Fps And Tvl Discussion

[LeonThePro]

You will probably find that 25fps per camera or certain cameras is a requirement set by the council for the town centre system.

I am not aware of any general Home Office or Police guidance that states DVR's must be capable of 25fps, in certain situations it would be a requirement, town centre, possibly custody suites, prisons etc.

[LeonThePro]

I to would of thought that better quality recording at a lower frame rate would be the preference.

I would agree it would be better to have high res recordings at lower frame rate rather than real time highly compressed recordings.

As always it's down to cost, in an ideal world you would want high res real time recordings.

The more information the better.

[james.wilson]

i concur, i say the book from ljd that was supposed to be by the police, looked like marketing info for ljd to me. I cant see how they can justify 25fps per channel, only mpeg based recorders can do this, and i hate mpeg

[james.wilson]

useless on ptz on tour, poor recording quality on all the ones i have seen. Yeah they have awesome framerates, huge recording times, but do not compare (IMO) to the dm for playback quality. And i think thats THE most important feature after fps, recording length etc

[Matt the Teckie]

Getting back to the original question,

On a 25fps DVR, you'll probably record about 4-5fps per channel unless the cameras are synced together (if they're not the video capture card's likley to miss fields).

Also, if the DVR claims 25"fps", it might be worth checking to make sure they mean frames or fields (a field is half a frame).

As far as TVL are concerned, you're not comparing apples with apples. TV Lines is an analogue measurement (generally horizontal), pixel resolution is a digital measurement. You could have the best camera in the world but you'll still record a poor picture at 352x288 MPEG4 resolution.

Another thing to bear in mind is that most PC's arn't designed to run 24/7. Dedicated DVR's are designed to be run in this way with (hopefully) extra cooling systems for the robust HDD's that they use.

Hope this helps PThomas

[SystemQ]

only mpeg based recorders can do this, and i hate mpeg

James.

Many JPEG DVRs now record 25fps per channel.

Even our budget 4 ways are true realtime.

Paul.

[PThomas]

Getting back to the original question,

On a 25fps DVR, you'll probably record about 4-5fps per channel unless the cameras are synced together (if they're not the video capture card's likley to miss fields).

Also, if the DVR claims 25"fps", it might be worth checking to make sure they mean frames or fields (a field is half a frame).

As far as TVL are concerned, you're not comparing apples with apples. TV Lines is an analogue measurement (generally horizontal), pixel resolution is a digital measurement. You could have the best camera in the world but you'll still record a poor picture at 352x288 MPEG4 resolution.

Another thing to bear in mind is that most PC's arn't designed to run 24/7. Dedicated DVR's are designed to be run in this way with (hopefully) extra cooling systems for the robust HDD's that they use.

Hope this helps PThomas

All makes sense. I am considering the Geovision cards with the version8.1 software which seems to offer lots of flexibility. I will sacrifice fps for cost as a 50fps card is almost twice the cost of a 25fps one.

Geovision can capture at 640x480 and I believe higher now. PC will probably be a rack mount one I have spare, plenty of cooling and will be in the new clean loft, where the noise doesn't matter so much. (May even be an old HP Server, certainly designed for 24hr running)

So at 640x480 what resolution and TVL cameras should I be looking for?

I thought perhaps 420-480 TVL for the front camera (maybe 6mm lens) and maybe 380-420 bullet camera for the side of the house where the subject would be a lot closer.

[Ricco]

Never known any hard recomendations for 25FPS, but as pointed out each council has different 'guide lines'.

I am supprised how many ppl skimp on camera quality in return for a higher FPS DVR. I would much rather sell a system with good quality images.

Also I have seen a few fake Geo cards floating about, so make sure you only purchase one from a known source.

As for rack mounted PC - pretty pointless IMO, if space is not an issue. Also don't forget to avoid VIA chipsets.

I usualy stick with Intel based mainboards and Intel CPU's, but thats not to say an AMD setup would not be option.

[arfur mo]

All makes sense. I am considering the Geovision cards with the version8.1 software which seems to offer lots of flexibility. I will sacrifice fps for cost as a 50fps card is almost twice the cost of a 25fps one.

Geovision can capture at 640x480 and I believe higher now. PC will probably be a rack mount one I have spare, plenty of cooling and will be in the new clean loft, where the noise doesn't matter so much. (May even be an old HP Server, certainly designed for 24hr running)

So at 640x480 what resolution and TVL cameras should I be looking for?

I thought perhaps 420-480 TVL for the front camera (maybe 6mm lens) and maybe 380-420 bullet camera for the side of the house where the subject would be a lot closer.

hi PThomes,

this will upset the 'pourists' amongst us, but imo Geovision give you lots bang for your money, remote access to a non-fixed ip is a breeze to set up.

we can run on and on about high frame rates and compressions, but at the end of the day it's down to you the users invisaged systems use. no point having a ferarri just for the shopping trip, so unless you over critacal in a photgraphic sense, have high value risk or just can't bear anything but perfect studio quality image's, it will do a very good job, even has watermarking (but has to be turned on).

if you go with it, get a decent office desktop/tower based computer, not some cheapy offerings which are not designed to run 24/7 x 365, definately not the old slogger thats been in the attick the last 2 years

regs

alan

[Guest]

never go below 470TVL, 4CIF and 5~6 FRAMES per second!!

i am only assuming that you want to also see what happened afterwards..

you are only wasting recording capacity if you go above 12fps and wasting your bandwith if you go above 6fps (takes too long to see remotely what happened)