Newbie to DVRs - Impossible Specification?

[JamesDVR 0]

Hello Everyone,

 

I do hope you might be able to help me. It seems like I've searched the 4 corners of the Internet and have yet to come up with any DVR unit that meets the specification I need.

 

The most important thing I'm looking for is a DVR that can record on up to 4 channels at the same time and at no less than 50 fps per channel (PAL). Ideally, the perfect solution would actually be on up to 8 channels, but I have a feeling this sort of quality might be unrealistic? Also, a fairly decent resolution would be of great benefit.

 

Does anyone know if such a model exists, and where I can get it from?

 

Many thanks in advance.

 

James 'DV' R.

[kandcorp 0]

The maximum Fram Rate PER CHANNEL is 30FPS NTSC/25FPS PAL for any DVR system. 50FPS per channel is not possible.

 

30FPS is realtime recording..It doesnt get better than that.

 

Some specs to look at or consider if you are concerned with quality of recorded video:

-Resolution

-Video Compression (Mpeg4, Jpeg, MJpeg, H.264, Jpeg2000)

 

Also, narrow it down to a Stand Alone embedded DVR or a PC Based System.

[VST_Man 1]

are you trying to do a live video show/movie with ptz control? what takes that fps you need? just thinking............

 

I'm workin on a project for a california type audio/video studio where the PC controls the ptz's. only issue I am wondering on is the quality camera available. I'll need to mount the studio quality camera to the PTZ base. From there it should be easy. Video feeds goto the recorder and live monitors. No "person" is required to work the cam's, just one quick moused fella.

[Thomas 0]

Do you mean 50 fields per second or 50 frames per second? 1 frame is 2 fields.

[kandcorp 0]

Is that true TOM??

 

I never have heard that. I thought they were the same(fields/frames). But I guess that would make sense.

 

PAL__25Frames/sec = 50Fields/sec

NTSC__30Frames/sec = 60Fields/sec

 

Thanks again for the info TOM.

[rory 0]

only alternative i can think of off the top of my head would be a 60fps GE DSR2000 .... but you would need 4 of them ...

[JamesDVR 0]

Thanks for the quick response.

 

I was looking for a stand alone DVR unit rather than anything PC based. I was aware of the '2 fields for every frame' rule, but when browsing the DVRs available over the 'net it hardly ever says whether the fps relates to fields or frames. 50 frames per second per channel would be awesome, but after reading kandcorp's comment, I'm unsure it is even possible.

 

kandcorp - are you sure about this or is it something you have concluded through experience?

[rory 0]

the DSR-2000 is 60 pictures per second (frames) and a stand alone RTOS, but a single channel. You can put it in 60pps though, but the quality is only "slightly" better.

[JamesDVR 0]

rory - thanks man. Do you have a link to the specification of the DSR-2000? Using 4 of them could be an option, but I would need to know the dimensions.

 

also, any recommendations for a stand alone DVR unit that can record on as many as 8 channels at a single time, where recorded video doesn't drop any fields and is recorded at a resolution of 720 x 288? The specification is so exact because the data collected could possibly be used as evidence. A more comprehensive list follows:

 

• Record up to 24 hours of video from each of up to a maximum of 8 cameras at a single time.

• Video connections 75 Ohm BNC

• Video signal has the following characteristics :

• PAL

• 50 fields/sec

• Resolution 720 x 288

• Recorded video must not drop any fields.

• Recorded video must be at full resolution.

• Storage format of video to be MJPEG.

 

Any help will be very much appreciated.

[rory 0]

I dont know any off hand, but some linux based Embedded Units that claim 480fps (320x240) generally will do 240fps in 720x480 (NTSC).

 

Most will have a selection of Mjpeg or Wavelet.

 

Ive never used any so cant confirm that.

 

Im using the Geo Vision PC system with 13 cameras at a night club in real time recording in 640x480 (as 720x480 was eating up too much space). In 640x480 a decent color 5 minute video is 287MB in Mpeg-4. Ive used the video as evidence in a couple of stabbings already. They used to use the DSR-2000 with a 16 channel multiplexer, so the speed upgrade is great with the Geo.

 

As for the DSR-2000, Here's the Datasheet.

http://www.ge-consultantlink.com/Docs/dsr_2000e_prd.pdf

 

The issue you will find with a stand alone non PC DVR, is that the evidence sharing is not going to come close to the quality of a decent PC based system (as most of them will only back up via compressed network video/images), hence my switchover from stand alone to PC in the above case. I still use a CCTV CRT Monitor for playback and live monitoring.

[JamesDVR 0]

ok... just re-read my own specification, and I'm asking for 50 fields per seconds per channel... so is that the same as 25 frames per second per channel, which is what most manufactures mean when they say 'fps'?

 

if this is right, then it would open up a lot more possibilities for me, because I have seen many DVR stand alone units that can deliver 25 frames per second per channel. But my problem still remains that the application I will be using the DVR in requires that:

 

"Every FIELD must be recorded. Not acceptable to record FRAMES, as these are made from two fields 20ms apart. It must be possible to skip through FIELD by FIELD..."

 

The statement above is talking about functionality that is well beyond my level of understanding when I'm looking at a Datasheet for any DVR. Does anyone know for sure if there is a DVR that would by true for the above?

[kandcorp 0]

which is what most manufactures mean when they say 'fps'?

 

Through my experiences fps usually means FRAMES per Second.

The only thing you have to watch out for is whether they are referring to total FPS or FPS per channel.

 

You should be able to find a DVR to meet your specs. I will research and give you my best recommendation.

[JamesDVR 0]

that would be great, kandcorp. i look forward to your, and anyone else's recommendations!

[rory 0]

If this is for surveillance, I have no idea what those specifitions are for that you have .. recorded surveillance video will never be clear like a DVD/DiVx quality, or you would need 10000's of TBs of Hard Drive Space, hence we compress the video. So whether it is 60pps or 30pps or 30fps or whichever one, according to what I have seen, it wont do what those specs say, as we are talking about CCTV Surveillance, which is designed for long term industrial recordings.

 

Whenever you compress video, you loose some of that video.

[JamesDVR 0]

Maybe I should have been clearer about what the DVR will be used for...

 

There will be camera's mounted high on street lights, monitoring roads, and they detect when a vehicle is passing. The camera's job is to make a record of what vehicle passed making note of Licence Plate. This data is processed electronclly without human intervention.

 

The idea of the DVR is that it will be used during the 'proving' stage of the application. We need evidential records that a human operator can go through frame by frame in order to make sure that what the application is seeing and reporting is actually true. I've been told this is why it is important to have 50 fields per second recorded (frame = 2 fields, and when movement between those two fields = blur), because anything less will cause a blur effect making the licence plate unreadable.

 

The period of time we will be monitoring each site is approx. 24hrs, after which we will return to the site, remove the DVR equipment, copy across the data to be processed later, and then install it at the next site.

 

Is this of any help?

[rory 0]

ok then basically you just need a 4 channel 120fps DVR. This is what is tyipically used for Licence Plate Capture.

 

Are these cameras zoomed in on the licence plate or the width of one lane?

Otherwise you would need something like a MegaPixel camera and Capture Card, not a DVR.

 

Since you are not recording Movies, and it is Surveillance, 30fps (NTSC) is all you need to capture licence plates. provided there is adequate lighting and the cameras and lenses are very good.

 

Do you know what cameras are going to be used and what lenses they are using?

[Thomas 0]

They do understand that with the way interlacing works, looking at fields will not let them see a whole picture? Or that it is very rare for encoded media to even have fields since PC monitors rarely use interlacing?

[rory 0]

I think the best bet would be to go with a proven package, if they are this picky then they will have no problem spending the money for an Extreme CCTV Licence Plate Capture package ..

 

http://www.extremecctv.com/reg_cat.cfm

they have the cameras, DVR, and software ready to go.

[JamesDVR 0]

the cameras have already been selected. i'm afraid i don't know what model they are, but i do know that most of them are using 25/8 lenses. several cameras are being used to monitor each lane, which is why i requested a 4 channel dvr.

 

thank you for all your help. i will be sure to suggest the alternative package, and let you know how i get on.

[rory 0]

i have self running demo software from the people that do the Licence Plate capture software for Extreme, PM me and ill send you a link to it. And if you need any more info on the Reg gear let me know, I have stacks of it here.

 

Otherwise you could look at the GeoVision PC based, tweak it good and it will be stable, they have Licence Plate software also which would be 1/10th or less the price of the Extreme software/dvr. I have a demo online for that also, let me know. Then all you would need is the Geo GV800-4 channel card and a decent PC. One of us can jump on and tweak it for you via VNC or you could follow some steps on another thread.

 

Alternatively GE Security have a 120fps 4 channel with DVD-RW - DVMRe-PRO-4

LIke i said though evidence sharing is much better quality with the PC system such as Geo.

 

Rory