IP Network Video Monitoring - Understanding the Technology
By Sony
It is important to remember that a video monitoring solution has the same 4 main components as a traditional security solution.
- The Camera
- The Cable
- The Recorder
- The Monitor
The following is an explanation of what the technology is all about using simple terminology. It shows you just how easy it is to put a video monitoring solution together.
The Camera
While an analog camera’s sole function is to capture images and send them down a cable to multiplexer or DVR, an IP network camera is a truly intelligent digital camera. It has a computer, CMOS chip, that carries out the same process in the camera as a DVR does in the recorder unit i.e. digitises, filters and compresses the image.
In IP video surveillance most of the functionality resides in the camera including intelligent functions like motion detection.
It must be remembered that CCTV did not spawn IP technology – CCTV is simply another application using existing IP technology. A basic difference between an analog and Network camera is that the Network camera has to translate the image and put it on the network as well as capturing the image.
From analog to digital
There is a huge analog camera legacy market out there and organisations are not simply going to throw away their existing cameras unless they absolutely have to. To address this issue a number of manufacturers have produced IP Video Servers and Codecs. These devices digitise and compress an analog image allowing it to be sent onto an IP Network.
Networking terminology
Including TCP/IP, compression, transmission, bandwidth, latency etc.
Unlike traditional CCTV, IP Networks are shared networks. They use an organisation’s IT network which is also used to carry data for other purposes. These LANs, Local Area Networks are digital networks used within organisations to link together computers and devices like printers, servers etc. A key factor in the growth in popularity of these computer networks is the ease with which a new device can be added when needed. Just simply connect it to the LAN and immediately link it with all the other devices on the network.
Nearly 90% of LANs use the Ethernet networking standard. Just as Ethernet is the dominant standard for networks so TCP/IP is the dominant protocol for communicating on networks. TCP/IP are two protocols that work together. TCP, Transmission Control Protocol verifies the data and checks that what was sent has been received. If not then it will request the data to be sent again. The IP, Internet Protocol, does the actual transport, location and addressing of the data.
IP Addressing
A fundamental concept of IP is “addressing” of hardware devices such as cameras, servers etc on a network. The IP address is a way of uniquely identifying each piece of equipment on the network just like a telephone number identifies a particular address. They are expressed in four part dotted decimal notation e.g. 101.98.126.8 and are assigned by the network administrator.
Compression
Why do we need to compress the images? The purpose of compression is simply to reduce the amount of data (data rate) of the digital video signal down to a level that is compatible with the transmission capabilities of a particular network. There are several compression methods-the best known and most commonly used are JPEG, MJPEG 2, MPEG 4, Wavelet and H323.
The cable/network - bandwidth
In Network Communication terms it stands for the amount of data that can be sent across the cable/wire at any moment in time. Each communication that passes along the wire decreases the amount of available bandwidth. It is fairly common practice to refer to the network as a pipe and this is quite a good analogy as for example the diameter of a pipe determines how much water would flow through it at any moment in time.
Research shows that 70% of buildings already have an network infrastructure in place. Nearly 90% of these are CAT5 Ethernet based. There are currently two types of Ethernet i.e. Standard Ethernet (10 BaseT) and Fast Ethernet (100 BaseT). It only really makes sense to transmit video images over Fast Ethernet – 100 Mbit/Second because video images are bandwidth hungry. Restricted Bandwidth can result in reduced frame rate and resolution as well as latency issues.
Latency
Latency issues affect the control of PTZ (Pan-Tilt-Zoom) cameras over a heavily utilised or slow network particularly if those cameras are being controlled through an IP server or Codec. If the operator is doing live tracking of an individual from camera to camera there can be a response delay to the pan tilt and zoom commands. However the pace of development of this technology is quite phenomenal and these issues are currently being resolved.
The Network Video Recorder
In IP the recorder is a PC similar to the one in most homes but because of the nature of the application will have as fast a chip as possible with the maximum amount of memory and as much disk storage as possible e.g. minimum of 512K RAM and 160 Gigabyte Hard Disk.
The IP Video Management Software
The IP video management software is probably the most important element of any IP security and surveillance solution. The most widely used packages have been designed to be extremely easy to install and to operate.
Software on the PC enables the images to be viewed, stored, time and date stamped and retrieved for reviewing of incidents. The software will sometimes have VMD (video motion detection) built in so if the camera does not have VMD functionality then it can reside in the PC IP software.
The software is either the simple browser type for viewing a camera over the Internet or packages designed for comprehensive security & surveillance applications. They even provide familiar multiplexed type screens with the ability to monitor live video streams from 4, 9, 16 and 25 cameras and any combination in between.
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