Method and apparatus for embedding second code into optical disc data by data modulation rule variation

Abstract

There are provided a method and apparatus for embedding a second level code into a first level code of an optical disc by data modulation rule variation. The apparatus includes a multi-level, varying rule based modulator (199) for modulating the first level code to obtain a channel bit stream representative of the first level code and having the second level code embedded therein. The multi-level, varying rule based modulator modulates the first level code using modulation rules respectively having different statistical properties of pit-land length distributions that preserve a readability of the first level code and that are distinguishable at readout of the optical disc. The different statistical properties represent binary or multilevel data of the second level code.

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