Digital audio watermarking using content-adaptive, multiple echo hopping

Abstract

A method, an apparatus and a computer program product for adaptive, content-based watermark embedding of a digital audio signal ( ) are disclosed. Corresponding watermark extracting techniques are also disclosed. Watermark information ( ) is encrypted ( ) using an audio digest signal, i.e. a watermark key ( ). To optimally balance inaudibility and robustness when embedding and extracting watermarks ( ), the original audio signal ( ) is divided into fixed-length frames ( ) in the time domain. Echoes (S′[n], S″[n]) are embedded in the original audio signal ( ) to represent the watermark ( ). The watermark ( ) is generated by delaying and scaling the original audio signal ( ) and embedding it in the audio signal ( ). An embedding scheme ( ) is designed for each frame ( ) according to its properties in the frequency domain. Finally, a multiple-echo hopping module ( ) is used to embed and extract watermarks in the frame ( ) of the audio signal ( ). An audio watermarking system known as KentMark (Audio) is implemented.