Steve Surfaro, security industry liaison, Axis Communications, Chelmsford, Mass.
This article originally appeared in the August 2012 issue of SD&I magazine
The now mature culture of bring your own device (BYOD) has enabled substantial growth of the smartphone. Nielsen reports that smartphones account for two-thirds of all U.S. mobile phone sales, with Android's share of the mobile-software market rising to 51.8 percent in the second quarter 2012, compared with 48.5 percent in the previous period. The great number of mobile applications available for the physical security industry has even prompted some solution providers to adopt a consumer-like delivery method of an App Store.
The massive adoption of smartphones, BYOD policies and security mobility Apps is bringing security information and situation awareness virtually everywhere. Near Field Communications (NFC) is enabling secure transmissions from device to device, with the goal of simplifying the credential process. The mobile access control pilot at Arizona State University (ASU) was the first to validate the use of digital credentials on student’s personal NFC-capable smartphones for physical access control on a college campus. It essentially puts a smartcard on an NFC-equipped smartphone.
Meanwhile, hosted video content is keeping owners in close contact with their businesses, and allowing them to participate remotely in loss prevention and operations management via any Internet-connected device. Virtually every video-based security solution offers access to live and recorded video content, but it is there where similarities end between solutions.
Success with mobile video
The successful presentation of video content on a mobile device begins with an understanding of end users’ mobile behavior, key information needed by the end-user, connectivity and how mobile platforms can render the content. Creating a mobile website, for example, often requires an independent design process as the needs of a mobile user can be totally different than the “desktop” client’s consumer.
Video mobility is used in every surveillance segment, from small edge-recording systems to managed video services. The bandwidth requirements for video mobility do not necessarily need to be as high as large format displays found in the command center or business owner’s office. The video refresh or display rate in frames or images per second should be matched to meet the mobile device’s display size (see Chart 1, “Mobile Device Resolutions, Frame Rate and Bitrate). Have you ever watched a YouTube video on your phone that looked high-quality, and then watched the same video on a monitor or HDTV and it looked lo-res? This is the same concept. Mobile devices with smaller display resolution can require a lower minimum frame rate and resolution for a given surveillance function; larger displays should require a higher frame rate.
There are many cases where the video stream needs to only be a minimal 480x640, 240x320 or even 120x160 pixels, for devices held in a “portrait” orientation. See Chart two: “HDTV and Mobile Surveillance Video Usage,” for typical bandwidth consumption, comparing lower resolution mobile devices with the higher, yet still efficient bandwidth required at 720p or 1080p HDTV. (Note: The numbers depicted in Chart two represent bandwidth estimates based on the Axis Design Tool and specific scene scenarios, which will vary with every installation.)
With the expanding video communications market, applications supporting Adaptive Bit Rate (ABR) will optimize video content delivery and often automatically transcode the video stream to prevent overutilization of both the network and consuming device. HDTV network cameras do not need to stream their full native resolution to mobile devices—the video stream received by the mobile device may be often 10 to 20 percent of the camera’s actual streaming capacity. Some of today’s network cameras can record full HDTV resolution on internal storage like SD cards, reducing the need to stream resolutions higher than what mobile devices will support. Additionally, for select security practitioners, multi-streaming from the camera is a worthwhile feature that enables different frame rates and resolutions to be viewed by certain devices.
Finally, the user’s vision also impacts the perceived image quality, as well as the required viewing distance of mobile devices. It’s no accident that Apple’s “retina” display can deliver images perceived as high quality. With its 326 PPI display, the iPhone 4S has a pixel density 14% better than the 286 PPI required to deliver a resolution compatible with a 20/20 visual acuity from a distance of 1 foot (see Chart 3, Maximum Visible PPI Related to Viewing Distance-Inch).
If the user’s vision is impaired, the required distance for maximum visible PPI decreases.
Yet, with these factors considered, if the user’s vision and device have the capability of interpreting and rendering HDTV video content and the network has the capacity, the mobile application should take full advantage of the HDTV network video source. And the future possibilities of enabling full-HDTV mobile usage in surveillance are growing stronger thanks to additional outside forces.
Industry advancements, policy-making agencies and the executive branch will significantly impact video mobility in public safety. The Presidential Executive Order (EO) recently released, “Executive Order—Assignment of National Security and Emergency Preparedness Communications Functions,” is significant:
“The Federal Government must have the ability to communicate at all times and under all circumstances to carry out its most critical and time sensitive missions. Survivable, resilient, enduring, and effective communications, both domestic and international, are essential to enable the executive branch to communicate within itself and with: the legislative and judicial branches; State, local, territorial and tribal governments; private sector entities; and the public, allies, and other nations. Such communications must be possible under all circumstances to ensure national security, effectively manage emergencies, and improve national resilience.”
Simply put, the National Broadband Plan (http://www.broadband.gov/plan/), which incorporates key technologies like LTE (Long-Term Evolution), will be expanded, standardized and managed to improve national security. With this EO, performance and dedicated spectrum needed to improve security data and video communications will be a reality in coming years.