提出了一种运用哈希函数进行MPEG-4内容认证的半脆弱可逆视频水印算法。在YUV视频进行MPEG-4编码的I帧中嵌入两个水印，一个运用哈希函数进行内容完整性验证并嵌入帧序号进行帧间篡改定位，另一个基于直流系数和低频系数用于帧内篡改定位。实验结果表明，算法能够对视频内容进行验证并实现篡改定位，且对MPEG-4压缩具有鲁棒性。另外，算法具有可逆性，能够在视频内容可信的前提下进行无损恢复。

This paper proposes an invertible semi-fragile video watermarking algorithm using a hash function to authenticate the MPEG-4 video contents. The proposed algorithm embeds two watermarks into I frame while encoding the YUV video to MPEG-4 format. One watermark using a hash function aims to authenticate the contents and embed the frame number for tamper localization between frames, and the other one based on direct coefficients and low-frequency coefficients is used for the detection of tamper localization within the frame. The experimental results show that the proposed algorithm is able to authenticate the video contents and detect the tamper localization, and it is robust for MPEG-4 compression. In addition, the proposed algorithm is exactly invertible, which means that the original video data is available as long as the watermarked video is credible.