• Journal of Digital Forensics
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• v.13 no.2
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• pp.63-73
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• 2019

When a traffic accident occurs, the vehicle's speed is an essential factor in the analysis of the cause of the accident. As more and more vehicles have a blackbox device installed, measuring the vehicle's speed through blackbox video is one of the ways to measure the vehicle's speed. This paper presents the results of comparing and analyzing the validity of the speed measured from re-recorded or re-encoded blackbox video. In this paper, we suggest that if it is impossible to measure the speed with the original blackbox video, it can analyze by re-taken and re-encoding video. For the verification, the accuracy of the measured speed by original video examined by comparing it with the actual speed confirmed in the smartphone navigation. After that, the speeds of vehicles in three re-taken videos and two re-encorded videos at different resolutions and frames per second measured. As a result of analyzing them, it verified that there is no significant difference between them and the speeds from the original video. Based on these results, it confirmed that the speeds measured from re-taken and re-encoded video are valid when measuring a vehicle's actual speed.