A novel spread spectrum audio watermarking scheme based on time-frequency characteristics

In this paper, we present a novel audio watermarking scheme based on spread spectrum techniques that embeds a digital watermark within an audio signal using the instantaneous mean frequency (IMF) of the signal. Audio watermarking offers a solution to data piracy and helps to protect the rights of the artists and copyright holders. Our content-based algorithm aims to satisfy and maximize both imperceptibility and robustness of the watermark. In addition, our technique uses the short-time Fourier transform of the original audio signal to estimate a weighted IMF of the signal. Based on the masking properties of the psychoacoustic model, we then derive the required sound pressure level of the watermark. From these results, modulation is performed to produce a signal-dependent watermark that is imperceptible. The proposed method allows 25 bits to be embedded and recovered within a 5 second sample of an audio signal. Experimental results have shown that our scheme is robust to common signal processing attacks including filtering, MP3 compression and noise addition.