An imperceptible, robust, and high payload capacity audio watermarking scheme based on the DCT transformation and Schur decomposition

This paper proposes a novel audio watermarking scheme based on the discrete cosine transform (DCT) and Schur decomposition. The proposed scheme uses the DCT transformation to increase robustness and the Schur decomposition to achieve perceptual transparency. The proposed scheme first applies the DCT transformation to the original audio signal and then applies the Schur decomposition to the mid-frequency band of the DCT coefficients that generate two matrices (U and S). The watermark bits are embedded into the diagonal elements of the triangular matrix S. The Schur decomposition increases the perceptual transparency and the DCT transformation increases robustness of the proposed audio watermarking scheme by effectively resisting several types of audio signal attacks. The imperceptibility of the proposed watermarking scheme is measured subjectively using subjective difference grades (SDG) and objectively using signal-to-noise ratio (SNR) and objective difference grades (ODG) metrics. Its robustness is evaluated against several types of attacks in terms of NC and BER for different types of audio. The resulting of payload capacity, SNR, NC, and BER are as high as 516.26 bps, 77.95, 0.05326, and 0.9727, respectively. Experimental results confirm the proposed scheme is efficient, imperceptible, and robust with a high payload capacity and no effecting audio signal.