Informed detection of audio watermark for resolving playback speed modifications

ABSTRACT

In this paper, we present a method for informed watermark detection in audio signals. In this context, informed detection refers to the mechanism in which the original media signal is used to improve robustness and/or complexity. Here, we focused on reducing complexity by addressing the geometrical distortion problem. In audio, geometrical distortion translates to time scaling. Generally, s speed changes of the audio signals necessitate a mechanism in the detector to retrieve the watermark. Usually this is done by some kind of (clever) exhaustive search algorithms. In this paper we show that the speed searching process can significantly be improved using fingerprinting technology. Particularly, an initial estimate of the speed is obtained by extracting the so-called local fingerprint time stamps. This initial estimate is then used as a starting point for the exhaustive speed search algorithm in the watermark detector. We also give analyses on the accuracies of the watermark detector and the fingerprint algorithm and the relations thereof. Moreover, we present the concept for integrating fingerprint algorithm in the watermark detector and discuss the influence of various parameters. We show that, apart from a significant complexity reduction, such integration can lead to an improvement in robustness as a byproduct.

REFERENCES

• 1: www.teletrax.tv
• 2: www.watercast.com
• 3: van der Veen, M., Lemma, A.N., and Kalker, A.A.C., Watermarking and fingerprinting for electronic music delivery, The International Society for Optical Engineering (SPIE), Conference on security and watermarking of multimedia contents, San Jose, USA, 2004.
• 4: J. Lichtenauer, I. Setyawan, T. Kalker and R. Lagendijk, Exhaustive Geometrical Search and the False Positive Watermark Detection Probability, In Proceedings of SPIE Security and Watermarking of Multimedia Contents V, 5020, Santa Clara, CA USA, 2003, pp. 203--214.
• 5: P.J.O. Doets, I. Setyawan, R.L. Lagendijk, Complexity-Scalable Compensation of Geometrical Distortions in Image Watermarking, in the Proceedings of ICIP 2003, Barcelona, Spain, 2003.
• 6: Darko Kirovski , Hagai Attias, Audio Watermark Robustness to Desynchronization via Beat Detection, Revised Papers from the 5th International Workshop on Information Hiding, p.160-176, October 07-09, 2002
• 7: A. Lemma, J. Aprea, W. Oomen and L. van de Kerkhof. A Temporal Domain Audio Watermarking Technique. IEEE Trans. on SP, Vol. 51, No. 4, April 2003, pp. 1088--1097.
• 8: I. Pitas and P. Bassia, Robust audio watermarking in the time domain, in EUSIPCO 98, Ninth European Signal Processing Conference, Rhodes, Greece, Sept. 1998.
• 9: Darko Kirovski , Henrique S. Malvar, Robust Covert Communication over a Public Audio Channel Using Spread Spectrum, Proceedings of the 4th International Workshop on Information Hiding, p.354-368, April 25-27, 2001
• 10: Mitchell D. Swanson , Bin Zhu , Ahmed H. Tewfik , Laurence Boney, Robust audio watermarking using perceptual masking, Signal Processing, v.66 n.3, p.337-355, May 1998 [doi>10.1016/S0165-1684(98)00014-0 ]
• 11: www.ebu.org
• 12: J. Haitsma and T. Kalker. Speed-change resistant audio fingerprinting using auto-correlation. Conf. on Acoustics, Speech and Signal Processing, Hong Kong, ICASSP 2003.

INDEX TERMS

Keywords:
audio, fingerprinting, informed detector, music distribution, watermarking