VCR equipment is an integral part of the CCTV system, because it can monitor the site's screen in real time, make a true record, and in the post-mortem retrieval verification, it can provide important clues and evidence for the detection of cases. With the development of digital compression technology and LSI technology, Digital Video Recorder (DVR) has got rapid development in the cctv camera manufacturer, there are a large number of DVR domestic manufacturers having the ability of self-development or production, and the structures or the approaches of each DVR are not the same.
The Development of Digital Video Recorder
The rapid development of the digital video recorder mainly depends on its simple mechanical structure and the use of high-precision package large capacity hard disk as the recording equipment, and therefore, as long as the image acquisition card is inserted into the computer expansion slot, and matched with the corresponding monitoring system software and application software, and all the features of the traditional tape recorders are achieved. Especially the subsequent embedded mobile digital video recorder has a more compact structure, more stable performance. From the aspects of core chip, some are based on a digital signal processor (DSP), and the other are based on application specific integrated circuit (ASIC), which based on DSP the structure is divided into different series, they are different for the different selection of the DSP from various manufacturers; form the aspect of handle video from DVR technology (video compression format), is based on Wavelet, M-JPEG, MPEG-1, MPEG-2 , MPEG-4, H.263, H.264 and other video compression format of a variety of different models.
The Different Type of Digital Video Recorder
The earliest DVR is the type of PC card, and the video capture card consists of the acquisition of the video signal, digital video compression processing and video buffer sections. with the upgrade of the core chip of CPU and memory, core clock speed and processing power of the computer have been continually improved, thus based on the single-card DVR, multi-card and multi-channel DVR is invented. As each piece of card corresponds to only 1 channel signal, and thus the number of acquisition card can be flexibly configured according to the requirements of the video signal ones. However, when several cards are inserted in the PC, the PC resources occupied are incread, such as CPU and memory resources, the number of expansion slots on the motherboard, the motherboard Power and so on. Therefore, when the number of camera source (ie, the number of capture card) is more, DVR must adopt a multi-slot IPC and with a large power supply, and the requirements on the CPU clock speed are also higher.
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