LAUSR

Analysis-by-synthesis linear predictive coding (AbS-LPC) is widely used in a variety of low-bit-rate speech codecs. The existing steganalysis methods for AbS-LPC low-bit-rate compressed speech steganography are specifically designed for one certain category of steganography methods, thus lacking generalization capability. In this paper, a common method for detecting multiple steganographies in low-bit-rate compressed speech based on a code element Bayesian network is proposed. In an AbS-LPC low-bit-rate compressed speech stream, spatiotemporal correlations exist between the code elements, and steganography will eventually change the values of these code elements. Thus, the method presented in this paper is developed from the code element perspective. It consists of constructing a code element Bayesian network based on the strong correlations between code elements, learning the network parameters by utilizing a Dirichlet distribution as the prior distribution, and finally implementing steganalysis based on Bayesian inference. Experimental results demonstrate that the proposed method performs better than the existing steganalysis methods for detecting multiple steganographies in the AbS-LPC low-bit-rate compressed speech.