DVR Purchase

[smokingjoe 0]

How is everyone? I am trying to catch on to this resolution stuff but it seams kind of complicated. When purchasing a DVR how do you find a good resolution at a good frame rate?

 

PC-Base 8 channel DVR

720X480 pixels @30fps

640X480 @60fps

352X240 @120fps

 

Do you pick which resolution you would like to have and then determine how big your hard drive needs to be to get the desired frame rate you need?

[scorpion 0]

I would say it depends on whether your choice is determined by

budget is of the essence, or

security is of the essence.

 

For budget choice then what you can afford is what you can afford.

 

If you are demanding 30 FPS on each of the 8 channels then you will want to take the 30 FPS, and mulitply it by the channels to come up with the total frame per second that the DVR will have to provide 30 FPS per channel. You will need a DVR that can handle 240 FPS.

 

120 FPS will provide 15 FPS per 8 channel DVR.

 

120 FPS will provide 30 FPS NTSC per 4 channel DVR.

240 FPS will provide 30 FPS NTSC per 8 channel DVR.

480 FPS will provide 30 FPS NTSC per 16 channel DVR

 

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http://scorpiontheater.com/lab.aspx

 

 

Now comes the difficult part. Some DVR companies use FPS, but you have to determine what their "FPS" means:

 

FPS Frames Per Second or

FPS Fields Per Second.

 

http://en.wikipedia.org/wiki/Frame_rate

 

It takes two fields to make one frame, or interlaced.

Progressive scan is one field.

 

http://en.wikipedia.org/wiki/Progressive_scan

 

 

DVRs can also be rated useing IPS, or images per second.

 

If security is of the essence then go with a company that you trust, and have them decide a DVR for your budget, and security needs that matches your specification.

 

When things go wrong down the road it is great to have someone to lean on when you need tech support.

 

If you are budget oriented then get the highest numbers that you can afford. You would be better doing a demo of products. If you cannot find a showroom, then at least ask the dealers to provide an online demo of the DVR with some cameras.

[smokingjoe 0]

Thanks for the information, especially the part about needing two fields per second to make one frame. I am sure this will help. I will also check out these sites. Thanks again.