| 摘要 |
A method of inserting an identification code into a digitally encoded signal such as that used in compact disc recording. A series of binary word locations in the material are selected, preferably at random, for modification by substituting a replacement digit or digits for one or more insignificant digits of the word. This allows subsequent identification of copies of the recorded material, by comparison with a copy of the random sequence or sequences used to determine the locations and values of the replacement digits. The method can also be applied to coding schemes which do not have a defined word structure, such as delta modulation, in which case digits can be replaced completely randomly without regard to relative significance. |
