DVR video capture card (at: the DVR video capture card noun is numerous, function also is different, the general common term include audio and video card, video card, the card, etc.; moreover some DVR video capture card built-in sound function, others are not. To be unified, this article shall be called the DVR video capture card) is the most important in the PC - -based DVR system core element, as in the computer CPU, deals with the whole machine's operation and operation.

General DVR video capture card can be divided into software compression card and hardware compression card; Software compression card image retrieval IC is required, and a PCI slot connected to host computer; If the card is much more a DSP (Digital Signal Processing, Digital Signal processor), becomes a hardware compression card.

It is understood that at present there are a lot of production by the makers of DVR video capture card, the internal use of image retrieval more than IC originated in the United States, Japan and South Korea... And other countries, such as PHILIPS, TI, TOSHIBA, etc., also have the manufacturer USES the domestic manufacturing of image retrieval IC, such as winbond IC.

Software compression card

Software compression card is based on the motherboard CPU compression mode will write programming related program, generally USES the AVI compression model provided by Microsoft, also have the manufacturer USES the mpeg-1, mpeg-2 and mpeg-4 compression mode.

No matter adopt what kind of compression mode, software of image compression, compression card operations such as action, must trust in computer motherboard CPU to support; And CPU in addition to support the operation of the DVR video capture card, still have to load other computer peripherals, so easy to cause system load is too high, lead to system instability, when the machine condition frequently.

If the future of CPU speed development faster and faster, software compression card can reduce the load of the system, its related features can improve; At present, a lot of software compression system using Pentium4 1.8 G to 2.6 G or more CPU, can meet the demand of software compression card on the system.

Hardware compression card

Hardware compression card mainly adopts DSP to compress DVR video capture card, the software compression card technology is more difficult, so the maturity of DSP design, will naturally affect the quality of the video.

Hardware compression card currently on the market for 4 ch, there have been no more than 4 ch products. We have learned, now really can achieve real-time video recording function (Real Time; under the NTSL standard, each one camera can be taken 30 images per second, under the PAL standard, each one camera can be taken 25 images per second) of DVR system, is the hardware compression technology products, therefore, more and more manufacturers began to develop hardware compression card.

The function of the DVR video capture card

Generally the function of the DVR video capture card, including:

　　1. All-weather 24-hour surveillance video recording function;

　　2. Network system function;

　　3. Security system function;

　　4. Automatic alarm function;

　　5. Humanized interface control function

In addition to the above features, there are more and more users require Real time feature, such as mainland China, even DVR products need to comply with the requirement of Real time will be listed; Real Time, therefore, this technology has become a highlight in the development of many manufacturers, and on the Real Time market standard  products are released.

There is, however, the manufacturer said, in fact, at present there are many claims to have the function of Real Time software compression card, not really achieve the function; Because to achieve Real Time effect, the more system resources, but relies on software compression card CPU is difficult to load; While hardware compression card can support higher image compression technology for itself, so more can meet the demand.

16 ch software compression card, for example, such as watching over 120 images per second, in theory, every ch 1 to 7.5 per second, but in fact really can playback image only 3 ~ 4, playback only half of it, not the Real Real Time.

CPU load is too large to solve software compression card of the problem, can only hope that the CPU technology development progress, higher speed, more let the CPU at the time of running other peripheral systems, have a plenty of resources to support software compression card.

DVR video capture card development bottleneck

At present, more and more DVR video capture card, but the image compression ratio and video playback quality has also been a manufacturer is eager to break through the problem. There are manufacturers of DVR video capture card, the compression ratio of 2400:1, compared with other products only for one percent of the compression ratio, obviously more advantages; But will the small image compression, decompression technology is needed for the higher, it involves video playback quality.

The most common image resolution is 320 x 240 or 640 x 480; If image compression ratio is very high, but the decompression technology, solve the image once amplification, is prone to Mosaic images.

In fact, the most excellent video playback quality, is to achieve the effect of the traditional VCR. Manufacturers committed to study the mpeg-4 technology at present, can appear only DVD effect, future companies will be the so-called MPEG - 7 (at) for the further popularization of multimedia data "the MPEG - 7 standard specifications, Industry groups" the MPEG - 7 Industry Focus Group "has begun operation) technology, in order to obtain better quality, more realistic image rendering.

In addition, the integrated is also the key point of the development of the current, if the volume of the DVR video capture card are getting smaller, the higher its compatibility, such not only can be installed in the computer, more can be built in other small home appliance, its application field will be more broad.