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An evolutionary approach: the migration to digital

Analog video cassette recorders have been supplanted in the last few years by digital hard-disk-based 'hybrid' devices.

It has not been until recently, however, that manufacturers have taken the next logical step and digitised every aspect of the video monitoring process - from image acquisition and distribution to storage and control. In particular, by replacing both the camera itself and analog network cabling with their digital counterparts, traditional CCTV systems are transformed into 'smart', highly scalable and cost-effective video monitoring solutions.

In the world of video monitoring, the shift to digital has seen an incremental evolution, beginning with the replacement of the traditional videocassette recorder with digital tape-based recorders and, more recently, dedicated hard-disk-based systems that offer the advantages of non-linear random access recording and playback. Digital technologies are inherently more reliable than analog video recording and playback, and picture quality remains consistent under a wide range of operating conditions, even after hundreds of repeated viewings. Digital video images can also be copied, edited, transmitted, stored and archived without quality loss.

As well as offering superior picture quality in comparison with analog recording, digital techniques also offer far greater flexibility and creative possibilities for the processing, control and distribution of video signals. For example, digital images can be enhanced to resolve fine details under 'difficult' lighting conditions, permitting the more effective identification of a subject's face or the accurate reading of a vehicle number plate.

Understanding the technology

It is important to remember that a video monitoring solution has the same four 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 ie, digitises, filters and compresses the image.

In IP-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 servers and codecs. These devices digitise and compress an analog image allowing it to be sent onto an IP network.

Networking terminology

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. 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 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 eg 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 a network infrastructure in place. Nearly 90% of these are CAT5 Ethernet-based. There are currently two types of Ethernet ie 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 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 eg, minimum of 512K RAM and 160 Gigabyte hard disk.

The IP software

The 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 and 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.

The benefits of using network video monitoring

An all-IP based infrastructure affords manufacturers, system installers and end-users alike a number of benefits - most notably reducing the capital and operational cost of network video monitoring.

IP-based systems present an extremely attractive business case as an alternative to traditional CCTV solutions. While the cost of IP cameras currently represents a slight premium over traditional analog cameras - reflecting their greater complexity and 'embedded intelligence' - this cost is offset by systems being scaled to support more storage; structured network cabling reducing installation costs compared with expensive, dedicated analog co-axial systems; and camera control signals being routed over the same network cabling reducing installation costs further.

Overall, by aggregating the total cost of cameras plus installation, network cabling, monitoring and storage components, IP-based network video monitoring can be significantly less expensive than proprietary hardware solutions.

Re-using existing office networks reduces the cost of new cabling and minimises physical disruption within the workspace during installation.

Using 'open' IT industry standards rather than proprietary camera, recording, monitoring and storage technologies reduces hardware costs as well as providing access to a greater range of other imaging, networking and storage products from other third party manufacturers.

IP networks are essentially unlimited by their physical size, scale and extension. Any networked PC can be used to view pictures as well as performing system management and camera control functions 'off-site' as well as 'on-site'.

It is simple and cost effective to scale IP-based networks by adding extra cameras or server-based storage at any time to meet growing needs. Storage can be scaled to meet any requirement by adding sufficient capacity to store and archive images from as many cameras as required, and for any desired length of time. Similarly, there is no restriction on the number of sites that can be used for simultaneous monitoring. For example, desktop PCs could display pictures from a camera mounted at the front door of an office building for every authorised employee.

IP cameras can be smarter than their analog counterparts, allowing remote control of camera functions including:

* On/off.

* Focus.

* Shutter/exposure mode.

* Pan/tilt/zoom movement.

All accessible from an operator's PC as well as sending alarm and event triggers from the camera.

IP-based network video monitoring solutions are inherently future-proofed in comparison with traditional solutions built around proprietary hardware and coaxial cabling. Since functionality of cameras and control systems is defined in software rather than hardware, features can be upgraded to reflect new developments at incremental cost rather than requiring replacement hardware.

The five myths surrounding video monitoring over IP networks

Networks are unreliable, a DVR is always there and is digital

Reliability has always been a top priority for networked video solutions. Safeguards like uninterrupted power supplies, secure off site storage and hot-swappable disk operation can make a networked video solution more reliable than traditional analog or analog/digital installations. Those that are unfamiliar with networked video solutions may believe that DVRs are state-of-the-art in the digital world. However, networked video solutions bring scalability, intelligence at camera level, remote accessibility and more cost efficient infrastructures.

It is not secure

Networked video solutions, originally developed as strategic tools for the American army, have convinced most high profile organisations such as banks and courts. Encryption, firewalls, virtual private networks (VPNs) and password protection create very secure solutions that are already in use in security sensitive industries. In contrast to this new digital technology, analog systems have no encryption process, making it very easy for anyone to tap into the cables and illicitly view 'secure' video transmissions, or even feed their own false video information into the network. This is impossible to do with secure IP networks.

It is more expensive

Network video cameras can be more expensive than analog cameras of similar specification. But the cost of a complete solution is less than analog CCTV. For networked video solutions, cable infrastructures are already in place, whereas analog systems require dedicated cables. And if you consider the costs of multiplexers, matrices, monitors, VCRs and/or DVRs commonly found in analog solutions, the price of a networked video solution is not only very competitive, but offers greater flexibility and better value.

Image quality is not good enough

In real cases fewer than 10% of images from analog VCRs are of high enough quality to be used for evidence in court. Network camera image quality is now surpassing analog cameras. High quality professional network cameras are often mistaken for lower-end PC webcams. Network cameras are much higher quality and built for professional use.

It is unproven technology

More than 300 000 cameras are already transmitting over IP networks. Moreover, a significant number of Sony cameras have also been used in high profile installations such as Munich Airport and Oporto Dragão Eurocup Stadium. Other projects include hospitals and high security venues.

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