DVR Architecture – How Dumb Is Your User?

I recently received an E-mail from a manufacturer’s rep with a deceptively simple question: “I am wondering if you have an article that you may have written that discusses the pros and cons of embedded vs. PC-based DVRs,” he asked. “We have an end user that wants to put PC-based systems in 650 retail locations and we think the embedded option would be best for them due primarily to having to maintain that many PCs in 650 different locations.”

The choice between PC-based and embedded digital video recorders is often more difficult than it looks.

Traditionally, embedded DVRs meant units that utilized an operating system that was booted from memory, not from a hard drive. These machines did not have as many features as PC-based products, were not upgradeable and had limited storage capacity.

On the other hand, they were more reliable, smaller and far easier to use. In fact, when I spoke to a sales representative for a major DVR manufacturer about this topic, he stated bluntly, “It all boils down to one thing — how dumb are your users?”

But these stereotypes are not always true. While embedded DVRs are usually easier to use and have fewer features than their PC-based counterparts, the features they lack are not needed by many users. Further, many features that are considered “mission critical” to many users came first on embedded DVRs, including the ability to transport video clips via USB “thumb drives” and removable hard drives.

Their software is often field upgradeable via an external PC, CD-ROM or USB drive, and some models can accept external hard drive modules or even RAID (random array of independent discs) storage. PC-based units have advantages of their own.
While they are often Windows®-based, several units now use proprietary operating systems or open-source operating systems such as Linux. Regardless of the operating system, PC-based units have made tremendous headway in terms of reliability. These are the machines to use if there are multiple machines that need to be networked or require advanced network configurations.

Let’s pause right here and mention enterprise digital recording systems. These units separate the digital video encoder and recorder portions, and are the preferred choice for large enterprise installations. As a category, they use a variety of operating systems, are infinitely scalable, provide dedicated hardware-based controllers and require fairly sophisticated networking experience to install, configure and maintain.

While they have many advantages, they’re beyond the scope of this article and are not what we’re talking about when we describe PC-based vs. embedded systems.

Consider Usage First
What should the selection criteria be between the two units? To a large extent, it’s how you think about DVRs that gives the greatest insight.

If you have a “set it and forget it” mentality, an embedded DVR is usually the best choice. Embedded DVRs are smaller than PC-based units, cost less and perform surprisingly well since their operating system — usually Linux — is often “tweaked” for performance with that exact hardware. While this often limits expandability, this limitation is not a factor for the type of user looking to reliably record video and only review it if there’s an incident.

On the other hand, if you’re looking for your DVR to be an active part of your surveillance team, a PC-based unit may be a better choice. It will have advanced search capabilities that allow such luxuries as search on direction, speed, loss or presence of something in a scene.

While either type of system can be upgraded, the PC-based system is generally easier to upgrade — often a requirement because of the frequent changes and patches required by the Windows operating systems many of these units use.

PC-based units also have more options than embedded units, such as the ability to scale video resolution and frame rate on a channel-by-channel basis. Since there are numerous PC-based processors on which manufacturers can build their units, PC-based DVRs can be found with higher frame rates (the amount of video images they can process each second) than their embedded counterparts.

It is also easier to upgrade PCs strictly on the basis of adding more hardware- and software-based features. Embedded units tend to get upgrades to fix bugs or add minor features that were promised but left out of their initial release.

With these features come some complexity — it can take a while to master all of the features of a PC-based unit. If these features aren’t needed, you may find yourself wishing for “the simple life” offered by the embedded products.

Manufacturer Positioning
Some of the differences between the two types of DVRs have more to do with how manufacturers position these products than with technical limitations in the software and hardware (see diagram on page 26 of February issue).

A PC-based unit is often used as part of a bigger system. On the other hand, embedded units tend to be standalone, with the exception of ASCII text interfaces for cash registers in retail applications.

At the same time, PC-based units are more likely to be integrated with access control or enterprise-wide point-of-sale systems and frequently have companion software interfaces to allow other manufacturers to write software that talks to them. This capability is extremely rare among embedded units.

The remote client interface is another example of manufacturer positioning. It is becoming more common for DVRs to be located in a remote area with the primary interface being browser-based or proprietary remote software.

While either type of unit should have similar technical capabilities when interfaced remotely, the PC-based units generally have more sophisticated clients because of the perceived market positioning. Again, look to see if these advanced features will ever be used to help with the buying decision. If the ability to look at multiple DVRs simultaneously from a single Web page is important, you can only find that feature on a PC-based unit.

Finally, we can’t ignore the pricing differential — in both hard and soft dollars. Embedded DVRs are usually much less expensive than PC-based machines. The cost of the Windows operating system can add $100 to the cost of each PC-based DVR, which usually translates to $200 more in the end user price. Motherboards, power supplies, cases and other expansion options contribute even more to the cost.

Meanwhile, an embedded unit contains only the components needed to do the job at hand — it wasn’t built on a platform that was also designed to handle business tasks or play state-of-the-art computer games.

On the soft-dollar side, embedded units usually require a trip to the machine to handle software upgrades when needed, while PC-based machines can often be upgraded across a network. This can eat up some of the hard-cost savings, particularly if you’re doing a large rollout over an extended period and want to keep your software versions consistent across all machines.

No Easy Answers
The fact that there are no clear-cut answers as to which unit is best can be attributed to the sheer variety of DVRs on the market, and the ever-expanding capabilities that come from advancements in technology.

While this article may give you some ideas to point you in the right direction, I’m a big believer in looking beyond the spec sheet.

The best unit in the world will quickly become a doorstop if you don’t get the support you need to keep it running, and that door may not have your name on it if you don’t do your homework!


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