# Reliable Integrity Preservation Analysis of Video Contents with Support of Blockchain Systems
## 4 Evaluation
### Experiment Results
Until the \"Allowed Difference Ratio\" is set to 0.40%, the accuracy measures are 100.0%. It is worth mentioning that if the \"Allowed Difference Ratio\" is set too high, some intra-frame forgery may not be detected during the comparison. For example, when \"Allowed Difference Ratio\" is set to 0.50%, the proposed scheme determines one intra-frame forgery video as a non-manipulated retouched file among the 100 intra-frame forgery videos. Similarly, when the \"Allowed Difference Ratio\" is set to 0.60%, the scheme misses two intra-frame forgery videos. Finally, we examine the processing speed of the proposed scheme against the video file size. Table 3 shows the consumed execution time on the Samsung notebook with a i7-core processor with 16 Gbytes memory. The average execution time of videos against the range of file size is depicted. The execution time of analyzing the integrity of input videos is slightly proportional to the file size, but almost close to about 220 ms. The processing time of analyzing the integrity is rarely affected by the file size, because this operation examines only the file header fields, but not the multimedia contents of the video. This processing time is mostly dominated by the speed of the smart contract program in the blockchain system. The execution time of comparing video frames between original videos and retouched videos heavily depends on the file size, as shown in the column \"Comparing\" of Table 3. This execution time is determined by the hardware performance of the front-end server, because it is carried out on the front-end server. The execution time for storing the comparison result is manifestly proportional to the file size, where the storing operation requires the hash function to compress the input video file into a 32-bytes hash value. The processing speed of storing the comparison result per mega bytes is about 212 (ms)/(Mbytes). This execution time is also affected by the hardware performance of the front-end server. The execution time taken when the comparison result is also manifestly proportional to the file size, because the search operation also calculates the hash value of an input file. The processing speed of searching the comparison result per mega bytes is about 74 (ms)/(Mbytes). The maximum execution time of the search operation is about 3971 ms against the input file with 1.98 Gbytes. The search operation is completed within,  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Allowed Difference Ratio** & **Non-Modified** & **Inter-Frame Forgery** & **Intra-Frame Forgery** \\ \hline
0.0\% & 0.0\% & 0.0\% & 0.0\% \\
0.025\% & 99.0\% & 99.0\% & 96.0\% \\
0.05\% & 100.0\% & 100.0\% & 100.0\% \\
0.10\% & 100.0\% & 100.0\% & 100.0\% \\
0.20\% & 100.0\% & 100.0\% & 100.0  
at most, four seconds in this experiment. The procedure to obtain the comparison result and store it into the blockchain system is called once for each video, whereas the search operation may be called repeatedly for each video. The operations of comparing videos and storing result are set for recording the transforming history of a retouched video, while the operation of analyzing integrity is separate and the operation of searching result is separate. The operation of analyzing integrity is completed within, at most, half of a second. The operation of the searching result is completed within, at most, five seconds. The operations of comparing videos and storing the result are completed within, at most, fifteen minutes. The coin fees required for analyzing integrity and searching result are zero, because these operations do not require data to be permanently stored in the blockchain. On the contrary, the coin fee required for storing the result is about 0.018756 Klay, where the coin fee is the amount of consumed gas \(\times\) fee per gas (\(250\times 10^{-9}\) Klay). This coin fee is required whenever storing the transforming history of a retouched video.