19-02-2013, 11:10 AM
Comparative Study of Digital Audio Watermarking Technique
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Abstract:
Broadband communication and multimedia data opened many challenges and opportunities for innovation. Broadband internet connection provides people to communicate and share digital information very easily and errorless. The uses of the simple software and digital devices have made it possible for people from all over the world to create, edit and exchange multimedia data. So, the protection of intellectual ownership and the prevention of unauthorized tampering of multimedia data become an important technological and research issue. Digital watermarking has been proposed as a new, alternative method to enforce intellectual property rights and protect digital media from tampering. Digital watermarking is defined as imperceptible, robust and secure communication of data related to the host signal, which includes embedding into and extraction from the host signal.
Introduction
The development of internet caused major changes in global society. Globalization and internet are the two main reasons for the rapidly spreading of the information. Broadband internet connection provides people to communicate and share digital information very easily and errorless. The uses of the simple software and digital devices have made it possible for people from all over the world to create, edit and exchange multimedia data. However, the ownership and copyright of multimedia files are not usually protected. Digital watermarking has been proposed as a new method for the intellectual property rights and protects digital media from tampering. It consists of process of embedding a digital signature, in order to mark its ownership, into the host signal. The digital signature is known as digital watermark. The digital watermark contains data that can be used in various applications, including digital rights management, broadcast monitoring and tamper proofing.
DWT based audio watermarking
In this section we explain the embedding and extracting procedure of audio watermarking based on the discrete wavelet transform.
DWT based embedding procedure
The embedding procedure performs three major operations: watermark preprocessing, DWT-based frequency decomposition of the audio signal, and watermark embedding in the DWT-transformed audio signal.
Analysis of watermarking techniques
In order to illustrate the robust nature of audio watermarking scheme, attacks including MPEG compression, resampling, requantization, noise adding, and random cropping are used to estimate the robustness of all the scheme. Table-1, 2 and 3 summarizes the various watermark detection results comparison against various attacks.
The watermarking systems have a number of differences. These differences can be considered in evaluating performance of watermarking systems and suitability of these systems for a specific application. These differences can be explained as follows:
(1) The watermarking method in DCT domain for copyright protection of audio data shows strong robustness against several kinds of attacks such as noise addition, cropping, resampling, re-quantization, and MP3 compression. Moreover, this method achieves good SNR values for different watermarked sounds. The results demonstrate that DCT watermarking method can be a suitable candidate for audio copyright protection [3].
(2) The watermarking method in DWT domain for copyright protection of audio data provides good robustness for both speech and music files and also provides high SNR values than DCT. DWT also gives high percentage match as compared to DCT. The result shows that embedding using DWT performs better as compared to DCT [4].
Conclusion
In this paper watermarking techniques based on DWT and DCT are explained. DCT techniques provide good robustness against requantization, cropping, compression etc; and hence it can be a suitable for audio copyright protection. DWT provides good robustness for both music and speech files and also provides good SNR than the DCT. Combination of DWT and DCT provides better imperceptibility and higher robustness against attacks compared to DCT or DWT only schemes.