a format for accessing content such as a full - length move from an optical disc uses an xml description file stored on the disc to generate one or more screens that a user employs to access the content . the decoding requirements of a hardware or software player are reduced by discarding specific elements of an encoding standard such as mpeg4 that is used to encode the content on the disc . the maximum average and peak bitrates at which the data is transferred are limited to further reduce the demands on the player .