Audio zero watermarking for MP3 based on low frequency energy

Compressed audio such as MP3 has now been widely used, and the copyright protection of compressed audio has become an important issue. In this paper, a robust zero-watermarking algorithm for MP3 compressed domain is proposed. The algorithm generates zero watermarking according to low frequency energy values of the frames in MP3 compression process. The low frequency energy is calculated by using MDCT coefficients produced during MP3 encoding process. It is proved that low frequency energy carries most information of the host audio. Thus the low frequency energy has great robustness to many attacks. Besides, since the algorithm is proposed in MP3 compressed domain, the zero watermarking is generated during MP3 encoding process. And the watermarking can be extracted while decoding MP3 audio file without extra extraction process. Therefore, the proposed algorithm is more efficient compared with many traditional algorithms. The results of the experiments show that the proposed algorithm is robust against common attacks, especially MP3 compression and recompression attacks. In addition, the algorithm can avoid the conflict between imperceptibility and robustness for using zero-watermarking technology.