okay I'm looking at this DVR for my business surveillance.

LINK

it's 120FPS, and I plan on running 12 cameras on it. My understanding was that the 120FPS will be shared by the 12 cameras so each one will be able to record at 10FPS. Which I think is a little low frame rate. The salesman however insisted that each camera will be able to record 120fps simultaneously. He said that he's being doing it for decades and knows what he's talking about.

anyone with knowledge in DVR's, I would appreciate you input

TIA.

 

From what I see on the description....

You have a choice of using 120fps or 60fps. 120 is not necessary for your application. 60 is more that enough. *Usually* the frame rate does NOT drop with the use of added cameras. The only thing that drops is how long it can save, since one drive is now divided into 12 cameras, rather than 1. I would advise AGAINST a standalone DVR like this one, and get a PC based system. That way, you can upgrade drives, and have much more control. Usually, in the long run, they run cheaper as well. At my job, we have a PC based system that can save 14 cameras for 13 days. I can upgrade the drive and have it save for 30 days.

 

thanks that helps. That's exactly what the sales guy was saying.

I don't know why I remember reading something about real time is approx 30fps or so, and you want a system that can handle fps close to that per camera. I could've been smoking who knows.

 

Ill take your word that real time is 30fps (I dont recall) so you can EASILY get away with 15-20fps. You can have cameras over money locations (registers) running at 30, but others (like a storage supply closet) can be set at 15.

 

While I'm not "plugged into" the consumer DVR market I do have some experiemce with DVRs. Let's say I'm "involved" in a large networked system of DVRs - we have ~ 6,000 DVRs and over 70,000 cameras recording 24/7, all of which are managed from and any of which can be monitored/uploaded to one of several central facilities. No I won't tell you who or where, (this is my real job).

Here is what you may want to consider:

1. Real time is 30 fps. Other than highly specialized systems, frame rates higher than 30 fps are not typically used. What are you going to play it back on? (most video gear is designed for 30 fps) Generally, casinos consider 15 fps to be good enough for "real time". Bank cash vaults sometimes don't run higher than 10 fps. Why? It's not needed and storage requirements become unbelievably large.

2. It's unusual for commercial DVRs to be rated by individual camera frame rate. Normally they are rated by SYSTEM frame rate capacity and you must share that frame rate with all cameras. System frame rate gives you a better feel for overall performance and will be reflected in the price.

3. Beware of getting "half the facts" when you look at specs. You can shove 12 video cards, each of which is capable of 30 fps, into a box that doesn't have the processing power to record all that data to a hard drive at any useable resolution. Sure, if you run 160x120 you can get it all, but at 640x480 you may max out at 3 or 4 fps per camera. Point is, frame size (# of bytes) varies by resolution and compression method, which affects every performance criteria of the system. And color takes more space than B&W, but most ratings are based on B&W.

4. While the salesman may have "decades" of video experience he does not have decades of DVR experience. viable Commercial products have not been around for much more than 8-10 years. Anything older than that was either top-secret government stuff or not really useable & reliable in a commercial environment.

5. Consider your HD storage size and long term video retention capacity, which is influenced by frame rate and frame file size (which I didn't see listed). Example - for a high compression system I work with, storing 16 cameras at 1 frame every second 24/7 (most cameras only when motion is present) fills 250GB in 45 days. If you're going to record at 30fps that means you'll need minimum 8TB of storage.

6. Consider network requirements if you plan to use one. That same system with 16 cameras at 1 fps each requires a full T1 to transfer the compressed, black & white video. Color takes more bandwidth.

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thanks for all the great info. This is not going to be a PC based system, so it won't involve adding dvr cards. It's a built in multiplexer/dvr.. with 160GB. I will be running 12 cameras so it will bring me down to 10 fps, which I think is low. Funny thing is, I already ordered the system since a few people told me that it the complete system fps is not divided by the cameras. I always thought it did, and you've confirmed it.

It is a really good deal considering I'm getting 4 digital sony cams, 160 dvr with cd-rw and remote access. includes a 17" lcd and everything installed for $1200. he'll even hook up my existing cameras to the system.

I'll keep my fingers crossed and hope that the system will be able to actively distribute fps as it detects motion in each camera. in other words, not all cameras will be recording at the same time, so if it only lowers the fps per camera if more cameras are seeing motion.