tailieunhanh - Lecture Steganography: Audio watermarking - Ho Dac Hung

Audio Watermarking introduces content such as applications, ownership protection applications, content authentication applications, requirements, perceptual transparency attacks, and algorithms. Download this lecture to see more. | Audio Watermarking Ho Dac Hung 1 Contents Applications Requirements Attacks Algorithms 2 1. Application In the ownership protection applications a watermark containing ownership information is embedded to the multimedia host signal. The watermark known only to the copyright holder is expected to be very robust and secure. 3 1. Application In the content authentication applications a set of secondary data is embedded in the host multimedia signal and is later used to determine whether the host signal was tampered. 4 1. Application It is even more demanding to use watermarks not only in the identification of the copyright ownership but as an actual proof of ownership. The problem arises when adversary uses editing software to replace the original copyright notice with his own one and then claims to own the copyright himself. 5 1. Application Additional data embedded by watermark in the fingerprinting applications are used to trace the originator or recipients of a particular copy of multimedia file. 6 2. Requirements Perceptual Transparency 7 2. Requirements Perceptual Transparency In most of the applications the watermarkembedding algorithm has to insert additional data without affecting the perceptual quality of the audio host signal. 8 2. Requirements Watermark Robustness Robustness of the algorithm is defined as ability of the watermark detector to extract the embedded watermark after common signal processing manipulations. 9 2. Requirements Watermark Bit Rate One of the most important properties of an audio watermarking system is watermarked bit rate usually determined by specific demands of the application the system is designed for. Bit rate of the embedded watermark is number of embedded bits within a unit of time and is usually given in bits per second. 10 3. Algorithms Least Significant Bit Coding The watermark encoder usually selects a subset of all available host audio samples chosen by a secret key. The substitution operation on the LSBs is performed on