Self-synchronization for spread spectrum audio watermarks after time scale modification

Andrew Nadeau; Gaurav Sharma

doi:10.1117/12.2039486

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19 February 2014 Self-synchronization for spread spectrum audio watermarks after time scale modification

Andrew Nadeau, Gaurav Sharma

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Proceedings Volume 9028, Media Watermarking, Security, and Forensics 2014; 90280E (2014) https://doi.org/10.1117/12.2039486
Event: IS&T/SPIE Electronic Imaging, 2014, San Francisco, California, United States

Abstract

De-synchronizing operations such as insertion, deletion, and warping pose significant challenges for watermarking. Because these operations are not typical for classical communications, watermarking techniques such as spread spectrum can perform poorly. Conversely, specialized synchronization solutions can be challenging to analyze/ optimize. This paper addresses desynchronization for blind spread spectrum watermarks, detected without reference to any unmodified signal, using the robustness properties of short blocks. Synchronization relies on dynamic time warping to search over block alignments to find a sequence with maximum correlation to the watermark. This differs from synchronization schemes that must first locate invariant features of the original signal, or estimate and reverse desynchronization before detection. Without these extra synchronization steps, analysis for the proposed scheme builds on classical SS concepts and allows characterizes the relationship between the size of search space (number of detection alignment tests) and intrinsic robustness (continuous search space region covered by each individual detection test). The critical metrics that determine the search space, robustness, and performance are: time-frequency resolution of the watermarking transform, and blocklength resolution of the alignment. Simultaneous robustness to (a) MP3 compression, (b) insertion/deletion, and (c) time-scale modification is also demonstrated for a practical audio watermarking scheme developed in the proposed framework.

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Andrew Nadeau and Gaurav Sharma "Self-synchronization for spread spectrum audio watermarks after time scale modification", Proc. SPIE 9028, Media Watermarking, Security, and Forensics 2014, 90280E (19 February 2014); https://doi.org/10.1117/12.2039486

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