Improving Audio Watermark Robustness Using Stretched Patterns against Geometric Distortion

One of the problems for audio watermarks is robustness against signal processing causing de-synchronization of the pseudo-random sequences. To tackle the problem, we previously introduced an audio watermarking method using a two-dimensional pseudo-random array, which is robust against pitch shifting and random stretching to some extent. In this paper, we explain a modification to the detection algorithm to improve the robustness against excessive distortion. The method uses multiple pseudo-random arrays each of which is stretched assuming a certain amount of distortion. Since most of the detection process for the multiple arrays is shared, the additional computational cost is limited.