Closed circuit television (CCTV) has helped tackle physical security and it is now possible to operate CCTV over the same IP network that carries the rest of your data. Video-over IP takes images from CCTV cameras and transmits them over an IP network. You can use traditional CCTV cameras (with analog output) connected to a small box called an IP Encoder, which digitizes the video and sends it to the IP network.
You can use “all-in-one” CCTV cameras that have digitization and compression electronics and use a RJ45 network socket to connect to the network. These are easier to install, but you can only select from the available IP enabled cameras. If you use analog cameras with an IP encoder, you can use the color, low light, monochrome, infrared and thermal imaging cameras on the market.
IP cameras and IP encoders can be set to use a range of protocols over the LAN. Most support multicasting, which allows for multiple viewers without increasing network usage. Most also support user datagram protocol (UDP) or TCP streams which might be better in LANs that are not suitable for multicasting.
Bandwidths vary depending on the image size and quality you want to view. Full-screen 25-frames per second video can use two Mbps for each camera being viewed for MPEG-4 based systems and up to six Mbps for JPEG-based systems. You can view a smaller image and video which is initially blocky (which settles into a high-quality image). In this case, bandwidths of 256 Kbps can be used.
CCTV images need to be recorded so they can be used as evidence, but that eats up disk space. If the network records JPEGs of 20KB each from 20 cameras at one frame per second, the network video recorder (NVR) will need one Terabyte of disk space to store one month of video. Some NVRs can record only when there is motion in the scene, which can reduce the amount of storage space needed.
Video-over IP will work equally well with wired and wireless networks. A viewer can be connected to the LAN via a wireless network, allowing them to roam while viewing. The video system can also be integrated with the network, so that it will accept alarms from triggered network-attached devices.
For instance, with an access control system, the act of swiping a card or presenting a proximity card to a reader can trigger the video-over IP system as an event. Video-over IP software can be configured to display video from a local camera on this event. Similarly, other security alarm products can be connected to a video-over IP CCTV system so that when an alarm is triggered – such as when a door is opened – video from a local camera can be displayed.
Video-over IP is another user of the network and has the same problems of denial-of-service (DoS) and snooping as any other IP service. Many video-over IP applications now support SSL connections between the camera and the viewer, allowing secure video to be sent. DoS is only a problem if the IP network being used is open to the public (unless you have a bad employee).
The setup cost for an IP-based camera is higher than for a traditional CCTV camera, but big savings can be made by running over existing IP networks. Video-over IP is cost-effective when sending images over a long distance – such as to a response center.
Currently, there are different standards for video-over IP. Some cameras and IP encoders send images as a stream of JPEG images, while others use MPEG-4. The protocols for controlling pan/tilt and zoom cameras also vary between manufacturers. To overcome this problem, some companies have written their own video-over IP viewing software that can connect to several different makes of JPEG camera and knows the specific capabilities of each make of camera.
Roger Hardiman is technical manager of the IVS Group.