First there were VCR’s and then Digital Video Recorders (DVRs) were introduced with improved storage reliability and duration.  Now there are many more ways to store the video from your surveillance cameras. The new Network Attached Digital Video Recorders (NVR) attach to the network and work with network attached cameras so you can view the stored video on your PC. The latest storage systems are intelligent and distributed on the network. They store video from network attached cameras, and allow users to view, control, store and retrieve video from your PC from anywhere on the Internet.  This article reviews the pros and cons of all these systems so you can select the right one for your application.
 
Video Recorder
Video recorders are modified VideoCassette Recorders (VCR) that use videotape to store video. Duration of storage is usually only one or two days, depending on resolution and frame rate.  These systems are simple to use and are very inexpensive, ranging in price from $500 to $2,000. Only the video from a single camera can be stored on the VCR.  Tapes can be stored for a number of years, but they must be changed almost every day. 
 
The downside is it’s difficult to find a specific videotape and specific time period, especially if it’s on a tape stored away in a cabinet. Tape is not too reliable, so even if you find the right tape you may find the video has deteriorated.
 
Digital Video Recorder
The Digital Video Recorder (DVR) converts analog video to digital data and stores the data on computer type hard drives.  They have analog video inputs for 8 to 16 cameras.  These systems provide far more storage than tape, are more reliable and provide almost instant access to the stored video. 
 
Since the video is stored in a form that’s more compatible with computers, the video can be processed and distributed easily.  DVR systems incorporate better video compression, and provide motion detection and alarms.  Data can be sent over the network and viewed on a PC or it can be stored on other computer storage devices such as CD or DVD-Recordable discs. The Axis 2460 is an example of a DVR that attaches to the network.
 
The upside is the ability to attach a variety of analog cameras into the network. The DVR system has a fixed amount of storage and is usually not expandable.  An exception is the Mitsubishi DVR system that allows external hard drives to be added to its' SCSI interface.
 
DVR’s cost from $1,500 to over $2,500.
 
Network Attached Digital Video Recorder
The Network attached digital Video Recorders (NVR) stores video from IP cameras rather than analog video cameras. This is one of the key differences between DVRs and NVRs. The NVR systems are much more flexible and expandable than DVR systems. They provide easy access to multiple cameras on any PC on the network. The storage can also be arranged in RAID configuration to improve system reliability. This type of system is very easy to install. Now you don’t have to run coax cables; all the signals travel on the network. Even power can be provided to the cameras through the Ethernet network using Power over Ethernet injectors.
 
As an example the NowVision NVR system takes advantage of some of the features built into many IP cameras. IP cameras include built-in motion detection, and pan/tilt/zoom cameras have built-in web pages that include PTZ controls that make it easy to control a camera from any web browser.  All of these features can be used by the NVR system.  The NVR also provides video storage, retrieval and display of multiple cameras on a PC window.  It uses standard computers, operating systems and hard drives. 
 
Since NVR systems connect to the network, you can attach many cameras to one NVR system. The limit is the bandwidth of the network rather than the number of BNC connections on the DVR system. 
 
NVR systems are easy to install and are very flexible since the cameras can be viewed at any location over the network or Internet.  The system works best with 10 to 100 camera systems that use MPEG-4 or M-JPEG compression. The downside is that these systems rely on the motion detection and PTZ functions provided by the IP cameras so there isn't a consistant way of controlling these cameras. Cameras without these capabilities will not be able to be controlled at all, just the video can be stored.  Pricing ranges from $2,900 to over $7,500.
 
Intelligent Network Attached Digital Video Recorder
The Intelligent Network attached digital Video Recorder (INVR) includes all the features of the NVR system and provides additional video processing functions.  The key difference between the NVR and INVR is that the intelligent system includes built-in software that provides motion detection; pan, tilt, zoom control; scheduled storage; individual camera frame rate control and more. 
 
For example the VideoZerver system is a complete video processing system that attaches to the network and communicates with many network attached cameras. This is a modular system with each module supporting up to 16 cameras. A number of VideoZervers can be attached to the network to grow the number of cameras and the capacity of the system.
 
The complete system uses only a single IP address on the main network. Over 1000 cameras can be supported. Lifecycle management allows rule based archiving of video to mass storage devices over a secure and dedicated network. Over a terabyte of storage, in RAID 5 configuration, can be installed in each module. 128-bit encryption with firewall protection allows cameras and data to be secure from hackers inside as well as outside the network. One of the nice features of this system is that it isolates the IP cameras from the main network reducing the bandwidth on the network.
 
The VideoZerver is very easy to set up and use. The system self configures, setting the IP addresses of all the cameras automatically. It allows the user to view all the cameras as well as managing and setting up the system on a standard web browser screen.
 
These systems are excellent for isolating the cameras from the main network, and are easy to install. The downside is that you need to run a separate camera network instead of using the inplace network. It also has a high entry price and works best with camera systems from 16 to 512 cameras. Prices range from $5,900 to over $15,000
 
Distributed Network Attached Digital Video Recorders 
 Distributed Network attached digital Video Recorders (DNVR) is similar to the INDVR systems, but provides more functions and allows all the functions to be distributed over the network.  This system consists of software that runs on a standard PC, and video storage that can be located on any hard drive on any computer on the network. The key difference between the INVR and the DNVR systems is that the DNVR can use any hard drive on the network including the hard drive in your PC. If the storage requirements are greater than the existing hard drive space on the network, you can add Network Attached Storage (NAS).  As a matter of fact you can select storage points for each camera, creating a distributed storage system. This is a very powerful system, yet easy to install and use. Everything in the DNVR system uses standard computer components, no special wiring is required and everything is controlled and monitored from your PC. Since everything is connected to the network, it can also be viewed and controlled from anywhere on the network or over the Internet. Because this is a modular system it is actually reasonably priced.

SoftSide32 Software
 
SoftSite32 is an example of this type of software. The software supports thousands of cameras by breaking them up into groups of 256. It provides on screen control of P/T/Z from any PC. You can set Guard Tours with 3 shift PTZ touring independent of the cameras capabilities. It includes Sub-Pixel based video motion detection with unlimited Region of Interest fields. Video is recorded and retrieved by date and time stamp. It’s easy to set up 7-day record scheduler with 96 schedules per day. Recording can be scheduled based on time-of-day, day-of-week and motion threshold.  Security is provided with logon name and password for changing settings. The system is powerful enough to view / record at up to 30 FPS. The Multi threaded engine supports video frame rates of 30 FPS on ALL cameras.  It provides Email notification of alarms. It supports resolutions of NTSC, PAL, HDTV and well beyond. You can even attach a Professional USB Joystick to drive all supported PTZ cameras. Since storage is distributed, you can store video from different cameras on different storage devices on the network. It provides archive capacity of over 16 Exabytes.   To maintain validity of video storage, the system uses 768-bit security codes and provides robust watermarking which does not modify the image data. If you require larger display capability, the system supports multi-monitor displays (16 monitors per PC currently available). The special retrieval functions make it easy to find things. The ssAreaScan function finds missing objects by scanning recorded archives for activity. 
 
Network Attached Storage (NAS)
You can choose Network Attached Storage that’s right for the application. The NAS systems are available in tower or rack cabinets and appear as a server on your network. They are very easy to install and use since they run independently from your network servers. This is a scalable system with capacities from 40GB to over 2TB of on-line storage.  You can select very high performance storage with hot-swap IDE hard drives arranged in RAID 0, 1 or 5 configuration. Global RAID hot-spare hard drives make it easy to recover from failures without interrupting the operation of the system. NAS units with RAID 5 configurations are very easy to expand since they include hot-expansion capability. Dual Fast Ethernet ports with failover and load balancing provide uninterrupted and robust access to the storage. If you require faster performance, you can select dual Gigabit Ethernet interfaces. Video can be archived to CD-R or DVD-R discs. The storage system can be backed up using standard network backup software. Data can also be mirrored to remote NAS systems increasing the reliability of the system.
 
This type of system is very flexible since you can start with a single camera and store video to a standard hard drive on your PC. The system can be expanded one camera at a time with storage migrating to distributed NAS storage. The video can automatically be archived to optical jukebox storage for longtime storage. The downside is that the software only runs on a Windows PC.
Prices range from $500 to over 20,000.

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