Spread-spectrum audio watermarking: requirements, applications, and limitations

Watermarking has been adopted as a technology of choice for many applications related to e-commerce of audio content. We present a brief summary of a set of spread-spectrum watermarking techniques for effective covert communication over an audio signal carrier. Watermark robustness is enabled using redundant spread-spectrum for prevention against de-synchronization attacks. We improve watermark inaudibility by detecting and not watermarking blocks of audio where a spread spectrum sequence, if added to the frequency spectrum, would be audible. Finally, we overview the security limitations of our technology with respect to parameter selection and position it with respect to three main applications of watermarking: (a) content screening, (b) tracing unlicensed content distribution, and (c) robust metadata