视频有助于保证学校安全

School shootings are in the news at a terrifying frequency, 而且不那么致命, 然而ap-palling, 暴力行为如病毒般蔓延来自学生的手机摄像头. In our school communities' search for a solution to bring peace, security cameras have become an overwhelmingly popular choice to improve accountability of student—and teacher—behavior and promote general safety.

When we think of streaming media used at schools, we picture traditional streaming media platforms where a few sources—teachers, 图书馆员, or media production groups—produce content for broadcast to a much larger 学生或公众观众. Security camera systems have the opposite viewership topology, where many sources (security cameras) stream to a central repository containing huge 大量的视频观看量非常小 empty-audience.

暂且不谈内容与收视率的比例组件具有可比性. The central repository requires video management software for associating video with metadata about which camera shot it when and for displaying video feeds in a secured webpage as individual streams or a composite multi-view. The hardware needs for the video management software are almost entirely in storage: The processing load for encoding video is distributed to dedicated hardware in the cameras themselves, which stream the compressed footage to the video management system over encrypted Transmission Control Protocol (TCP)/
IP网络连接.

Security cameras differentiate themselves by the sophisticated tricks they use to achieve 可用的镜头在低比特率. 许多 these tricks are familiar video compression techniques effective for video with intermittent activity in the frames, like varying the frame 速率和组图长度镜头前发生了很多事情. Expertise with continuous shooting in suboptimal environments also provides security camera manufacturers with esoteric techniques for handling the video noise typical for their specific sensors in low-light conditions and 更极端的情况是在下雪或下雪的时候暴雨, 通过忽略来降低比特率 frame variation 那 can be classified with high confidence as visual noise.

寻找压缩之间的最优 and fidelity in the video streams is critical, since the cost of video storage adds up quickly. Hard policy decisions must be made in defining the retention policy for how long video is kept before being cycled off the storage 数组之间的平衡行为有多深 time you can check the tape versus how deep into your pockets you can dig.

The authoritative government publication on the topic of school safety policies is the 学校罪案及安全调查(SSOCS). The most recent SSOCS data from 2017–2018 reports 那 a whopping 93.美国6%的公立高中.S. 使用监控摄像头. In fairness, the standard for this question asks only if at least one 使用相机. 尽管如此，还是有很多摄像头，视频管理系统，硬盘驱动器，还有服务器. 大多数学校可能会从一个停车场里很少有摄像头一定是小车祸，盗窃，还有小骚乱. 然而，需求更多对事件的愤怒驱使着摄像机那没有被摄像机拍到. 因为安全 cameras are relatively inexpensive; the costs 对网络, 权力, and staffing are largely sunk; and the data retention policy somewhat elastic, 抵制这种需求是困难的. 因此，许多学校最终花费在安全监控系统上花更多的钱而不是课程视频系统.

在未来的几年里，寻找教育 institutions and vendors to creatively squeeze 学校固定摄像系统的价值 by expanding the audience for the video footage while avoiding critical safety or privacy problems. 教室内安装的摄像头 could be repurposed as "lecture capture systems" (not security cameras) to prevent sick students from falling behind their classmates. Hallway security cameras could be renamed "live cams," with active PTA members invited to crowdsource hall monitor duties in real time.

犹豫了一下，计算机视觉技术正在部署至少一个美国人 school with the task of identifying weapons and barred individuals. Facial recognition could be used less controversially to more efficiently accommodate 家庭教育权利和隐私法(FERPA) 请求. 美国.S. Department of Education asserts 那 some security footage of a student maintained by or on behalf of a school is an educational record and thus must be provided to the parents of a minor student upon request.