视频数字隐写具有隐藏容量大的优点，但是通常在获得隐藏容量的同时，却忽视了安全性。为了在二者之间取得平衡，利用纠错码信息隐藏的原理，提出了一种以压缩视频为载体的数字隐写算法。该算法在进行秘密信息嵌入时，采用了二次嵌入的策略，即首先将秘密信息嵌入到纠错码码字，然后将得到的载密纠错码码字嵌入到与不采用差分编码的系数相对应的行程幅度对的幅度值，同时采用比特率控制策略来减小信息嵌入前后的视频流长度变化。实验及分析表明，该算法的隐写结果不仅具有较好的视觉和统计上的不可感知性，而且满足密码学中的“Kerchhoff准则”。此外，该算法在确保一定的嵌入容量的情况下，能够使视频流长度在信息嵌入前后保持近似不变。

Video steganography has the advantage of large embedding capacity,but the security is usually neglected when obtain the capacity.In order to balance the two aspects,a secure steganographic algorithm for embedding secret information in compressed video is proposed utilizing the principle of steganography based on error-correcting code.The strategy of two-time embedding is designed to embed secret bits.In other words,the secret bits are firstly embedded into the error-correcting codeword.Then by modifying the level value of run-level pair corresponding to the DCT coefficient which is not differentially encoded,the stego error-correcting codeword obtained by first-time embedding is secondly embedded.At the same time,measures are taken for the purpose of preserving video stream size.Experimental results show that the algorithm has a good visual and statistical imperceptibility,and satisfies the Kerchhoff rule in cryptography.Furthermore,the algorithm has a considerable embedding capacity,and can keep the nearly invariant size of video stream.