An improved patchwork-based digital audio watermarking in CQT domain

In nowadays digital audio watermarking still remains one of the hot research topics in the view of multimedia copyright protection. In this paper an improved patchwork-based audio watermarking algorithm in Constant-Q Transform (CQT) domain has been proposed. The advantage of CQT in music analysis lies in its nonlinear frequency spacing. However the absence of exact invertible transform still prevents CQT from the wide application. In this paper it is overcome by frame pair selection, which is carefully performed according to frame pair energy ratios of the middle frequency range to avoid the disturbance of watermarking embedding and degradation in signal quality afterwards. Watermarks are then embedded by modifying the energy of selected frame pairs. The experimental results indicate that the proposed method outperforms the latest patchwork-based audio watermarking algorithm in Discrete Cosine Transform (DCT) domain with better signal quality of embedded signals and yet more robust to the conventional attacks.