Video Inter-Frame Forgery Detection: a Survey
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ISSN (Print) : 0974-6846 Indian Journal of Science and Technology, Vol 9(44), DOI: 10.17485/ijst/2016/v9i44/105142, November 2016 ISSN (Online) : 0974-5645 Video Inter-frame Forgery Detection: A Survey Staffy Kingra*, Naveen Aggarwal and Raahat Devender Singh UIET, Panjab University, Chandigarh - 160014, Punjab, India; [email protected], [email protected], [email protected] Abstract Objectives: This paper summarizes all the proposed techniques involved in digital video inter-frame forgery detection for MPEG-1, 2, 4 and H.264/AVC encoded videos. Methods/Statistical Analysis: Double compression detection techniques structure.are classified Video here inter-frame on the basis forgery of footprints detection analyzed techniques during are detection. then analyzed The detection on the basis methods of type designed of forgery for they videos detect that anduse thefixed type GOP of structure codec used for forfirst video and encoding.any of the Findings:subsequent Digital compression videos often are different provide forensicfrom the evidence videos that in legal,use different medical GOPand surveillance applications but are more prone to inter-frame forgeries, which are not only easy to perform but are equally on the number of frames tampered and video codec used to encode the videos. Among these proposed techniques, double MPEGdifficult compression to detect as well.was bestThe analysisdetected of using the literature the technique ascertained which that utilizes majority Benford’s of the law proposed and was techniques proposed are by dependent Chen and gave sound results for all kinds of inter-frame onShi forgeryon MPEG-1 detection and MPEG-2 in MPEG-4 encoded encoded videos. videos On the and other thereby hand, such Wang techniques et al. have not been discussed in many survey papers.forgeries Moreover, on MPEG-2 digital encoded cameras videos especially by utilizing surveillance the measure cameras of optical which flow generate consistency. massive Since amount very fewof videos authors these focussed days have built-in MPEG-4 codec because it offers a better compression rate. Application/Improvements: Video forensics domain, therefore, is in dire need of a technique that will detect any kind of inter-frame forgery in MPEG-4 encoded videos. Keywords: Digital Forensics, Inter-frame Forgery, Video Forgery Detection, Video Forgery Detection Survey, Video Tampering Detection 1. Introduction forensics was conceived. Digital video forensics encom- passes tools and techniques which help clarify whether Video editing techniques were primarily meant for the contents of a given digital video are veritable or not. enhancement of the digital content. But the increase in Video forgeries can generally be classified as inter-frame availability and usage of inexpensive and easy-to-use con- or intra-frame. tent editing software has escalated the side effects and potential hazards of such editing techniques. Any indi- 1.1 Intra-frame Forgeries vidual can utilize these techniques to make unauthorized A digital video is essentially a sequence of still images modifications to the video content thereby harming its or frames and intra-frame forgery tends to tamper each integrity and authenticity. Although majority of the forg- frame individually. Intra-frame forgeries can be further eries are not visually identifiable, they meddle with the classified as: underlying characteristics of the digital content under • Pixel-level Forgeries: Pixel level is the most basic consideration and introduce certain abnormalities. These level at which visual contents can be modified abnormalities, when statistically analyzed, make it easy using copy-move, splicing and re-sampling tech- to observe the artifacts left by tampering. To ensure the niques1. authenticity of digital content, the domain of digital video *Author for correspondence Video Inter-frame Forgery Detection: A Survey • Object-level Forgeries: These forgeries entail review of the techniques designed to detect inter-frame cloning an object or region from one location to forgeries. Section 4 concludes the survey and provides another in a single frame and inserting or remov- future directions to determine new research problems in ing an object to/from a frame2–5. the field of video inter-frame forgery detection. • Frame-level Forgeries: These forgeries imply manipulating the whole frame. For instance, 2. A Brief Overview of Video upscale-crop forgery is a kind of frame-level forgery where a frame is enlarged and cropped to Forgery Detection Approaches remove the evidence of a crime occurring on the Video forgery detection procedures attempt to ascertain 6 frame extremities . whether the given digital content has undergone any unethical post-processing operations. Such operations 1.2 Inter-frame Forgeries leave some footprints in the reconstructed signal. Video These exploit temporal correlation between frames and forgery detection mechanisms analyze these footprints in rely upon the detection of characteristic footprints left by order to differentiate between original videos and tam- video processing operations. These are classified as: pered ones. There are two fundamental approaches to video forgery detection: • Frame Removal7. • Frame Insertion8. 2.1 Active Approach • Frame Replication9. The active approach embeds authentication data like watermarks or digital signatures in the video, either at the Over the years, numerous digital video forgery detec- time of recording or later with the help of some special- tion methods have been proposed. Some techniques ized software, so as to enable verification of the origin and detect forgeries based on sensor pattern noise10 while authenticity of its contents afterwards. The problem with some techniques detect intra-frame forgeries like object this approach is that pre-embedding of watermarks or sig- insertion or removal in a particular frame. Video inter- natures degrades the quality of the video. Moreover, not frame forgery detection has been an important problem all camera manufacturers support pre-embedding14–17. in the past decade. One can easily insert or remove a particular frame or set of frames to tamper the original video content. To illustrate, consider surveillance foot- 2.2 Passive Approach age of traffic on a street. From such a video sequence, it These techniques rely on the intrinsic characteristics of would be very easy to remove a passing vehicle by remov- the video content instead of data that provides authenti- ing a handful of frames. It would also be quite feasible cation. These arealso known as blind tamper detection to insert vehicle captured using different camera and/or techniques and generally work under the assumption that at different time periods. But detection of such kind of tampering introduces specific static and temporal arti- inter-frame forgery is a complicated task because in such facts in the video content which can be examined in order cases, human eye can’t easily comprehend the difference to detect fallacious videos. This is the most commonly between an original video and a forged one. Different utilized approach in video forensics domain due to its sig- survey papers11–13 are available in the domain of video nificant advantages over active approach. Categorization forensics; to the best of author’s knowledge, neither they of various proposed video forgery detection techniques is analyze all the available video inter-frame forgery detec- shown in Figure 1. tion technique nor do they address forgery detection in MPEG-4 videos. This paper presents an overview of vari- 3. Video Inter-frame Forgery ous video inter-frame forgery detection approaches that Detection have been designed so far. Section 2 presents an overview of active and passive approaches for video forgery detec- Digital videos take up a lot of space and therefore, to tion to provide a foundation for understanding the basics enable effective storage and transmission, these are of the video forgery detection domain. Video inter-frame usually stored in a compressed format. So, in order to per- forgery detection is addressed in Section 3 followed by form any type of tampering operation, individual frames 2 Vol 9 (44) | November 2016 | www.indjst.org Indian Journal of Science and Technology Staffy Kingra, Naveen Aggarwal and Raahat Devender Singh are first extracted and edited with the intention to deceive the previous approaches. Wang and Farid first proposed the user. The reconstruction of the tampered video using a method19 to detect double MPEG compression in video the edited frames results in double compression because sequences by analyzing periodic pattern in the histo- some amount of compression is inevitable whenever gram of DCT coefficients of I-frames and motion error a video is saved. The earliest innovations in the field of of P-frames. They did not provide any quantitative analy- video inter-frame forgery detection were based on detec- sis of the performance of their approach but claimed that tion of traces of double compression in video sequences. their method worked well if number of frames deleted or These techniques are discussed in Section 3.1. However, inserted was a multiple of 3. Furthermore, the technique’s double compression occurs even if video is transmitted, performance dropped if an entire GOP or multiples of uploaded, downloaded or even viewed18. This means that GOP were deleted. Thorough analysis of this approach a video that shows signs of recompression may not neces- revealed that it also failed to detect forgery at macro- sarily have undergone any inter-frame forgery. So, merely block level where different quantization scales were detecting double compression to detect the presence of used during the first and second compression. The same forgery in video sequence is not considered to be an effec- authors proposed another technique to detect double tive approach for forgery detection. This induces the need quantization by extending their former work19 to macro- to detect the presence of inter-frame forgery artifacts with block level20. This technique detected doubly compressed the help of some other specialized methods that do not videos which were either manually compressed or were rely on recompression artifacts.