Robust FFT Based Watermarking Scheme for Copyright Protection of Digital Audio Data

Digital watermarking has drawn extensive interest as a means of protecting digital contents from unauthorized copying. This paper proposes a robust audio watermarking scheme based on the Fast Fourier Transformation (FFT) for copyright protection of digital audio data. The watermarking scheme transforms the original audio into the frequency domain. The magnitude spectrum of the original audio is divided into an arbitrary number of segments and the energy of each segment is calculated. Watermarks are then embedded into most prominent peaks of the highest energy segment of the original audio. Watermarks are extracted by performing the inverse of the watermark embedding process. Simulation results indicate that our proposed watermarking scheme resists various attacks such as noise addition, cropping, re-sampling, re-quantization, and MP3 compression. Moreover, it outperforms Cox´s method in terms of imperceptibility, while keeping comparable robustness with the Cox´s method. Its SNR (signal-to-noise ratio) values range from 20 dB to 31 dB, in contrast to Cox´s method whose SNRs range from only 11 dB to 23 dB.