Authentication of H.264 streams by direct watermarking of CAVLC blocks
Authentication of H.264 streams by direct watermarking of CAVLC blocks
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DOI：
10.1117/12.703369
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发表时间：
2007-02
期刊：
影响因子：
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通讯作者：
B. Mobasseri;Yatish Naik Raikar
中科院分区：
文献类型：
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作者：
B. Mobasseri;Yatish Naik Raikar
在这项工作中，我们报告的第一个H.264认证水印，直接在比特流中工作，不需要视频解码或部分解压缩。264协议中的一个可水印码空间的识别。该算法在H.264代码空间中创建只有解码器理解的“异常”，同时保持比特流语法兼容。代码空间在协议的上下文自适应可变长度编码（CAVLC）部分上定义。使该算法成为可能的是发现大部分H.264代码空间实际上未被使用。水印安全地将合格的CAVLC映射到代码空间的未使用部分。通过嵌入器和解码器之间的共享密钥来实现安全性。水印流保持其文件大小，保持视觉透明，是安全的，防止伪造和检测。由于水印是在压缩后放置的，因此它对于重新编码和其他篡改尝试仍然是脆弱的。
In this work we report on the first H.264 authentication watermarker that operates directly in the bitstream, needing no video decoding or partial decompression. The main contribution of the work is identification of a watermarkable code space in H.264 protocol. The algorithm creates "exceptions" in H.264 code space that only the decoder understands while keeping the bitstream syntax compliant The code space is defined over the Context Adaptive Variable Length Coded(CAVLC) portion of protocol. What makes this algorithm possible is the discovery that most of H.264 code space is in fact unused. The watermarker securely maps eligible CAVLC to unused portions of the code space. Security is achieved through a shared key between embedder and decoder. The watermarked stream retains its file size, remains visually transparent, is secure against forging and detection. Since the watermark is placed post compression it remains fragile to re encoding and other tampering attempts.