DVD signal vs CCTV cam

[Orion 0]

This is probably a very basic question, but I need to be sure.

When I build a Geo system and I need to make a quick check of the card

or something, I usually plug in a DVD to a video input.

The compressed video from the DVD looks excelent in Geo.

I will never get as good image from a cctv cam even with really expensive cams in perfect light.

The strange thing is that a good cctv cam

plugged directly to the tv does produce an excelent image, close to the dvd quality.

Why is the cam image more affected by the comression?

 

The cams used to produce the DVD image is of course very very expensive stuff.

[kensplace 0]

If your recording a test signal DVD then (in general, not used geo myself) those should be outputing a nice *stable* output, with little to no variation in the colours, ie a red is red, and stays at the same level all the time. A camera will in general have a slight variation in the colours of each pixel on each frame, also their output can be 'noisier' than the nice clean output from a dvd with a test disk.

 

The compression has to account for all the changes between frames, so the more picture noise or movement, the more it has to compress, and the risk of the picture quality degrading increases.

 

Also, pictures usually look better on a tv than they do on a standard PC monitor, and TFT monitors (at least mine anyways) are even worse....

 

I usually watch my avi's/mpegs on my tv via a tv out port on my graphics card, and the improvement is vast compared to watching them on the 19 inch sharp TFT.

 

You may find using different compression settings (if geo allows it) would improve things, also try watching the recorded output on a TV, see what it looks like...

[kao 0]

The strange thing is that a good cctv cam

plugged directly to the tv does produce an excelent image, close to the dvd quality.

Why is the cam image more affected by the comression?

 

The cams used to produce the DVD image is of course very very expensive stuff.

 

Keep in mind that when you plug a camera straight into a TV, there is no processing, compression or recording taking place between the camera output and the tv input.

When you put a DVR card and PC in between the camera signal and the output monitor (tv, pc monitor, etc), you will be in effect 'slowing down' the signal a bit due to compression and image processing.

[Orion 0]

Keep in mind that when you plug a camera straight into a TV, there is no processing, compression or recording taking place between the camera output and the tv input.

When you put a DVR card and PC in between the camera signal and the output monitor (tv, pc monitor, etc), you will be in effect 'slowing down' the signal a bit due to compression and image processing.

 

Yup, I do know about compression. The question is as follows:

 

1. CCTV cam --> TV (or monitor) = Very good image.

 

2. TV signal (or DVD) --> Geo system = Excelent image. (With compression.

 

3. CCTV cam --> Geo system = Not-as-good-as-expected image.

 

I'm puzzled of the signal noice in case 3 even with really good cams. Sorry if I wasn't clear in my question.

 

I've used cctv cams through sonys videoserver and Milestone as soft, produces a better image then the Geo system.

I've used Mirasys stuff with sony cams and that gives a very good image.

It is strange that Geo produces the low quality with a cctv cam but not with a DVD signal input. In a Mirasys system the difference is smaller.

[Thomas 0]

Keep in mind that DVD's are supposed to give a signal with a S/N ratio in the 60's. Most CCTV cameras are in the high 40's. That's a huge differance.

[kao 0]

I see your point.

As a matter of fact, I have a dvd player looping a chapter on a demo system and I compared that image side to side with a std cctv camera that is plugged into the same system.

 

The dvd stream does appear much 'crisper' than the cctv camera and I suspect it has to do with a few things.

1. I believe the native resolution coming out of the dvd player is much higher than that of the cctv camera.

DVD output is 720x480. Most cctv cameras are around 470x320.

2. Light handling. As you mentioned, the cameras that they use to make the movie that is on dvd are very good cameras. They handle light very well. Also - digital editing and filtering may be done on the final picture you see on dvd - creating a very nice video. Cctv has to deal with 'real life' without all of those finishing touches.

 

While not as robust as a hollywood camera, I hooked up my sony camcorder to the Geovision system and found that it dealt with light much better than any security camera I have used (with the exception of some nice PTZs) and provided a picture almost as nice as the dvd player.

[rory 0]

Most high res 480 - 520TVL cameras should be 811 H x 508 V (NTSC)..

 

With the lower res 380TVL being at 542 H x 492 V (NTSC)

 

Other factors are lens focal setting and the cable being used.

[Orion 0]

Keep in mind that DVD's are supposed to give a signal with a S/N ratio in the 60's. Most CCTV cameras are in the high 40's. That's a huge differance.

 

Jepp, thats must be it. Most cams seems to have S/N ratio between 45-55.

Is there any cams on the market with higher rate?

[Orion 0]

I see your point.

As a matter of fact, I have a dvd player looping a chapter on a demo system and I compared that image side to side with a std cctv camera that is plugged into the same system.

 

The dvd stream does appear much 'crisper' than the cctv camera and I suspect it has to do with a few things.

1. I believe the native resolution coming out of the dvd player is much higher than that of the cctv camera.

DVD output is 720x480. Most cctv cameras are around 470x320.

2. Light handling. As you mentioned, the cameras that they use to make the movie that is on dvd are very good cameras. They handle light very well. Also - digital editing and filtering may be done on the final picture you see on dvd - creating a very nice video. Cctv has to deal with 'real life' without all of those finishing touches.

 

While not as robust as a hollywood camera, I hooked up my sony camcorder to the Geovision system and found that it dealt with light much better than any security camera I have used (with the exception of some nice PTZs) and provided a picture almost as nice as the dvd player.

 

1. I agree to Rory in that case. I never use a cams with less then 480 lines.

2. My example is in a lab enviroment with excelent light. I should have mentioned that. Sorry.

 

That camcorder experiment is interesting. Have anybody else done this experiment with tha same result? It is interesting that a cheap camcorder

is cheaper then a really good ccvt cam. Wouldn't look so good with camcorders hanging from the roof though (but it would include autofocus an a nice zoom )

[Orion 0]

Most high res 480 - 520TVL cameras should be 811 H x 508 V (NTSC)..

 

With the lower res 380TVL being at 542 H x 492 V (NTSC)

 

Other factors are lens focal setting and the cable being used.

 

Cable is the same in my example. A short (2 meter) koax.

Lens used in this case is auto-iris zoom lens. Not the most expensive,

but not the cheap crap. Focus is set on 19" tft monitor aiming at a test sheet.

Have you seen any cams that have a good noice reduction that dosn't blur the image?

[kao 0]

Most high res 480 - 520TVL cameras should be 811 H x 508 V (NTSC)..

 

With the lower res 380TVL being at 542 H x 492 V (NTSC)

 

Sorry..I was getting my picture elements and resolution mixed up :/

[Arockerdude 0]

I experienced the same thing with my hand held Sony Hi 8 camera. The quality of video was much better! Than my Hi Res. Day Night cameras that I paid a fortune for. I was able to zoom in on the neighbors licence plate from 5 houses away. And the auto focus was great. And it worked in color mode with a sharp picture at night. I only paid $150 for that video camera. I think it would fit in an outdoor enclosure. The only problem I had was. When I was not recording. The camera would shut off after three minutes. I had an idea that maybe if I cut the recording tape and hit record it may not turn off. But I hate to think of all those parts in the camera turning 24 hrs. a day. the other problem is it said Rec. on the screen at all times. I went into the the menu and there was no way to stop the auto shut off. Or the Rec. display on the screen. I wonder if the new digital cameras would even display a better picture than the Hi-8. You can get open box small digital video camera for a $150 all day long. The thing that was amazing. The picture was way better than my Pelco 1390 Day Night camera and my Panasonic Day night camera. I am not happy with the way my pelco and panasonic look at night. To much snow from the gain. If I turn down the gain. I can't see enough at night. The hand held video cam works better in dark conditions. I called a CCT camera store and the guy told me it would cost about a thousand dollars to purchase a camera with the features and quality of picture that my hand held video camera could produce. So here is my questions. What is the deal? does it make sense that the cheap video cameras produce better images? Are they cheaper but actually better than CCTV cameras because they can sale mass quantities of the hand held video cams. Maybe CCTV cameras are more expensive because they don't sale as many. So they cant offer as good of components for the money?

I am going to do some more testing with the video camera into the Geovision. What are some of your thoughts on the hand held video cameras hi 8 and digital verse the CCT cameras. Thanks. Dave

[Jasper 0]

Sound Interesting.

 

I have an old HI-8 Sony Cam that would be nice to use as a camera pointing out a window. But like you I experience the auto shutoff.

 

The camera is not designed to be on 24-7, but if you could figure out a way to bypass the shutoff feature you could at least try it for awhile.

 

If you don't care about the camera then if it fails on you it won't be that big of a deal.

 

Let us know what you find out or figure out.