What DVRs are for video surveillance. The angle of view

Choice criteria and functional capabilities of modern video surveillance systems

The effectiveness of the video surveillance system directly depends on the functionality and technical characteristics of the DVR. Therefore, it is necessary to carefully analyze the criteria on the basis of which experts select devices, and have a certain idea of ​​how the DVR works.

Which DVR to choose depends on the operational requirements for the video surveillance system:

• Compatibility with video cameras of various technologies:

• Analogue, with a low level of resolution CCTV. up to 800 TV (DVR);
• High resolution video cameras: AHD, HDTVI, HDCVI;
• Network cameras (NVR). IP;
• Hybrid DVRs capable of maintaining several types of equipment (HDVR);

IMPORTANT! The generally accepted division of video cameras into analog: CCTV, AHD, HDTVI, HDCVI and digital. IP, is fundamentally incorrect. All types of modern video surveillance chambers have a processor for converting a light signal perceived by a photosensitive matrix into an electronic pulse stream. Therefore, it is correct to call the IP video chambers network, since they transmit data with packages in accordance with generally accepted network protocols.

Technical parameters of DVRs

Video resolution. It is especially necessary to approach this parameter when choosing DVR DVRs for video surveillance. An inexperienced user can purchase a high.resolution camera with Full HD (1920 × 1080) resolution levels and a budget DVR, which will be able to record a video file with an extension of D1 (704 × 576). Responsible areas should be determined where a detailed image is necessary. For example, for cash regions, a level of a level of at least HD (1280 × 720) is required in order to clearly distinguish between banknotes. Detailization of a similar level is desirable and to identify persons with an automated bandwidth on the passage. But to determine the offender in the territory, 960n is quite enough.

The dependence of the quality of the image and the level of perceived permitted resolution

Recording speed and resolution are interdependent parameters. The ideal indicator for human vision is 25 to/s-a living video (Real-Time). However, a recorder for video surveillance with such an indicator for each recording channel is a very expensive equipment. over, such high speed in practice is not always necessary. For example, for gambling establishments, such as casino, tracking at tables is recommended to be carried out at a speed of 25-30 by/s/s., since the speed of swindler movements is quite high. To control office personnel, 12-15 f/s is quite enough, and to control the surrounding area-3-6 f/s.

IMPORTANT! Some manufacturers indicate this characteristic for each individual channel, and some. a general indicator for the entire DVR. For example, 200 f/s. For the 8-channel apparatus, it will be standard 25 fans per channel, and for 16-channel-already 12 to/.

The size of the archive. As a rule, the HDD disk in the DVR is not provided, and it must be purchased separately. Professionals advise specialized disks of Western Digital, Seagate or Hitachi manufacturers. They cost somewhat more expensive than ordinary “hard drives” for PC, but such costs are quite justified by the need to significantly increase the rewriting resource, since the maintenance of video files on the HDD disk is carried out constantly and cyclically. When choosing equipment, it is necessary to take into account the capabilities of the registrar himself. Some budget models do not support large volumes of 4-6 TB. In addition, you should adhere to the appropriateness-for the DVR for the home 1-2 TB for 3-4 chambers for storing data in high resolution at least a month.

Inte Wee. the number of inputs and outputs on the registrar panel, to which you can connect external devices. As a rule, this is:

• The number of analog (BNC) and digital (RJ-45) inputs;
• Connector for RCA Connector. audit. There may be one or by the number of video channels;
• A similar connector for the video output;
• Monitor connection: VGA, SVGA, HDMI or BNC TV;
• Control of rotary ptz devices via RS-485;
• Contact bar for connecting alarming devices.
• RJ-45 for connecting Ethernet network.

4-channel DVR DVR

How does it work

The DVR performs a record in several stages:

The image can be of different qualities. Everything will depend on the type of equipment selected that reads information. Registers with slight performance are not able to provide good clarity, so the image from such a device will have low quality. To avoid this, it is worth giving preference to powerful devices that are equipped with a processor and a signal processing chip. In this case, the device will be able to fix even the smallest details and transmit a high.quality picture to the monitor without defects and color distortions.

The set of analogue equipment for video surveillance includes:

Analog recorders are demanded devices, the demand for which is reasoned by their affordable cost and simple setting. But digital models that occupy the upper positions in the ratings work much better.

Additional opportunities

The IP camera has more and more modern important functions. Since each camera has a built-in IP address and web server, it is possible to view video files through an available Internet browser on any device (iOS, Android or PC).

Integrated FTP server will save the resulting video information on any carrier, registrar or remote computer. IP cameras contain a mail customer and when the sensor is triggered, and there are enough of them (with motion sensors, smoke, locking locks, flooding with water, gas leakage), makes an email newsletter, and when appropriate tuning to several clients at once.

Thanks to this variety of functions, you can organize an effective online protection system based on a video surveillance system. You can view a video from an object in real time even at threat moments. This video can be an evidence base of an event or crime. Combining a large number of cameras will help NVR registrar.

Selection criteria

To create a video surveillance system for a summer house, home or apartment, you need to decide on the number of video cameras and what functions they will perform. It is necessary to take a DVR with a large number of camera connectors, as expansion may be required in the process, but this applies to separate houses. For observation in the apartment, the DVR is not needed. The server will take over the home computer.

Cameras are connected to a computer or another gadget using Wi-Fi. This set will need a router, it will provide a connection. To watch video via the Internet anywhere in the planet, you need cloud storage. Cameras, in the option with an apartment, will be required with less resolution, since the distance to the object is not enough and you do not need an increase in the image. Organizing video surveillance in the conditions of a cottage and a private house is a more difficult task, here you will already need a DVR.

• It is better to use the chambers here combined, with different resolution depending on the goal (how much it is necessary to consider the object) and the distance to the survey object. A pair, three or 2 mpx and a couple of three or 5 mpx are suitable.
• CCD cameras do not recommend using on the street. They are poorly resistant to environmental effects. Therefore, it is better to use devices with CMOS matrix on the street. The size of the matrix is ​​best considered regarding other camera indicators, since the principles acting in the basis of ordinary cameras for shooting are not always suitable for.
• Another important indicator is the frequency of the frame. To shoot a busy street with speed movement, it will take 25k/s in real time. And if you still need to recognize the face of the driver or car number, you will need an even higher camera resolution.
• They also take into account at what light the video will be held. A photosensitivity indicator is responsible for this. So, for shooting at night, an indicator from 0.01 luxury is suitable, for illuminated areas, 1 luxury is enough.
• The use of lenses with optical zoom or fixed lenses. Depends on whether you need to allocate a certain object during shooting.
• Cameras with IR backlight are used at night. Although at the moment there are cameras with the function of automation of IR radiation. The technology is called Smart-IR.
• Built.in microphone if you need a sound recording.
• The choice of camera body depends on the purpose of use. There are plastic ones, are in a metal case (anti.vandal). With various standards of moisture and dust protection.

Having examined all the functionality of cameras and DVRs, the conclusion suggests itself that the most important parameters when choosing are resolution, size and variety of the matrix, and necessarily the frequency of personnel. Although the last indicator can be neglected and set for the same money not one, but several cameras with a lower frequency. In this case, we get the opportunity to reduce the amount of applicants for the memory of the device.

In the end, not a single living organism can move at a speed above the shooting speed of 15k/s.

Cameras complete with DVRs can cope with the following tasks:

• visitors monitoring;
• protection of private housing, office, houses, cottages;
• fixing machine numbers;
• Control of production type rooms;
• tracking banking halls, cash transactions.

Types of CCTV DVRs

The type of suitable registrar differs depending on the sphere where it will be applied. Like camera cameras are analog and digital. Depending on the type, the complexity and cost of the repair of the DVR is determined.

How to choose a video recorder for video surveillance

The number of channels

The figure indicates how many analog cameras can be connected to one device. They can be from 4 to 32. IP video cameras work as part of the network and are connected to one connector, so their number is stipulated separately in the characteristics to the device. It is recommended to choose equipment with “margin”. Such models will expand the network in the future without installing additional recording devices.

Type and volume of drives

The characteristics of hard drives determine the time of continuous preservation of video files without a change in the drive. For what period is enough memory depends on the resolution, recording speed, compression format. For example, with a continuous recording from an analogue camera in a maximum resolution of 720×576 video lasting 1 hour, it will take about 1.5 GB with an archive standard MPEG4.

Type of the processed signal

Depending on the type of video cameras, one of the three models of DVRs is chosen:

. Devices operate in systems with analog cameras, accept and record information in various formats, recorders are designed to switch IP equipment. The model works with both analog and digital signals, and also supports high-resolution video standards.

Permission

There is an opinion that the registrar saves files in the archive with the parameters in which it takes a video camera. But this is not so. The resolution of the device is limited, and it must be correlated with the characteristics of other components of the system. For example, a low.resolution DVR will record 960N archives and worse, even if Full HD cameras are installed on the network.

You can connect several models to one network at once. For example, for areas where it is important to track only the fact of moving the object, you can choose an inexpensive low resolution device. If in certain areas you need a detailed picture, then a registrar with high characteristics is connected to video cameras.

Manufacturers also offer two.way equipment. On the main stream (Main), the video is stored on a hard drive in high resolution. On a secondary (SUB), the operator usually views files over the network in real time, so the resolution on the branch is lower.

Recording speed

The parameter must be considered together with the number of channels of a particular model. For example, if the speed of 100 f/s is indicated for the 8-channel device, this means that on each stream the value will be about 12 to/s. To record the Real-Time video files, the characteristic should be not lower than 25 to/s on each branch, but such models are more expensive and are not always needed. To control the work of personnel in the office, there are enough 12 to/s.

Some models of registrars allow redistributing the total speed in manual settings mode. For example, you can connect a stream with 15 f/s to one branch, and to three remaining-3 f/s (for a 4-channel model with a record of 25 f/s).

Inte Wees

• Audio outputs and auditors (RCA). An audit is necessary to record sound from a video camera or from a separate microphone. Columns or announcements are attached to the audio output.
• Alarming entrances and outputs. Devices of detecting certain events are connected to the input connectors: motion sensors, door opening, fire, etc. D. An alarm exits are designed to switch the response tools: detector, rotary chamber, spotlight, etc. D.
• Monitor connection. It is necessary to take into account the type of connector and type of screen. For example, computer monitors are switching through VGA, television. through BNC. High resolution screens need HDMI connector.

additional characteristics

Support for network protocols. Almost all modern DVRs are designed to work on a local network, even DVR. To the models for which network protocols are indicated, you can remotely connect via the Internet and adjust the settings, view the online video, find archival records, copy files and perform other actions.

Connection of the detector movement. The DVR will start a hard drive after receiving the sensor signal. With a constant picture, video files are not preserved. The ability to work with the detector allows you to reduce the volume of the archive on the hard drive, quickly find the necessary notes without viewing many hours of video.

Multitasking. Different devices can simultaneously perform one or more tasks:

• Simeplexes. single.assembled models. For example, while searching and viewing archival files, the video recording stops.
• Duplexes. two.packed models. The user can simultaneously work with the archive and record.
• Triplexes. allow additionally to record and view the files to display the picture to the monitor.
• Pentaplex. multitask models. Allow you to simultaneously perform several operations: broadcast videos to the monitor, find files in the archive, remotely configure the operation of devices, etc. D.

Compression formats. The most popular equipment with support for.264. This compression format allows you to record high.resolution video, while saving a place on the hard drive. Detailing the picture after archiving is preserved. Formats that were used on the devices of previous generations carry out compression worse. The difference is especially clearly visible on frames with quick movements of objects.

Summarize

To choose a DVR, optimal for a specific video surveillance system, you must answer the following questions:

• What video cameras will be connected to the device (technology).
• How clear the image should be?
• Is it planned to recording sound from a microphone or video camera?
• How many alarming sensors will be connected to the equipment?
• Shooting at the facility is carried out continuously or only upon receipt of an alarm signal?
• Will the monitor be connected to the registrar?
• How long will it be necessary to store archival videos?

The specialists of our company are ready to provide a detailed advice on the assortment of registrars and help in choosing a model for a specific video surveillance system. Professional recommendations are saving your money and personal time. Call us by phone 7 (495) 191-18-62 to get an individual profitable offer.

In high-clearing video surveillance systems, both network DVRs (NVR) and HDCVI, HD-TVI and AHD formats for coaxial cameras are successfully used. The feasibility of using one or another format depends on the following factors:

Distances from cameras to DVR;

System type: modernization of the analogy system or installation of a new system.

Both network and coaxial DVRs can have powerful functionality capable of solving most problems of video surveillance.

Which video recorder for video surveillance cameras to choose?

Let’s figure out what you need to pay attention to when choosing.

When choosing, pay attention to this so that the registrar maintains a resolution not lower than the chambers intended for him. The most modern digital registrars are capable of keeping with a resolution of up to 12 megapixels (4K).

There is such a characteristic of DVRs as a recording speed with a certain resolution. Real Time. This is 25 frames per channel. Some models give out a smaller number of personnel with maximum resolution. For example: 12, 8, 6 f/s. Such registrars are cheaper, and if you do not need to remove dynamic scenes (cars at high speeds), then the smaller number of frames will be enough (used to protect the perimeter) and the size of such a video will take less space, t.e. your archive volume increases.

If you need to connect several microphones to the AHD/TVI system, then select a DVR with the desired number of auditors, they may be: 2.4,8,16. When using the IP of the video surveillance system, the microphone can be connected directly to the camera itself (if it has an audit), in this case, the presence of an audit on the registrar itself is not required.

Number of hard drives and maximum volume.

When constructing video surveillance systems with a large number of cameras or a large number of megapixels, the archive will take up a lot of space. In this case, it is worth choosing a registrar with support for several hard drives. The size of the archive can be calculated using our calculator.

Alarm/outputs (RS485).

Additional security equipment can be connected to them: siren, signaling, spotlight, traffic sensor, windows of windows and all of them will work for alarming events, notifying you with the removal of messages or sending messages to the post office. AHD/tvi swing ptz chambers are also connected to RS485.

The presence of a cloud service.

It will be required for remote connection from mobile devices: phones/tablets or computer. A very useful option. The most popular free cloud service in XMEYEE.

Questions, Комментарии и мнения владельцев and suggestions write to: samhvalov@rucam-video.ru

Advantages of DVRs

The use of such equipment is due to a number of advantages that provide video surveillance of the object. Attackers strive to bypass the place where there is a security system with video surveillance cameras. The main advantages of DVRs include:

• Picture quality;
• Memory size;
• Real.time broadcast (if there is an Internet connection);
• Remoteness of tracking and management;
• Supplying the search option for the required part of the recording;
• Data archiving;
• The use of for various purposes in most areas of activity;
• Image recording in full.scale mode;
• Convenience of viewing;
• The possibility of carrying out continuous monitoring of the object;
• Ensuring the safety of property.

Using the DVR, you can clarify the events or details of the incident, determine the perpetrators and victims, prove their case in law enforcement or judicial authorities. Registers with a set of video surveillance cameras are used:

• Security agencies or private individuals in apartments, private houses, offices;
• To perform control functions during cash transactions in trade and banking halls;
• To control the territory, industrial premises;
• For fixing vehicles;
• When monitoring visitors in public places.

Types of DVRs

According to the standard of video cameras, these products are divided into such subgroups:

The first option is used to save information from analog cameras. Analog DVRs are compatible with almost any equipment. They are appreciated for the simplicity of installation and settings. Video recording is chosen. If necessary, such equipment is equipped with a microphone. Among the advantages of such equipment, an affordable price segment and uninterrupted operation are noted. There are practically no disruptions during recording, but it is not possible to increase or decrease the image. Signal encryption is not carried out due to technical equipment. Compression of the signal from the analog type camera can create a powerful load on the processor, so it is impossible to track the video, just connecting to the PC. In the presence of other wires next to the fiber cable of other wires, minor interference can be observed.

The main questions that need to be answered when choosing a registrar:

• How many cameras and what formats (CVBS, HDTVI, HDCVI, AHD, IP) you plan to install?
• Detailing what level do you need in the video?
• What is the recording speed?
• Is it planned to use alarming entrances and exits of the registrar (motion sensors, smoke, sirens, etc.)?
• Are you going to record sound?
• Will the record be kept constantly or only “by event”?
• Will the rotary (PTZ) cameras be connected?
• How much time and in what volume the video will be stored?

The number and format of video cameras

Basically, registrars have 4, 8 or 16 (there are options with 256 channels) video inputs for connecting video surveillance cameras are presented on the market. The number of cameras is selected based on your needs in the “closure” of all the alleged control points, and the registrar (and their number) is respectively selected based on the resulting number of cameras.

According to the format of supported standards, recorders are divided into 960H DVR, HDCVI DVR, HDTVI DVR, AHD DVR, SDI DVR, NVR and HDVR, respectively. What are similar and how the standards of video recording are distinctly shown in table 2. HDVR (Hybriddvr). Hybrid DVRs capable of working with cameras of various standards are most widely represented on the market.

Photo and video quality

Examples of the quality of the image of video surveillance cameras with various resolution

As well as the cameras, the DVRs have a characteristic showing the maximum possible resolution of the video. This means that even if your video camera is able to record in a higher resolution than the registrar allows you to record, it will still lower it to its maximum possible value. Remember this when choosing both cameras and registrars. Cameras from those areas where you just need to see the fact of moving people, can be connected to a registry with a lower resolution. If on the record, for example, you need to clearly distinguish between people’s faces or denomination of banknotes, then you will need a camera and registrar supporting high resolution. For a regular home, country or office of video surveillance, resolutions of 720p/1080p are quite suitable.

Examples of permits

Recording speed

The permission of the DVR should be considered in conjunction with another parameter. recording speed, since they directly depend on each other. The higher the recording resolution. the lower its speed, and vice versa.

The best option. Record with a speed of 25 fps on each channel, it is also called Real-Time/Live Video. However, such registrars are expensive, and the high recording speed may not always be needed.

If the manufacturer indicates only one number of permits. Most likely, this refers to permission at the minimum recording speed. Also, sometimes manufacturers in the characteristics indicate not the speed of recording a separate chamber, but a common for all cameras. To find out the speed for each chamber, this speed must be divided by the number of connected chambers.

Using additional equipment

DVR connectors for connecting various equipment

LAN (RJ-45). Network port for connecting an IP camera.

Auditums (RCA). For connecting microphones.

Audio output (RCA). To connect an audit equipment.

USB/SATA. To connect a hard drive and other equipment.

Alarm entrances (RS-485). Connectors for connecting traffic sensors, fire, breakdown of glass, etc.

Alarm exits (RS-485). Connectors for connecting sirens, spotlights, etc.

PTZ RS-485. Designed to connect the control of the rotary (PTZ) camera.

Information storage device (hard drive)

For a competent construction of a video surveillance system, you also need to purchase a hard drive to record information from cameras. Since the desired disk volume is selected individually, in the registrars there is usually no built.in HDD.

I draw your attention to the fact that special types of discs of increased reliability are used for video surveillance systems. Household “computer” discs are not suitable primarily due to less exploring time of work, as they are designed to work in 8/5 mode. At the same time, specialized HDDs for video surveillance are made for continuous operation in 24/7 mode. Also, unlike PC-disk, professional HDD have an incomparably larger recording resource, t.to. In video surveillance systems, outdated data are constantly overwritten in an endless cycle.

In this article, we examined the main characteristics of video cameras and registrars for security and video surveillance systems, we advise you to read our other article on the competent selection of equipment for video surveillance for a country house and cottage. If you learned everything you needed, you can visit our catalog of video surveillance equipment and buy products of such security manufacturers as Novicam, Hiwatch, Hikvision, RVI, Amatek, Dahua, Trassir and others.

If something is not clear to you, our operator will gladly answer your question (only during working hours#128521).