NVR — network video recorders.

NVR — network video recorders.

A network video recorder (NVR — Network Video Recorder) is the most important element of a network video surveillance system based on IP cameras and encoders. NVR records video streams, archives them, and transmits recorded data on request for visualization. A network video recorder implements the main advantage of IP systems — recording at any point in the network, regardless of the distance from the video cameras.

Formally, an NVR is a network drive on which sections are created for recording data: video and audio streams. Unlike a digital video recorder (DVR — Digital Video Recorder), an NVR does not digitize and compress video or audio signals. As a rule, an NVR does not provide image visualization, transmitting recorded data for display on monitors of IP system workstations. However, for a security system, unlike video monitoring systems, the issue of recording process reliability is the most pressing. And here the role of a network video recorder in an IP system cannot be overestimated. Therefore, it seems strange that there are no publications about network recording devices in industry publications against the background of numerous comparisons and tests devoted to IP cameras.
Unlike the market of IP camera and coder manufacturers, the list of companies supplying network image recording devices is not that large.
There are numerous programs, the so-called universal software platforms, capable of working with numerous IP devices from different manufacturers. The programs provide administration, visualization and recording of images from IP cameras and encoders using a regular personal computer running Windows OS. Formally, the software includes a module responsible for organizing recording. The number of recording channels is determined by the capacity of the software license. In turn, the developer often calls this software module a network video recorder — NVR. However, such systems do not guarantee stable quality and reliability of recording. They can be recommended for remote video monitoring systems or as a budget solution for a small office. (Terminology issues and features of solutions were covered in previous publications devoted to IP video surveillance systems.)
The most professional approach is to implement recording of video streams on a separate device, developed, like an IP camera or encoder, by one manufacturer. This is a network video recorder — NVR, tested in production taking into account the declared characteristics of resolution, speed and duration of recording. In addition, the consumer receives a guarantee for the operability of the device. Disadvantages — a higher cost of the solution and the need to use the entire line of devices of this manufacturer (IP cameras, encoders, workstations).
The NVR is based on a specialized computer with a well-thought-out cooling system, power supply, and the ability to install in a cabinet or rack. Windows currently dominates as an operating system. However, there is a trend towards a more stable OS Linux. The choice of Linux is also associated with lower costs for purchasing a distribution, which is reflected in the price of the device.
The typical number of video and audio streams for recording on an NVR are 16, 32 and 48 streams. Typical video stream characteristics: 25 fps with a resolution of VGA (640 x 480) or 4CIF (704 x 576). For megapixel cameras, the number of recording streams does not exceed 4-6 streams. The limitation is primarily related to the performance of the computer that provides simultaneous recording to disk and broadcasting the image for playback. Before the advent of the SATA interface, the bottleneck was the throughput of the hard drive bus with the PATA interface, as a result, recording to an external SCSI drive was often used. At present, the SCSI interface is becoming a thing of the past. It has been replaced by the highly efficient iSCSI network protocol — SCSI commands and data encapsulated in IP packets. The disk space for recording is increased by including iSCSI drives in a gigabit IP network with network video recorders. There are no fundamental restrictions on the number and remoteness of iSCSI drives. Thus, network video recorders have truly gigantic volumes of disk space — tens of terabytes! No DVR can compare with an NVR in terms of recording duration. In addition, NVR manufacturers are implementing additional technologies for the effective organization of video archives, such as: recording alarm frames in a separate area of ​​the disk array with a long storage period or automatic deletion of secondary records after a period of time determined by the operator.
Network video recorders are usually administered using the software interface of the IP system workstations. The user can assign a stream from a specific IP camera or encoder to record on a specific NVR. Recording parameters are set independently for each camera, taking into account event and alarm recording. Some network video recorders have a built-in WEB interface for programming and do not allow centralized administration. This is a serious drawback if the system has a large number of devices, since setup and reprogramming are time-consuming. On the other hand, it is possible to launch the WEB interface on the recorder itself and work with the archive without the need for a workstation.
The network video recorder does not store administrative information of the system (user data, alarm scenarios, script programs), but only video recording. Thus, unlike the DVR, the failure of the device does not lead to a failure in the operation of the system as a whole, and the operator can work with a live image from IP cameras. However, NVR manufacturers try to maximize the reliability of the devices. This is obvious, since recording is of fundamental importance for a security system. Currently, there are several technologies that guarantee the reliability of the recording process in IP systems.
First of all, network video recorders use RAID controllers, which ensure the creation of disk arrays from independent hard drives installed inside the device case. The most common model is RAID 5, in which incoming data is divided into blocks and distributed across all disks. All disks are also used to store parity blocks, which can be used to restore information if any hard drive fails. NVRs with a RAID5 array model use a hot spare disk system — you can replace a failed disk without disconnecting the device.
In turn, the IP system administrative service monitors the connection with the recorders. Accordingly, in the event of a connection failure or NVR shutdown, the system administrator receives a notification.
Some systems use the UPnP protocol: devices join the network dynamically, receive an IP address, report their capabilities upon request, and collect information about the presence and capabilities of other devices. As soon as IP cameras, encoders, and NVRs are connected to the network, the recording process begins automatically — there is no need to program and configure the NVR, the settings can be adjusted later. Thus, it is possible to organize automatic switching of streams from a failed device to a backup NVR.
IP cameras and encoders themselves can have built-in storage media – flash cards, recording to which is carried out in parallel with recording to the NVR. After the connection with the network video recorder is restored or its functionality is restored, the data is sent to the NVR archive area, where there is no recording.
Finally, some systems provide the principle of duplicating recording: the stream is recorded on two identical network video recorders. This is the most expensive, but, of course, the most reliable solution.
It should be noted once again that the technologies for reliable NVR operation and data recording are most fully present in the finished device, but not in software platforms. The cost of network video recorders is usually about 40% of the cost of the entire IP system. In this regard, some manufacturers offer the installer a choice between a finished solution and a network video recorder program. Thus, the installer has the opportunity to save money and practice creating a network video recorder on his own.
What are the development prospects for network recording devices?
A serious reduction in cost is unlikely. Despite the constant reduction in the cost of a gigabyte of recorded information, the release of new, more capacious hard drives, the consumer's appetite is growing faster. Recording megapixel resolution streams will require new records in the capacity of NVR archives. However, for small systems, a reduction in cost is still possible. This will make NVR competitive with numerous software platforms and DVRs.
The release of universal network video recorders capable of recording streams from devices from different manufacturers is also unlikely. The responsibility for correct operation is too high when IP camera manufacturers regularly change the firmware for their devices.
However, we can confidently say that the number of complete solutions, i.e. the release of ready-made NVRs, will increase, primarily in the budget systems sector.

Axis 262+ Network Video Recorder

Easy to use and install, the Axis 262+ network video recorder is a complete video recording solution with direct connection to a computer network and remote control via a local network or the Internet. It allows simultaneous recording, real-time monitoring and remote access to recorded material from up to 8 Axis network cameras.
Scheduled or event-triggered video recording, such as motion detection, can be performed at up to 240 frames per second with QVGA/CIF resolution or up to 120 frames per second with VGA/4CIF resolution. A 250 GB hard drive allows, for example, storing video images from 8 channels with VGA resolution and a frame per second for 13 days with no loss in video quality compared to the original video received from the camera. Recorded data can be exported as files from the Axis 262+ video recorder to a local PC.

8-channel Axis 262+/M-JPEG NVR with up to 400 GB HDD

The classic network video recorder Axis 262+ from the Swedish company Axis Communications is designed to record and store video from 8 Axis IP cameras, including in vibration conditions. Video of any resolution is recorded on a built-in hard drive with a capacity of 250 GB, which can be replaced with an HDD up to 400 GB. Video is recorded in M-JPEG format at a speed of up to 240 fps and a resolution of CIF or at a speed of up to 120 fps and a resolution of 4CIF on all channels. Simultaneously with recording, Axis 262+ allows you to view video in real time, as well as search through the archive. The NVR can record and play video with a megapixel resolution without reducing image quality. Up to 50 users can work with the device. For connecting external security sensors, Axis 262+ has 4 alarm inputs.

Divar XF (Bosch)

High performance and impeccable image quality Divar XF allows you to get the most out of CCTV images. With a high frame rate and 4CIF resolution, Divar displays every last detail.

Bosch’s advanced H.264 compression technology in the Divar XF reduces bandwidth and storage requirements by 30% compared to traditional MPEG-4 systems, allowing you to record lots of images without breaking the bank. Recordings are stored on the Divar’s four hard drives. They are easily accessible and easy to maintain, and additional storage can be added as needed. Recordings can be exported by loading them onto a USB recorder or exporting them remotely using the Control Center software. Divar makes it easy to manage and move recordings. The recorder has 8 or 16 channels of video and 8 or 16 channels of audio. Recording and playback is in real time with true 4CIF resolution per channel. Advanced H.264 hardware compression. Integration with Bosch Video Management System and third-party control programs using the VideoSDK. Local storage on four hard drives, accessible from the front panel. Control Center software for centralized viewing, playback, and remote configuration.

Intellex IP system (ADT)

This is an intelligent digital video surveillance system based on the IP protocol, which combines the principles of multiplexing, alarm and event detection, as well as recording of audio signals, text data and video images using IP video devices. Functional support for IP cameras and encoding devices. Recording speed up to 400 ips (images per second — for the PAL standard). Recording images with a resolution of up to 4 CIF. Dual built-in network interface card with gigabit throughput. SATA hard drives with a configuration of 250 GB and 500 GB.

Combo CDRW/DVD drive. Remote access and control via Network Client Remote Management Software. Front panel KVM ports. Two-color LEDs for system status. Integration of live and recorded audio. Internal floppy disk drive for storing system settings and individual images. Internal CDRW/DVD for exporting video, audio, and text. Windows® 2000 operating system.

16-Channel Network Video Recorder VR-N1600E (JVC)

Network video surveillance systems based on the new VR-N1600 network recorder have such important characteristics as reliability, flexibility, ease of setup, control and management. The recorder comes with already built-in Milestone XProtect Enterprise software with licenses for 16 channels. This software provides the entire necessary set of functions both for real-time monitoring and for video archive analysis.

The VR-N1600 hard drive capacity is 500 GB, the interface used is SATA. In addition, it is possible to install an additional HDD inside the device, as well as connect an external HDD via a USB port. The total memory capacity in this case will be 5 TB. For reliable operation, the recorder supports RAID1 and NAS technologies. Two network connectors are built into the rear panel of the recorder: LAN1 and LAN2. This allows you to separate video streams coming from network cameras from the main network, which is used to view video and control the system.

Hybrid video recorder VR-N900 with 4 analog and 5 IP channels (JVC)

9-channel network video recorder VR-N900 is designed to record video in digital MPEG-4 or M-JPEG formats from 4 analog and 5 IP cameras or 9 IP cameras on a built-in HDD with a capacity of 250 GB. At the same time, the disk space for the video archive can be increased to 4 TB.

Recording is performed with a resolution of up to 1280 x 1024 pixels at a frequency of up to 120 fps or with a VGA resolution and a frequency of 30 fps. For control and connection of external devices, the video recorder is equipped with 5 USB ports, as well as an RS-485 port for controlling PTZ functions of dome cameras that support Pelco protocols. The built-in Milestone XProtect Enterprise software allows the operator to select options for controlling the VR-N900, and the Remote Client application allows up to 9 users to access the video recorder over the network at the same time.

Network recorder NSR-100 (SONY)

The NSR series is an ideal solution for multi-camera monitoring, recording and playback. Each model can operate in standalone mode or in a client/server configuration. The NSR-100 recorder, which provides the widest range of capabilities, allows you to simultaneously work with 64 cameras and record up to 480 frames per second.

Supports MPEG-4 (video) and JPEG (still images) image compression formats, 240 fps in stand-alone mode, 480 fps for client/server. 1000 GB hard disk. It has the ability to work in stand-alone mode with up to 48 cameras (up to 64 cameras for client/server), intelligent video analysis, privacy masking function. The NSR-100 recorder has easy-to-use intelligent setup, 3 Gbit Ethernet ports with dedicated NAS output, RM-NS10 keyboard (optional).

DVR SymDec16Plus4/MPEG-4 with 16 analog, 4 IP channels and HDD up to 3 TB (GE Security)

The multi-channel digital video recorder SymDec16Plus4 from GE Security is a hybrid video recording device that can work with 16 analog and 4 IP cameras. It can record video in MPEG-4 format with a resolution of up to 720 x 576 pixels at a frequency of 25 fps on each of the 20 channels on a built-in disk with a capacity of 230 GB to 3 TB.

To control PTZ cameras, the video recorder is equipped with RS-232/422/485 ports, and a mouse and external storage devices can be connected to 4 USB inputs. Together with video, SymDec16+4 can record 4 audio channels and output images to monitors via BNC, VGA and DVI video outputs. For remote control, the device is connected to an Ethernet network with a bandwidth of up to 3 Mbps, and is equipped with SymNav or SymBrowser software and an IR remote control.

re_porter (GEUTEBRUECK)

re_porter can have various video data sources — both analog and network cameras. At the same time, a large number of IP cameras are supported, including megapixel and network servers of most well-known manufacturers. These can be simple fixed cameras, dome cameras, cameras on pan-tilt platforms. MPEG4CCTV — a proprietary video data compression algorithm from GEUTEBRUECK based on the well-known MPEG standard of the same name, specially adapted for video surveillance tasks. Dynamic GroupOfPicture Size — dynamic management of a long group of frames. Variable Frame Rate — variable frame rate of video data transfer. Variable Bit Rate — variable bit rate of video data transfer.

Some functions and characteristics:
Dynamic Storage EXpansion — dynamic expansion of the video database.
Dual Channel Streaming — dual-channel stream management.
Dynamic Livechannel Streaming — dynamic management of the real-time video data stream.
Intelligent Compression Dynamic — intelligent dynamic management of video data compression.
Fading Longterm Memory — partial deletion/thinning of the archive.
GSC/Web Web server function.
Tamper-proof image format from GEUTEBRUECK.

NV100 Network Video Recorder (Mitsubishi Electric)

This model is the final link in the new products being introduced to the market, consisting of a line of IP cameras and network software for managing cameras, as well as any models of Mitsubishi Electric recorders. Thus, the user is given the opportunity to flexibly expand an existing video surveillance system or build a completely new one based on IP solutions.

The NV100 network recorder concept is based on the Plug-and-Play principle, which allows you to build a video surveillance system by simply connecting IP cameras and network recorders to a single Ethernet network. After distributing IP cameras across recording devices (up to 16 cameras per device) and initial configuration of network recorders, the system is ready for autonomous operation. NV100 does not require constant software operation, which eliminates the possibility of system failure due to external shell errors. The network recorder receives and processes alarms from cameras and other external events, automatically responding to any changes in the situation.
The NV100 network recorder is a modern link in the evolutionary scale of video processing and recording devices, a continuation of the traditions of reliability and quality expected by users of analog VCRs and digital video recorders from Mitsubishi Electric..

These are devices for recording 24 (NVR5124) or 48 (NVR5148) video and audio streams from IP cameras and Pelco ENDURA encoders. The recorders use Linux Embedded OS, which ensures high stability of the devices. The devices support stream recording in three formats — CIF, 2CIF, 4CIF and 25 images/sec. Built-in disk space: up to 9 TB (RAID5) with hot-swappable disks. Expansion of disk space through the use of iSCSI drives SEB5100 (up to 8 pcs. of 9 TB each). Endura Store storage technology provides automatic reduction of recorded frames upon reaching the set term. The device has a built-in backup power supply and is designed for installation in a 19« cabinet.