The NVR is an abbreviation for (Network Video Recorder). The most important function of the NVR is to receive the digital video code stream transmitted by the IPC (Network Camera) device through the network, and store and manage it, thereby realizing the distributed architecture advantage brought by the network. Simply put, with Nvr, you can simultaneously view, browse, play back, manage, and store multiple webcams. Get rid of the computer hardware, no longer need to face the tedious installation software. If all cameras are networked, then the only way to go is to have a centralized management core.
Dvr, the full name of Digital Video Recorder (DVR), which is a digital video recorder, is often referred to as a DVR, also known as a DVR, compared to traditional analog video recorders. It is a computer system for image calculation and storage processing. It has the functions of long-term recording, recording, remote monitoring and control of images/voices and dynamic frames. The DVR combines video recorder, picture splitter, and pan/tilt lens control. Five functions, such as alarm control and network transmission, can replace the functions of a large number of devices in the analog monitoring system with one device, and gradually gain advantages and popularity in terms of price.
The difference between NVR and DVR
The DVR differs from the NVR by a letter, but it determines the huge essential difference between them. The DVR digitally encodes and compresses the analog video and stores it on the hard disk. The “D” letter mainly involves the encoding and storage technology, and has little relationship with the network transmission. Therefore, the DVR is usually installed in the equipment room near the analog camera. The NVR obtains the encoded and compressed video stream from the network and then stores and forwards it. The letter “N” refers to the network transmission. Therefore, we generally cannot see the direct connection of the video signal on the NVR device, and its input and output are all And IP data that encodes and adds network protocols.
For the NVR, the first difference with the DVR is that the NVR cannot work independently and become a self-contained system. The NVR needs to be used with the front-end IP camera or DVS to implement storage and management of the front-end video. For the DVR, you can directly connect the analog camera for video acquisition, storage and management, and you can work independently from the system.
2, physical location
In practical applications, the deployment of the NVR is flexible and not limited by physical location. That is, the NVR is not limited by the physical location of the camera, the encoder, and the control center, but only requires network connectivity. The main consideration is the network. Reasonable allocation and deployment of video streaming broadband. Because the DVR is directly linked to the analog camera, the physical location is subject to the layout of the field device. Usually, the camera, the audio device, and the auxiliary input/output device are required, and the transmission distance and signal transmission loss are considered, which have certain limitations.
The NVR system is a truly digital, networked, and open system. It can achieve true HD storage and video forwarding with front-end HD cameras. If you need to achieve true HD, you need HD support from video capture, encoding compression, storage to display. The current high-definition implementation is mainly implemented by the front-end “HD IP camera + NVR” mode. The HD IP camera can generate megapixel-level images and then directly transmit, store, display or play back the network. The DVR system is subject to the analog camera’s own technology, channel transmission bandwidth limitation and chip processing limitations, and can not achieve true HD video, and supports up to D1 resolution.
The NVR adopts an open IP architecture and needs to be used with encoders, management platforms, operating systems, network transmission and storage devices to achieve complete functions. Therefore, the NVR has a good integration capability, which is more convenient and flexible in terms of video interconnection and integration with alarms and access control systems. In addition, the NVR can be operated based on a general-purpose server and operating system. Therefore, it gradually breaks down the proprietary and closed structure of the security monitoring field, and gradually integrates with IT to facilitate user purchase and maintenance. DVR system always, because it has its own functions of video capture, encoding compression, storage, management, etc., it can work independently in its own system. Therefore, it is less concerned with the compatibility between different vendors’ systems, and lacks the “teamwork spirit”. Usually video coding methods, network transmission protocols, video file systems, etc. are privatized, which is not conducive to integration.
5, the interface
DVRs usually have a rich interface, including video input and output, audio input and output, PTZ control interface, alarm input and output interface, storage expansion interface, network interface, etc. These interfaces are essential for the DVR of the self-contained system; For the NVR, its function is located in the storage and forwarding of video, and is usually deployed as a “middleware” in the secondary computer room, which means away from the scene, away from all kinds of video audio input and output, away from the alarm interface, away from the workstation, therefore, Its deployment of redundant interfaces means an increase in cost.
Tip: The above discussion of the DVR in the NVR only increases the reader’s understanding of the mentality of the two products, and does not have to argue about the advantages and disadvantages. In fact, the two have different applications under different projects and different needs. Advantages will coexist for a long time, so the key lies in reasonable selection.
Which NVR and DVR are good?
DVR Chinese is called a hard disk recorder. It can be used to store an analog camera connected to the DVR. Note: The DVR is connected to an analog camera.
NVR Chinese is called a network hard disk recorder. It is similar to a disk array, providing network storage space for IPC or DVS, that is to say, the code stream after encoding and network transmission is stored. NVR is connected to the network camera
Analog camera (Camera):
The analog camera (Camera) is a front-end device for acquiring images of the surveillance scene. It uses a CCD image sensor as a core component, plus a synchronization signal generation circuit, a video signal processing circuit, and a power supply. In recent years, new low-cost CMOS image sensors have developed rapidly, and CMOS image sensor-based cameras have begun to be used in videophone or conference television systems where image quality is not critical. Since the resolution and low illumination of the CMOS image sensor are not comparable to the CCD image sensor for the main indicators, the camera used in the TV monitoring system is still a CCD camera. The signal output by the analog camera (Camera) is a video signal, which can only transmit one-way video signals, and needs to be connected to a monitor or a hard disk recorder for monitoring and recording.
The IP Camera integrates a video compression and network transmission processing module (DVS) based on an analog camera (Camera), which combines the technical features of an analog camera and a video server. The network camera can be operated independently as long as it is placed in any location with an IP network interface. In addition to the image capture function of the traditional camera, the network camera also has a digital compression controller and a WEB-based operating system (including a web server, an FTP server, etc.), so that the video data is compressed and encrypted, and then passed through the network ( The LAN, Internet or wireless network is sent to the end user, and the remote user can access the network camera on the PC using a standard web browser or client software, monitor the target scene in real time, and can access the image data. Real-time storage, in addition to the camera to control the pan/tilt and lens of the camera for full-scale monitoring. Some network cameras also have other functions, such as voice intercom, alarm input, relay output, motion detection, analog video output, and SD card local storage video data.