A DWT-based Digital Video Watermarking Scheme with Error Cor(10)

Abstract. In this paper, a digital video watermarking algorithm is proposed. We present a novel DWT-based blind digital video watermarking scheme with scrambled watermark and error correcting code. Our scheme embeds different parts of a single watermark in

Fig. 11. NC values under statistical averaging. After this attack is applied to the watermarked video with different numbers of video frame colluded, watermarks are extracted and NC values are obtained. It is found that the proposed scheme can resist to statistical averaging quite well.

3.3 Experiment with Lossy Compression

This experiment is aimed at testing the robustness of the scheme under attack by lossy compression. Fig. 12 shows the NC values of the extracted watermarks with different

quality factors of MPEG.

Fig. 12. NC values under lossy compression. From the experiment, we found that the proposed scheme improves the robustness for watermark protection.

The performance of the scheme is significantly improved by combining with audio watermark, especially when the quality factor of MPEG is low. This is because when the quality factor of MPEG is low, the error of the extracted watermark is increased and the watermark is damaged significantly. As the error correcting code is provided from the audio watermark, it can survive the attack by lossy compression which is applied to the video channel. The proposed scheme without audio watermark has similar performance with other DWT-based scheme because both of them satisfy the following condition. Higher frequency DWT coefficients of the watermark are embedded to higher frequency part of the video frame and high frequency sub-band DWT coefficients (HH) of video frame are not watermarked. This approach makes the watermark survive MPEG lossy compression, as lossy compression removes the details of the image [20].