Reversible Audio Watermarking
In this paper, we present a fragile and high capacity-watermarking technique for digital audio signals. The watermark itself is reversible, which in this context refers to the ability to restore the original input signal in the watermark detector. In summary, the approach works as follows. In the encoder, the dynamic range of the input signal is limited (i.e. the signal is compressed), and a part of the unused bits are deployed for encoding the watermark. Another part of these bits is used to convey information for the bit-exact reconstruction of signal. It is the purpose of the watermark decoder to extract the watermark and reconstruct the input signal by restoring the original dynamic range. In this study we extensively tested this new algorithm with a variety of settings using audio items with different characteristics. These experiments showed that for 16bit PCM audio sampled at 44.1 kHz, capacities close to 44000 bits per second can be achieved, while perceptual degradation of the watermarked signal remained acceptable.
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