## 4 Experiment
### Threshold Estimation and Scenario-Based Experimental Results
#### 4.2.2 Scenario 1  
In scenario 1, the investigators secured manipulated videos and detected original and manipulated videos from a suspect's mobile device. Table 6 shows the manipulated video secured by investigators (BNM_E) and the query video, which is the query section selected by the investigators within BNM_E. Under this scenario, the investigator set the whole BNM_E as a query section and ran the test. The video names in Table 4 show the video criteria. If a video is original, it is labeled 'O' (original) after the underscore (_); if manipulated, it is labeled 'E' (edit); and if unrelated to an original video, it is labeled 'D' (different). Table 7 shows videos of a suspect's mobile device. As shown in Figure 7, these videos were used for an optimized comparison with the query video. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Video Name** & **Running Time** & **File Size** & **Frame (Width \(\times\) Height)** & **Frame Speed** \\ \hline Edit video (BNM\_E) & 2 min 10 s & 49.8 MB & 1920 \(\times\) 1088 & 29.97 frames/s \\ \hline Query video & 2 min 10 s & 49.8 MB & 1920 \(\times\) 1088 & 29.97 frames/s \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Video secured by investigators and query video (scenario 1). Figure 7: Comparison for scenario 1. The similarity comparison between videos is applied to scenario 1, and each of the following steps is applied:  
**Step 1. **: Determine a query section in a reference video. In scenario 1, the entire reference video is a query section. **Step 2. **: Cut a video frame-by-frame based on Table 1.
**Step 3. **: Cut a comparison video frame-by-frame based on Table 1. The number of frames is checked, and the unit of frame continuity is determined based on Table 2.
**Step 4. **: Process similarity comparison from the middle of the running time of the comparison video based on the frame continuity unit. **Step 5. **: Detect a video that ends up being similar on the basis of the thresholds in Table 5, and then go to the next video. If not similar, go to the next video. **Step 6. **: In the next video, repeat the process from Step 3. Figure 7(a) illustrates the result from the correlation similarity comparison with the videos in a suspect's mobile device under scenario 1. The suspect's mobile device has five videos: three videos irrelevant to the query video (DNM_D, Dark+Near+Middle_Different videos; BNM_D, Bright+Near+Middle_Different video; and BNH_D, Brighy+Near+High_Different video), one original video of the query video (BNM_O, Bright+Near+Middle_Original video), and one manipulated video (BNM_E, Bright+Near+Middle_Edit video). Because these five videos have a different running times, their total number of extracted frames are different. A comparison was carried out in the order of videos listed in Table 7. Beginning with the middle of the total frame number for each video, a frame was compared with the query frame in accord with the pseudocode shown in Figure 3. After that, a similar video was identified based on the BNM threshold of Table 5. If all results from the three algorithms for one frame were within the range of thresholds for over 10 separate trials, the comparison process stopped and the video was identified as identical or manipulated. For the three videos irrelevant to the query video (DNM_D, BNM_D, BNH_D), the optimization search began from the middle of the video in line with the pseudocode shown in Figure 3. As a result, no frames had a similarity of 0.47 or more in terms of the threshold of the correlation algorithm under the BNM environment. For this reason, after all frames were searched, the comparison process moved to the next video. For the original video BNM_O and the manipulated video BNM_E, the comparison was processed from the middle of the total extracted frames in each of the two videos in accord with the pseudocode shown in Figure 3. Within an extremely short time, it was concluded that they were similar, and thus the search stopped.