Synchronized double watermark audio watermarking scheme based on a transform domain for stereo signals

Digital watermarking technology is interested in solving the problem of copyright protection, data authentication, content identification, distribution, and duplication of the digital media due to the great developments in computers and Internet technology. Recently, protection of digital audio signals has taken a great attention from the researchers. This paper proposed a new audio watermarking scheme based on Discrete Wavelet Transform (DWT), Singular Value Decomposition (SVD), and Quantization Index Modulation (QIM) with synchronization code embedded within double encrypted watermark images or logos into stereo audio signal. In the algorithm, an original audio signal is split into blocks and each block is decomposed into two levels discrete wavelet transform, and then the approximate low frequency sub-band coefficients are decomposed by the SVD transform, obtaining a diagonal matrix. The prepared watermarking and synchronization code bit stream is embedded into the diagonal matrix using Quantization Index Modulation (QIM). After that, we apply ISVD and IDWT to obtain the watermarked audio signal. The watermark can be blindly extracted without knowledge of the original audio signal. Experimental results show that the transparency and imperceptibility of the proposed algorithm is satisfactory, and robustness is strong against popular audio signal processing attacks. High watermark payload is achieved and performance analysis is presented.