SD cards are small and tucked away, but we should never take them for granted as they can make a significant contribution towards end users achieving maximum benefit from their video surveillance systems. Here, Uri Guterman sings the praises of SD cards and provides some particularly useful guidelines on what to look out for when buying them.
SD cards are supplied in various formats for you to choose from, although your decision will obviously be affected by what your cameras’ memory slots are capable of accommodating. The good news here is that many of today’s HD IP cameras have slots which provide the option to use most – if not all – of the available SD card formats.
Why, though, are SD cards so important? The migration from analogue to IP network-based video surveillance solutions has created a common scenario whereby the recording and storing of images can be quite remote from a camera’s location. SD cards will help to keep data safe in the event of network disruption.
In this respect, if you want to avoid any gaps in what may be crucial video evidence, it’s recommended that, before buying, you take a close look at a camera’s specifications to check it has an Auto Recovery Back-Up. This feature will ensure that any activity recorded on the SD card during network disruption is automatically transmitted to the remote recording device when network service is eventually restored.
The massive processing power of the chipsets at the heart of the latest generation of HD open platform cameras provides the opportunity to run multiple on-board third party analytics applications such as ANPR, heat mapping and people counting in the same way apps are used on smart phones. These elevate video surveillance from just being a security system which assists in monitoring and detecting suspicious activity to a smart solution delivering so much more.
The data captured by these applications can be recorded on SD cards and remotely downloaded for analysis as and when required. End users should look out for cameras which have dual SD memory card slots. These will provide you with greater storage capacity, as well as the option to use one SD card for edge-based applications and the other for recording images.
Matters of capacity
I suspect there may be many end users who hold the perception that SD cards, including those which are capable of storing up to 256 GB of data, are too limiting in terms of how much information or video that can hold. While they’re not intended to negate the need for a Network Video Recorder, SD cards should have more than enough capacity to store the short term demands caused by network disruption and record analytics data, or perhaps store images which have been captured as a result of the triggering of a camera’s motion detection function.
Equally important, an SD card write speed should be taken into consideration. The large file sizes of images captured by Full-HD and ultra HD 4K cameras dictates that it would be wise to specify a Class 10 SD card that’s capable of write speeds of 100 Mbps. These are on offer from most of the well-known SD card manufacturers, such as SanDisk, who will also provide you with peace of mind in terms of quality and reliability.
The options available to today’s end users? SD: Up to 2 GB. SDHC: 4 GB to 32 GB. 3DXC: 32 GB to 2 TB.
Whatever you’re hoping to achieve from a video surveillance system, make sure you populate the SD card slots before the cameras are commissioned. Leave it until it’s too late and you might just miss out on recording some critical data.
Uri Guterman is Head of Product and Marketing at Hanwha Techwin Europe
*Do you have some questions about SD cards to which you need answers? If so, e-mail Uri Guterman at firstname.lastname@example.org