# Reliable Integrity Preservation Analysis of Video Contents with Support of Blockchain Systems
## 4 Evaluation
### Experiment Results  
To examine the performance of the implemented tool, we prepare two hundred original video files and their retouched video files. The two hundred original videos are generated using USB web cameras with Windows 10, Galaxy smartphones with Android and Apple smartphones with iOS. These two hundred video files are retouched with five video editing tools: Movavi Video Editor, VapMix, GomMix, FFmpeg and Pinnacle Studio. We first transform these two hundred original videos without any modification into their corresponding retouched videos, referred to as non-modified videos. Next, we transform these two hundred original videos with some modification into their corresponding retouched videos, referred to as non-modified videos. One hundred files among the two hundred original files are transformed with frame deletion, referred to as inter-frame forgery videos, and the other one hundred files are transformed with image modification within frames, referred to as intra-frame forgery videos. The position of the deleted frame and the location of modified images are selected randomly. Table 1 shows the integrity analysis accuracy and the execution time of the proposed scheme. The proposed scheme detects the exact name of camera devices or the name of video editing tools in all cases. Based on the detected name, the scheme classifies the input videos into original videos and retouched videos. However, the scheme does not classify the group of retouched videos: non-manipulated, inter-frame forgery and intra-frame forgery. The execution time of the proposed scheme is less than one second in all cases, whereas the maximum execution time of the scheme is 443 ms. The average execution time for integrity analysis of original videos is 221 ms; for non-modified videos, it is 227; for inter-frame forgery videos, it is 228 ms; for intra-frame forgery videos, it is 232 ms.  
Table 2 shows the comparison accuracy between the original video and the retouched video in the proposed scheme. In Table 2, \"Allowed Difference Ratio\" means the maximally allowed difference ratio of red, green and blue components in each pixel of the retouched video against those in each pixel of the original video. Even though there is no modification when transforming the original video into the retouched video with video editing tools, the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Measure** & **Original Video** & **Non-Modified** & **Inter-Frame Forgery** & **Intra-Frame Forgery** \\ \hline Accuracy & 100.0\% & 100.0\% & 100.0\% & 100.0\% \\ Avg exec. time & 221 ms & 227 ms & 228 ms & 232 ms \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Accuracy and execution time of integrity analysis. Figure 11: Procedure to search the integrity preservation trace with a hash of input file. red, green and blue component values in the original video file are slightly different from those in the retouched video file. This variance comes from the re-compression procedure of codecs in the video editing tool, which is different the compression procedure of original codecs in the video recording device. Therefore, if any difference between original video and retouched video is not allowed, the first frame of the original video is determined to not be the same as the first frame of its corresponding retouched video in all cases. As result, when \"Allowed Difference Ratio\" is 0.0%, the accuracy of comparing original video and retouched videos is 0.0% for all transformations of non-modified, inter-frame forgery and intra-frame forgery videos, as shown in Table 2.  
When the \"Allowed Difference Ratio\" is 0.025%, the accuracy becomes close to 100.0% but not equal to 100.0%. Comparison between original video and retouched video is correct for all static scenes, where objects rarely move in subsequent frames. However, comparison becomes incorrect for some dynamic scenes, where objects moves very quickly in subsequent frames. When the \"Allowed Difference Ratio\" is set to 0.05%, the accuracy measures of all transforming operations are 100.0%.