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Edge-based recording on the rise

July 10th, 2013 by Frank Crouwel

Axis edge recordingOriginal SD cards, called ‘SD Standard Capacity’ or SDSC, could provide only 2GB of storage only 10 years ago. High Capacity SD cards (SDHC) offering up to 32GB reached the market in number some five years ago. This development prompted an explosion of IP surveillance camera launches with in-built SD card slots designed for edge-based recording.

Moore’s Law continues to go to work so that today SDXC cards (eXtended Capacity SD Cards) already offer 2TB of storage capacity. 128 GB SDHC and SDXC cards are available today in larger and larger numbers and prices are falling fast. This is a game changer for edge-based recording because it makes the storing of high frame rate HD video images increasingly easy and inexpensive.  To give you an idea of the level of penetration of edge recording – of the 69 network cameras listed in Axis’ latest product comparison tables published in February 2013, 45 now offer SD card slots. Almost every new camera model launched this year comes with a SD card slot.

Edge-based recording is now offered in a wide range of cameras from the entry-level AXIS M1013 fixed network camera, right through to the market leader’s top of the range thermal camera – the AXIS Q1922-E. Where Axis goes the market generally follows.

So why has edge-based recording gained ground so rapidly in the last few years?

1. Expansion of SD card capacity

The most obvious reason for edge-based recording gaining popularity is the wider availability and lower pricing of higher capacity SD cards with 32GB being the breakthrough in terms of local storage capacity in our view. You can view the storage capacity table based on the use of 32GB SD cards via Axis’ website here or see the table below.

Axis SD card storage estimates

Even when recording at HD 720p resolution at 30 frames per second it is possible to store up to nine days of images assuming the default 30% H.264 compression and other standard parameters including the use of motion detection. If you quadruple the SD card’s capacity to 128GB, suddenly it becomes possible to record a month’s worth of HD images at the edge, potentially only backing up into a central storage archive facility periodically or on analytics triggered events or known security incidents.

2. For installations where network bandwidth is variable or non-existent

The trend to higher resolution video means increased demand for bandwidth, which is not always there. Edge-based recording offers a distinct advantage in such low bandwidth scenarios. A CCTV user can view the live streaming images from cameras in low resolution, using little bandwidth, while recording HD quality CCTV footage locally on the cameras. These high quality images can be easily retrieved from the SD card following incidents which demand further investigation.

3. For local recording backup and analytics capability

Increasingly it is possible to do more sophisticated analytics processing in the camera. Leading manufacturers fit motion detection, audio detection, even ANPR, tamper alarms, auto tracking and tripwire analytics capability in many cameras today. At IFSEC we saw some high-end Mobotix cameras with very sophisticated ‘learning the scene’ analytics which helps differentiate genuine movement from background movement associated with wind, water, rain or snow for example. Reliable facial recognition will soon be possible in-camera also.

It’s possible that a camera can be programmed to record to its SD card at different frame rates and resolutions depending on the type of alert, time of day and perceived threat level and if the network connection is lost at that time.

Fail-over recording, as it is sometimes called, means that images can be temporarily stored in the camera in case of network failure. This adds resilience to mission-critical security systems. Central video management systems are often configured in these scenarios to retrieve and merge local video recordings seamlessly so that a complete video sequence is restored in order of the actual events. Genetec Omnicast Archiver recording management software can do this for example – automatically retrieving and permanently archiving the edge-captured video from the camera to fill central recording gaps sustained in a period of network outage.

4. For distributed organisations where low maintenance local recording is desirable

Increasingly restaurant, pub and other retailers are part of larger and larger chains. In this scenario centralised security management may not be practical or even desirable.  In one increasingly popular scenario network cameras fitted with SD cards permanently store video data at local stores. The manager of a store might check on video recordings or view live images, perhaps following pre-configured alerts, via his PC or mobile device if he is away from the outlet.

On the ground

Our experience bears out the above drivers. Many of the construction sites that we are asked to install cameras at offer no bandwidth connections and sometimes no power source at the outset. For one site we recently had to deploy solar and wind turbine-powered surveillance systems for example.  There are many remote locations for surveillance which lend themselves to local recording with periodic centralisation of recordings for backup and archiving purposes – either for post-event analysis or simply to add resilience.

The fact that Video Management Systems (VMS) are being redesigned for easier deployment and integration (e.g. Milestone Arcus) also makes it possible for camera manufacturers to embed VMS functionality into cameras themselves. If there is one underlying trend it is to put more and more functionality at the edge not just the video recordings but analytics processing and video management tasks.

Our view is that with the rapid growth of edge-recording and increasing availability of more robust Video Surveillance as a Service (VSaaS) the physical centralisation of video storage and management (with its associated banks of servers loaded with enterprise versions of VMS software on them sitting in the back rooms of large Centralised Monitoring Units) is fast becoming just one of several configuration options, even for the largest surveillance system owners.

What’s your experience of edge-based recording?  Do you think it is all it’s cracked up to be or is it still inherently insecure? Do you see more and more functionality being pushed out to the edge in order to reduce network traffic and take pressure off hard-pressed central monitoring resources? Do let us have your views.

NW Systems Group provides IP video solutions which can incorporate edge-based recording.

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