Why Centralized NVR Recording Does Not WorkBy John Honovich, Published Jul 10, 2008, 08:00pm EDT
Centrally recording video from remote sites is as frequently claimed as it is wrong. It is an exciting concept that fails due to basic technical details. Vendors claiming their system eliminates local recording are almost invariably wrong. The problem is simple - the cost of long-distance (WAN) bandwidth is very high and it destroys any savings you might achieve from eliminating the local device.
[UPDATE 2012: While VSaaS vendors have promoted such an archictecture, the reality 4 years later is that centralized NVR recording is still not viable for anything more than a trival number of cameras per site and even then the economics remain poor.]
You are a retailer, organization or corporation with multiple stores, locations or branch offices. Today, at each of those locations, you have a DVR with storage at each of these remote sites. It's expensive to buy all of these units. It is hard to maintain them because when they break, someone needs to be dispatched far away.
It would be far better if we just had IP cameras and used an IP network to stream the video directly from the cameras to a centralized storage cluster. This would significantly reduce equipment cost, increase storage utilization and make fixing hardware failures easy because the equipment is all in one simple to access location.
The key problem is bandwidth. If you are not comfortable with how much bandwidth is available and how much it costs, please read my bandwidth basics tutorial.
While bandwidth is cheap inside of buildings, connecting a facility to a remote facility is usually very expensive. Getting 10 Mb/s of bandwidth can easily cost $1,000+ USD per month.
If you are going to record off-site, even if you only have 8 cameras, it can easily take 10 Mb/s. And that's just for standard definition cameras. If you start to use megapixel cameras, the situation is far worse.
As a customer, it will cost you far more in bandwidth than what you can save in system costs. Over a 5 year period, the bandwidth cost will be $60,000 per site. The DVR itself costs less than $10,000 so even if you magically eliminated the DVR, the bandwidth increase would still make it a loss.
Most vendors are prepared to handle rebuttals to this. Here are a couple and the truth to them:
- "Of course, you need to have the bandwidth": This is the "it ain't my fault" rejoinder. The vendor's point is that their system is capable of doing, it's someone else's fault. I find this entirely unconvincing. Since almost no one has the bandwidth available to do this cost-effectively, they should simply drop the pitch rather than try to spin the customer"
- "You may have the bandwidth": You may have the bandwidth but almost no IT department wants to waste such valuable resources to reduce equipment cost. Large 'pipes' across the WAN are usually used for business critical operations and running surveillance video 24/7 will generally be seen as a poor use."
- "Bandwidth is Getting Cheaper": Bandwidth to remote sites is getting cheaper at a very slow rate. Your cable modem speed and pricing is not that much different than it was 10 years ago even though your computer offers 10x the CPU speed at less cost. Bandwidth for this application has not got much cheaper and there is no real explanation of why it will get significantly cheaper in the next few years."
- "You can Record at a lower rate and resolution": Since bandwidth is very expensive, if you lower the bandwidth per camera, then you can make it fit. This usually results in recording at CIF at only a few fps. This is a very significant tradeoff that most people do not want to make. It significantly undermines the quality of the video which at a basic level, is somewhat self-defeating."
- "You can put Storage in the Camera.": This is the hot new spin that takes 2 forms; using (1) flash or (2) hard drives. While the price of flash is dropping faster than the price of hard drives, flash is still drastically more expensive than hard drives. Plus video consumes lots of storage. The economics of flash are not even close for general usage. Hard drives inside of cameras has unrealistic economics and logistics as well. VideoIQ has recently started pushing cameras with built-in storage. It is significantly more expensive than normal cameras (they claim $1295 MSRP for their cameras with an 80GB hard drive). The form factor is quite large and prevents customers from using discrete domes (which are often preferred). It currently requires to use their video management system. They claim that their hard drives last 4 times as long as normal hard drives, an extremely hard to believe claim. I expect to see more claims of storage in cameras and that such products will be a poor fit for most customers.
I hope this article helps clarify the problems with the oft-repeated claim that you can or should do centralized NVR recording. While it's a nice concept, the chances are extremely high that it will not work for you. Hopefully vendors will take a more responsible and prudent approach going forward.
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