SD cards come in various formats although the decision as to which choice to make will obviously be affected by the cameras’ memory slots and what they are capable of accommodating. The good news is that many of the high definition IP cameras produced by manufacturers, such as Hanwha Techwin, have slots which provide the option to use most, if not all, of the available SD card formats.

The migration from analogue to IP network based video surveillance solutions has created a common scenario where the recording and storing of images can be quite remote from a camera’s location.

SD cards will help keep data safe in the event of network disruption. In this respect, to avoid any gaps in what may be crucial video evidence, it is recommended before buying, to take a close look at a camera’s specifications to check it has an Auto Recovery Backup. This feature will ensure activity recorded on the SD card during network disruption is automatically transmitted to the remote recording device when network service is restored.

The massive processing power of the chipsets at the heart of the latest generation of high definition open platform cameras provides the opportunity to run multiple on-board third-party analytics applications such as ANPR, heating mapping and people counting, in the same way Apps are used on smartphones. These elevate video surveillance from just being a security system which helps monitor and detect suspicious activity, to a smart solution which delivers so much more.

The data captured by these applications can be recorded onto SD cards and remotely downloaded for analysis as and when required. Look out for cameras which have dual SD memory card slots. These will provide a greater storage capacity, as well as the option to use one SD card for edge based applications and the other for recording images.

"There may be many who have a perception that SD cards, including those which are capable of storing up to 256GB of data, are too limiting in terms of how much information or video that can hold." says Guterman. 

He expalins that whilst they are not intended to negate the need for a Network Video Recorder (NVR), an SD card should have more than enough capacity to store the short term demands caused by network disruption and to 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 files sizes of images captured by Full HD and ultra high definition 4K cameras dictates that it would be wise to specify a Class 10 SD card that is capable of write speeds of 100Mbps. These are on offer from most of the well known SD card manufacturers, such as Sandisk, designed to provide peace of mind in terms of quality and reliability.

The options include SD up to 2Gb, SDHC 4Gb to 32Gb and SDXC 32Gb to 2Tb.

Which ever model is selected and to what ever is required from the video surveillance system, it is advised to ensure the SD card slots are populated before the cameras are commissioned. Leave it until it is too late and you might just miss out on recording some critical data.