Digital watermarking in audio for copyright protection

Digital watermarking is a technique that consists in hiding binary information within a signal in an imperceptibly way. This technique plays an important role for copyright protection of multimedia data. In this paper an efficient robust audio watermarking algorithm based on double transforms is introduced. In a first step, the original signal is decomposed by discrete wavelet transform (DWT). Then the prominent approximation coefficients are segmented in non-overlapping 2D blocks. Singular value decomposition (SVD) is applied on each one. The watermark is embedded in the singular values (SVs) for each block. Watermark extraction is non-blind and it´s done by performing inverse operation of embedding process. Experimental results show that this scheme provides high robustness against common signal processing attacks such as noise addition, resampling, filtering, MP3 compression and maintains good perceptual transparency. In addition, this method use a double key for insertion and extraction, making it suitable for secure application such as copyright protection.