As more and more CCTV cameras are upgraded with IP technology, so the recording and storage of video is also changing.
If we think back to the evolution in the consumer market, 35 mm film cameras stored images on an analogue medium (film and negatives) which could then be transferred to photographic paper and stored conveniently.
Home video cameras often used mini cassettes which could then be transferred to larger format VHS and kept for longer periods. Now, surveillance video is being stored on hard drives, discs – and on the focus of this month’s blog: memory cards within the cameras themselves.
This is often referred to as ‘storage at the edge’ (of the network) or ‘edge storage’.
Memory cards in the security space
So why is the humble memory card, a common consumer purchase, being seen increasingly in security application?
One of the reasons is down to pure economics. As recently as 2006 the maximum capacity of an SD card in the retail environment was only 2 GB. Such a card cost between GB pound 45 and GB pound 64, depending upon manufacturer and exact format. The price per GB of storage was around GB pound 32. If this were the current cost and we wanted four cameras to each have 32 GB of storage, it would cost around GB pound 4,000 just for the onboard storage.
Compare this with a number of DVRs on the market today and, economically speaking, it wouldn’t make any sense at all using SD storage.
In fact, back in 2010 when Sandisk released the world’s first 32 GB SD card, PCPro ran the headline: ‘The 32GB SD card that costs 12 times its weight in gold’. Weighing in at only 0.5 g and costing GB pound 145, the SD card cost 12 times the equivalent weight in gold according to Wolfram Alpha.
Fortunately, the cost of SD storage has tumbled and it’s now possible to find Class 4 32 GB SD cards for as little as GB pound 19. Our storage in the above scenario is now only GB pound 76 – a huge 98% reduction in cost. Compared to other storage solutions, this is now becoming far more attractive.
Add to the economics of edge storage the fact that the life expectancy of an SD card can be longer due to the lack of moving parts, SD offers significantly smaller form factor and power consumption is far less (an SD card consumes around 300 mW compared to a DVR which requires around 40 W of power) and the case becomes stronger still.
On-board storage using SD cards
What, then, is stopping the security sector from moving over to on-board edge storage using SD cards?
Well, one argument today is that the cards don’t offer enough capacity. With HD quality images and faster and faster frame rates, 32 GB of capacity of storage can run out relatively quickly (calculations estimate that, with HD 720p resolution and 10fps as well as around 20% of triggered motion detection, most cards will reach capacity after 20-ish days).
This, however, is also the case with a number of DVR solutions on the market which offer 160 GB and are optimised for four-channel systems.
The answer? If we consider how quickly technology is improving and the associated price decrease, SDXC storage cards with 2 Tb of storage aren’t far away, and it will be difficult to ignore edge storage as an option when they do arrive.
Phil Doyle is regional director for northern Europe at Axis Communications (UK)
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