An adaptive audio watermarking with frame-wise control parameter searching

Yuzhu Wang, Yiming Xue, Xingpeng Liu, Juan Wen

Abstract: For adaptive audio watermarking methods based on singular value decomposition (SVD), the choice of the embedding strength parameter is a crucial factor for satisfying the balance between imperceptibility and robustness. In traditional methods, the embedding strength parameter is usually the product of a constant control parameter and a variable related to the host signal. However, since the host audio signal is generally divided into frames with different energy, it is not wise to use the same control parameter to embed watermarks into different frames. In this paper, in order to achieve control parameter adaptive adjustment according to the frame energy, an adaptive audio watermarking method with frame-wise control parameter searching is developed. Firstly, the host audio signal is partitioned into paired segments through the time-sequence-segmented method. Then the watermark is embedded into the deviation value between the two largest singular values of the paired segments. We first propose an effective search algorithm called the outer loop (OL) method to find the suitable control parameter with the highest signal-to-noise ratio (SNR) under the condition of equal robustness. Then the inner-outer loop (IOL) method is further developed to find different control parameters with the lowest bit error rate (BER) while maintaining high SNR. Through the combination of the two loops, different control parameters are used to embed watermarks into different frames, contributing to an excellent balance between imperceptibility and robustness. By comparison with the existing state-of-the-art audio watermarking methods, the proposed method enhances robustness against various common attacks while ensuring high imperceptibility.