Code modulator and code modulation method

摘要

A method and apparatus are provided for modulating code for use with written optical disks such as digital video disks (DVD). The invention falitates {fraction (8/16 )} modulation by eliminating duplicate code conversion and by reducing the number of times that conversion codes must be looked up from a conversion table. A conversion code corresponding to a received input code is specified from among a plurality of conversion codes. Duplication information corresponding to the input code is read from a pre-processing table and duplicate information indicated duplicate conversion codes in the plurality of conversion codes is stored. Conversion code corresponding to the input code is read from the conversion table and is selectively stored with duplicate conversion codes being ommited.