视频监控在案件侦办中的应用

城市视频监控遍布大街小巷,能够直接或间接地记录犯罪过程,使案件侦办从以前的分析、推理、判断发展到今天的直观可见。但基于现有案件侦办模式和监控图像质量等方面的限制,视频监控的利用率还远未达到人们的预期目标。提高视频监控这一普遍存在物证源在案件侦办中的作用,是当前公安部门研究的重点内容之一。     

论公共视频监控中公民隐私权的保护

公共视频监控是当前公安机关确保城市公共安全的主要技术手段,是技术防范手段在公安工作中的具体体现。但公共视频监控如果运用不当,则会侵犯公民的隐私权。应从以下几个方面采取措施对公民隐私权予以保护：1.健全相关法律法规;2.制定统一的视频监控标志;3.规范视频监控部门的管理制度;4.提高公众保护自我和尊重他人隐私权的意识。     

Validation of LAB color mode as a nondestructive method to differentiate black ballpoint pen inks

Nondestructive digital processing methods such as lab color mode (available in Adobe Photoshop) are emerging as alternative methods for forensic document examiners to use when attempting to differentiate writing instrument inks. Although these techniques appear to be viable, little data currently exists regarding the known or potential error rates associated with these techniques. Without adequate data, the validity and reliability of these techniques, including lab color, can not be established. In an attempt to begin to address these issues, 44 black ballpoint ink pens were obtained and used to create 990 pen-pair samples for analysis using established lab color mode techniques. No erroneous findings of "different" were reported following the examination of the known pen-pair combinations in which the same pen was used to create the samples (n = 44). Of the remaining 946 samples, 737 pen-pair samples were differentiated using the lab color mode method, while 209 samples were unable to be differentiated and were recorded as either being "similar" (n = 153) or "unsure" (n = 56). Comparison of the lab color mode results with the results obtained through additional testing using traditional infrared reflectance and infrared luminescence test methods showed that lab color differentiated 102 pen-pair samples (11%; 102/946) that were not differentiated using a VSC-4C.     

Integrity verification of the ordered data structures in manipulated video content

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.     

REM算法用于分层组播流量控制的设计方案

主动队列管理算法REM可作为对端系统的辅助加入到分层组播流量控制中，利用运行REM的路由器上收集到的标记指示信息来推测网络状态，驱动发送速率和同步点设置的更新，以提高流量控制的效率，解决当前分层组播中流量控制机制的不足问题。     

Towards a new generation of CCTV networks: Erosion of data protection safeguards?

CCTV networks are progressively being replaced by more flexible and adaptable video surveillance systems based on internet protocol (IP) technologies. The use of wireless IP systems allows for the emergence of flexible networks and for their customization, while at the same time video analytics is easing the retrieval of the most relevant information. These technological advances, however, bring with them threats of a new kind for fundamental freedoms that cannot always be properly assessed by current legal safeguards. This paper analyses the ability of current data protection laws in providing an adequate answer to these new risks.     

Differentiating synthetic and optical zooming for passive video forgery detection: An anti-forensic perspective

A video can be manipulated using synthetic zooming without using the state-of-the-art video forgeries. Synthetic zooming is performed by upscaling individual frames of a video with varying scale factors followed by cropping them to the original frame size. These manipulated frames resemble genuine natural (optical) camera zoomed frames and hence may be misclassified as a pristine video by video forgery detection algorithms. Even if such a video is classified as forged, forensic investigators may ignore the results, believing it as part of an optical camera zooming activity. Hence, this can be used as an anti-forensic method which eliminates digital evidence. In this paper, we propose a method for differentiating optical camera zooming from synthetic zooming for video tampering detection. The features used for this method are pixel variance correlation and sensor pattern noise. Experimental results on a dataset containing 3200 videos show the effectiveness of the proposed method.     

越南理论思维革新下的影视文化发展

作为文化的一种表现形式,影视文化在当代越南具有较大影响。随着越南革新开放不断深入,其影视文化也有了较快的发展,成效显著。越南影视文化坚持以马列主义和胡志明思想为指导,注重民族文化的宣扬。同时,从过去的偏重政治宣传,到注重反映人生和社会生活,也开始发展与外国的交流合作。为促进中越友好关系的发展,应加强中越影视文化交流与合作。     

分层视频组播策略分析

分层组播可以适应视频传输中接收者的异构性要求并具有良好的可扩展性,为异构网络环境下组播的有效实施提供了解决办法,目前存在的主要问题在于整体视频接收质量不稳定以及对网络拥塞响应缓慢等。通过网络仿真器NS就协议的运行效率和公平性特征进行了实验评价。     

油脂物证的荧光分析方法

为建立一种简便、灵敏、准确的油脂物证鉴别方法。采用文检仪对42种市售车用润滑油样品的荧光特性进行了研究。根据不同激发光照射下样品的荧光颜色和强弱不同,可将42种样品区分为XXIII类。验结果表明：该方法具有简单、快速、直观、高效等特点,为油脂物证的检验提供了一种新的技术。