Video Anywhere, Anytime
Whether for alarm video verification at a central station or for a manager to check up on his/her employees, requests to monitor video remotely have become the rule rather than the exception.
It is usually one of the first questions we get. “I can watch this from home, right?” It’s normally followed by the qualifier, “I’ve got [broadband connection of choice], so it’s not a problem.” Unfortunately, that is a loaded statement that needs to be clarified in a hurry.
Even though remote video monitoring is becoming commonplace, there are still several challenges that need to be understood before undertaking such a project. Let’s look at a couple of ways to mitigate traffic tie-ups on the network, as well as one obstacle you will most likely encounter.
The Size of the Pipe
When putting video on a network of any kind, care must be taken not to overload that network with traffic. I’m sure we all understand by now the large size of video files, as compared to the average E-mail or Web page. In a LAN situation, with 100MB and GB links, this isn’t usually a problem, unless the system is unusually large.
On the WAN, however, space is at an extreme minimum. I am using the term WAN to describe leased and/or private connections between campuses in an enterprise layout, as well as a public connection over the Internet. Both have severe bandwidth limitations, but are essentially dealt with the same way, as far as video goes. 
WAN connections of any serious size (3MB+) tend to have one thing in common — they are all very expensive. It is this cost-to-MB ratio that forces us to examine ways to minimize the amount of traffic generated across that link. If we look at the size of commonly available WAN links, it is not hard to see how this would restrict the quality and amount of video we can transmit.
Look at the picture of the target. You can see the common bandwidth amounts for each type of connection. The most common DSL packages run anywhere from 800kb to 1.5Mbps. A T-1, which has a synchronous (same up as down) bandwidth of 1.5Mbps, has certain guarantees for service quality that a consumer DSL does not. But even then, a good quality, high resolution, high image rate IP camera could push 2Mbps or more! That definitely won’t work over DSL, or even T-1.
There are other connection types not listed in the diagram such as cable modems and bonded T-1s, but the results are basically the same. Cable modems do offer typically higher available bandwidth than DSL, but because the cable network is a shared resource within a neighborhood, it is subject to speed loss during peak times and other issues. Most DVRs, NVRs and IP cameras have some method of throttling the bandwidth when necessary. This could be a manual setting or, in some newer systems, the change might be made automatically, with the device detecting the available bandwidth and adjusting its throughput as necessary.
The trade-off, of course, when scaling back the amount of traffic, is image quality. This has been a constant source of struggle between integrators and end users. It is also an ideal opportunity for education. Most mom-and-pop users know that they have this broadband thing at home, so they should be able to see all the cameras at their chain of antique stores, and if they can’t you must be doing something wrong!
Compromising image quality to fit video over a small pipe comes down to a couple of basic principles: lowering image rate, increasing compression or lowering resolution. Any of these can cause an unacceptable image at the other end of the link. As most people can’t afford several thousand dollars a month for a T-3 to the home, the unacceptable has become acceptable.
We are seeing, however, faster broadband speeds being rolled out across the country. New fiber-to-the-premises projects are being seen more and more. New technologies such as WiMax and Ethernet over power (EoP) lines are also being developed to try and answer our need for speed.
There is another way to minimize the amount of video being sent across a WAN link, and that is to be selective.
Oh, Behave One of the new “hot” technologies in video surveillance right now is the use of behavior detection, or analytics. Analytics are basically intelligent video systems that use elaborate mathematical algorithms to detect certain behaviors or activities in video.
We have had motion detection capabilities in DVRs and cameras for quite some time, but behavior analysis goes well beyond that. Imagine having a system that would only show you video if a car was driving east, not west; or would ignore trucks crossing a border but alert you if a person on foot traveled the same path. This is the benefit of analytics.
Some common behaviors that are being marketed out there include: direction of travel; virtual tripwire (where an alarm is generated when a person crosses a determined boundary); object left behind; object removed; and others. 
So how does this technology relate to remote monitoring? By being selective of the type of incidents and video you want to store or transfer, you greatly reduce the amount of video that needs to be sent across the network. In a remote security office situation, only video that meets certain rules or parameters will be sent to the monitoring station, reducing the amount of raw video that needs to be transmitted.
Cernium Corp., a manufacturer of video analytics products, offers the High-Density Analytics Server that can provide analysis of dozens or even hundreds of cameras, only offering relevant video incidents, thereby saving both manpower and network time needed to monitor large systems.
While the video still takes up a large amount of bandwidth, intelligent systems like this can make whatever network is available more efficient by filtering out undesired or irrelevant images and only transmitting video that is truly needed. For more on video analytics, see this month’s “Tech Talk”.
Hitting the Wall
One of the most common methods of securing a network is with the use of a firewall. A firewall can either be a hardware device or software running on a computer that selectively blocks packets from either leaving or entering a network. While discussing all the ways firewalls work would be too numerous to go into here, the most basic method is for a firewall to block ports. We’re not talking about physical cable ports here, but virtual ports.
Let’s say a computer is like an apartment building. If the address on the front of the building is like an IP address, then each apartment door would be like a port. A port is a virtual doorway through which two devices communicate, once each device’s address is reached.
Ports are numbered all the way up to 65,535. Most ports up to 49,151 have official, or registered, uses. Examples of these uses are Port 80 for HTML Web browser traffic, or Port 25 for E-mail transmission. Ports 49,152 and above are dynamic and can be used by anyone for just about anything.
Network video systems use these ports to send video and control information back and forth. The reason this can be a problem is that some ports are blocked by network administrators because they can provide access to a network for attackers if not monitored or blocked properly.
As an installer, it is crucial you communicate your need to open up ports on whatever routers you may be traveling through to the IT admin. If the necessary ports (different for every manufacturer) are not open, your video will not travel across the network.
Across the Miles
Incorrectly configured video systems can quickly overwhelm WAN links. The cost associated with
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