Six Challenges of DVR and Analysis of Image Quality Impact

The most important function of the DVR is to play back the historical video. The playback quality is one of the most important performance indicators of the DVR. The clarity of the image quality and the image size affect whether the management monitor can detect the suspicious situation in time, which is crucial to the case. effect.

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Six challenges of the DVR

From a system perspective, a complete HD system needs to be composed of acquisition, transmission, processing, storage, display and other links. DVR is in it, its high-definition development not only needs its own upgrades and changes, but also needs other links to support. In the process of promoting the development of DVR towards HD, many problems need to be solved.

Challenge 1: Collection

High-definition video capture is the source of the link, the importance of this link needless to say. At present, the development of this link is basically entering the fast lane. Most monitoring vendors have introduced various types of high-definition network cameras: resolution from VGA resolution to 5 million or even higher pixels; , indoor hemisphere, mini hemisphere, card type until the outdoor hemisphere, etc.; industry applications have also been further subdivided, such as financial special, transportation dedicated, etc. Although the product is rich and diverse, but high-definition network cameras still need to solve the standard, ease of use, And the problem of intelligent applications.

Challenge 2: Transmission

In the era of standard definition, the communication network uses 100M network card transmission, but once HD is on, 1 channel HD video needs 8M bandwidth at the lowest. If there are 16 to 32 channels or even 64 channels of HD data, it can be connected to HD DVR at the same time. Even a 1000M network card may not be enough. Therefore, you must use 1 to 2 or more NICs for load balancing.

Challenge 3: Storage

The large amount of data brought by high-definition video not only brings trouble to network transmission, but also a new challenge to storage.

The amount of data in HD relative to SD is 4 to 5 times higher. It is enough to use the IO bandwidth and storage capacity of the SD system. Therefore, high-definition DVRs must research new storage technologies to increase IO bandwidth and storage capacity.

Challenge 4: Display

HD video is ultimately needed to be displayed to customers. At present, many manufacturers claim that their DVR is high-definition, but there is no HDMI interface (high-definition multimedia interface), or there is only a device, such a device can not achieve "high-definition". Therefore, high-definition DVR must adopt HDMI high-quality transmission technology to achieve high-definition display.

Challenge 5: Compatible

After the DVR is upgraded to HD, new standards and new solutions will be adopted. In this way, how to be compatible with other systems? Or will it affect other products in the system? We need to have a clear understanding of this. Can not blindly pursue high definition, resulting in high-definition DVR and other common equipment is not compatible, can not share a platform, resulting in the waste of the original investment.

Challenge 6: Data Mining

HD is just a means, the key is still to apply. We pursue high definition, the real purpose is to obtain better images and more details to improve the level of intelligent video processing and application, thereby improving the performance of the monitoring system. Therefore, many manufacturers in the development of high-definition, but also pay attention to the mining and full use of high-definition data, this is the future development direction of high-definition DVR in the future, which also requires deep accumulation of technology and industry experience to continue to explore.

DVR picture quality impact analysis

So, what are the major factors that affect the quality of DVR surveillance images?

First, the chip

Here we mainly talk about the chip of the soft card. The common chips of the soft-pressure DVR card on the market are FUSION878A, CX23811, CX25851 of CONEXANT Company of the United States, SAA7130, SAA7134 of PHILIPS Company and TW6800, TW6802, TW6802B of American TECHWELL Company. TW6805.

CONEXANT is the first manufacturer to make video capture card chips. It has developed CX25835, which is very competitive. It has ultra-low power consumption, low heat generation, true color reproduction, no color cast, fine and clear picture quality, and price. There is no outstanding advantage, and it may become the mainstream chip of DVR card in the future. At present, it cooperates with domestic WAPA (wave particle) to develop a soft pressure D1 eight-in-one card, which will be a history of the global DVR board industry. Sexual transition. This chip was originally made in Shenzhen Dongpu, but it has not been matched with good software and the price is very expensive. It is not accepted by the market. There is no price advantage in similar products, and now the new 6802C in the image quality is Prices are more advantageous than such cards;

PHILIPS' SAA7130 chip has a 9-bit high-definition picture quality, soft and warm color, and low noise. It has always been the mainstream chip for soft-press cards. Due to market reasons, the 7130 delisted, there are also product chip defects, and replaced by 7134, the same product chip investment this piece is currently only in Shenzhen, the effect is not expected to be better! Mainly the same The chip of the industry is stronger than the chip in compatibility and implementation, because the choice of the chip is easier than before, so it is relatively free and unrestricted in the factory; thus the SSA7134 will not become the mainstream product in the market at present;

TECHWELL has introduced TW6802, 6800, 6802B, and 6805 chips for soft-pressing cards since 2003. The biggest advantage of this card is that it can do non-frame-shifting acquisition when doing non-real-time DVR, and they are synchronized in audio and video. The effect is also better than other chips. At present, most of the acquisition cards for audio and video synchronization in soft cards are this chip. Such chips also solve the product full compatibility products, which is the reason why such chips can become mainstream. Some people say that compatibility is a software problem, and some people say that it is a hardware problem. In the end, there is no clear statement, but practice Can explain everything, the card with the best market compatibility is only this kind of chip;

In summary, the quality of the DVR and the chip of the capture card have a direct relationship, but the quality of the first-class capture card depends on the DVR software, DVR board design, especially the monitoring software, no matter how good the chip is not mature. The monitoring software matches, so its quality is also general.

As the major chip manufacturers not only enter the security field, their investment is constantly increasing, and the chip processing and image clearing ability is also getting better and better, so that before a chip is done all the way, now a chip to process Four or eight channels are more prominent in terms of effect and picture quality, including more advantages in chip processing, less speed and compression, and also lower hardware costs. Quality assurance and stability, this is also a sign of behavioral progress; those who have used the acquisition card know that the multi-chip is much higher than the single-chip maintenance rate; this piece of Henderson Security based on market research found ratios of 7% and 1 %. It is also a mainstream development of products, which can reduce after-sales maintenance and reduce costs! This piece of Zhongli Hengan is a relatively complete company, first proposed the first five-year warranty for video capture cards.

It is conceivable that the product quality and confidence are very confident, and the direct support of the chip manufacturers is inseparable from the R&D team.

Second, the algorithm

In the DVR industry in the domestic market, the commonly used algorithms are H.264, MPEG-4, wavelet algorithm, MJPEG, etc., but now according to the requirements of the project and various considerations, the compression ratio, image clarity, video footprint, etc., H.264 is used to reach a balance point.

Third, the resolution

Resolution, as the name implies, is to see the clarity of the object. There are two things we need to focus on: display resolution and video resolution. The resolution of the monitor is the resolution of the monitor you are monitoring. Although the resolution of the monitor can reach 1280*1024, most manufacturers' software does not support 1280*1024 HD resolution, but it is forced to squeeze or pull up and down. Stretching, the image looks distorted, the effect is not good, the current soft card software in the market can achieve HD, only one or two can do it. Video resolution mainly affects the quality of the image is determined by the algorithm. As long as you remember, the video resolution is proportional to the video capacity and image clarity. Now almost all manufacturers are recording every hour in CIF format. More than 230M, as far as I know, Zhonghengji's super-discharged third-generation software is only 150M in CIF format (unlimited stream), and D1 resolution recording capacity is about 4 times that of CIF.

Fourth, the code stream

The code stream is simply the amount of data in the image. The more data is stored per second, the higher the sharpness of the image, the lower the code stream, that is, the partial details in the image are lost, the image data is less, and the space is also occupied. It's small, but the image is not clear, and the stream and image are also proportional. Therefore, controlling the code stream is also an important factor affecting image quality.

5. Several suggestions for getting a clear image

First: buy a good brand of display, the quality of the display depends on the panel used in the display, the current quality of the display is PHILIPS, Samsung, ViewSonic, etc.;

Second: Please try to buy ATI graphics card, because the quality of ATI graphics card is recognized as the best in the industry, the graphics card industry is better than rendering, line management, processing speed, 3D texture, etc., ATI graphics card may not be as good as other manufacturers in some aspects. However, the quality of the picture is much better than other brands of graphics cards in terms of color, exquisiteness, sharpness and color reproduction;

Third: set the video resolution and code stream high. If the above analysis video resolution is high, the image is clear, the code stream is high or the code stream is not limited, the image is clear. In addition, here is the code stream of the PTZ. Because the PTZ is rotating at the moment, the picture changes a lot, the amount of data is large, and the more the picture changes, the larger the amount of data. Under the same parameter setting (that is, the compression ratio of all channels is the same), the video file of the channel with the PTZ will be larger than the others. This is a normal phenomenon. If the video stream of this channel is forcibly restricted, the video playback will be blurred. Clear, so it is not recommended to do code stream restrictions on the gimbal.

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