Perceptual-based DWPT-DCT framework for selective blind audio watermarking

• A DWPT-DCT framework is used to perform variable-capacity blind audio watermarking.
• Balanced performance between robustness and imperceptibility can be achieved.
• A back-propagation neural network serves to seek suitable segments for watermarking.
• The proposed scheme can survive many DSP attacks including amplitude scaling.

Motivated by the human auditory perception, a framework jointly exploiting the discrete wavelet packet transform (DWPT) and the discrete cosine transform (DCT) is presented to perform variable-capacity blind audio watermarking without introducing perceptible distortion. To achieve a balanced performance between robustness and imperceptibility, a perceptual-based quantization index modulation technique is utilized for embedding the watermark bits. The effectiveness of the proposed scheme has been proven using the perceptual evaluation of audio quality (PEAQ) and bit error rates of recovered watermarks under various signal processing attacks. Experimental results show that the proposed DWPT-DCT scheme is comparable to three recently developed methods in robustness while it is the only scheme surviving the amplitude scaling attack. Moreover, to ensure the watermark in a harsh environment, a back-propagation neural network has been adopted to seek suitable segments for watermark embedding. With the employment of the selective scheme, the embedded watermark receives significantly better protection against serious attacks.