| 摘要 |
PROBLEM TO BE SOLVED: To prevent an audio signal from being illegally copied. SOLUTION: A digital audio signal in a prescribed block unit supplied via a segmentation part 12 is fast-Fourier-transformed by an FFT(fast Fourier transform) part 13, and a resultingly obtained frequency spectrum is supplied to a spectrum operating part 14. When the frequency spectrum is received from the FFT part 13 by the spectrum operating part 14, copyright information is comprised in its one spectrum component or more, and is outputted to an IFFT(inverted fast Fourier transform) part 15. In this IFFT part 15, the frequency spectrum from the spectrum operating part 14 is inverted-fast-Fourier- transformed in the same block unit as in the case of the FFT, thus outputting the audio signal with the copyright information buried in one spectrum component or more. |
