There is a large selection of Digital Video Recorders on our website alone, we understand trying to buy the right one is not simple, and differs for each situation. So we have put together some information about the features available so that you can try to make a better decision. Simply look through the features listed below, and try to see what is important for you, keeping in mind the purpose of your CCTV system.
Some common features are covered below, for those with no knowledge about a CCTV set up - The Digital Video Recorder is the "brain" of a CCTV system, it takes the images from the cameras and stores them on to a hard disk drive. You can then look at the images recorded on the hard drive, and review what the cameras have been viewing by connecting a monitor (or other form of display unit) to the DVR. You can forward & rewind through the images in much the same way you may have done so with a typical Video recorder. On many you can search for specific dates & times to quickly find the footage you want to view.
Once you have your images recorded on the hard drive, from time to time there may be an incident which you will be required to give to the police as evidence, you will then need to back up the data they require from the hard drive on to another storage device.
Importantly, and this goes for all DVRs if you are fitting your own hard drive, always use a purpose built hdd. By this we mean a pc hard drive is not designed to be constantly in use twenty four hours a day - seven days a week. But the large hard drive manufacturers also provide hard drives that have been purpose built with for CCTV industry and 24/7 use.
CCTV recorders - aka Digital Video Recorders or DVR for short, are reffered to by their channels (e.g a 4 channel DVR). The number of channels is the maximum number of cameras that can be connected to the recorder, so for example you could connect a maximum of 4 cameras to a 4 channel DVR.
Digital Video Recorders come in several sizes, most commonly :
4 Channels (1 to 4 cameras)
8 Channels (1 to 8 cameras)
16 Channels (1 to 16 cameras)
32 Channels (1 to 32 cameras)
When deciding what you require, have a good look around your premises and decide how many cameras you are going to need, you should take your time with this and make sure you have all the angles covered. Failure to do so will leave 'blind spots'.
Buying a CCTV recorder with more channels than you actually require, isnt a bad thing, as many people find they want to add cameras in the future that they didnt initially think about.
The very latest SD recorders have a resolution called 960H - but currently more common are D1 resolution recorders.
960H
D1
HD-SDI Recorders can recorder either:
1080P
720P
IP Recorders are available in many different resolutions, from D1 upto 20 Megapixel and above. Here at JMC we try to limit the range with:
5.0 Megapixel
3.0 Megapixel
1080P HD
2.0 Megapixel
1.3 Megapixel
720P HD
The frame rate at which a DVR records is measured in frames per second (fps) (sometimes referred to as Images per second (ips)), 25fps per channel is considered 'real-time', this means a 4 channel system would need to record at 100fps to record real-time on all 4 channels.
Frame rate options often varies depending on what resolution you choose on the dvr, it is important to check the specifications of a DVR before you purchase it, to make sure it will record a suitable frame rate in the resolution you want.
Although 25fps (per channel) is real-time, and of course that is the best possible frame rate, it's not always required - and keep in mind, the more images being recorded per second, means the hard drive within the DVR is having to store more information every second. So it will reach capacity quicker and start to overwrite.
We usually advise a minimum frame rate of 6fps per channel - in the highest resolution possible. If you imagine it takes someone 5 seconds to walk towards your camera, at 6fps you will still have 30 images of that person.
However for some situations real-time recording is required - trying to capture fast moving objects like registration plates on moving cars for example. Also some bars / pubs are required to record real-time, so if you are looking at CCTV for your pub please be sure to check with your local police dept about what frame rates they require.
Almost every Digital Video Recorder on the market comes with motion detection built in nowadays, this can be a very important feature that can considerably extend the recording capacity of your Digital Video Recorder.
It works on a fairly simple principle, the cameras that are connected to the digital video recorder are constantly sending images to the dvr. The dvr reads these images as thousands of pixels, and it simply waits for the sequence of pixels to be different from the previous image. Once it notices a change in pixels, it begins to record.
Some DVRs have different levels of motion "sensitivity" levels, this simply works by changing the number of pixels that need to be different from the previous image. For example, a digital video recorder on motion sensitivity level 1 may require 100 pixels to be different, but on level 5 it may require 1000 pixels to change.
The higher end Digital Video Recorders also allow 'Masking' which is a handy feature within motion detection, basically it allows you to mask certain areas of the screen where you do not want motion to be detected. Useful to mask objects like trees that may move in the wind and cause recording for no reason.
There are many variables that will adjust the recording times of any DVR, this is why any 'recording time tables' on this website, or anywhere else for that matter, are only an approximate guide.
Some of these variables are listed here:
Hard Drive Size
Frame rate
Motion detection settings
Actual scene (image recorded)
Recording times can vary dependent on settings chosen by you. For example you may set a dvr to record only when there is motion detected, which obviously we could not estimate what kind of recording time you would get if you activate this feature.
But to give you an idea see below recording times guide for 24/7 recording.
| Cameras Connected | D1 (4CIF) resolution / 6fps | 2CIF resolution / 6fps | CIF resolution / 6fps |
|---|---|---|---|
| 2 cameras | 41 | 82 | 164 |
| 4 cameras | 20 | 41 | 82 |
| 8 cameras | 10 | 20 | 41 |
| 16 cameras | 5 | 10 | 20 |
The above is based on a 500Gb HDD, other hard drives will record for different periods of time for example a 1000Gb would record for double the above times and a 250Gb would record for half the above times.
Likewise, if you were to double the frame rate to 12fps, then you would half the recording time.
Recording times are only a guide and will vary dependent on the actually scene being recorded.
| Cameras Connected | 720P HD resolution | 1.3MegaPixel resolution | 1080P HD resolution | ||||
|---|---|---|---|---|---|---|---|
| Frame rate (per channel) |
6fps | 25fps | 6fps | 25fps | 6fps | 25fps | |
| 2 cameras | 20 | 5 | 15 | 3.75 | 9 | 2 | |
| 4 cameras | 10 | 2.5 | 7.5 | 2 | 5 | 1 | |
| 8 cameras | 5 | 1.25 | 3.75 | 1 | 2 | 0.5 | |
| 16 cameras | 2.5 | 0.5 | 2 | 0.5 | 1 | 0.25 | |
The above is based on a 1000Gb HDD, other hard drives will record for different periods of time for example a 2000Gb would record for double the above times and a 500Gb would record for half the above times.
Recording times are only a guide and will vary dependent on the actually scene being recorded.
All CCTV Recorders store information on a hard drive, something you should consider when choosing your DVR is how you will back-up this data if there is ever an incident that you may be required to provide evidence of to the police.
Even the low cost DVRs will have USB back up - this is when you will need to connect a USB Penstick to your CCTV recorder and copy the required evidence from the HDD to the penstick. This is probably the most efficient way of going about it, although some DVRs will also offer back up by DVD-RW (sometimes built in, sometimes USB DVD-RW's can be connected) or even "Network back up", which means you can log into the DVR remotely and copy the evidence to your PC.
Last but by no means least, when choosing your Digital Video Recorder, bare in mind if you want the option of viewing it over the internet from another location. If you do make sure you choose a Digital Video Recorder with Networking (often referred to as remote viewing) capabilities.
Networking a DVR can be quite complicated, but the basics are you connect the recorder to your router and configure the DVR with an IP address on your network etc. Once done that would mean the dvr could be viewed on your local network. To then get it working remotely you need to port forward your router (port numbers would be in the DVRs menu). How you port forward is different for every router model, we of course offer help with this over the phone, but for some useful information about port forwarding see www.portforward.com.
Once the DVR is networked correctly you can also download the manufacturers apps for most modern smart phones and view the DVR from you mobile phone.
