Elsevier

Digital Investigation

Volume 18, September 2016, Pages 1-7
Digital Investigation

Integrity verification of the ordered data structures in manipulated video content

https://doi.org/10.1016/j.diin.2016.06.001Get rights and content

Abstract

Video content stored in Video Event Data Recorders (VEDRs) are used as important evidence when certain events such as vehicle collisions occur. However, with sophisticated video editing software, assailants can easily manipulate video records to their advantage without leaving visible clues. Therefore, the integrity of video content recorded through VEDRs cannot be guaranteed, and the number of related forensic issues increases. Existing video integrity detection methods use the statistical properties of the pixels within each frame of the video. However, these methods require ample time, because they check frames individually. Moreover, the frame can easily be replaced and forged using the appropriate public software. To solve this problem, we propose an integrity checking mechanism using the structure of ordered fields in a video file, because existing video editing software does not allow users to access or modify field structures. In addition, because our proposed method involves checking the header information of video content only once, much less detection time is required compared with existing methods that examine the entire frames. We store an ordered file structure of video content as a signature in the database using a customized automated tool. The signature appears according to the video editing software. Then, the suspected video content is compared to a set of signatures. If the file structure matches with a signature, we recognize a manipulated video file by its corresponding editing software. We tested five types of video editing software that cover 99% of the video editing software market share. Furthermore, we arranged 305,981 saving options for all five video editing suites. As a result, we obtained 100% detection accuracy using stored signatures, without false positives, in a collection of 305,981 video files. The principle of this method can be applied to other video formats.

Introduction

Vehicle accidents are an unavoidable part of our daily lives. When we become involved in a vehicle accident, there is no doubt that one of the most important problems, with the exception of saving lives, is clarifying responsibility for the accident, including any legal issues. In the last decade, Video Event Data Recorders (VEDRs) have been used as effective and trustworthy witnesses to vehicle accidents and even other criminal incidents. VEDRs are also known as Car Dashboard Camcorders, Vehicle Road Dash Video Camera, Car Black Boxes, and Driving Recorders. In this paper, we refer to such devices collectively as VEDRs. The installation and use of VEDRs is increasing rapidly, and there are a number of countries that mandate the installation of such devices. However, sophisticated video editing software makes it easy to manipulate video content without leaving visible clues. Therefore, it is not possible to be entirely convinced of the integrity of video content recorded by VEDRs (Poisel and Tjoa, 2011, Lee et al., 2015). Some efforts have been directed at ensuring the integrity of video content in digital images and video files in advance (Hu et al., 2015). However, such technologies have a limitation wherein the video recorder system must be pre-processed when it is established, for example, by calculating hash values, embedding watermarks into the video, and so on. Therefore, digital video forensics has become a popular technique for video integrity verification without pre-registration or pre-embedded information; this process is referred to as passive-blind video forensics.

Existing methods mainly focus on digital still images. Zheng used the statistical anomalies of each pixel in an image (Zheng et al., 2015, Rad and Wong, 2015). Qu used the statistical characteristics of image compression (Qu et al., 2014, Cao et al., 2014). Geradts checked the trace caused by a camera color filter and charged-couple device (CCD) (Geradts et al., 2001). Carvalho examined the geometric relationship between an object and light (Carvalho et al., 2015). The principles behind these methods can be applied to video content. However, such evidence can easily be replaced and forged in the image source using publicly available software (Sencar and Memon, 2008). In addition, existing methods must check entire frames in order to detect video forgeries (Wang and Farid, 2007). On an average, 1 min of video content contains 1800 frames, and thus these methods must repeatedly check all 1800 frames. If the video content has low resolution, the detection rate for these methods is reduced significantly.

To address these problems, we propose a mechanism for detecting the modification of video content with video editing software. We focus on the ordered data structures in a video file for integrity verification. The internal ordered data structures are particularly valuable and contain distinct information on video editing software authentication. Existing video editing software and metadata editors do not modify the file's data structures (Gloe, 2012). Therefore, data structure information is reliable for checking video integrity. In addition, this method requires relatively little time for detection, because it simply checks the header information of video content a single time. Moreover, this method is not affected by the resolution, because it checks the data header information exclusively.

We investigate the video file structure characteristics for each type of video editing software that would leave traces from processing the video editing software. Because such traces are an inherent characteristic of each respective video editing software suite, we can detect the specific video editing software used to manipulate the video, in addition to whether the video was, indeed, manipulated. To evaluate the accuracy of this technique, we examined 296 unmodified Audio Video Interleave (AVI) video files. We performed this examination using popular versions of video editing software, namely, Adobe Premiere CS3, Adobe Premiere CS4, Adobe Premiere CS5, Adobe Premiere CS6, Adobe Premiere CC, Sony VEGAS 9, Sony VEGAS 10 Sony VEGAS 11, Sony VEGAS 12, Sony VEGAS 13, Edius 6, Edius 7, Avid Media Composer (Avid MC) 5, Avid MC 6, and Avid Studio 1. These software suites comprise 99% of the video editing software market share. (Notably, we excluded Final Cut, because it does not support the AVI format without an additional plugin.) Although the same video editing software is used in certain cases, depending on the rendering option, the files can appear to have different ordered data structures. Therefore, we arranged 305,981 saving options for all five video editing software suites.

As a result, we found that the AVI data structures in modified video files appear consistently according to each video editing software suite. Each resulting data structure is unaffected by the original video file structure. These ordered data structures are stored in a database as the signature of each type of video editing software. Moreover, given the need to include other video editing software, the database can be extended easily. We used our own customized file parser to read, extract, and detect video content. As a result, we obtained 100% detection accuracy using the stored signatures, with no false negatives (FNs) or false positives (FPs) in our experimental environments. Using the proposed method, we can check the integrity of suspected video, and we can also find the video editing software used for the manipulation.

The main contribution of this paper is the proposal of a method for detecting the integrity violator of video content. To the best of our knowledge, this work is the first attempt to generate a video editing software signature database. Our method does not require pre-processing, and its detection accuracy is not affected by the resolution.

In the following section, we explain the general AVI file format structures. Then, we introduce the practical test setup and explain the proposed signature algorithm. Based on this method, we analyze the original video contents and store video editing software specifications into a database. Using this database, we then describe our evaluation of its detection accuracy. Finally, we summarize our investigation and provide a discussion of the experimental results.

Section snippets

Background

The majority of the multimedia formats used in VEDRs are AVI files. The second most common format is MP4. Only a few test devices use WMA containers. Nevertheless, the proposed method can be applied for AVI, MP4 and WMA formats. Without loss of generality, we discuss the case of the AVI format in this paper. For clarification, we explain the general AVI file format structure.

Video editing software

We collected 232 original videos from an internet VEDR community site,1 along with 64 videos from a forensic center. We classified them according to a sequence of field data structure types.

For each original video field data structure type, video editing software was used to manipulate the video content. We examined the videos using five types of video editing software, representing 99% of the video

Automated signature collection method

We analyzed hundreds of thousands of video content samples. Therefore, for efficiency, we created a customized file parser. This parser extracts field structures and stores them into the database as a signature, which makes it easy to extend the database. We extracted field data structures from manipulated video content using our customized parser. If the extracted field data structure is new, we store it, as shown in Fig. 3. This principle was used while collecting original VEDR field data

Video editing software observation results

There were 12 different AVI field data structures in the original 296 video contents, as shown in Table 2. In order to generate manipulated video content, we manipulated 12 types of original video content. We applied all 12 types to one type of video editing software. The resulting field data structure is not affected by that of the original video content. Therefore, we manually tested 305,981 options in a single file. To improve the rendering speed, we used a small AVI file. As a result, all

Detection algorithm and evaluation

Using the video editing software signature database, we can detect manipulated video content. In order to automate such detection, we designed an automated detection parser.

Algorithm 2

Script for verifying the integrity of video.

Algorithm 2 shows the pseudocode for the process of detecting integrity based on our database. The basic principle to this detection algorithm is the same as the principle for the database algorithm. It reads four bytes for the chunk name from suspicious video content. Then, it

Discussion

In addition to AVI, we have applied the same approach to MP4 media format. We collected three different types of MP4 field data structures (Table 6). We manipulated three types of original video contents by Adobe Premiere series. As a result, we have constructed the signature from the field data structures of the content by Adobe Premiere series as shown in Table 7. While the proposed method can be applicable for detecting Adobe Premiere series as a working example, extension to other video

Summary and conclusion

As video editing software advances, malicious individuals can easily modify VEDR video content without leaving visible clues. Therefore, it is important to verify the integrity of videos used as evidence in criminal investigations. Existing methods require considerable detection time, and low-resolution images can degrade the detection rate.

For higher efficiency and faster detection, we proposed a detection algorithm that can easily collect signatures into a database and detect manipulated

Acknowledgments

This research was supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2012M3A2A1051118).

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