Digital Watermarking for Digital Audio Signal Based on DWT

A special self-synchronizing watermark algorithm for audio signal is proposed in which self properties of audio signals are utilized and synchronization and embedding are processed separately. The low frequency components after DWT have the properties of energy concentration and robustness to interference which act as positioning indexes of watermarks. Characteristics are extracted by filtering the low frequency component. Watermarks are embedded repeatedly at the positions of middle frequency component appointed by these characteristics. The algorithm has perfect robustness and security by using multiple secret controlling and accurate synchronization.