Video Helps Keep Schools Secure
School shootings are in the news at a terrifying frequency, and less deadly, yet appalling, acts of violence virally stream from students' phone cameras. 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, librarians, or media production groups—produce content for broadcast to a much larger student or public audience. Security camera systems have the opposite viewership topology, where many sources (security cameras) stream to a central repository containing huge amounts of video viewed by a very small—even empty—audience.
Content-to-viewership ratios aside, some components are comparable. 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 network connections.
Security cameras differentiate themselves by the sophisticated tricks they use to achieve usable footage at low bitrates. Many of these tricks are familiar video compression techniques effective for video with intermittent activity in the frames, like varying the frame rates and group-of-picture length when not much is happening in front of the camera. 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 more extreme cases like during a snow- or rainstorm, reducing bitrate by ignoring frame variation that can be classified with high confidence as visual noise.
Finding the optimum between compression 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 array—a balancing act between how deep in 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 School Survey on Crime and Safety (SSOCS). The most recent SSOCS data from 2017–2018 reports that a whopping 93.6% of public high schools in the U.S. use security cameras. In fairness, the standard for this question asks only if at least one camera is used. Still, that's a lot of cameras, video management systems, hard drives, and servers. Most schools would likely start with a few cameras in the parking lots, where there are bound to be fender benders, thefts, and minor scuffles. However, the demand for more cameras is driven by outrage over incidents that weren't caught on camera. Since security cameras are relatively inexpensive; the costs for networking, power, and staffing are largely sunk; and the data retention policy somewhat elastic, defying that demand is difficult. Consequently, many schools end up spending much more money on security camera systems than on curricular video systems.
In the coming years, look for educational institutions and vendors to creatively squeeze value from fixed camera systems in schools by expanding the audience for the video footage while avoiding critical safety or privacy problems. In-classroom mounted cameras 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.
With some hesitation, computer vision technology is deploying to at least one American school with the task of identifying weapons and barred individuals. Facial recognition could be used less controversially to more efficiently accommodate Family Educational Rights and Privacy Act (FERPA) requests. The U.S. Department of Education asserts that 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.
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