To apply video watermarking technique in real⁃time streaming media security transmission,a real⁃time streaming media digital watermarking system was designed. On the basis of client/server(C/S)frameworks,the system is designed by mod⁃ularized method. The server⁃side supports video streaming inputted in digital form,and the client⁃side can extract digital water⁃marking information while decoding playing. To guarantee real⁃time and security transmission of streaming media,an improved watermarking algorithm is proposed. The algorithm calculates cumulative sums corresponding to all variable length codes(VLC)in each code streaming. When the cumulative sum is larger than 30,the last VLC value in code streaming in this section is modi⁃fied. The proposed algorithm and classical differential energy watermarking(DEW)are compared in the aspects of robustness, imperceptibility,watermarking capacity and computing complexity. The comparison results show that the advantage of the pro⁃posed algorithm is outstanding.%为了将视频水印技术应用于实时流媒体的安全传输，设计并实现了一个实时流媒体数字水印系统。该系统基于客户机/服务器（C/S）架构，采用模块化的思路进行设计，服务器端支持以数字形式输入的视频流，客户端可以在解码播放的同时实时提取出数字水印信息。为了满足流媒体的实时、安全传输，提出了一种改进的水印算法，该算法计算每段码流中所有可变长度码（VLC）对应的游程累积和，当累积和大于30时修改该段码流中最后一个VLC的值。最后将该算法与经典的差分能量水印（DEW）算法在鲁棒性、不可感知性、水印容量和计算复杂性等方面进行了对比，结果表明提出的算法优势明显。
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