Magnesium Nitrate,Magnesium Nitrate Granular,High Tower Magnesium Nitrate,Magnesium Nitrate Hexahydrate SHANXI HUAXIN FERTILIZER CORP. , https://www.sxhuaxingroup.com
You should pay attention to a few big areas: whether it is soft compression or hard compression, what kind of card quality is best, whether it can realize remote functions, convenient backup, and how to deal with after-sales service. Below we will distinguish and understand the advantages and disadvantages of various DVR cards, as well as the relevant knowledge of the optional acquisition card.
Soft compression and hard compression Now as long as you buy a DVR card, the owner usually asks which type of card you want - soft card or hard card? Here we will first introduce the difference between a soft card and a hard card. 
DVR with soft card is generally called soft compression DVR. It is actually a video capture card. It is equipped with monitoring software to realize video surveillance, video recording, playback history video and remote monitoring. Its hardware is one or more video capture chips. (eg: fusion878a, saa7130/7134, tw6802B/6805, etc.) Receive signals from analog cameras, convert them to digital signals, and then enter the motherboard directly from the PCI gold finger through the PCI bridge chip. The original digital video signal is executed in the memory. The CPU instructs the operation to compress and process the video and then store it on the hard disk. In addition, the original video data is also sent directly to the graphics card, previewed through the display.
The circuit board of the soft card is very simple. There is no compression chip and temporary memory chip on the board. The cost is low, generally about 1/3 of the hard compression, so the price is its biggest advantage. In addition, we can see from the principle that the soft compression DVR There is CPU compression, so its compression quality is good, video clarity is high, in the case of sufficient CPU resources, soft compression DVR in the video, network and other functions is no less than hard compression DVR.
Second, hard compression DVR
Hard compression DVR, also known as video capture compression card, is basically the same as soft compression principle. The difference is that after analog video is converted to digital signal, it is not directly sent to the motherboard, graphics card, memory through PCI, but by hard compression first. The DSP of the DVR card replaces the computer CPU to execute the compression algorithm instruction, compresses the memory chip on the DVR card, and then enters the motherboard through the PCI gold finger. Therefore, the hard-compressed DVR board has more DSP or other compression chips and memory chips. Therefore, the main advantages of hard-compressed DVR are mainly reflected in the large-channel monitoring, such as 32-channel full-time real-time surveillance video, soft compression is difficult to achieve, this market gap can be occupied by hard compression.
Third, the summary <br> Through the above principles, we can see that the advantages of hard compression are:
1. Video compression is completed by its own DSP, without taking up computer CPU resources;
2. Compress first before entering the PCI bus to save PCI bus bandwidth. However, due to the rapid increase in CPU cost performance, a very cheap CPU can easily compress 16 CIF videos, resulting in a hard degradation of the hard card. In addition, with the emergence of PCI-E on the motherboard, hard compression can save the advantages of PCI bandwidth. It is also weakening and eventually losing its meaning. And its main drawback is that the DSP chip that comes with the card makes it very expensive;
3. The digital video is first compressed on the DVR card, and then the compressed video is decompressed and then delivered to the display of the video card for preview display. In fact, everyone does not know that this process will cause the video signal to be damaged and the image quality to decrease.
Note: The semi-soft semi-hard card that is often heard in the market, this does not exist, there is no such statement, friends must pay attention, this is mainly in 2002-2004, because CPU processing performance is limited, expensive The soft card can only meet 4-8 real-time surveillance video, and the domestic real-time 8-32 channel monitoring has strong demand and market in government engineering. At this time, hard compression increases DSP and memory on the soft compression DVR card. The chip, realizing high-channel real-time monitoring, has been widely used. At the time, there were almost no genuine soft-compressed DVRs in the domestic DVR market, most of which were pirated, while government projects generally did not use illegal pirated products. The DVR industry has experienced rapid growth. In 2004, there was a well-known domestic hard compression company that once claimed in the media that the soft compression DVR has entered the countdown to the annihilation. After three years, the soft compression DVR not only did not die, but also gradually developed and expanded, and the total sales The amount has surpassed the hard compression DVR. Especially in the field of civil monitoring, relying on cost-effective competition market, soft compression is a clear advantage? Later, dealers lied about semi-soft and semi-hard cards for the sake of profit. In fact, they are generally soft compression cards.
[ Huaqiang Security Network News ] Now there are a large number of fake and shoddy capture cards on the market, teaching you to see the broken capture card. First, soft compression DVR