# MPEG and DA-AD Resilient DCT-Based Video Watermarking Using Adaptive Frame Selection
## 4 Experimental Results
### Results
#### 4.2.2 Robustness Assessment  
A watermarking scheme must be robust, which implies that an embedded pattern should be difficult to damage through a non-hostile signal process, such as MPEG compression or digital/analog-analog/digital conversion. Thus, an embedded watermark pattern must incur little damaged from these non-hostile signal processes. Tolerance is demonstrated through the calculation of the average BER for the extracted watermark information after undergoing video processes. Evaluations were conducted with various watermarking factors, i.e., \(\alpha=0.4\), 0.9, and 1.5.  
Table 4 lists the robustness results for the benchmark Set-4, where the watermark strength \(\alpha=0\), the PSNR is 44.02 dB, and the SSIM is 0.9945. With an MPEG quality factor of zero, all watermarks were damaged and no data were detected. It is important to note that video compression with a factor of zero triggers a substantially strong level of content loss, and the factor is not adopted, except under extremely unique circumstances. Regarding the test conducted with an MPEG quality factor of 10, regardless of the negligible watermark strength, we succeeded in detecting the watermark in both experimental videos #2 and #8. This is because the motion was relatively small in these videos; hence, the watermark damage owing to MPEG compression also appeared to be small. At a certain level of MPEG compression (qf > 40), all watermark bits were successfully detected. Note that a PSNR of 44.08 dB is more than 6 dB higher than 38.0 dB, which is generally regarded as the minimum distortion value for which a human can detect a watermark, and thus no distortion can be detected by the human eye.  
Tables 5 and 6 list the robustness results and compressibility of the various MPEG quality factors. In the evaluation with a watermark strength of 0.9, the embedded data bits were successfully detected from four videos, #2, #8, #20, and #23, whereas the mean compressibility was \(1/604\). At a watermark strength of 1.5, the embedded watermark information was accurately detected for all evaluated quality factors, as shown in Table 6.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \multicolumn{2}{c}{**MPEG Quality Factor**} & **50** & **40** & **30** & **20** & **10** & **0** \\ \hline \multirow{2}{*}{\#2} & BER & 0.000 & 0.000 & 0.000 & 0.000 & 0.000 & \(\times\) \\ \cline{2-7}  & compressibility & 1/139 & 1/191 & 1/232 & 1/307 & 1/432 & 1/1029 \\ \hline \multirow{2}{*}{\#8} & BER & 0.000 & 0.000 & 0.000 & 0.000 & 0.000 & 0.000 \\ \cline{2-7}  & compressibility & 1/139 & 1/193 & 1/253 & 1/321 & 1/445 & 1/606 \\ \hline \multirow{2}{*}{\#20} & BER & 0.000 & 0.000 & 0.000 & 0.000 & \(\times\) & \(\times\) \\ \cline{2-7}  & compressibility & 1/139 & 1/190 & 1/253 & 1/321 & 1/444 & 1/460 \\ \hline \multirow{2}{*}{\#23} & BER & 0.000 & 0.000 & \(\times\) & 0.000 & \(\times\) & \(\times\) \\ \cline{2-7}  & compressibility & 1/138 & 1/193 & 1/249 & 1/322 & 1/400 & 1/395 \\ \hline \multirow{2}{*}{\#46} & BER & 0.000 & 0.000 & 0.000 & \(\times\) & \(\times\) & \(\times\) \\ \cline{2-7}  & compressibility & 1/129 & 1/183 & 1/236 & 1/296 & 1/386 & 1/443 \\ \hline \multirow{2}{*}{Average} & BER & 0.000 & 0.000 & 0.200 & 0.200 & 0.600 & 0.800 \\ \cline{2-7}  & compressibility & 1/137 & 1/190 & 1/245 & 1/313 & 1/422 & 1/587 \\ \hline \end{tabular} \(\times\): watermark is not detected (BER is considered as 1.000).  
\end{table}
Table 4: Robustness results for the benchmark Set-4 with the watermark strength \(\alpha=0.4\) (PSNR 44.03 dB, SSIM 0.9945, \(\alpha=0.4\)).