Pitfalls to avoid when implementing an IP network surveillance system

Structured cabling systems have become ubiquitous in commercial and industrial buildings and facilities around the world in recent decades. At the same time, Internet Protocol has become the norm for communicating over this infrastructure. While their fundamental applications were initially for voice and data systems, many other building services applications, such as video surveillance, are emerging on these platforms to take advantage of their simplicity to deploy and operationally integrate.

IP-based video technology is being increasingly utilised in buildings and other facilities to provide high-quality surveillance services. It can also be deployed over an existing structured cabling system within the facility, but there are a number of factors that need to be taken into consideration to ensure the system operates effectively.

IP vs analog video surveillance

IP-based video surveillance solutions have many clear advantages over analog systems; these advantages being vital for the effective deployment of video surveillance activities. Many of the characteristics of IP-based systems are unquestionably superior to the equivalent analog systems. For example, IP-based systems provide improved image quality, increased flexibility and less maintenance and servicing requirements than analog systems. They are also freely scalable and can be consolidated into a company’s IT resources, making it more attractive than an analog system. There are, however, certain pitfalls that must be taken into consideration when designing and installing the deployment of an IP surveillance system to ensure its effectiveness and optimise its advantages over analog systems.

Infrastructure

One of the major challenges that must be addressed for an IP-based video surveillance system is the network itself. Using category 5 or higher UTP cabling, the effective distance per length for an analog installation is 300 m, while an IP-based system is generally no more than 100 m. It is therefore not recommended to follow an existing analog cabling structure in the instance of migrating from an analog to an IP-based video surveillance system.

A fibre-optic cabling network provides an excellent option to UTP cabling. It is a technically sound and operationally robust solution with high bandwidth and extensive distance capacities. However, one issue to consider with optical fibre is the project time to install such a network, often because it is generally lengthy, as it is often laid underground. In addition to the extensive site works, the exercise may also involve time-consuming activities to retrieve all of the permissions from different authorities. The ideal situation is if the network already exists.

Power over ethernet

Although Power over Ethernet (PoE), in most cases, is a standardised form of supplying power to IP cameras, it is broken down into further sub ratings, for example, PoE Class 1, 2, 3 and High PoE. Therefore determining and delivering the required power for each unit is essential.

Hardware - server

Four hard disk drives in a RAID set-up are recommended for an effective IP-based video surveillance system. SCSI hard drives are also recommended for the installation, in terms of performance, but this can be a major cost driver. If Serial ATA and IDE drives are selected, they should be installed in such a way that makes them easy to replace. It is important to keep in mind that video recording is a ‘write-’ and ‘read-intensive’ task for the hard drives.

Some video surveillance designers and installers make a number of incorrect assumptions that have the potential to hinder the success of a system. Below is a list of some of these assumptions that should be avoided:

• Using non-server grade hard disks. A hard disk used within a video surveillance environment will most likely have a 100% utilisation rate due to the constant data streaming from cameras. Therefore, the mean time between failures (MTBF) of a desktop hard disk is much lower compared to that of a server-grade hard disk. The potential of video footage being lost is therefore higher and also, in the long term, the cost is higher to replace the storage required.
• Camera to storage assignment. Ensure that the hard disk is able to cope with the number of simultaneous data streams. Assigning too many cameras to be recorded onto a single hard disk will cause overload to its read and write capacities, resulting in the loss of data (video footage). As a general rule of thumb, no more than 10x data streams per hard disk should be assigned if video is recorded in Motion JPEG format; and no more than 15x data streams if the recording is in MPEG-4/H.264 or equivalent formats.
• Data storage capacity. A ‘gigabyte’ is not always a ‘gigabyte’. When performing storage calculations, always add approximately another 20% to the result, due to the ‘bit to byte’ conversion, eg, 1024 kB within a MB. Therefore, a 1 TB hard disk will only have 880 GB of usable memory. Not factoring in this conversion ratio will result in inadequate footage/data retention. For example, retaining an expected 30 days of video footage may amount to only being able to keep 25 days of footage if the data storage capacity is not appropriately calculated.
• Redundancy. Most storage calculators will not take into account redundancy, which is an important requirement within most IP-based surveillance applications. The type of redundancy measures will greatly affect the amount of storage required. As an example, a RAID 1 configuration will double the storage requirements.

Software - video management system

A model used in most video management systems (VMS) is to stream video from all cameras to a local server for recording. A video stream will be generated to the remote client at a requested frame rate, resolution and quality only if living images or playback is requested, to avoid using more bandwidth than necessary. Before selecting a vendor for VMS, it is recommended that the needs for bandwidth optimisation be specified and the VMS system offered meets those requirements.

The following important questions will also affect the choice of VMS:

• How many operators will have access to the system?
• How many operators will simultaneously operate the system and view its video footage?
• Will the operators be located at an operator station, or is there need for remote viewing?
• How many clients are there and where will they require access from (local and/or headquarters)?
• Is there a requirement for mobile clients?

Identifying the requirements and selecting an appropriate VMS is therefore crucial to delivering an IP surveillance solution which meets the end-user clients’ needs.

Camera installation

It is important to understand what purposes the cameras are going to be used for. Surveillance cameras can be used for a wide variety of applications. Typically their applications can be generalised as being used for either identification or for general overview (safety and security) purposes. When designing a system, one should consider that a camera placed for identification purposes rarely functions as an overview camera and vice versa.

Standard resolution fixed cameras are well suited for overview deployment. Often they are mounted high on light poles and/or on buildings to provide a general overview of an area to be observed. For high-resolution overview images, HDTV cameras can be used.

High-performance pan tilt zoom (PTZ) domes, with features such as powerful zoom and high resolution (eg, HDTV capability), are well suited for identification purposes. The strategic placement of these cameras could be town squares, business streets, intersection of roads, entrance gates and high-risk areas.

In addition, if thermal network cameras are used, it is important to understand that they are excellent for detecting people, objects and incidents in darkness and other visually challenging conditions. However, thermal cameras do not deliver video images that allow reliable identification - that is why thermal cameras and conventional cameras should be used together to complement and support each other in certain surveillance installations.

Specifications

End users, designers and installers should not just rely on specification documents when making decisions on IP-based video surveillance systems. Cameras should be evaluated and tested out for each specific intended application, so that the decision-maker can better understand what the cameras are capable of and what they can offer as a solution to the clients’ specific needs.

Image quality

An ever-increasing number of high-resolution IP-based video surveillance cameras are now available on the market. However, it is essential to identify when and where high-resolution cameras may best be utilised to ensure the optimal performance of the overall system and the network itself. For example, high-resolution cameras are best suited to use in critical or large coverage areas, whereas low-resolution cameras are best suited to narrow, non-critical areas. Choosing to utilise high-resolution IP cameras at every location will result in increased network traffic and higher storage requirements.

Although many cameras today are capable of delivering high frame rates, it is not always essential to configure every unit to stream at the maximum frame-per-second rate. Doing so will again result in increased network traffic and incur higher storage requirements. In low-priority areas, it may be advisable to lower the frame rate, which will, in turn, allow for other units that are covering more critical areas to stream at a higher frame rate. Identifying the requirements of each location will result in a much more efficient utilisation of available bandwidth and storage.

Multi-streaming is another issue that must be addressed to ensure the system can be optimally operated. In situations that require this feature, it is advisable to identify which video streams are more critical than others and assign a priority to them. One example of how this is accomplished is where a video stream is continuously being recorded in low resolution and low frame rate and then, when a predetermined event occurs, it triggers the video to be recorded in a higher resolution and streamed at a faster frame rate.

Conclusion

When designing or installing an IP-based video surveillance system, the following checklist should be kept in mind:

1. Start by defining the surveillance needs of the area(s) to be protected;
2. Select the most appropriate network cameras and their operational features;
3. Select the most appropriate hardware components, including the network type;
4. Select the most appropriate software; and
5. Address the ongoing operations and maintenance issues.

Wai King Wong, Axis Country Manager, Australia and New Zealand