Spread spectrum watermarking robust to silk vocoder using sub-optimal detectors
Ali Sattari, Mohammad Ali Akhaee · 2016
Robust data hiding in speech signals through real-time voice encoders is an interesting but difficult method for watermarking. Spread spectrum watermarking is one of the most robust approaches that is implemented in additive and multiplicative manners. In this paper, a robust detection method is proposed for spread spectrum watermarking in Skype audio codec SILK that reduces the error probability through the definition of vectors perpendicular to the key and correlation estimation of the host signal. This method is presented for the additive watermarking and only requires the second order statistical moment of the host signal which can be estimated at the receiver side. Next, the multiplicative method is turned into an additive one being passed through a non-linear function, and undergoes the proposed method. Moreover, the Skype audio channel effect is considered by SILK output signal statistics being embedded in the detection function.