Abstract: To solve the problem of H.264 video copyright protection, a new blind watermarking algorithm was proposed. Based on the texture features of the picture, watermarking information was embedded on the Discrete Cosine Transform (DCT) domain of Instantaneous Decoding Refresh (IDR) frames. First, a rectangular sliding window was used to search the region of complex textures. Second, in the selected region, a 4×4 sub-block of maximum energy was chosen for embedding one watermarking bit. Last, one Alternating Current (AC) coefficient value of the selected 4×4 sub-block was modified adaptively. The experimental results show that Peak-Signal-to Noise Ratio (PSNR) decreases 0.15dB and the bitrate rises 0.49% on average, and the accuracy of watermark detection is above 91%; moreover, the algorithm can effectively resist the re-coded attacks of different Quantization Parameter (QP).

Key words: H.264, blind watermarking, Discrete Cosine Transform (DCT), intra predict, texture complexity

摘要： 为了解决H.264视频信息的版权保护问题，提出了一种基于即时解码刷新(IDR)帧离散余弦变换(DCT)域的盲水印算法。该算法首先分析IDR帧的纹理特征，利用滑动矩形窗根据图像的梯度特性提取出复杂纹理区域；然后，计算该区域内每个宏块的16个4×4子块能量，得到能量最高子块；最后，通过自适应修改子块的一个交流(AC)系数幅值以达到嵌入水印的目的。实验结果表明：对CIF分辨率视频测试序列嵌入水印后，视频图像的峰值信噪比(PSNR)平均下降0.15dB，码率平均增加了0.49%，水印检测准确率达到91%以上，并且该算法能够有效抵抗不同量化参数(QP)的重复编码攻击。

关键词: H.264, 盲水印, 离散余弦变换, 帧内预测, 纹理复杂度