Objective evaluation of sound quality for attacks on robust audio watermarking

Various attacks on robust audio watermarking have been proposed. Excessive intentional modifications and/or perceptual coding to the distributed stego audio degrades sound quality and can prevent the extraction of hidden data so that piracy detection systems using automated watermarking and crawling are disrupted. Reversible signal processing attacks, such as linear speed changes, also degrade the sound quality of distributed stego audio. However, the inverse processing of the reversible processing attack can recover the original sound quality of the audio received after illegal distribution. Therefore, the degradation of sound quality induced by perceptual codecs and reversible processing attacks followed by inverse processing should be considered to determine whether the intensity of these attacks is realistic. In this study, objective audio quality measurement was applied to audio signals, including typical perceptual coding, MP3, tandem MP3, and MPEG4AAC, and reversible signal processing techniques, including linear speed change, noise addition, frequency scale modification, time scale modification, bandpass filtering and echo addition. The results provide requirements that watermarking should be robust against and a list of attacks that are feasible against high-quality audio watermarking.