西北民族大学电气工程学院电子信息工程(1)班
西北民族大学电气工程学院电子信息工程(1)班
DWT和DCT结合的变换域音频水印
摘 要 近年来随着网络通信和多媒体技术的迅速发展，盗版问题非常明显，数字水印是一种可以在开放网络环境下保护版权和认证来源的新技术。它将特定意义的标记隐藏在数字图像、音频等数字产品中，来验证创作者对其作品的所有权。
音频水印技术主要利用了人类听觉模型，在不影响音频信号质量的前提下，将水印信息隐藏在人耳不能感知的位置，来隐藏水印数据。本文研究DWT和DCT结合的音频水印算法，首先对音频信号进行DWT和DCT变换，根据水印的大小把DCT系数均匀分段，采用量化的方法把直观的二值黑白图像嵌入音频中，然后利用攻击函数攻击音频信号，再从含水印的音频中提取出水印信息，最后通过MATLAB仿真计算信噪比和归一化系数，验证该算法是否具有良好的安全性、鲁棒性和不可感知性。 关键字 音频水印，离散小波变换，离散余弦变换
ABSTRACT
In recent years, with the development of the network communication and multimedia technology, the problem of piracy is becoming more and more obvious. Digital watermarking is a new kind of technology, which can be used to protect copyright and certificate source under the opening network environment. The technology will hide the special markers in the digital image、audio to prove the creators' ownership of their works.
On the condition of not affecting the quality of audio signal, audio
西北民族大学电气工程学院电子信息工程(1)班
watermarking technology mainly uses the human hearing model to hide the watermarking information in the position where peoples' eyes can not perceive. The paper studied the audio watermarking algorithm based on DWT and DCT. Firstly made DWT and DCT transformation, then DCT coefficients were segmented equally according to the size of watermark. By using the quantification method, intuitive binary black and white images were embeded into the audio signal. Later attack functions are used to attack the audio signal and then extract the watermarking information. At last though the MATLAB simulation, calculate signal to noise ratio and normalized coefficient to prove whether the algorithm satisfy the requirements of imperceptibility, safety and robustness or not.
Key word: Audio watermark, Discrete wavelet transform, Discrete cosine transform
西北民族大学电气工程学院电子信息工程(1)班
目录
1. 绪论 ......................................................................................................................................... 1
1.1 音频水印的发展 .......................................................................................................... 1 1.2 数字水印原理及简单模型 .......................................................................................... 1 1.3 数字音频水印存在的问题 .......................................................................................... 3 2. 数字音频水印 ......................................................................................................................... 4
2.1 数字音频水印原理及模型 .......................................................................................... 4
2.1.1 数字音频水印的原理及一般模型 .................................................................... 4 2.1.2 音频水印的要求 ................................................................................................ 5 2.2 数字音频水印的算法 .................................................................................................. 6
2.2.1 音频水印算法的分类 ........................................................................................ 6 2.2.2 音频水印的攻击算法 ........................................................................................ 7
3. DWT和DCT结合的音频水印算法 ...................................................................................... 8
3.1 小波变换与余弦变换的理论知识 .............................................................................. 8
3.1.1 小波变换的理论知识 ........................................................................................ 8 3.1.2 离散的余弦变换 .............................................................................................. 10 3.2 图像的置乱与加密技术 ............................................................................................ 10
3.2.1 图像的Arnold置乱及其恢复 ......................................................................... 10 3.2.2 混沌序列的产生 .............................................................................................. 12 3.2.3 混合光学双稳模型加密水印图像 .................................................................. 12 3.2.4 量化嵌入水印的原理 ...................................................................................... 13 3.3 DWT、DCT相结合音频水印的算法步骤 .............................................................. 14
3.3.1 水印嵌入前的预处理操作 .............................................................................. 14 3.3.2 嵌入水印 .......................................................................................................... 14 3.3.3 提取水印 .......................................................................................................... 16 3.3.4 性能分析 .......................................................................................................... 16
4. MATLAB仿真与结论 ........................................................................................................... 18
4.1 MATLAB 仿真测试 .................................................................................................. 18
4.1.1 不可感知性的测试 .......................................................................................... 19 4.1.2 安全性的测试 .................................................................................................. 21 4.1.3 鲁棒性测试 ...................................................................................................... 22 4.2 总结 ............................................................................................................................ 25 4.3 展望 ............................................................................................................................ 25 参考文献 .................................................................................................................................... 27 答 谢 ...................................................................................................................................... 28