| 摘要 |
<p>A watermark encoding system encodes an audio signal with both a strong and a weak watermark. The strong watermark identifies the content producer and is designed to survive all typical kinds of malicious attacks. The weak watermark identifies the content as an original. The watermark encoding system converts an audio signal into frequency and phase components. A mask processor determines a hearing threshold for corresponding frequency components. A pattern generator generates both the strong and weak watermarks. The watermark insertion unit adds the strong watermark to the audio signal when the signal exceeds the hearing threshold by a buffer value and adds the weak watermark when the signal falls below the hearing threshold by the buffer value. When the signal falls within the buffer area about the hearing threshold, the insertion unit takes no action. A watermark detecting system determines if the strong or weak watermark is present in a block interval of the signal.</p> |
