. But by using VBR and multi-pass, encoder "knows" that this piece is Ok with lower bitrate and that bitrate can be then used for more complex scenes, thus creating better quality for those scenes that require more bitrate.
  
  Two most popular formats that can use multi-pass encoding are SuperVCD and DivX.