Study And Realization On Information Hiding Algorithm Based On Transcoding Between AMR And G.729

In the field of information security, information hiding technique has drawn more and more attention due to its advantages of security, transparency, robustness, and etc. As an effective supplement to conventional encryption technique, information hiding has been widely used in multimedia copyright protection and hidden communication applications. Among all kinds of carriers, speech is the most common, most effective and most direct form. Therefore, it is very important and significative to study the speech-based information hiding algorithms to protect the company's profit, national security and social stability.With the rapid development of modern communication technology, the merging between the wireless network and Internet becomes a very important issue. Because different networks often employ different speech codecs, the transcoding is essential, which means to transfer the bit stream generated by one coder to that of another coder seamlessly. Considering ARM and G.729 are the most popular speech codes in WDCMA and VOIP respectively, this paper studies the information hiding algorithms based on the transcoding between ARM and G.729.According the different effects of different bits in bitstream of CELP (Code Excited Linear Prediction) encoder on the quality of speech, two information hiding algorithms based on Pitch and Fixed Codebook are proposed respectively. According to the characteristics of the generating process of LSP parameters, an information hiding algorithm based on ABS is proposed. The experimental results show that the three algorithms can provide relative good transparency, robustness, security and large embedding capacities. A transcoding based speech hidden communication platform is designed and realized. The performances of the platform tested in LAN are satisfactory.