Digital Watermarking Scheme Based on Fast Fourier Transformation for Audio Copyright Protection

Digital watermarking is now drawing attention as a new method of protecting digital content from unauthorized copying. This paper proposes a new watermarking scheme in based on Fast Fourier Transformation (FFT) for copyright protection of digital audio. In the proposed watermarking scheme, the original audio is segmented into non-overlapping frames. Watermarks are embedded into the selected prominent peaks of the magnitude spectrum of each frame. Informal listening reveals excellent imperceptibility of the embedded watermark. The proposed watermarking scheme is tested by various kinds of attack to demonstrate the robustness of watermarking. Simulation results suggest that the imperceptible watermarks embedded with the proposed method are highly robust against various kinds of attacks such as noise addition, cropping, re-sampling, re-quantization, MP3 compression, and low pass filtering. We observe that the proposed scheme shows similar robustness compare to Cox’s method. In addition, the proposed method provides better performance than Cox’s method in terms of SNR result because of embedding watermarks into the selected prominent peaks of magnitude spectrum of each frame of the original audio signal. Our proposed scheme achieves SNR (signal-to-noise ratio) values ranging from 20 dB to 28 dB, in contrast to Cox's method which achieves SNR values ranging from only 14 dB to 23 dB.