根据H.264编码标准帧内预测模式的特点,提出一种高容量视频信息隐藏方案.方案中用Tent映射选出待嵌入宏块,根据帧内预测模式及哥伦布编码特点,设计了一种最小角偏移预测模式替换算法,通过修改Ⅰ帧中4×4亮度宏块帧内预测模式来嵌入秘密信息.为增加秘密信息安全性,先用Tent映射加密秘密信息,并用其生成的密钥选出待嵌入宏块.只需对帧内预测模式进行解码,便可从编码后的视频流中直接提取秘密信息.实验结果表明,该方案可有效嵌入秘密信息,不可见性好,视频流长度变化微小,并可通过调控控制因子Ⅳ来调控嵌入容量,从而调控视频质量.
A high-capacity video information hiding scheme based on the intra prediction mode for H. 264 coding standard. Tent mapping is used to select the 4 × 4 macroblocks which is to be embedded, according to the characteristics of intra prediction mode and Columbus coding, we designed a minimum angle shift replacement algorithm. Hide the secret information by modifying intra prediction mode of the 4 × 4 luminance macroblocks of I frames. In order to increase the security of confidential information, first use the Tent mapping to encrypt the secret information and generate a radom key, then select the macroblocks,which are to be emdedded, by the key. By only decoding part of the intra prediction mode, the secret information can be extracted from the encoded video stream directly. The experimental results show that the scheme can effectively embed the secret information into the intra prediction of 4 × 4 luminance macroblocks, it has a good imperceptibility, a small change of video stream length, and it can control the scheme's embedding capacity by regnlalting the control factor N, thus it can regulate the video quality after embedding.