1. A scrambling apparatus comprising: a processor; a conversion motion vector code table generator which generates a conversion motion vector code table comprising motion vector codes obtained by converting motion vector codes corresponding to motion vector values of input video data in a standard motion vector code table; and a conversion controller, executed by the processor, which randomly determines whether a motion vector value is encoded using the conversion motion vector code table or the standard motion vector code table, wherein the conversion motion vector code table generator generates the conversion motion vector code table based on a random number, wherein the conversion motion vector table comprises at least one unconverted motion vector code which does not satisfy a predetermined condition after the conversion of a motion vector code corresponding to the at least one unconverted motion vector code.