How to choose a suitable hard disk video recorder

At present, DVR brands and types appearing in the market are dazzling, and products with fast recording speed, large storage capacity, high compression ratio and high image definition abound. Faced with a dazzling array of functions, how should we distinguish their advantages and disadvantages and choose the products that suit us? How to choose a suitable hard disk video recorder

Distinguishing the quality of a digital video recorder (DVR) can be judged from such important performances as recording rate, storage capacity, picture clarity and operation and use mode. But in the comparison of these points, there are many misunderstandings in the market. Many users blindly pursue high speed, large capacity and high definition, but they don't know that these three indicators are actually mutually restrictive, and it is impossible to require all three to achieve the best; Whether the operation is simple or not is often ignored by the equipment selection personnel of most engineering companies until the installation process, which wastes a lot of time.

Indicators to distinguish DVR from DVR.

1. Video recording speed

As far as the recording rate is concerned, in fact, all DVRs are 30 frames per second or 60 fields per second (NTSC format) in real time, and any advertisement exceeding this index is unrealistic. If images of 16 channels are recorded simultaneously, the rate of each channel is only 30/ 16 frames per second or 60/ 16 fields per second. In multi-channel video recording, some DVR adopts advanced image displacement detection method, which greatly improves the recording speed, and the recording speed of moving images is almost real-time, which is many times faster than that of video recorders without image displacement detection function. However, it should be noted that video recording of image displacement detection refers to full-screen compressed recording of cameras with image displacement, not just the part of each camera image with image displacement activity. Although the latter can also improve the recording speed, in European and American laws, this image will not be used as evidence in court.

2. Storage capacity and backup

The larger the recording capacity, the better, but the most important thing is to have an interface to connect external digital storage devices to back up image data. Only by frequent backup can valuable images be safely saved and transmitted easily. It is unwise to store months of images on the machine's built-in hard disk. Once the machine is damaged, all data will be completely lost.

3. Image clarity

Image definition directly reflects the quality of DVR, but technically speaking, the higher the definition, the greater the storage capacity, so it is the best design to let users adjust the definition according to the actual situation, and almost all brands of products have done so.

4. The operation is simple.

Whether the operation is simple or not ultimately determines the adaptability of the product in practical application. More and more users hope that the devices they use can complete all the functions with one button. Many manufacturers ignore the overall quality of users' use of electrical equipment, and the designed products are multifunctional and too complicated to be popularized. In order to improve this deficiency, many manufacturers are constantly improving their products, such as using humanized keyboards to simplify daily operations, or adding computer network interface functions to conform to the trend of network development, so as to expand their share in the international market.

Choose the best DVR for you.

When choosing DVR, users should avoid falling into some of the above misunderstandings and ignore the real advantages and disadvantages of the product; And we should choose the most suitable products according to the needs of our actual engineering application, and we should not blindly pursue various high-tech indicators. After all, the more functions, the higher the technology, and the more suitable for every user. The following three schemes are put forward for the reference of engineers and end users.

1. The performance meets the project requirements.

When choosing a DVR, you should first determine where the device is used. It is a security monitoring project (such as buildings, airports, museums, etc. ) or a bank teller project that requires high video speed? The products used in security monitoring projects are characterized by complete functions, good network transmission function and slow video recording speed, but through the linkage with sensors and motion detection, video resources can also be allocated to the most needed places. The products used in the bank teller monitoring project are characterized by fast video recording, each channel can reach more than 20 frames, and should have the functions of real-time video recording and multi-channel audio and video synchronization. However, due to the huge workload of image processing, its network and other functions are relatively weak. Different types of DVR should be used for different types of monitoring projects to avoid cost waste and poor operation effect. For example, in the bank teller project, the equipment suitable for security monitoring project is not properly planned, and its video recording speed can not meet the needs of users. However, because the bank teller project requires higher computer configuration and hard disk capacity, the cost is also relatively increased. In other words, if the products suitable for the bank teller project are used when planning the security monitoring project, the cost will be wasted, and the security monitoring project often needs transmission and separate control, which is the weakness of the bank teller project system. At the same time, we need to remind everyone that DVR is a multifunctional device, not a multifunctional device. There are often users who hope that one device can solve all the problems, but in fact, the technical level of computer software and hardware can not completely meet the requirements of users. Because the bus transmission speed, CPU processing speed and hard disk recording speed of a computer are limited, it is impossible to transmit, process and record so much data at the same time unless a supercomputer is used. But the cost is quite high, which is unacceptable to users.

2. After stability verification.

If the stability of DVR is not enough, it will lead to many serious problems if it can't burn images when it is important. The stability of DVR can be mainly considered from two aspects: hardware structure and software program. Since there are many types of DVRs on the market at present, the following are only examples of PC-based models:

1. Hardware structure

DVR is multi-input, and the hardware can be multi-card or single-card. Sometimes, in order to improve product performance, such as increasing video recording speed, multi-card method will be adopted, but it is easy to cause conflicts between hardware, such as the bank teller project equipment mentioned above. Generally speaking, the less acquisition cards are used, the better, because the single card mode has higher integration and better stability than the multi-card mode. In addition, the heat dissipation of the equipment is also a factor to be considered.

2. Software programs

The quality of software programming can only be known through long-term operation and verification, and special attention should be paid to the stability of hard disk recovery. A key advantage of DVR is that it doesn't need to constantly change storage media. It will constantly refresh the hard disk, clear out the expired data and save the latest data. However, some DVRs often have problems in this process, which is often ignored by engineers and users. Therefore, it may be the shortest way to choose products that have been widely used and praised by users.

3. Increase the feasibility and extra cost of hard disk.

Generally speaking, the capacity of DVR's own hard disk is not enough. For example, DVR used for bank teller monitoring requires that 30-day images be saved and the video recording length should be at least 200 hours. If you use an eight-channel real-time DVR, even if each frame of image data is compressed to 2K, the required hard disk capacity is at least 300GB. If the image data is compressed to 2K, it is hard to say whether the image quality is acceptable. Therefore, it is very important to increase the storage capacity by adding hard disks. In addition, because the cost of hard disk is still high, whether the additional cost in the future can be borne must also be taken into account.

conclusion

To sum up, engineering companies and users should fully consider whether the equipment performance just meets the demand when choosing DVR, and can't force all functions to be powerful; It is necessary to inspect the stability of the equipment in many aspects to avoid problems in use; In order to ensure that the image storage time meets the requirements, the feasibility, convenience and extra cost of adding hard disk should be considered in advance; Finally, we should know the limitations of the development level of computer software and hardware technology on the performance of hard disk video recorder, so as to clearly and correctly judge whether the function of the product is exaggerated. In addition, based on the principle of "seeing is believing", I suggest you pay more attention to the performance of products in image and communication, so as to choose the most suitable product among many products.