Study On The Technique Of Robust Digital Audio Watermarking In The Transform Domain

As the extensive application and development of the internet and multimedia technology, as well as the gradual maturity of the multimedia data compression technology,many digital products including image,audio and video are widely issued through internet.In order to prevent the multimedia information from being infringed and illegally tampered,the copyright protection of the data is becoming more and more important.As an effective method for the copyright protection of digital product,digital watermarking technology has been widely studied and employed,thus becoming a research focus among present academia both at home and abroad.Taking the audio data as the host signal,the contents and achievements of this thesis are as follows:(1) The robust audio watermarking method based on the block-wise Discrete Cosine Transform and quantization is studied.By using the energy compression feature of Discrete Cosine Transform,the watermark is embedded in the host audio signal through quantization method.This method can realize the blind extraction.And the DC(direct current) part of the block DCT coefficients is chosen as the embedding coefficients.In the process of watermark extraction,the proposed method has not only a good transparency but also the better robustness under various attacks or conventional signal processing operations.(2) The self-synchronization and multi-copyright audio watermark method based on Blind Source Separation is studied.In response to the poor synchronization characteristic of existing audio watermark methods,a method with self-synchronization that searching the peak localization of disguised audio signal is proposed.Comparing with the method of embedding synchronizing information,this method can not only omit some operations,which are used to embed the synchronizing code,but also resist the synchronizing attack of the time axis.Experimental results show that both of the two methods can satisfy the requirements of the transparency,robustness and the security;the watermark signal can be extracted without the host signal.The watermark scheme proposed in this paper can be applied in copyright protection and tampered areas localizing.