CPT-Based Data Hiding in Selected Subband Using Combined Transform and Decomposition Method

A digital copyright on an audio needs a special protection to prevent it from illegal distribution. Hiding a copyright into an audio is a solution for securing its ownership. In this paper, we propose an audio watermarking using combination method of Lifting Wavelet Transform (LWT), Discrete Sine Transform (DST), Singular Value Decomposition (SVD), and Cartesian Polar Transform (CPT) using Quantization Index Modulation (QIM). A host audio is first decomposed by LWT. Next, a subband is selected then transformed by DST. Then, DST selected coefficients are decomposed into U, S and V matrices by SVD. S matrix is then selected. S elements in position (1,1) and (2,2) are converted by CPT to magnitude and phase coefficients. The phase coefficient is finally used for embedding a bit of watermark by QIM. The simulation result shows that the proposed method offers very high watermark capacity with good imperceptibility and robustness.