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Top1. Introduction
With the rapid development of multimedia and network, the amount of information storage becomes larger and larger. At the same time, editing and copying is so convenient, which speeds up the spread of information. Currently, a lot of digital works are suffering from illegal acquiring and malicious tampering, among which audios are the popular ones. Integrity protection and ownership rights certification of audio files have attracted great attentions, which can be realized with watermarking.
There are two types of watermarking, robust watermarking and fragile watermarking to protect audio files. Robust watermarking (Malvar, 2003; Naderahmadian, 2014; Tian, 2016; Rani, 2014) is used to label copyright information so that protecting copyright. On the contrary, fragile watermarking (Zhang, 2009, 2008; Qin, 2012) is usually used for content integrity authentication, which is asked to be sensitive to the slight change so that editing the content slightly will be detected. Reversible watermarking mainly is used for fragile watermarking, which can restore both the embedded watermark and the host signal. The reversibility is very important in some special situations, such as high-quality music, legal evidence, military intelligence and criminal investigation.
At the early age, (Barton,1997) proposed the idea of reversible data hiding (RDH). Later on, many efficient methods for images spring up. The current algorithms are divided into five mainstream techniques: lossless compression based schemes (Celik, 2005; Lin, 2011; Zhang, 2012), expansion based schemes (Tian, 2003; Ni, 2006; Thodi, 2007; Hong, 2009; Wang, 2013; Ou, 2013; Li, 2011), content adaptive schemes (Kamstra, 2005; Li, 2013) and integer transform schemes (Alattar, 2004; Chen, 2010; Peng, 2012).