Temporal synchronization for audio watermarking using reference patterns in the time-frequency domain
Temporal synchronization is an important part of any audio watermarking system which involves an analog audio signal transmission. We propose a synchronization method based on the insertion of two-dimensional reference patterns in the time-frequency domain. The synchronization patterns consist of a combination of orthogonal sequences and are continuously embedded along with the transmitted data, so that the information capacity of the watermark is not affected. We investigate the relation between synchronization robustness and payload robustness and show that the length of the synchronization pattern can be used to tune a trade-off between synchronization robustness and the probability of false positive watermark decodings. Interpreting the two-dimensional binary patterns as one-dimensional N-ary sequences, we derive a bound for the autocorrelation properties of these sequences to facilitate an exhaustive search for good patterns.