Study On The Digital Audio Watermarking Technique

With the rapid development of computer network and multimedia technology, various software for audio processing is widely used, this not only made it easy to be attacked when people operated it, such as transmission, storage and copy, but also the infringement was much easier and serious. So how to protect the multimedia information has been became the hot topic on international studies. It is more and more widely watched because digital audio watermarking is considered as an effective way to resolve the copyright protection of digital audio products. It embeds some logo information into the original audio at the premise of not affecting the use of audio signal. Integrity and copyright information of audio file can be confirmed through watermark detection.Some basic knowledge of digital audio watermarking techniques is systematically discussed by this paper, including its development, background and its application. Then,the paper formulates the basic principles, general system structure, the evaluation criteria and the attack of the digital audio watermarking in detail. We have a study on the audio watermark algorithm which based on the forenamed content. The main tasks are as follows:Studied many algorithms in time-domain and the frequency-domain about digital audio watermarking, and then analyzed the advantages and disadvantages about various algorithms. Prime watermarking algorithm based on wavelet transform was proposed. It was an improvement about the transparence in wavelet-domain. Pretreatment to the watermarking image with Arnold transform is given first,this could use the cyclical of Arnold transformation to remove the correlation between the watermark image and it can also enhance the robustness of watermarking .The proposed algorithm embeds the watermarking information in the absolute mean of low frequency sub-band coefficients in order to get a good imperceptibility. Experiments results show that the proposed algorithm had a good robustness and has an excellent imperceptibility to common signal processing but weak at resisting de-synchronization attacks, complexity is bigger, these all need to be improved. It is a blind watermarking.Because most audio watermarking algorithms presented in DWT domain are not obvious to resist de-synchronization attacks, according to the improvement upon the first algorithm, an adaptive digital audio watermarking method based on DCT and lifting wavelet transform was proposed which is effective to resist de-synchronization attacks.In order to improve embedding and extracting rate, the original audio signal was decomposed into low-frequency and high frequency component after lifting wavelet transform firstly. Then DCT was performed on the low-frequency component and watermarks was embedded into the DC coefficient sequences according to the largest DC auditory tolerance after DCT coefficients transform think of the robustness, this could have a good robustness not only to common signal processing but also the de-synchronization attacks. Meanwhile considering the balance between the imperceptibility and the robustness of the audio watermarking, the adaptive adjustments were used for embedded watermarking. Extracting the watermark signal doesn't need original audio and original watermark image. Meanwhile the algorithm enhances signal processing speed, this will be more benefit in the hardware area.Experimental results show that the proposed method in improvement algorithm is much better in the robustness than the prime watermarking algorithm, the same as the imperceptible and signal processing speed.