CCTV Cameras, Security Cameras, or Video Surveillance, whatever you want to call them, are very important for homeowners, businesses, or anyone who requires monitoring personnel or property. Nowadays, we have compact and independent security cameras that can record locally to a microSD card or connect to Wi-Fi and store data to the cloud. This is fine if you have one or two cameras. What if you want to monitor a large premises (a large house or a retail outlet) that needs many cameras? A reliable camera system with a decent recorder becomes essential.
Speaking of recorders, we have two main options for recording and managing the footage from security cameras. They are DVR and NVR. Security professionals will know the differences between them but things may not be straightforward for regular users. In this NVR vs. DVR comparison guide, we would like to help you understand the basics of DVR and NVR systems. In the process, we will look at how each system works, what are their components, and a list of pros and cons.
Whether you are going the ‘DIY’ route for installing security cameras or want to assign a contract to a professional, learning the differences between the two will help you pick the right set of cameras and recorders.
What Is A DVR?
A Digital Video Recorder or DVR is an electronic device that records or stores digital video usually on a disk drive (HDD or SSD) but sometimes on SD Cards or USB Flash Drives. Before their involvement in the field of home or commercial security systems, DVRs were once popular for recording content off of a TV so that the user can watch a TV show or a sports broadcast at a later time.
Coming to security cameras, a DVR captures videos from several security cameras, stores the videos on a hard disk, and allows for easy playback of the recorded/stored footage.
Before DVRs became popular, we relied on Video Cassette Recorders (VCRs) to store footage on VHS tapes. Both the cameras and the video files were analog. The entire operation was cumbersome and unreliable, to say the least as the job involves manually changing the tapes, while the tapes are prone to data corruption, damage, or accidental erasing.
DVRs eliminated most of these problems. The cameras are still analog but everything else is digital.
Components Of A DVR System
A typical DVR-based security system consists of the following three components.
Analog Security Cameras
Until the early 2000s, all security cameras were analog types known as CCTV Cameras. An analog security camera will capture the image of its sensor (either CCD or CMOS) and transmit the raw video data for displaying it directly on a TV screen or for further processing (such as a DVR). The recorded video is analog and so is the data sent to the DVR.
Since the job of these analog CCTV cameras is to just capture raw data and transmit it to a DVR, they are much less complex and inexpensive. Irrespective of the manufacturer, all CCTV cameras essentially do the same job and transmit the same data. So, you have the flexibility to choose cameras from different manufacturers and pair them with the DVR.
Coaxial Cables
CCTV Cameras transmit raw video data to DVR over a coaxial cable either with a BNC connector or RCA connector. Coaxial cables are data-only cables and do not carry power. So, while installing CCTV Cameras, you have to take care of the separate power supply cable or alternatively use a special cable that includes two cables in the same package (one for video data and the other for power).
Regular CCTV cameras and DVRs do not usually support audio recordings. For that, you need slightly advanced CCTV Cameras and DVRs that support audio recording. However, standard BNC-based coaxial cables do not support/transmit audio data. In systems with audio recording capabilities, there will be an additional cable with an RCA connector that plugs into a dedicated audio-in port of the DVR.
One of the issues with coaxial cables is signal loss with lengthy cables. If the cable is over 300ft, then the image quality starts to degrade. This is for high-quality coaxial cables. Low-quality cables will start to degrade at even shorter lengths.
DVR
The raw video data from CCTV cameras comes to a DVR over the coaxial cables. But how does it store the video data, which is in analog format, on a hard disk drive, which supports only digital data? This is where the actual magic of DVR happens, thanks to a special hardware/circuit known as an Analog to Digital converter or simply an ADC.
As the name suggests, an ADC converts analog video data into digital format. After this conversion, another special circuit known as a Video Encoder will process the digital video data into a suitable video file format that is easily viewable as well as low on storage.
Some DVRs support recording audio as well. As it requires a separate port, the number of audio ports on DVRs is usually much smaller than video ports.
How Does A DVR Work?
The core operation of a DVR involves capturing analog data from the security cameras, converting it into digital, processing the digital data, storing the files, and allowing access for playback.
Receive Video Signal From CCTV Camera
DVRs start their operation by capturing the incoming video signal from security cameras. The signal is usually analog (as most CCTV Cameras are analog) but newer cameras are digital. If the video signal is digital, the DVR can directly process it. However, if the signal is analog, DVR performs data conversion first.
Analog To Digital Conversion
When the DVR receives an analog signal, it must convert it into a digital format. The DVR uses an analog-to-digital converter (ADC) for this task. The ADC samples the analog signal at regular intervals, measuring its amplitude. It then converts these measurements into a series of binary numbers, representing the digital signal. This process is important in the DVR’s operation as it can easily process, store, and retrieve digital data.
Video Encoding And Compression
Once the signal is in the digital form, the DVR applies video encoding and compression. Raw digital video data consumes significant storage space. Therefore, the DVR uses codecs like MPEG-2 or H.264 to encode and compress the video data. The encoding process transforms the digital video into a specific format that the DVR can efficiently store and process. Compression reduces the file size by eliminating redundant data without compromising video quality.
Storing Digital Video
After encoding and compression, the DVR stores the video data on its internal hard drive. DVR can categorize and organize this data so that it can easily retrieve data whenever needed. In case there is more than one camera, the DVR allows for simultaneous recording from multiple cameras.
User Interface, Playback, And Video Decoding
Most DVRs offer a user-friendly interface to access and playback recorded content. We can easily sort videos by their date of creation or title. Some DVRs allow us to search, pause, rewind, or fast-forward through the recordings.
When we select a particular video file for playback, the DVR retrieves the stored data from the hard drive and prepares it for video decoding. During playback, the DVR decodes the compressed video data back into a viewable format. The DVR uses the same codec that encoded the video to perform this decoding process.
What Is An NVR?
A Network Video Recorder or NVR is a computer system that captures or stores footage from a camera on a disk drive (HDD or SSD). How is this different from a DVR? First of all, the cameras that connect to an NVR are not regular CCTV Cameras. They are IP (Internet Protocol) Cameras or Network Cameras, which are completely digital and work over a network.
Instead of transmitting video data over coaxial cables, IP Cameras connect to the NVR either directly or via a network switch through an ethernet cable.
Next, an NVR, if it is a standalone unit, runs on a special embedded operating system. Alternatively, we can configure any computer to act as an NVR as long as it has network connectivity and uses a special software application (Video Management Software) to control and manage the digital video data from IP Cameras.
Components Of An NVR System
IP Camera
The first major component of a typical NVR system is the Digital IP Camera or Network Camera, a camera with an IP Network connection. Unlike regular security cameras that record analog video and transmit it to DVR for additional processing, an IP Camera does all the data processing in the camera unit itself.
It captures video directly in digital format, eliminating the need for an analog-to-digital converter. A processor inside the IP Camera performs some digital signal processing on the digital data so that it is ready to be transmitted over ethernet either for storing or additional processing. The advantage of IP Cameras is the analog data is converted into digital data right in the beginning stage (when the sensor captures the data). All the subsequent operations (storing and processing) of the video files are performed on this digital data. As a result, the footage from IP Cameras will usually be of very high quality.
Ethernet Cable
The second important component in an NVR System is the cable that carries video data from the IP Camera to the NVR. We use standard ethernet cables with RJ-45 connectors for connecting IP Cameras and NVRs.
Some modern IP Cameras support Wi-Fi connectivity. In this case, you don’t need ethernet cables as all you have to do is connect the camera to the Wi-Fi network and transmit data wirelessly.
Regular IP Cameras need a separate power supply. But the trend is PoE (Power over Ethernet). If the IP Camera and the corresponding NVR support PoE technology, then you can use only the ethernet cable to transmit data from the camera to the NVR and supply power to the camera from the NVR, all using a single ethernet cable.
You can use ethernet cables up to 100m without installing additional network switches. As the data transferred over ethernet cables is completely digital, there won’t be any data loss.
NVR
NVRs have multiple ethernet ports to connect many IP Cameras. Since all the data conversion is performed locally in the IP Camera, the job of an NVR becomes very simple. All it has to do is receive the digital data from the IP Camera over ethernet and properly store it on the hard drive. Some NVRs however perform additional digital video compression and encode the video to decrease the file size without impacting quality.
How NVR Works?
NVRs offer a simple, reliable, and efficient way to record, store, and manage video footage from IP cameras.
IP Camera Signal Capture
NVRs begin their operation by capturing video signals from IP cameras. Unlike DVRs, which work with analog cameras, NVRs deal with digital IP cameras. These cameras capture video in digital format directly and don’t need any analog-to-digital conversion. The IP cameras then transmit the video data over a network, typically using Ethernet cables or Wi-Fi connections.
Data Packet Reception
After the IP cameras capture and transmit the video data, the NVR receives it as data packets over the network. The NVR processes these packets, which contain encoded video, audio, and metadata such as timestamps or camera identifiers. The NVR must receive and organize these packets correctly for seamless video recording.
Video Encoding And Compression
Even though IP cameras typically encode and compress video data before transmission, the NVR may reprocess it. The NVR uses specific codecs like H.264 or H.265 to maximize storage efficiency. These codecs compress the video to reduce file sizes without affecting video quality.
Storage
Once the NVR processes and compresses the video data, it stores it on a hard drive, similar to a DVR. However, NVRs can also use network-attached storage (NAS) devices or cloud storage. The NVR also categorizes the data based on time, date, and camera location.
Access And Playback
Similar to DVRs, NVRs offer a simple UI either for local access or remote access (to view live or recorded videos from anywhere in the World with internet access). The NVR may also support multiple output formats so that we can view the video on various devices such as smartphones, tablets, or desktop computers.
NVR vs. DVR: Differences
Despite their similar purpose in video surveillance systems, NVRs and DVRs differ significantly in several aspects.
Type Of Camera
The primary difference between NVRs and DVRs is the type of camera they use. DVR systems use analog cameras that capture video in analog format. DVRs require analog signals to be converted into digital data for recording and playback.
On the other hand, NVR systems work with IP or Network cameras. These cameras capture and transmit video in digital format over a network. Additionally, IP cameras provide superior image quality and advanced features such as motion detection and video analytics.
Cable Type And Length
DVRs, or the cameras to be specific, require separate cables for video transmission and power. They generally use coaxial cables for transmitting video data. These cables are bulkier, harder to install, and limit the distance between the DVR and cameras.
Coaxial cables can transmit video signals up to 300 feet (90 meters) before signal loss becomes a concern. The video quality may degrade beyond this distance. If the setup needs longer cable lengths, you may need to use amplifiers or signal boosters to maintain clarity.
NVRs use Ethernet cables such as CAT5 or CAT6 to connect IP cameras to the network. While older cameras require a separate power supply, modern IP Cameras work with PoE technology that allows both power and data transmission through a single cable. Ethernet cables can transmit data up to 328 feet (100 meters) without any signal loss. We can extend this distance even further with the use of PoE switches or network extenders
Video Processing And Quality
As they use analog cameras, DVRs primarily handle all the video processing. They receive raw analog video signals and convert them to digital format. This can potentially reduce the overall video quality. DVR systems may struggle to maintain high resolution, especially when handling multiple cameras simultaneously.
NVRs on the other hand use digital IP Cameras. All the video data is processed at the camera level, where the IP cameras encode and compress the video before transmitting it to the NVR. This results in better video quality, especially at higher resolutions like 4K. Additionally, NVRs support high-definition videos from multiple cameras
System Flexibility And Scalability
DVR systems require direct connections to each camera. This severely limits the placement of the cameras and the scalability of the system. It is quite difficult to add new cameras to a DVR if free ports aren’t available.
NVRs connect to IP cameras over a network, either directly or through a network switch. This allows you to place cameras virtually anywhere as long as they are within the network’s range. Additionally, you can easily add more cameras to an NVR system without extensive rewiring or additional equipment. Some NVRs also support both wired and wireless cameras to be a part of the same system.
Security And Remote Access
DVR systems primarily focus on local storage and playback. They rarely support network connectivity and remote access. This makes them much safer when it comes to hacking or cyberattacks.
NVRs however operate entirely on the network. If the network has internet connectivity, cybercriminals can get access to the footage using just a browser (or a smartphone app). Hence, we must encrypt video data to protect it from unauthorized access. NVR systems also provide remote access so that authorized users can monitor live feeds or recorded footage from any internet-connected device.
Cost
DVR systems generally have less upfront cost due to their use of analog cameras and coaxial cables. Analog cameras are less expensive than IP cameras, and the older technology lowers the overall system cost. While NVR systems, especially the IP Cameras are often more expensive, they compensate for this with better video quality, easier installation, and advanced features.
NVR vs. DVR: Pros And Cons
DVR
| Pros | Cons |
| Simple setup | Low-quality videos |
| Cheap to implement (both cameras and DVRs) | Signal degradation might occur due to coaxial cable (typically when the cable length is over 300m) |
| Wide camera compatibility | |
| No chance of online leakage |
NVR
| Pros | Cons |
| Very easy to install (provided there is existing networking infrastructure) | Expensive than CCTV and DVR setup |
| High-quality footage with support for high-resolution cameras | Interoperability is less |
| Some models support PoE (one ethernet cable for data and power) | Cybersecurity risk |
| Supports several features (two-way audio, motion detection, etc.) | |
| Both wired (ethernet) and wireless (Wi-Fi) cameras can exist in the same network | |
| Local as well as remote access |
Which Is Better, NVR Or DVR?
If you consider the overall big picture, both the NVR and DVR basically record footage from security cameras on hard disk drives. The differences however lie in what kind of cameras they use, how they process data, and the cost of the system.
On paper, an NVR system with a bunch of high-resolution IP Cameras looks like the best choice. It is true that IP Cameras have much better image/video quality than old analog cameras. However, analog cameras are catching up in this regard where you can get decent models that can record in Full HD resolution (1080P) for under $30 (can be much cheaper if you buy a complete set).
For small properties that require fewer cameras (up to 8) and can work with coaxial cables of under 300ft, the DVR system looks like a decent choice. The overall cost of the system will be very low and with modern DVRs, you can add a couple of IP Cameras and even enable remote access.
That said, NVR systems with IP Cameras are very easy to install, expand, and access remotely, and the quality of the footage is next level. They can be slightly expensive though. The wiring becomes simple with PoE functionality and you can add very high-resolution cameras to the network. Speaking of which, you don’t have to directly connect these cameras to the NVR as long as they are connected to the same network (through a switch). This gives a decent flexibility in terms of distance between the camera and the NVR.
