Constant Bitrate Image Scrambling Method Using CAVLC in H.264

Abstract

As the digital multimedia industry has grown, demand for protecting the copyright of the multimedia contents has increased. Digital video scrambling is a digital video protection technique, and is known as an effective strategy to protect the contents. In this paper, a digital scrambling method based on a shuffled VLC table and the use of coefficient levels scrambling are proposed as content protection techniques. In the CAVLC procedure, the levels of each coefficient are first transformed by the key. The VLC tables are then shuffled using another key mapping procedure. This method can be applied to the latest video CODECs such as MPEG-4 and H.264. The image can be reconstructed by the key with the correct information. We found that the compression performance does not decrease due to the scrambling, so that attaching CODECs is worthwhile. The implementation is made possible by the substitution of codewords in the look-up table, which keeps the computational complexity low. The experimental results show that both content protection techniques investigated are able to efficiently scramble the images without any overhead or complexity.