Digital audio watermarking based on holographic nonlinear limiter

A new approach of digital audio watermarking by use of nonlinear amplitude limiting computer-generated hologram (CGH) is proposed to significantly improve the robustness than traditional CGH method. The amplitude and phase are extracted on the basis of traditional Fourier transform holography. Binary Fourier hologram was formed by nonlinear amplitude limiting algorithm when the phase information as input function and the amplitude information transferred into a bias function. The robustness of audio watermarking is much high because the binary hologram has stronger anti-interference property than the normal hologram. And because of the small amount of data in binary hologram, redundant embedding method can further improve the robustness. The CGH is embedded into audio signal by quantification technology and discrete-cosine-transform (DCT) algorithm. It can be extracted without the original audio signal and the security key provides good security. Experimental results show that the algorithm has more robustness than audio watermarking algorithm based on general CGH against common signal manipulations and attacks, such as lossy compression, re-sampling, low-pass filter, noise, and so on.