The Use of Spectral Shaping to Extend the Capacity for DWT-Based Blind Audio Watermarking

A spectral shaping technique is adopted to expand the operating frequency range for DWT-based blind audio watermarking. The process is performed framewisely over the 3rd level approximation subband, of which the spectrum spans from 0 to 2756 Hz. The effectiveness of the proposed scheme is demonstrated using the perceptual evaluation of audio quality and bit error rates of recovered watermarks under various signal processing attacks. Experimental results show that the proposed scheme reaches a capacity as high as 818.26 bps while still remains satisfactory robustness and imperceptibility.