Complete Guide to Surveillance Systems (Part Two): DVR/NVR


Welcome to the second part of the "Complete Guide to Surveillance Systems". In this part we will talk about and even expand in details both "Digital Video Recorder" and "Network Video Recorders" devices or simply DVR/NVR devices. If you didn't read the first part of this guide in which we talked about security cameras types and features you may find it here. At the end of our current -second- part we will make a quick tour through Top Manufacturers and producers for surveillance cameras and DVR/NVR devices, in order to make our guide a complete reference in this field for newbies and complete tutorial seekers.


1- Video recording device types.

2- PC based DVRs.

3- Basic DVR/NVR specifications.

4- Advanced video analytics in DVR/NVR devices and servers.

5- Quick tour through top vendors.

6- At the end “There is always more”!.


1- Video recording device types

Surveillance systems video recorders can be divided into three main types with respect to which signal type it can accept as follows:

1st Digital Video Recorders or DVRs

DVR device

DVRs are most dominant in small and medium size installations. It replaced VHS tapes used by the older analog recorders with hard disks and digital storage media.


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DVR devices can be connected to both traditional and HD analog cameras through coaxial cables. DVRs receive these analog signals and convert them into a digital compressed form that can be stored efficiently on hard disks.

2nd Network Video Recorders or NVRs

NVR device

NVRs are merely DVRs designed to deal with modern IP cameras instead of analog cameras, NVRs can be connected directly to IP cameras through Cat5 or Cat6 cables to record video. Some NVR types can supply IP cameras with power through its PoE (Power over Ethernet) features ports, and some others may provide only one ethernet port that can be connected to network switch or wireless access point devices who will take care of concentrating all data streams coming from camera endpoints into one cable to NVR. NVRs can also send PTZ movement order messages through network cable, if it’s compatible with Onvif protocol mentioned earlier.

In very advanced applications, huge and fully featured servers are used as NVRs, NVR servers usually have an enormous amount of storage and processing power, and can be connected to hundreds of cameras and surveillance networks that may span a complete city.


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NVR servers usually offers very advanced video analytics and information extraction features using A.I (artificial intelligence) technologies and image/video processing.

3rd Hybrid, Tribrid and Pentabrid DVRs

At first NVRs and DVRs were manufactured and marketed as separate devices, however as IP cameras started to get momentum -although at higher price-, manufacturers started to make hybrid digital recorders that combine the best of best of both worlds. Hybrid DVRs can be connected to both analog and IP cameras at the same time, so end users can benefit from lower analog cameras prices and the high image quality of IP cameras. 

When HD analog cameras technologies appeared, camera manufacturers started to combine latest HD technologies one by one, and we started to hear about Tribids DVRs and even Pentabrids DVRs that can support major camera technologies like (CVBS, TVI, CVI, AHD and IP). At the meantime Hybrid DVRs are market defacto, so if you hear the word DVR it usually means one of the hybrid types.

2- PC based DVRs 

PCs can be converted to a fully featured DVR/NVR device using one of the many software packages dedicated to this purpose like ZoneMinder or ispy (read don't trash your old PC article on dealna), PCs can be connected directly to IP cameras, but in case you want to connect analog cameras you will need to add new hardware which can be a CVBS to USB converter -commercially known as Easycap-, or a PCI DVR expansions card, however these last two doesn't support HD cameras except very few exceptions like this one, so if you want HD you probably will have to use IP cameras with your PC based DVR/NVR.


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 Various connections can be used in PC based DVR( easycap on the right, PCI card on the left)


3- Basic DVR/NVR specifications 

 An inside look of a DVR (harddisk on the right, motherboard in the middle, power supply on the left)

Basic specifications for DVR/NVR devices include:

1- Camera ports: which includes total number of cameras that can be connected and their types (CVBS, TVI, CVI, AHD, IP).

2- Harddisk capacity: usually DVR/NVR comes empty of harddisk, which should be added by end user. How much video time can be recorded by the device is determined mainly by the capacity of the hard disk in addition to other factors like “video compression algorithm” used and the total number of connected cameras.


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3- Video compression algorithms: if the “uncompressed video signal” sent by analog cameras is stored in its original form on the DVR, it would consume a huge space. DVRs handle this problem by utilizing video compression algorithms to reduce storage amount occupied by video record. Video compression is also used by DVRs -and even IP cameras- to reduce bandwidth required to send the video over the network.

Many compression algorithms are available like Mjpeg, H.264(AVC encoding). The latest and greatest - at the time of this writing- is called H.265( HVEC encoding) which enables upto 50% saving in disk storage and network bandwidth when compared with its predecessor H.264 encoding. When you buy a new DVR, you must get sure that -at least- it supports one of these latest compression algorithms(i.e H.264 or H.265) or even both of them.

4- Advanced video analytics in DVR/NVR devices and servers

A few years ago, NVRs/DVRs were solely used for storing and retrieving surveillance video captures by security cameras, however in the last decade this started to change. Modern DVRs/NVRs started to add what is so called “ advanced video analytics” which are used to -systematically and automatically- extract and describe information contained in surveillance footage even without any huVarious connections can be used in PC based DVRman operator intervention!, in the last five years these technologies reached a fascinating level of perfection and accuracy after the utilization of deep learning A.I and cloud computing technologies.

In the next few lines i will try to give you a small glimpse of what these “advanced video analytics” can do, so you get informed about the possible and innovative applications of these technologies.


4.1 Motion detection features

Available in most modern DVRs, by which you can be notified if something moved in front one of your cameras or even in a specific spot in the captured video frame. Modern DVRs can notify you using e-mail, sms or it can even activate audible alarm.

An illustration for Motion detection setup


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4.2 Auto tracking feature

Usually found in DVRs/NVRs supporting PTZ cameras. This feature enables the DVR to instruct PTZ camera to follow certain objects that violated/entered a predetermined zone. after tracking is finished DVR instructs the camera to return to its initial position. The next video shows a demo for this feature from the Chinese Hikvision company.


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4.3 Object recognition and search

Equipped with this feature, DVR/NVR or a cloud service starts to analyze all captured video and continuously identifies any object that appears in front of the camera ( car, man, animal, truck .. etc) and tags that specific moment when that object appeared in a unified database that can be used later to search for specific moments where such (ex: green BMW car) appeared !. If you find this hard to believe you can visit one company website icrealtech which allows you for -demo purpose- to connect your home cameras to one of its cloud solutions and try it yourself. You can even search some live streaming cameras installed in liverpool!. Visit their demo page from here.


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4.4 Loitering detection

Modern surveillance systems can detect loitering actions (ex. walking around house windows, missing with a car doors .. etc) using special A.I algorithms. you can see this in action in the following video from the german Bosch Security company.

4.5 luggage/idle object detection

Also using A.I backed image processing, modern DVRs -and even some IP cameras- can be trained to recognize permanent static background of the scene, then detect any emergent, non-human shape, idle objects like luggage, bags ..etc.

This feature can even detect -within few seconds- what a human eye may miss and even generate an immediate alarm to grasp operators attention to what can be a threat to the public safety.

check the next two demo video from “IPS analytics” to see this feature in action.

Another application for this feature is the detection of cars and vehicles violating no parking zones 

see this application in action in the next video from Bosch security.


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4.6 Face detection and recognition

Although this A.I based technology is not fully matured, some vendors reached about 88% of accuracy in face recognition and identification, some governments already applied this technology in the public safety domain to aid security officials searching for suspects. see the next video for a brief illustration of this feature on one of Hikvision NVRs.

4.7 Business analysis features

Security cameras vendors aim to make their systems a one stop point for not only for security services but also for business intelligence and analytics. Features like Traffic/Heatmaps, people counting, Queueing detection, car plate recognition and even more features that can help store/retail owners tune their business flow and store layout to maximize profit and losses as much as possible.

For example you can make a setting in your DVR/NVR systems to generate a chart of how many people get in or get out of your store against daytime or weekdays to help you identify peak times and properly organize workers shift time or shift transition.

Another example is that you can config your DVR/NVR to generate what so called Traffic/Heatmaps which allows you to how your customers tend to flow around you store and at which shelve they tend to spend their most shopping time.

Book store Heat map


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5- Quick tour through top vendors

In this section of our article we depended on the annual “Security 50 Rankings” report from a&s mag -published in 4Q 2018- for the best performing companies in the field of security and surveillance systems. The a&s mag report depends on both Annual Revenue and Revenue Growth to judge company performance. The report also offers a partial evaluation for companies performance in each field of the security systems domain, which we exploited -at to identify the top five security cameras vendors in the worldwide market. 


1st Hikvision digital technologies


Hikvision is a Chinese company that is considered the no.1 security cameras producer in the whole world, with a total annual revenue of 5.3 billion dollars in 2017. 

Hikvision specializes mainly in manufacturing security cameras and DVRs/NVRs with all types, however the company also manufactures drones that can be equipped with visible or thermal cameras. Also the company has camera solutions for machine vision and quality control applications.


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2nd Dahua technology

Dahua Technology

The Chinese Dahua occupies the second place world wide, from the perspective of total annual revenue that was estimated to be about 2.6 billion dollars, the company spends 10% of this late figure on its R&D department which contains about 50% of its total employment. And as a result of this interest in R&D activities, technologies like HDCVI -used for HD analog video transmission- came to light from the company laboratories.

Dahua -like Hikvision- specializes mainly in manufacturing surveillance cameras systems, however it’s also trying to explore new fields like IoT, machine vision, video conference, drones and others.


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3rd Bosch security systems

Bosch security

Bosch came as the third worldwide manufacturer for surveillance systems with a total annual revenues of above 2 billion dollars in 2017. The company manufactures smart and A.I based surveillance systems that enjoys -in our opinion- an exceptional level of flexibility that is even superior to the market Chinese giants. Bosch A.I based solutions can be automated via (VCA task script) which opens a new horizons for applications  that has no limit except end user imagination, in contrary of ready made A.I templates -mentioned some of it- promoted by others.

Facial detection and recognition solutions are offered through a partnership between Bosch and ISS which provides solutions like SecureOS™.

Bosch also provides Building management systems (BMS) solutions (i.e fire detection, Public address systems ..etc) for efficient management of airports, hotels, mosques and others with a high level of integration between all of its solutions.


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4th Axis communication

Axis communications

Axis communication is a Swedish company, and it occupies the 4th position with a total annual revenue of 976.2 million dollars in 2017 which is 16% higher than 2016.

Axis has a broad range of network cameras and DVR/NVR products, in addition to some video management system and A.I video content analysis solutions. The company also provides sound systems, smart access control systems, video encoders and many light current networks accessories in general.


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5th FLIR systems

FLIR systems

FLIR systems comes in the fifth position with an annual revenue of 777.2 million dollars. FLIR is well known for its Thermal cameras solutions (hint: type thermal cameras on google and see the first result), and it's also known for its professional surveillance cameras solutions for defense and governmental applications or thermal imaging for industrial applications. however the company has many camera products targeted at home or even personal level.


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6th Other companies

Many surveillance systems manufacturers and producers have a significant footprint in the market and are considered successful with high a&s rankings, but sadly we cannot detail them all at here, so we will leave you a concise -revenue ordered- list with their names and websites, so you follow them up and know their new products and services.

1-  Hanwha Techwin (Korea).

2- TIANDY TECHNOLOGIES (China) and it's well known with it's starlight product line (see this video).

3- INFINOVA (China).

4- VIVOTEK (Taiwan).

5- CP PLUS (India).


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6- At the end “There is always more”!

Surveillance cameras systems is a huge topic and has lots of detail that may have't been mentioned in our concise simplified articles. So we advice our dear readers to stay informed about the topic through continuous reading and following manufacturer's websites to know new products and industry trends.

And remember that you can always use our website to get prices and features comparisons for security cameras and DVR/NVR systems from buyers all around the world.