Dvr Record Resolution Query

[apr400]

Hi,

I am looking to install a domestic CCTV system to try to discourage breakins to our cars, and general vandalism on the street outside our house. I need to cover an area about 6 x 6 metres outside the front of our house (well lit by PIR activated lamps). Given that I am installing a system I may as well do the garden at the back (approx 5 m wide and 7 metres long, also lit by PIR activated lamps) and also have a camera or two inside the house to cover obvious things like the tv, dvd etc.

I am looking at bundles from web stores such as

iViewCameras

y3kvision

sct

(Other suggestions welcome!)

I have had a search through the forum and most of my questions have been answered, but I have a few left!

- I have seen conflicting views of y3kvision - the further back you go, the more negative - any current info (they do seem to have good prices, but if the service is still bad...)

- I am leaning towards Day/Night cameras with integrated IR illumination for all three sites as the viewing distance as reasonably small. However, I am wondering whether this will conflict with the security lighting - as I understand it the IR filter in Day/Night lights is mechanically moved to go into Night mode - presumably there is therefore a discrete period of time for the camera to go from one mode to the other as the security lights go on and off? Futhermore am I going to wear the filter mechanism out (we get a fair amount of light activation by cats)? How long do the LEDs typically last in normal usage (although presumably extra LED illumination can be added later if they die).

- I am somewhat confused by the resolution specs for the DVRs. For instance they may quote something like 360 x 288 normal and then 720 x 288 hi res. I gather (rightly or wrongly) that the vertical resolution doesn't increase for high res because of interlacing at the camera. What does this mean for the image quality (also wouldn't the interlacing affect the dvr at normal res too?) - for instance do you therefore require at least two images to capture both the even and odd lines. Would a dvr typically reconstruct this in output? Presumably this can lead to blurring unless the frame rate is high enough? Would anyone like to estimate the maximum number of tv lines it is worth going for in the camera for a dvr capable of 720 x 288 (I realise this can only be an estimate). For instance is it worth going for a 480 tvl camera with such a dvr or will half the info be lost?

- Finally - location of the dvr. I am a Mac user so from what I have read network connection to the dvr is out. I guess I could put the dvr in the loft, but then I suppose that I would have to go up there to review the info. Any solutions for bringing the picture from the dvr to a TV on the ground floor (pref not a video sender - don't want to broadcast my internal cctv to the neighbourhood!) AND also allowing me to control the machine from the ground floor? Alternatively I guess that there are products for securing the dvr so that it can't be easily stolen/vandalised by a burgar even if in plain view - any suggestions?

Sorry for the long post, and many thanks in advance for any help and suggestions. Finally anyone in the Birmingham area who is interested in selling me something and/or letting me preview the system at their shop first - let me know! I am looking for a complete system with all required accessories (ie power supplies, cables etc) for something in the region of 5 - 750 pounds, and I am going to need something that is of sufficient quality to allow recognition of the culprits. I am also keen on the idea of motion detection so that I can maximise the duration of recordings, but grab high res high framerate stuff when required.

[LeonThePro]

- I am somewhat confused by the resolution specs for the DVRs. For instance they may quote something like 360 x 288 normal and then 720 x 288 hi res. I gather (rightly or wrongly) that the vertical resolution doesn't increase for high res because of interlacing at the camera. What does this mean for the image quality (also wouldn't the interlacing affect the dvr at normal res too?) - for instance do you therefore require at least two images to capture both the even and odd lines. Would a dvr typically reconstruct this in output? Presumably this can lead to blurring unless the frame rate is high enough? Would anyone like to estimate the maximum number of tv lines it is worth going for in the camera for a dvr capable of 720 x 288 (I realise this can only be an estimate). For instance is it worth going for a 480 tvl camera with such a dvr or will half the info be lost?

Good Evening,

Some bits on resolution to help you make a better choice.

In analogue terms Full PAL resolution is 720x576.

Thats 576 lines and each line is sampled 720 times from left to right.

Each Frame is split into two fields of 288 lines. Which are interlaced odd then even in PAL.

In Digital full PAL resolution is called D1 and is 704x576. Which is actual 576 lines with 704 pixels per line.

Digital video is progressive and not interlaced.

So with a resolution of 720x288 you are recording half height images that are scaled up to 576 by the dvr for viewing.

The DVR converts the analogue signal from the camera to a digital one and then back to an analogue one for display on a CRT TV. This is know as scan conversion.

Quality of the image recorded is based on a number of factors including camera, lighting, postion, encoding method, export or display method.

Hope that helps.

[LeonThePro]

I am looking at bundles from web stores such as

iViewCameras

y3kvision

sct

(Other suggestions welcome!)

Vista.

[Neutech]

APC Concepts....google them

Good company, godd products

[baywatch]

We get a lot of domestic stuff from RF Concepts.

[apr400]

Hi All,

Thanks for the replies. I have taken a look a Henry's, APC Concepts and RF Concepts (although I found the manual for the RF200 DVR was broken, so it's difficult to know if it meets my needs - I will have to contact them) and seen some interesting bits and pieces to consider. I could only find the Vista on Norbain, which is trade only. It looks like a nice bit of kit for my needs although I have no idea if it's in my budget.

I'm afraid I am still a little confused on the resolution issue. LeonThePro, you mention:

"So with a resolution of 720x288 you are recording half height images that are scaled up to 576 by the dvr for viewing."

So which half is discarded? Presumably by even and odd lines rather than top or bottom! But how does the DVR then scale up to 576 - does it interpolate the non recorded lines, or integrate two consecutive frames? In the former case you would presumably get far worse images? (I realise that there are all sorts of other factors to consider as well, but if the dvr is junking half the info you are stuffed before you start)

I am further confused in that some cheaper DVRs list max resolution as 720

[LeonThePro]

Welcome to the digital world. Why did we ever change from VHS to Digital? Certainly not because of best evidence.

I will write a more thorough reply to you when I get chance.

But a quick one the resolution specs.

To confuse things further we have things like this in the specs:

Recording Speed PAL 50fps( Full ),100fps( Dual ),200fps( Quad )

Recording Resolution Full (720x240 / 720x288), Dual(360x240/ 360x288), Quad (360x120 / 360x144)

I get that the recording speed is a function of the overall frame rate divided by the number of cameras, but this seems to imply that the resolution is also affected which makes no sense (afterall 1 camera at 100 fps or 4 cameras at 25 fps is the same amount of data to process so why the need to drop the resolution?) Maybe I am missing the point on that one.

From your post the specs are implying that each frame for dual will contain two different cameras rather than one frame for each view (camera) so half the number of cameras = double the fps but you get half the size for each camera images, and for quad one frame with four cameras in it. If that makes sense.

[Neutech]

Have a look at the APC 4T1 Lite ,it will give you all the features you require and save you a few

[apr400]

Hi

Leon, I see what you mean regarding the full, dual, quad etc. Look forward to your longer reply when you have a chance. Hopefully that machine will also allow me to lower the frame rate and record full res on four cameras, but I will contact APCConcepts directly on that one.

Agree with you regarding VHS, Digital etc. I guess this is a transistional period, and given a bit more time the DAC - ADC - DAC steps will be removed and everything can just be one format or the other! (ie like IP cameras but without the need for the IP element).

Neutech, I have compared the 4T2 and 4T1 and other than the TCPIP (which is useless for me as a Mac user), number of HDDs and PIP function they seem to have much the same capabilities - thanks for the suggestion - a good saving.

Re IR - I note your point on spiders ). However, we only have PIR - no street lighting, and the PIR is not of the best quality - ie there are some creep zones. So I think I do need IR illumination. I had planned to mount the camera directly below windows for ease of cleaning, however, that might put them a little too high for a good view, so I will also look at separating the lighting and the camera.

Presumably if you use separate IR light sources you don't have to worry about spiders so much - they may still colonise the light source but I guess that the web would have to be pretty thick to significantly dim the light, compared to a much thinner accretion on a camera degrading the view. Also with separate lights I can put the cameras low for a good facial view and the lights high for easy cleaning.

I had been looking at these cameras as vandal resistant appeals to me in this area. However, these have IR LEDs. I have found it reasonably hard to find day/night cameras that don't have LEDs. Any suggestions, around the 75 - 100 pounds ex vat w/o cables mark. The cars would be about 3 to 4 metres max from the camera so I guess I would need a 3 - 4 mm lens to cover both. Alternatively, how difficult is it to disable the LEDs typically (or is that equivalent to asking about the length of a piece of string) - I am competent with electronics.

I have also been thinking about an ultrawide angle to get an overview of the whole frontage (ie monitor rather than identify), alongside the dome above (which would just watch the cars). I have been looking at things like this and this.

Both are interior, neither are day/night. Questions - If I mounted this in the soffit board under the eves (ie camera body in the attic but lens poking through to outside), and sealed around the edge of the lens with silicone - would that be sufficiently 'interior'? Anyone know of a budget day/night exterior fisheye?

Again many thanks - I am getting there!

Alex

[Alarm Co]

i use bundles from LJD very good eqipment have a look guys

also voltek day/nights and dvrs aint bad but the picture

quality of ljd is astonishing