Managing IP video on the network

The growing popularity of video surveillance is fueled by the shift to IP video systems that are less expensive than traditional analog systems and make it easier to add or relocate cameras and multicast video signals to multiple locations.

Yet, every system is limited by two finite resources: network bandwidth and disk space.

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A 100Mbps network connection can support nearly 85 cameras producing 10 15KB images per second (about 1Mbps each), but the network will be running at 100% utilization. Whether the IP video system is on the existing IT network or a parallel network, enterprises need to set a realistic bandwidth target and then determine how many cameras can be supported by their infrastructure.

To ensure efficient bandwidth usage, security integrators can help design fluid systems that adjust to accommodate traffic surges. For example, frame rates can be reduced temporarily while the sharpness of each image is maintained, or the same number of frames can be recorded at a lower resolution.

Video content analysis (VCA) embedded in an IP encoder — the device that translates analog camera signals into digital — also can reduce the amount of traffic sent across the network. With VCA at the edge, it is possible to only transmit video that generates an alarm due to a security concern — such as a person loitering, theft of an object or an object left behind in a scene. By selecting specific portions of video to forward, VCA diminishes the amount of bandwidth required for surveillance but enables all camera channels to be monitored effectively.

Of course, storing all of that IP video represents a challenge. A 200GB hard drive can store approximately two weeks of video data, depending on the quality of video. For some industries, such as correctional facilities and gaming, regulations require that recorded video is stored for a longer period of time — up to 30 days or even a year in some states.

Enterprises can reduce storage costs by improving and optimizing how the available storage is shared among cameras. The traditional storage approach uses network video recorders (NVRs), which are PC servers that act as gateways to directly attached SCSI RAID storage or storage-area network storage. By moving the intelligence to the edge, it is possible to configure an IP camera or IP encoder to stream directly to an iSCSI RAID, bypassing the NVR and the associated capital and ongoing costs.

The difference in this architecture is particularly noticeable in dispersed systems where the WAN lacks the bandwidth for centralized recording. Instead of installing NVRs in each building, which can be a maintenance nightmare, enterprises can install storage that is directly attached to IP cameras or to IP encoders.

Consider a university with 20 buildings and 25 cameras per building. Each camera is recording high-quality video at 2.8Mbps per camera for 90 days. With an NVR solution, the university would need 1,500TB of storage and 40 NVRs spread over each location. With direct-to-iSCSI recording, the 40 NVR PCs are not required.