Fragile watermarking scheme based on index constrained vector quantization
一种基于索引约束矢量量化的脆弱音频水印算法*

Unlike normal vector quantization, index constrained vector quantization can limit the range of searching codewords by select an constrained position in the index in the process of quantization. This paper makes use of this special searching method to propose an audio watermarking scheme. The original audio signal is first segmented into several frames, DCT transform is performed on every frame and the middle-frequnency coefficients are extracted to form vectors. The embedding procedure can be described as finding matching codewords to modify the DCT middle-frequency coefficient vectors in accordance with the watermarking bits and the constrained bits. Normal vector quantization is adopted in the extracting procedure. The constrained bits in the same position are extracted as the watermarking information. This scheme is real-time because the watermarks can be embeded in the quantization process. The experimental results show that the watermarking is fragile and can be used for authentication.