Understanding the differences between a DVR and an NVR

Now , We need to start somewhere and if you've gotten thus far,  you know by now that picking out the equipment for your CCTV (Closed Circuit Television) system isn't as simple as you may have originally thought.  Don’t worry though;  we’re going to make this fun again.  We just need to cover some more of the basics and you’ll be back in business in no time.

Like the names of all these devices imply, they are all meant to record video from security cameras.  The main difference between them is what types of cameras they’re meant to play nicely with.

DVR, NVR, and Hybrid Comparison

Digital Video Recorder (DVR)

The DVR is intended to work with standard analog security cameras, HD-SDI cameras and HD-CVI cameras.  This doesn't mean that every DVR works with all of these cameras.  Unlike the other video recorder options, there are actually three sub-categories of digital video recorders.  These categories simply line up with the previously mentioned types of security cameras. For example: Standard analog cameras are intended to be paired with standard analog DVRs just as HD-SDI, HD-AVI and HD-CVI cameras are intended to be paired with their corresponding DVRs.

Hardware features of DVRs vary between manufacturers and may include but are not necessarily limited to:

  • Designed for rack mounting or desktop configurations.
  • Front panel switches and indicators that allow the various features of the machine to be controlled.
  • Connections to external control devices such as a mouse, keyboards, POS device, or PTZ controller.
  • Controlled outputs to external video display monitors.
  • Data ports for network connections consistent with the network type and utilized to control features of the recorder and to send and/or receive video signals.
  • Internal optical drives or HDD typically for archiving video.
  • Connections to external storage media.
  • Alarm event inputs from external security detection devices, usually one per video input.
  • Alarm event outputs from internal detection features such as motion detection or loss of video.
  • Single or multiple video inputs with connector types consistent with the analogue or digital video provided such as coaxial cable, twisted pair or optical fiber cable. The most common number of inputs are 4, 8, 16 and 32. Looping video outputs for each input which duplicates the corresponding input video signal. These output signals are used by other video equipment such as matrix switchers, multiplexers, and/or an individual video monitor.

Network Video Recorder (NVR)

The NVR is paired with IP/network security cameras.  There are two different types of NVR's, but don’t worry, they’re both still used with IP cameras.  The first type, and much more common, requires that you connect your IP cameras to your router or a switch.  This will mean using the search function on the NVR to “ping” the cameras and then add them to the NVRs device list to begin viewing.  While this is not a very complicated step, it may be one you don’t feel like taking.

 The second Type is to go with an NVR that has built in network or PoE (power over Ethernet) ports.  This will allow you to connect your IP cameras directly to the back of your NVR just as you would with a DVR.  This will remove the step of having to add them manually to a device list, and it will remove all worries of ensuring that they are connected to your network properly.

Hybrid Video Recorder (HVR)

The Hybrid recorder is quickly growing in popularity because of it’s versatility.  Hybrid video recorders (HVR) are compatible with both standard analog cameras and IP/network cameras.  The HVR's can be a little misleading at first.  An 4, 8 or 16 channel Hybrid aren't really 4, 8 or 16 channel video recorders.  You’ll want to double check, but most sellers of these recorders advertise them in the same way.  The channel quantity that’s listed is almost always the channel quantity for each type of camera the recorder is compatible with.  What we mean is that an 8 channel HVR is actually 16 (8 analog and 8 IP). In other words, you’re getting twice as many channels as is being advertised in most cases.

Now it’s not just the fact that you get a lot for what you pay for that makes the HVR's so attractive to consumers.  If you’re only in the market for an 8 channel DVR, it still makes sense to purchase an 8 channel HVR even though there’s really 16 channels.  You can connect perfectly acceptable analog cameras to the HVR with Cat5e/Cat6 and baluns initially and years down the road when you’re looking to upgrade your system, it’ll only be a matter of replacing the cameras instead of a DVR and all of your cable.  Depending on the size of your system, this can save you thousands of dollars on the upgrade.

Take a deep breath…

We’re about to cover a lot of features of these devices.  This isn't to confuse you, we just want to make sure that you get everything that you’re entitled to out of a recording device.  There’s lot’s of brands with a lot of difference features out there so we’re just going to go over what has become industry and market standard.  Make sure that your video recorder has these things before you make any commitment:

Recording

I’m sorry if this is obvious by now, but these devices are all intended to record video from your security cameras.  The way this works is with an internal hard disc drive (HDD).  The amount of time that you need or want to have backed up will dictate the size and/or quantity of the hard drive(s).  The way the recording works on these units is usually people’s biggest fear at first.  When the hard drive has reached it’s capacity and is full of recorded video, it will begin to over-write.  This just means that it’ll start back at the beginning and record over whatever is there.  This also means that you won’t have to format video or remove video manually if you don’t actually need it. Depending on the size of  your hard drive, on average, a one tera-bite HDD is giving you two weeks of recording and if nothing happens in that time where you need to back up video, you can just let things run their course.

Video Back Up

Your video recorder is recording the security camera footage to an internal hard drive.  If you have to turn over a portion of that footage for any reason, you’ll obviously not want to have to remove the hard drive in order to do so.  You’ll usually have several options.  With most video recorders having USB ports now, you should have no problem connecting a flash/thumb drive, external hard drive, or external DVD burner to them. 

 From here, you’ll be able to back up video from the video recorder to one of these external devices.  Another option, and normally more convenient for people, is to back up the video from a computer on the same network.  By logging into your video recorder from a computer within the network, you’ll be able to download video on that computer from your video recorder through the network.  More often than not, DVRs, NVRs, and HVR are positioned in limited or no access locations.  Being able to download that recorded footage from a separate locations is a huge advantage.

Local Access

What we’re talking about here is what your options are for accessing your video recorder within the same network; your network being everything within the same router or switch As long as you are connected to the same sub net mask, if you Gate way is 10.0.0.*** your recorders IP address needs to be 10.0.0.***and computer needs to be 10.0.0.***, whether it be hardwired or wireless, you should be able to use any desktop computer, laptop computer, iPad, Android tablet, iPhone, or Android smartphone.  Desktop and laptop computer have two options.  They can either login through the internet browser using the recorders IP address, or they can access the recorder by using software after adding the recorder to the device list.  On tablets or smartphones, you’ll just need to use the appropriate application.  After installer the application, you’ll add your recorder to the device list just as you would with the computer based software. The most common mistake our clients make, having there recorders IP address not set within the same sub-net mask.

Remote Access

Your options for remote access work the same way they do with local access.  The biggest difference here is the extra setup needed for this feature to work.  Port forwarding is what we’re talking about here.  We will go in depeth about port forwarding in  a future artical, so we’re not going to go into that any further.  Once the port forwarding process is completed, you’ll access your recorder via your network IP address now instead of the recorder IP address.  When you access your network, you’ll be accessing it through the port that you opened during port forwarding and you’ll automatically be redirected to you video recorder.

Frame Rate

You’re going to want to pay special attention to this.  Companies have a lot of different ways of reference the frame rate and, sometimes, they’ll leave you needing to do a little math.  You’re specifically trying to find out what the maximum frame rate is for each channel and at what resolution.  If you want real-time recording (30 frames per second), you want to make sure that the video recorder is capable of that on all channels simultaneously and that it’s at a resolution appropriate for your cameras.  There’s not a lot of point in having high resolution cameras if the video recorder isn't capable of recording at the resolution at the frame rate that you’d like.

Resolution

Do your homework and plan accordingly.  As we just said, make sure that your video recorder is capable of recording at the appropriate resolution for the cameras you purchase.   Not only that, but make sure you can record at the frame rate you also want at that same resolution. There’s really nothing else to say here other than shop carefully.

Storage Capacity

The amount of storage you need is ultimately dictated by how many days you need to have backed up.  The other things that contribute to this are the recording resolution, the frame rate, the bit-rate that you’ll be recording at, and your personal recording schedule and how often the cameras are set to be recording for.  No one expects you to know exactly what size hard drive you’ll need.  If you can’t find a calculator somewhere out on the internet, just ask the company you’re looking to purchase from.  The most accurate answer you’re going to receive here is usually based on worst case scenario.  Since many people aren’t familiar with bit-rates , or frame rates, or what their recording schedule is going to look like, it only makes sense to assume the worst and go with the largest amount of storage that you could potentially see yourself needing.

HDD Storage Calculator and Recording Schedule

Input & Output Options

Digital Video Recorder (DVR):

Obviously you’ll be needing the correct number of video in channels for your number of cameras.  For those of you with microphones, just like video inputs, ensure that there are enough audio inputs.  Look for multiple USB ports.  Every video recorder should have at least two; if you don't, you might find video backup to be a big headache.  Your options for video outputs are also important.  Most DVRs will have RCA, VGA, BNC, and HDMI video output abilities.  If you’re going to attach a monitor or television to your video recorder, make sure that the video recorder has a compatible video output option for you.  Depending on whether or not you have microphones, keep your eye out for audio out capabilities as well in addition to the HDMI port.  Last but not least, make sure that there is a network/Ethernet port on the video recorder.  Without that, you’ll have no ability to do anything unless it’s done physically through the video recorder using the mouse and on screen display.

Network Video Recorder (NVR):

Pay attention to all the same things here as you would with the DVR with the exception of the video and audio inputs.  We discussed the possibility earlier of having Cat5 and PoE ports or none at all.  In general, just make sure the NVR has the right number of channels for your number of cameras.  If your IP cameras have built in microphones, it’ll use the same Cat5 cable that’s connecting it with the appropriate hardware.

Hybrid Video Recorder (HVR):

We just covered digital video recorders and network video recorders.  Slam those two lists together and you’ll have everything you’ll need for HVRs.  Since hybrids are compatible with both analog and IP cameras, you'll need to act as if it's both a DVR and NVR