DVD

DVD

A DVD (Digital Video Disc) stores and plays digital information on a disc similar in size to a normal CD. The output is also clearer, sharper and uses higher colour resolutions than previous formats. Even audio is sharper. A DVD disc can store up to 9 hours of video and multichannel surround sound audio and interactive multimedia computer programs. Otherwise it can be used for over 30 hours of CD quality audio. Previously impossible features with movies (or games) on tapes are now made possible by DVD. DVD players can play from any point on the disc, pause, play in slow motion and fast forward or freeze frames. Random new features allow the viewer to for instance choose which ending a movie should have. They also include first-person interactive video games and multiple camera angles. With parental control parents can password protect programs that they don't want their children to view. Another form of parental control is storing different versions of a movie on the same disc. A disc can then for instance contain an R-rated version of a movie and a PG-13 version. Up to eight languages for one movie can also be stored on a DVD disc.

The mastering process formats data so that it can be read by DVD players. By using MPEG-2 video encoding standard the mastering process can manipulate the large amounts of information into a format that the more common DVD player can understand. The discs are made of reflective aluminium foil encased in a clear plastic. Data can be stored on the foil as small pits arranged in a tight spiral. For a double sided disc two halves, with their foil full of data, are bonded back to back.