Decoding the Digital Picture

By Laura Spadanuta


Once a company has settled on resolution, compression, and other aspects of the system, there is the question of where to put all the data that is streaming out of these cameras and encoders.

Fortunately, the technology keeps improving for storage systems. In digital surveillance systems, the options range from DVRs and NVRs to the larger-capacity network-attached storage (NAS) units.

Standalone DVRs have been the replacement to the analog VCR, but some experts predict that DVRs will soon go the way of the VCR, as they are replaced by their networked cousin, the NVR. In addition to being on the network, NVRs tend to have more storage capacity than DVRs.

There are inherent benefits to being directly on the network. Data can be managed with more flexibility and sent out to extended drives, according to Jeff Fenton, engineering manager of SFI Electronics, a SecurityNet member. NVRs can also receive input from more cameras.

One downside is that NVRs are completely dependent on the network. If the network is down, so is the NVR.

There is a long list of features that end users should look for in an NVR, says Wilson. For example, it should include basic video functions, such as live viewing and possibly remote pan-tilt-zoom control. Additionally, it can include multiple recording options, such as event, manual, and continuous. It should also provide basic features such as the ability to play back video and audio.

Searching should allow for “smart” searching through the archive and export of images with watermarks and timestamps. NVRs should be able to simultaneously manage IP and analog video streams and have the ability to work with equipment from various vendors.

Sometimes neither DVRs nor NVRs are enough. A company may need more storage, especially if it has many cameras and plans on keeping data for the long haul. For many companies, that means using network-attached storage (NAS), which is basically an array of hard disks. These external devices provide centralized storage that is network accessible. NAS is proliferating with the increase in multimedia data storage needs.

NAS is a good choice for clients who do remote monitoring, because it can centralize data from various recorders and locations, Sarangan says. There is a wide range of NAS storage choices that offer varying total storage capacity amounts, including up to several terabytes.

The main concern for security managers when dealing with NAS is “scalability,” or the ability to grow. “Scalability of NAS is not limited by the number of internal or external ports of a server’s data bus, as a NAS device can be connected to any available network jack,” Wilson says.

Some standard features of the NAS include operating systems, remote management capability, and universal connectivity, notes Wilson. He recommends adding a RAID (redundant array of inexpensive disks) to allow for a drive failure without the loss of data.

The NAS could either be factored into the original system or added on later.

As CCTV merges more with IT, Bosch has employed iSCSI (small computer systems interface, which is a commonly used massive storage option, over IP) RAID storage. It is network-based but communicates directly with cameras and encoders, so it does not rely on the NVR or the network in order to record.

Retrieval. Bordes says advances are being made not only in storage ability but also in the quality of future replay. He cites Hie Electronics, which won Frost & Sullivan’s 2007 North American Video Surveillance Product Innovation of the Year Award. Hie’s TeraStack solution puts together removable storage towers of 125 DVDs which fit into chassis that hold up to 50 terabytes of data.

TeraStack, which runs on 800 watts (equivalent to the amount of energy needed to run a small microwave), is able to store data from up to 64 cameras for 9 to 12 months. In addition, the stored video will all be available for search and replay at high resolution and 30 fps, while other systems are often limited to shorter time periods. 

Some storage media have data management capabilities built in to facilitate retrieval and playback. Another option is the router-type system put together by Steelbox, called the DMSS. 

Steelbox built the product from the ground up. It works between the video source and the video recipient, and it sends the video streams—which can vary in terms of frame rate, compression, resolution, and other factors—from up to 512 cameras into different recipient areas, including NAS. “It’s like video plumbing, in essence,” says Howes.

DMSS substitutes for an NVR and aspects of the video management system. Howes highlights the scalability of DMSS and the number of channels it can deal with. Additionally, he says it allows people to rewind or search any video stream at any point without affecting other aspects of the system or other individuals also viewing video.



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