SP&T News

News
Mega Video Solutions

IP-CCTV systems are not just a cheaper and more flexible alternative to traditional analogue systems but they have opened up new opportunities for security that are simply not possible with the old technology. It is changing the way the security industry implements CCTV surveillance and has spawned a new concept – Mega Video Solutions.


March 28, 2008
By Barry Keepence

Mega Video can be defined as large scale virtual matrix CCTV systems
with 1000+ cameras, 200+ monitors, 50+ operators, 100+ NVRs with at
least one petabyte of storage, that are continuously displaying and
recording high-quality video across IP networks that span entire
plants, communities and countries.

This may be a new concept but real Mega Video projects have been
deployed and running reliably for a number of years, such as the
Brussels Airport 1000+ camera system, which has been IP-based since
2001.

When comparing the architecture of Mega Video solutions to traditional
analogue CCTV systems it soon becomes clear why certain large-scale,
wide-area surveillance applications are either not possible or are too
expensive to implement with analogue 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 analogue/DVR based systems. The
nearest video monitor or workstation is therefore the nearest IP
network connection and as the network is typically everywhere in a
building so the monitors and workstations can be too. Total flexibility
with video display options are possible due to the distributed nature
of Mega Video solutions.

Replacing Video Monitors with PC Workstations
PC workstations are now replacing traditional video monitors as PC
technology has become increasingly more reliable and cheaper. Some IP
Video vendors supply their video management software as license-free.
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
compares very well with the huge cost of installing a large analogue
video matrix and associated video walls.

PCs are also very good at replacing monitors. Simply run them in full
screen mode and lock the keyboard away, and with the appropriate
password an expert user can access the full features of the software
e.g. playback of recorded video, which is not possible with analogue
systems. Some large sites have now deployed IP-CCTV systems that are
100per cent PC based with no analogue monitors at all.
This distributed architecture works well because the cost of the video
management software is either low or free. If the cost of the end user
software is high, then this leads integrators to build centralized
architectures – just the same as analogue!

The storage architecture for CCTV systems can be typically categorized as either centralized or distributed.

IP Multicasting

Centralized Storage Architectures
One of the key features for transmitting video over long distances and
to many users without huge impact on the network bandwidth is
multicasting. IP Multicasting is an extremely powerful feature of IP
networks that allows CCTV video footage from the same camera to be
efficiently viewed and recorded by multiple CCTV operators at the same
time. Multicast networks make sure the video stream only goes to the
people who need to see it, thereby reducing the overall bandwidth. IP
Multicasting requires compatible network switches and routers; however,
multicasting capabilities are now available on entry-level devices.

Designing Mega Video Solutions
Conceptually it’s easy to see the benefits of a distributed Mega Video
IP network based system. However, many people say that the network and
storage requirements are just too demanding for these systems to be
implemented. Apart from the fact that such systems have been deployed
and have been reliably working for a number of years, Mega Video
systems can be designed as long as these three cornerstones are
implemented correctly:
• High video compression without losing quality
• Network design
• 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 currently employed in IP Video systems. H.264 is the latest
official video compression standard, which follows on from the highly
successful MPEG-2 and MPEG-4 video standards and offers improvements 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 per cent and 50 per
cent on bandwidth and therefore 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
hence 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 the Network Video Recorders (NVRs). The two points of
maximum data bandwidth are at the NVR and at the viewing stations. The
key to network topology is therefore to group the transmitters and NVRs
into ‘nodes’. This configuration also produces a fault-tolerant network
where a single network cable failure can only take out 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 is huge and
continuous. The amount of data coming from the NVR to the users is very
low and periodic. The workload is constant, i.e. the rate of writing
data to the disk is constantly 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 which 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 in Network Design above, with small NVRs
distributed across the network. If PC based NVR servers were used, then
many separate PCs would be required each with their own local attached
storage, which comes at a significant cost. An alternative would be to
use dedicated, standalone NVR units which have the processing hardware
and storage in a single compact unit. These are considerably less
expensive than a PC server and equivalent storage. These standalone
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, with 30 stations along 49km of
track, includes 63 standalone NVRs with a total storage capacity in
excess of 60Tb, recording 897 cameras.

Summary
For large-scale CCTV applications analogue 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 analogue 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 concept!

Barry Keepence is the CTO of IndigioVision