Abstract: For low bit-rate H.264/AVC video, this paper proposed a semi-fragile content authentication algorithm in VLC domain. Utilizing the intra prediction mode and coded block pattern in VLC domain, the algorithm chooses those macro-blocks. The signature is extracted according to the relationship between the energies of quantized low-frequency coefficients of submacroblocks from these macro-blocks, embedded by modifying the trailing coefficients. The experimental results show that this algorithm performs well in visual quality impact, keeps the bitrate basically unchanged and enhances the watermark capacity. By verifying the extracted signature, the algorithm can efficiently detect and locate the tampering on the video with high real-time.
 

Key words: video watermarking, content authentication, variablelength coding (VLC) domain, semifragile watermarking