New concept for CCTV describes key elements in design
- By Barry Keepence
- Mar 03, 2009
IP-CCTV systems are not just a cheaper and more flexible alternative to traditional analog systems— they have opened up new opportunities for security that are simply not possible with the old technology. They are changing the way the security industry implements CCTV surveillance and have spawned a new concept—mega video solutions.
Mega video can be defined as large-scale virtual matrix CCTV systems with 1,000-plus cameras, 200-plus monitors, 50-plus operators and 100-plus NVRs with more than 1 petabyte of storage. These systems are continuously displaying and recording high-quality video across IP networks that span entire plants, communities and countries. This may be a new concept in the United States, but real mega video projects have been deployed and running reliably for a number of years in Europe, such as in the Brussels, Belgium, airport, where a 1,000-plus camera system has been operational since 2001.
When comparing the architecture of mega video solutions to traditional analog CCTV systems, it soon becomes clear why certain large-scale, wide-area surveillance applications are either not possible or too expensive to implement with analog technology. The IP network, combined with video management software, becomes the video switching matrix, or the virtual matrix, as it is commonly known, replacing the centralized switching hardware of analog/DVR-based systems. The nearest video monitor or workstation is the nearest IP network connection. The network is typically everywhere in a building, and the monitors and workstations can be too.
Total flexibility with video display options is possible due to the distributed nature of mega video solutions.
PC workstations are now replacing traditional video monitors as PC technology has become increasingly reliable and less expensive. Some IP video vendors supply their video management software as licensefree. This allows end users to install CCTV viewing workstations at any location on the network for no more than the cost of a PC. This is comparable to the huge cost of installing a large analog video matrix and associated video walls. PCs also are good at replacing monitors. Simply run them in full-screen mode and lock the keyboard away. With the appropriate password, an expert user can access the full features of the software, such as playback of recorded video, which is not possible with analog systems. Some large sites have now deployed IP-CCTV systems that are 100 percent PC-based with no analog monitors.
This distributed architecture works well because the video management software is inexpensive or free. If the cost of the end-user software is high, then this leads integrators to build centralized architectures—just the same as analog.
IP-CCTV systems have opened opportunities for security that are simply not possible with old analog technology. License-free software allows end users to install CCTV viewing workstations at any location on the network for no more than the cost of a low-end PC. Dedicated stand-alone NVRs are considerably less expensive than PC servers with equivalent storage.
One of the key features for transmitting video over long distances and to many users without huge impacts on the network bandwidth is multicasting. IP multicasting is a powerful feature of IP networks that allows CCTV video footage from the same camera to be efficiently viewed and recorded by multiple CCTV operators simultaneously.
Multicast networks ensure the video stream only goes to the people who need to see it, reducing bandwidth. IP multicasting requires compatible network switches and routers; however, multicasting capabilities are available on entrylevel devices.
It’s easy to see the benefits of a distributed mega video IP network-based system. However, many people say the network and storage requirements are too demanding for these systems to be implemented. However, such systems have been deployed and reliably working for a number of years. Mega video systems can be designed as long as three cornerstones are implemented correctly: high video compression without losing quality, network design and storage design.
Compression. The key to reducing bandwidth and storage requirements is choosing the best compression technology available. There are a number of compression standards employed in IP video systems. H.264 is the latest video compression standard, which surpasses MPEG-2 and MPEG-4 in both video quality and compression. The most significant benefit for IP video systems is the ability to deliver the same high-quality, low latency, digital video with savings of between 25 and 50 percent on bandwidth and on the storage requirements.
By selecting a system based on H.264, further savings on storage can be achieved. Even though H.264 is more efficient than MPEG-4, there are still differences between vendors’ implementation of the standard and the amount of bandwidth and storage required.
Network design. It is important to understand the data paths through the network. Almost all video is never looked at; it goes straight from the camera transmitter/ receiver (codec) to NVRs. The two points of maximum data bandwidth are at the NVR and at the viewing stations. The key to network topology, therefore, is to group the transmitters and NVRs into nodes. This configuration also produces a fault-tolerant network where a single network cable failure will only affect a small part of the network.
Storage design. The two key factors here are NVR performance and storage architecture. The amount of data coming from the cameras to the NVRs has increased volume and is continuous. The amount of data coming from the NVR to the users is low and periodic. The workload is constant—the rate of writing data to the disk is consistently high—not in bursts as with typical IT applications.
The processing overhead for writing and reading the video streams to disk is therefore an important factor in the overall performance of the NVR. There can be a considerable difference in this overhead between different vendors of NVR software. Software that can minimize this processing will be able to handle many more camera streams per NVR. The best NVR server software on the market has such a low CPU loading that 500 camera streams can be recorded on the lowest specification server PC.
For large mega video systems, the storage architecture needs to be distributed as outlined previously, with small NVRs distributed across the network. If PC-based NVR servers were used, then many separate PCs would be required, each with its own local attached storage, which comes at a significant cost. An alternative would be to use dedicated, stand-alone NVR units that have the processing hardware and storage in a single compact unit.
A Changing Dynamic
The video wall has become a common component in CCTV control rooms. The classic CCTV model has a large analog matrix in one room and a CCTV viewing room next door displaying the wall of monitors. With the advent of distributed IP-CCTV systems, this is changing. No longer do you need to take the people to the video. With distributed IP networked systems, you take the video to the people. When comparing the architecture of IP video solutions to analog CCTV systems, it soon becomes clear why the video wall is no longer needed.
While large video walls allowed many people to view the same video at the same time, IP-CCTV systems allow many people to view the same video simultaneously on the screen in front of them, whether it is live or recorded and are considerably less expensive than a PC server and equivalent storage. These stand-alone robust hardware units can have redundant power supplies and network connections, RAID configurations and hot-swappable drives to provide a resilient and reliable storage solution. For example, the IP video surveillance system on Skytrain, the world’s largest automated light rapid transit system in Vancouver, British Columbia, with 30 stations along 49 kilometers of track, includes 63 stand-alone NVRs with a total storage capacity in excess of 60 TB, recording 897 cameras.
For large-scale CCTV applications, analog technology is no longer a match for IP video technology. The new breed of mega video systems are providing infrastructure projects with a CCTV solution that was simply not technically possible or cost effective with analog equipment. The benefits to end users are significant, and the implementation and reliability of mega video solutions are already field proven—making it no longer just a concept.
This article originally appeared in the March 2009 issue of Security Today.