Index modulation for H.264 video watermarking and temporal synchronization based on feature statistics
Keyword -- H.264; video watermark; block polarity; index modulation; temporal synchronization.
H.264 is a new advanced standard. The applications of video on Internet or wireless networks become very popular nowadays. However, these digital contents can be easily modified and copied by end users. Hence copyright protection, copy control and integrity verification has become important issues in recent years. Digital watermarking is a means of claiming ownership of a data source.
In the proposed system, block polarity and block index modulation are used to achieve watermark embedding. The block polarity is determined based on the nonzero quantized DC coefficient in each 4x4 integer DCT block. The block index is the pseudo-quantized block activity that is represented by the sum of magnitude of quantized AC coefficients. The watermark embedding is actually performed by the index modulation that will modify quantized AC coefficient values by a small amount to force the activity to be quantized into a specific region.
For resisting temporal attacks, such as frame dropping, frame insertion, and frame transposition, we also propose a temporal synchronization method for video watermarking by matching feature statistics. The feature statistics are calculated by local variances or eigenvalues in video content and sent as side information. Temporal attacks can be detected by comparing side information and feature statistics that be calculated from the received video.
Simulation results show that the proposed method performs well and extract embedded watermark without the original video signal. Additionally, the algorithm is not very complex and appropriate for real-time applications. Based on the extracted feature statistics, the video watermarking system is more robustness against temporal attacks.