A high capacity quantization-based audio watermarking technique using the DWPT

Transparency, robustness and hiding bit rate are the three major constraints of digital watermarking techniques. Unfortunately, these requirements are conflicted so they cannot be fulfilled together in the same time. In this paper, we propose a new quantization-based audio watermarking system that tends to conciliate between these constraints. The proposed technique is based on the application of the QIM (Quantization Index Modulation) technique on the DWPT (Discrete Wavelet Packet Transform) coefficients. The DWPT is used to decompose the host audio signal into a multiple subbands that approximate the CB (Critical Bands) structure of the HAS (Human Auditory System). This way, the quantizers resolution used by the QIM technique are adjusted over each selected CB to ensure transparency and maximize robustness. Furthermore, to increase the hiding bit rate without losing transparency a multi quantization strategy is exploited. The experimental results shows that the proposed system permits a high embedding capacity of about 134kbps without significant perceptual degradation, and provides robustness against some specific attacks.