Patent ID: 7773751

Claim:
A control code embedding apparatus for embedding control code controlling copying and playing of copyrighted digital audio contents, comprising: a control code dispersion timing determination part for determining timing dispersedly embedding control code into digital audio signals; a control code embedding part for designing filter corresponding to the control code and embedding the control code into the digital audio signals through filtering in the designed filter at the timing determined in the control code dispersion timing determination part; and a digital audio signal summation part for summing control code-embedded digital audio signals and control code-free digital audio signals and generating the summed digital audio signals, wherein the control code embedding part includes; a control code conversion part for receiving control code information and selecting filter corresponding to the control code; a filter design part for designing a filter based on the information from the control code conversion part; and a filtering part for filtering the digital audio signals components by using filter coefficients outputted from the filter design part and for attenuating signals of particular frequency band, and wherein the control code dispersion timing determination part includes: an eigenvalue extraction part for extracting eigenvalues from the digital audio signals inputted; and a random number generation part for using as an initial solution the eigenvalues inputted from the eigenvalue extraction part and for generating random numbers determining timings at which the control code are embedded.