对于视频压缩领域，基于上下文的自适应编码(CAC)是一类新出现的高效熵编码方法。为了对数字视频进行实时安全编码，提出了一种基于CAC的数字视频安全编码方案，并首先建立了以CAC安全编码器为核心的安全编码链，然后给出了基于上下文的自适应二进制算术安全编码(CABASC)和基于上下文的自适应变长安全编码(CAVLSC)两种安全编码操作。实验结果表明，该方案具有较好的安全性、实时性和软件易实现性，可作为进一步研究CAC安全编码的基础。

based adaptive coding (CAC) is a class of new high-efficient entropy coding techniques for video compression. In this paper, a CAC-based scheme is presented to achieve realtime secure coding for digital video, and a secure coding chain is built based on CAC secure coder. Two kinds of secure coding operations, including context-based adaptive binary arithmetic secure coding (CABASC) and context-based adaptive variable length secure coding (CAVLSC), are given. The experimental results show that this scheme has significant improvement on security, real-time performance and flexibility of software implementation. These properties make it a sound foundation for further research on CAC secure coding.