Should You Use Video Encoders?By John Honovich, Published Mar 17, 2009, 08:00pm EDT
Many people want to go IP but 95% of deployed cameras are analog. Encoders are the most common solution but is that the best approach?
What are Encoders?
Encoders are appliances that convert analog video feeds to digital so that the video can be transmitted over IP networks and stored on digital storage like hard drives. Encoders generally cost $300 USD to $400 USD per analog camera.
While DVRs encode and store video, encoders simply encode video and transmit the video to a remote storage location. If you are not familar with encoders, I recommend a very good encoders tutorial from SDM.
Axis Makes the Case for Encoders
In a recent whitepaper on encoders [link no longer available], Axis recommends using encoders as "the easy path to network video."
In it, Axis dismisses DVRs as an alternative, saying:
"[DVRs have] never been able to deliver more than a handful of the benefits that can be provided by full-fledged network video systems. With DVRs, video is still stored on proprietary equipment, which makes integration with the fast-growing market of software applications for network and video management."
We have 2 claims: (1) a general claim about lacking benefits and (2) a specific claim that DVRs do not integrate with software applications.
The Key Need for Encoders
Encoders have clearly been the best and most frequent option for migrating to network video. I see two practical reasons:
- DVRs generally did not support IP cameras
- IP Video Software generally did not support video stored in DVRs
It's the combination of these two factors that makes designing systems so difficult. On the one hand, if you connect analog cameras to a traditional DVR, you are stuck with not using IP cameras. On the other hand, because IP Video Software has very limited support for DVRs, you cannot integrate your analog cameras connected to a DVR with your IP cameras.
What's Not a Barrier
Other technical elements in using DVRs or IP video software are generally not a barrier. Both DVRs and IP Video Software offer significant capabilities in access control integration, remote viewing, client UIs, PoS/ATM support, mapping, analytics, etc.
In the old days, you had to use encoders because of these two historical barriers. They were used despite the fact that separating encoding from storage almost always significantly increased the cost, complexity and service requirements of deployments.
The big challenge with encoders is the separation of encoding and storage into separate devices. Relative to doing both together, it requires:
- Setting up a network between the recorder/storage and the encoders
- Configuring the encoders AND configuring the recorder
- Physical set up and power to both encoders and recorders
- Purchasing two sets of products that cost more than buying them as a set
- Multiple IP addresses
- Knowledge/training on both encoders and recorders
- Reduce cost for supporting analog cameras (by eliminating encoders)
- Yet retain flexibility to use wide varieties of IP/megapixel cameras
On the other hand, because camera manufacturers are now adding on-board storage, IP Video Software providers are increasingly being asked to add support for remote video storage. To the extent that IP Video providers do this, this would provide the technical foundations to increase support for DVRs.
Nonetheless, hybrid DVRs are the key tool TODAY for eliminating encoders. In the future, IP Video systems supporting DVRs may be a way to eliminate encoders and provide a more seamlessly integrated solution.
Application Best Fits
The most important and basic criteria for choosing encoders is whether your VMS system supports hybrid DVRs. If they do not, you have to use encoders. Since many VMS do not, encoders will be your only choice.
For those using VMS systems supporting hybrid DVRs, the decision should then be made based on how many analog cameras are located in close proximity to one another. Specifically, the key element is where the coaxial cables are terminated (or can be terminated). If there are 8 or more analog cameras than can be terminated in a single location, a hybrid DVR is likely to be more economical. Fewer than this and an encoder is probably better.
Of course, in any application where the encoders would need to transmit over a low-speed Wide Area Network (like DSL, Cable Modem, T1), using a hybrid recorder is ideal (because you will need to record on-site anyway).
IP manufacturers and integrators need to accept that hybrid systems are playing a greater role and that adding support for DVRs can be advantageous.
Encoders are not really the easy choice. They simply were the only choice for a long time.
Supporting DVRs and using hybrid DVRs does extend the life of analog. To that end, it is not ideal for IP vendors. On the other hand, it provides a greater opening for IP to grow than the alternative of simply staying stuck in analog.
IP vendors should come to accept and embrace the role of these encoder alternatives as ways to stimulate broader accept of IP.
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