the format for a dvd usally refers to the aspect ratio of the screen size which are 4:3 also called pan and scan (it's the same size as a normal television screen) 16:9 (wide screen) and 2.40:1 which if viewed on a widescreen will still show bars top and bottom. there are a few other ratio's but most where only used for a couple of movies then dropped. the great escape with steve mcqueen had a very wide aspect ration almost half the screen was taken up by bars. but if this isnt the answer you wanted then it might in which way are movies encoded then the answer is mpeg2