A few newbie questions about DVRs

[PeterI 0]

I'm a computer vision programmer, and a month ago, as favour to a friend, I wrote a simple program that helps a local franchise monitor their display floor.

 

They are quite happy with the program, corporate heard about it, and now they want to do the same at some other locations. The problem is that corporate wants to keep my machine vision software only at their headquarters, and instead of a high end computer in every location, they want to just have the cameras and DVR that can be locked tight in a box.

 

The problem is, I have no idea about what dedicated DVRs can do. I'm used to capturing the video from the camera as it comes in, and record it at whatever resolution/FPS/compression I need. With DVRs in remote locations, I will need to worry about disk size, and about finding a balance between loss of detail, frames per second, and the size of the video file I need to transfer over a bandwidth limited connection.

 

I spent a few hours browsing the internet about information, and I am quite disheartened. It seems that DVRs have a huge variety of capabilities, and there is no standard set of parameters one can set, a standard way of retrieving footage over TCP/IP, a standard file format, or really anything. So please allow me to throw a number of newbie questions at you.

 

0. Do you know of any dedicated DVR hardware that comes with a Software Development Kit (SDK) and can be customized to a great extent?

1. Do you know of any DVRs which let you directly access the videos stored on their hard drives over the network? For example, as if they are a network drive or FTP host, not through a browser.

2. Is it possible to instruct a DVR to record multiple videos at the same time? For example, their 'regular' surveillance video, and a video that only records one frame for every ten minutes.

3. Is it possible to instruct a DVR to record at a particular FPS? For example, an especially low one like 1FPS or even 1/10 FPS.

4. Is it possible to instruct a DVR to use a particular codec? For example a lossless one like Lagarith.

5. How well do DVRs implement access control? I heard that some DVRs let anyone who knows the IP watch the surveillance video.

6. How well do DVRs recover from power interruption? Can they keep their settings, and be ready to serve video after a reasonable amount of time (a few minutes)?

7. How well do DVRs tolerate high temperature? (120F and above)

 

Thanks, for reading all the way to the bottom. By the way, if you are a reseller, do not hesitate to recommend your high end unit to me, and try to convince me that it will be just perfect for my needs... as long as it is below the price range of a good number crunching PC ($1500)

[ljarrald 0]

most DVRs have firmware that can be upgraded via a USB stick.

i guess if you know what you are doing and have alot of skill and time you could write/modify some firmware for a dvr...

[Soundy 1]

Just off the top of my head, it sounds like you'd be better off using PC-based DVRs on the sites, so you can code some custom recording software, rather than trying to battle the confines of a closed standalone system.

 

Better yet, maybe look at using IP cameras at the stores, and connect them directly to the head office via VPN, and do all your processing there.

[rory 0]

0. Do you know of any dedicated DVR hardware that comes with a Software Development Kit (SDK) and can be customized to a great extent?

Dahua - though not customization in the firmware side itself besides changing logos etc, they offer an SDK with API calls for Networked Live video and playback, as well as DVR control, alarms, etc. GeoVision PC based also offer an SDK but it is in the way of an ActiveX control instead of API. They do offer some minor API calls as well. Most DVR manufacturers will be using ActiveX controls only for their SDK.

 

1. Do you know of any DVRs which let you directly access the videos stored on their hard drives over the network? For example, as if they are a network drive or FTP host, not through a browser.

PC based would give more options for that, though you can download the videos from some stand alone DVRs, especially when using SDK.

 

2. Is it possible to instruct a DVR to record multiple videos at the same time? For example, their 'regular' surveillance video, and a video that only records one frame for every ten minutes.

Using the DVR firmware itself that depends on the DVR firmware. Otherwise using the SDK you can do anything you want in that regard.

 

3. Is it possible to instruct a DVR to record at a particular FPS? For example, an especially low one like 1FPS or even 1/10 FPS.

Yes

 

4. Is it possible to instruct a DVR to use a particular codec? For example a lossless one like Lagarith.

In general no, they are closed in that regard. You get what they offer and nothing more. Many use proprietary codecs.

 

5. How well do DVRs implement access control? I heard that some DVRs let anyone who knows the IP watch the surveillance video.

Most will include access control along with individual permissions.

 

6. How well do DVRs recover from power interruption? Can they keep their settings, and be ready to serve video after a reasonable amount of time (a few minutes)?

They keep their settings, startup time depends on the DVR and its firmware - not all are built the same.

 

7. How well do DVRs tolerate high temperature? (120F and above)

Stand alone DVRs do very well, it is one of the main reasons I use them and not a PC DVR anymore.

RTOS, basic board, simple components, no fast CPU to overheat, power adapter cord instead of big ATX power supply - ofcourse hard drive can always be another fail point.

 

I don't know what language you code in but I will leave you with this as an example:

http://www.bahamassecurity.com/vb-code/visual-basic-6-code/dahua-sdk-vb6.asp

and the bottom of this page has all the SDKs for Dahua:

http://www.bahamassecurity.com/downloads/dahua-downloads.asp

Even if you dont use Dahua it could give you an idea of the capabilities.

It's the most thorough SDK I have ever seen from a DVR manufacturer.

I am sure there are others though, well if there are perhaps they can send me their SDK.

[PeterI 0]

Thank you for the prompt and informative replies, guys, and my hat's off to you, Rory, you seem to know DVRs like the back of your hand. That SDK looks very interesting, it seems to be exactly what I need.

 

As an aside, I know that the project would be easiest to complete with PCs on every site, but the customers do not want that, as they have concerns about employees messing with the equipment, PCs developing problems, etc...