Historically, it has been relatively easy for copyright owners to protect their works from
unwanted and unauthorized copying. The cost and difficulty associated with illegal
copying was simply too high to allow any such copying to be widespread. As digital
multimedia works like video, audio and images, become available for retransmission,
reproduction, and publishing over the internet, a real need for protection against
unauthorized copy and distribution is increased. Digital watermarking has been
proposed as one way to accomplish this. Digital audio watermarking is a technique for
embedding additional data along with audio signal. Embedded data is used for copyright
owner identification. In this dissertation, two techniques of digital audio watermarking
are proposed. One of the techniques exploits the characteristics of Fourier Transform,
while another technique is based on wavelet transformation. Both techniques are robust
against format-changing of audio data, while very fragile to time-changing processing.
The audio signal is first transformed into either Fourier domain or Wavelet domain.
Then a series of value is extracted from respective domain and embedded with
watermark. Watermarked audio signal is obtained by inverse transformed the signal in
respective domain. Signal-to-Noise Ratio, watermark similarity, correlation coefficient,
and Bit Error Rate are used to evaluate the performance of watermarking techniques.
The experimental results clearly demonstrate that the proposed algorithms are able to
detect the embedded watermark, and robust to certain digital signal processing
operations.
Digital Watermarking for Audio Signal_Saw Si Xing_E3_2007_875000061_NI