An audio watermarking method using two-dimensional pseudo-random array

In this paper, we describe a multiple-bit audio watermarking method which is robust
against wow-and- utter, random sample cropping, and pitch shifting. Though these
distortions are easy to perform, they are diAcult for audio watermarks to survive,
because they create mis-synchronization between the embedded watermark and the
detection pseudo-random sequence.
Our main counterstrategies to resist these attacks involve two-dimensional pseudo-
random arrays, magnitude modications, and nonlinear subbands. The embedding
algorithm modies the magnitudes of segmented areas in the time-frequency plane of
the content, according to a two-dimensional pseudo-random array (PRA), while the
detection algorithm correlates the magnitudes with the PRA. The two-dimensional
array makes the watermark robust against cropping because, even when some por-
tions of the content are heavily degraded, other portions can match the PRA and
contribute to watermark detection. Secondly the magnitude modication enables
detection even from displaced detection windows. This is because magnitudes are
less in uenced than phases by uctuations of the analysis windows caused by ran-
dom cropping, The last idea, the use of wider bandwidths at higher frequencies,
improves the correspondence of the embedded and detection PRAs even for pitch-
shifted content. We theoretically and experimentally analyzed the robustness of the
proposed algorithm against a variety of signal degradations.