Few newbie questions about CCTV

[JohnSmtihh2 0]

Hi i just got into CCTV recently, i bought analogue 800TVL cameras and D1 DVR however not happy with resolution and video quality being kind of low end.

 

Here's the questions i have so far.

 

1. I got DVR that records D1 using H264 compression, i set video compression settings to maximum that it allowed, however Image detail is significantly lower when i playback recording versus live view.

 

I also notice lags when i play back more than 2 cameras at the same time and say jump to 5 minutes ahead it takes few seconds for DVR to load every camera footage and if i speed up to 4x 8x 16x it works very slow.

 

I guess compression limitation and playback lag is because DVR has slow CPU and low Memory however i am sure hard drive has to do with that too as it has to seek 4 different spots on hard drive for 4 camera footage.

I was thinking about installing 256 GB solid state hard drive. You think it will improve the performance speed of DVR?

 

3. My current camera resolution is 1020x508 and recording is done to 720x480 (D1), question if i buy camera that is 1296x1041 even though it records to D1 it still uses all pixels of camera to record just scaling it to 720x480 afterwards so i probably will have better face recognition?

[PsychoMantis 0]

Dear John,

The camera pixel count you are referring to is not it's "effective pixel" count. It is rather sensor pixel count, it has now become a trend to use megapixel sensors in analog cameras, which helps attain better details but doesn't affect the recording resolution. The maximum resolution you can actually record using an analog recorder is 960H or sometimes called WD1 960x480 for NTSC. You'll need a 960H recorder for that.

At the end you can only record the resolution your DVR is capabe of.

[JohnSmtihh2 0]

Thanks for replay PsychoMantis.

 

Dear John,The camera pixel count you are referring to is not it's "effective pixel" count. It is rather sensor pixel count, it has now become a trend to use megapixel sensors in analog cameras

I agree that camera's megapixel count is sensor spec, not actual pixels you will get. Say for camera "1.3 Megapixel camera" resolution is 1280x960 and if we multiply it we get ~1.22Megapxel. However i dont think they give false pixel count for NTSC resolution spec, i will try to connect camera to my PC and see if i get same amount of pixels in PC capture software.

 

 

I thought this over and here's my presentation click image to zoom,

 

Are following statements correct?

 

Note 1: Blue camera is square therefore image looks stretched on resolution 920x480. I dont see much difference in facial recognition by just having 20% more horizontal pixels even if you later convert video stretching vertical pixels to get correct aspect ratio, quality would be almost same as to D1. Plus you have to convert video say if you give it to someone.

 

Note 2: Red camera is rectangular so it looks good at 920x480 resolution and ugly at 720x480 plus we lose 20% of horizontal resolution, to keep little more detail and avoid need to resize video later its best to stay at 920x480.

 

Note 3: Green image is pixelated because we adjusted lens angle to match camera with more pixels, but we have significantly less pixels to cover this area.

 

Conclusion high resolution analogue cameras are better in rectangular aspect ratio to take advantage of higher resolution (920x480) resolution and its good to have DVR that supports 920x480 as typically on such DVR you can chose to record 920x480 or 720x480.

 

 

Now i see what my problem is, i have varifocal 2.8-12mm camera with resolution 1020x508 at maximum angle (2.8mm) and is in Note 3 i have not enough pixels for this large area and that's why facial details are low.

[SunnyKim 2]

JohnSmtihh2,

It is a good guess. But let me add.

RGB is related to camera sensors. The unit is the pixel number. One pixel needs R-G-B, 3 components. That is the side of sensor. But the signal you get from analog camera is the TV signal (NTSC or PAL). So your resolution shall be limited to 480 Lines X 960H X 30 Hz Frame Rate or 588 Lines X 960H X 25 HZ Frame Rate. If they claim 1280X 960 per camera, it should be their displaying size with scaled up.

You are correct in that their CPU lacks power to carry out full channel X full frame recording and full channel X full frame decoding and playback at the same time. The DVR seems overstated. So you better buy a new one with a good brand name.

 

TV signal has 4:3 aspect ratio. But 960H is almost 16:9 aspect ratio. But even Sony's 960H sensor did not bring 16:9 ratio. That's why you see the video horizontally expanded. But it is true that 960H carries more resolution. Hoping cleared.

[JohnSmtihh2 0]

I dont want to deal with analog cameras anymore unless i have to, as they limited a lot in resolution analog will never go pas ~1 megapixel.

At same time 2-3MP IP cameras now are very inexpensive plus on Sony website they already have 5 and 12 MP CMOS sensors, i believe analog is thing of the past or of tight budget.

 

And for IP i belive its possible to use Laptop / PC with certain software instead of NVR then you can pack any hardware you want into your computer.

NVR's are very similar to DVR's in sense that they have limited hardware specs just enough to make recording at 1080p/720p resolution, but not a bit more.