dvr DigitalVideoRecorder (DVR), a digital video recorder, uses hard disk recording as opposed to traditional analog video recorders and is often referred to as a DVR, also known as a DVR. It is a set of computer system for image storage processing, with long-time video / audio recording, recording, remote monitoring and control functions.
Whether it is the development of high-speed network transmission technology, or the increasing popularity of front-end network cameras, the market demand for digital monitoring, let us see the direction of digital monitoring, NVR gradually replace DVR, but does not mean that DVR like video tape recorders Same dead!
From a technical point of view, after a long period of development, the DVR has the functions of recording, recording, remote monitoring and cloud mirror control of the image / voice, and integrates the functions of screen division, alarm control linkage and network transmission. At present DVR technology has basically matured, the basic functions of sound, DVR technology in the future development of five directions:
1, the hardware can be summarized as faster processing, longer storage time. 2, the encoding is more advanced, currently on the market mainstream DVR using compression technology MPEG-4, H.264, M-JPEG. MPEG-4, H.264 is the most common compression method in China, and H.264 / H.265 has become the mainstream because of its more suitable network transmission requirements. 3, interoperability easier, relative to the IPC proposed ONVIF protocol, etc., DVR upgrade software version is slow, lack of integration and consistency seems open. 4. Intelligence 5. Application of Cloud Computing To sum up, with the development of network technology, identification technology, microelectronic technology, codec technology and operating system technology, the embedded DVR will make the embedded DVR move towards intelligent, integrated, Wireless, high-definition, personalized, interactive direction.
DVR purchase experience talk
After the initial selection of the manufacturers to meet the requirements, we have to address the manufacturer's product introductory preliminary selection. Of course, users and contractors according to their own needs, choose the right product for their own needs, this is a pragmatic choice. If you choose a feature-rich embedded DVR, but do not need to use these features in the project, will undoubtedly cause the cost to rise. Therefore, you need to pay attention to the following points:
1, the image clarity
Image sharpness is a controversial topic, each user wants to buy the product image is the clearest, but technically speaking, the higher the resolution, the greater the disk storage space occupied, the required network transmission The higher the bandwidth Therefore, users can adjust the level of clarity based on the actual situation of the design, is the best design. Therefore, the user according to (project) the actual situation, the choice of products for users, is the engineer's rational approach.
Now, the resolution of the market CIF format is the mainstream resolution, but some manufacturers have also developed a full D1 multi-channel embedded DVR, but also high definition, but requires a high code stream. Currently respected on the market are dual-stream technology, the use of D1 resolution when recording, network transmission using CIF resolution, so a good solution to the video quality and network transmission bandwidth limitations.
2, real-time image
At present, the real-time image is a topic of great discourse in the industry. China DVR products in the promotion of one of the major things in common is that no matter how many roads are to promote all real-time functions can be achieved. In fact, in the purchase of DVR, the thing to consider is whether this DVR product really can achieve full real-time? Or is it really necessary to do it in real time? In terms of recording speed, all DVRs are actually 25 frames per second (PAL format) or 50 images per second (PAL format) in real-time, and advertising that exceeds this metric is impractical. Also need to pay attention to is to observe the real-time motion pictures to see if there is delay and smear, while observing the highest bit stream is much.
3, compression algorithm
Currently, the embedded DVR image compression algorithms are mainly MJPEG, MPEG-4, H.264, etc., these algorithms have their own advantages and disadvantages. To achieve full real-time, high-definition, very low mosaic, high smooth and smooth image quality, you must at the expense of hard disk storage and network bandwidth at the cost. Therefore, it is the wish of every contractor to choose a product that can meet the image quality of customers' needs and save hard disk storage space while ensuring the compression algorithm transmitted in real time on a low-bandwidth network. From the current technology point of view, H.264 compression algorithm to meet the higher quality image quality under the premise of the compression rate is greater than the MPEG-4 has greatly improved, and its technical features more suitable for IP network, wireless network transmission. Currently, H.264 compression algorithm has not really achieved high compression ratio, and the true H.264 algorithm there is a certain gap, but it is the most ideal compression algorithm.
4, network function
Under the impact brought by digital monitoring, users have an urgent demand for the network function of the DVR. Therefore, the network function of DVR is also a factor which must be considered when choosing. In a large surveillance platform, front-end layout of a large number of cameras and DVR, then whether the center's monitoring and management system can be remotely controlled by the device, it is very important. Therefore, we not only need to see whether the product provides an Ethernet network interface, but also depends on whether to provide supporting centralized monitoring and management system software to truly control the DVR through the network.
5, alarm linkage
DVR must have the alarm and linkage interface, and related records of events, such as location, date, time, user address, name, telephone number, name of unit, police intelligence category; once transmitted to the center, due to the control system between the units The transfer of time functions requires the ability to retain data for a period of time before the alarm signal is received, facilitating process analysis during forensics. There are also product support SMS alarm. The principle is that when the monitoring equipment monitors the abnormal situation, it immediately activates the SMS sending equipment to send the alarm information to the preset mobile phone in real time, so that the user can timely process the abnormal situation.
6, compatible with good or bad involved
Compatibility in DVR device selection is also an important aspect to consider. This includes the network system compatibility and software compatibility. For the network compatibility of the equipment, whether it can rely on the nearest monitoring system for remote control, whether there is enough Ethernet interface and device connection, are very much related to the overall system investment. The software compatibility, it is related to whether the DVR can be used in more functions to expand, or get better security and so on.
7, storage and backup
The bigger the recording capacity is, the better, but the most important thing is to have an interface to connect an external digital storage device for image data backup. Only regular backups can ensure that valuable images are safely stored and easily transferred . It is unwise to have months of images stored on the built-in hard drive of the machine, and all the data will be lost once the machine is destroyed.
In addition to regular backups, network backup is also a viable backup method. Therefore, builders should pay attention to the purchase of DVR equipment storage and backup performance.
8, operational convenience
What is operational convenience? To put it plainly is the feeling of using the device is easy, simple. Therefore, in the purchase must personally experience. First, we must pay attention to DVR equipment on the front panel design and layout of the keys is clear, the key of each key is clear. The second depends on the software menu is intuitive and friendly, whether the user-friendly settings and browsing. The third depends on whether the embedded DVR supports mouse, remote control and other modes of operation. A very easy to operate embedded DVR, but also to some extent, shows that companies have accumulated rich experience in engineering practice, for the sake of users, not behind closed doors. According to the survey, almost all of the contractors hope that the user interface and system can be simpler and easier.
9, video reliability and security
The operating system used by the system is directly related to the design level of the application software used by the system. Currently, DVRs are mainly based on computer and digital technologies. Therefore, relatively mature fault-tolerant technologies in various computer fields can be easily applied to the system, so that the reliability of monitoring video information is more guaranteed.
10, video retrieval convenience
For a long-running embedded DVR, the video file is very large, especially in different algorithms, the same time period of the video file size is not the same. Therefore, when the event occurs after the need to find the relevant video for analysis, if there is no convenient video retrieval method, then find the difficulty is great. Therefore, before purchasing a product, please understand whether the product has a convenient video retrieval method, and personally experience the operation.
11, product cost
No matter how advanced the product's functional technology, the price of the product is often taken into consideration first. In the case of meeting the needs of Party A project, as far as possible to choose more price advantage products. For example, Party A has arranged 24 cameras in a certain area. If the cost price of choosing one 16-channel embedded DVR and one 8-channel embedded DVR is higher than choosing a 24-channel embedded DVR, you should definitely choose By.
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