针对音频信号内容完整性鉴定的需要,提出基于音频内容的非均匀离散余弦变换的脆弱音频水印算法。算法中水印通过量化音频三级小波近似分量的平均值而产生,并对三级小波近似系数做非均匀离散余弦变换NDCT,将生成的水印通过量化的方法嵌入到NDCT域第2个系数(即首个交流系数)上。非均匀离散余弦变换的频率采样点由密钥控制的混沌产生,提高了水印系统的安全。仿真实验表明:提出的算法对MP3有损压缩、滤波、重采样、量化等信号处理操作十分敏感,对恶意的替换操作等非同步攻击能够报警并能做出篡改定位。
In view of the need of audio content integrity authentication, the content-based non-uniform DCT fragile audio watermarking algorithm was put forward. The watermark was generated by quantifying the third-level audio wavelet approximation coefficients. The watermark was embedded into the second coefficient (namely the first active coefficient) in the non-uniform DCT (NDCT) domain. The embedding method was to quantify the active coefficient. The NDCT frequency sampling points were set by key-controlled chaos and security of the watermark system was improved. Simulation experiments demonstrate as follows: The proposed algorithm is extremely sensitive to signal processing manipulations such as MP3 lossy compression, filtering, re-sampling, quantization,etc; the algorithm can detect and localize illegal tampering.