How To Choose A Hard Disk Recorder

By Author: orange
Total Articles: 35
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Currently on the market are many kinds of DVR products. How to choose a most suitable hard disk video recorders, for many engineering companies have is a problem, especially the novice, it is impossible to start, select the hard disk video recorders, hard disk video recorders should be inspected in the way of image compression , image quality, real-time, network performance, stability and price, compression technology is the core of the hard disk recorder, select the compression method which is most critical. Here it is necessary to take into account the quality of images, but also take into account the image storage and transmission speed. The current video card hard drive appeared on the market are mainly compression M-JPE, wavelet algorithms, MPEG-1, H263, MPEG-4, H.264 and so on.
1, M-JPEG is a JPEG-based still-image compression technology developed in the dynamic image compression technology, the drawback of low compression efficiency first, M-JPEG algorithm is based on the contents of ...
... each frame image compression, rather than the difference between adjacent frames to be compressed, thus creating a lot of redundant information is repeated storage, storage space occupied by the large per frame 8 - 20k bytes, it is best to do only 3k bytes per frame . Another point of difference is its real-time, in every way to ensure that all must be the premise of high-definition, it is difficult to complete real-time compression, and frame loss is serious, if the use of high compression ratio of the video quality will be seriously reduced. Tends to phase out such cards, but the price is cheap.
2, the wavelet algorithm technology is to make the image signal in time domain and frequency domain resolution, while the highest resolution. Kernel is used to compress and decompress in the way of the road, up to 70:1 or higher compression ratio, JPEG compression complexity of about 3 times, it is used for the MPE cited as the wavelet decomposition is very suitable for video image compression, so that image compression of wavelet theory to become the most successful areas of application. Of such cards by the MPEG-4 video card, hard drive, this might become obsolete.
3, MPEG-1 and M-JPEG technology comparison, MPEGI in real-time compression, the amount of data per frame, processing speed has improved significantly, PAL system for, MPEGI meet up to 16 more than 25 frames / sec compressed speed, the compressed stream and the clarity of the line 352 x288 pixels, each frame size is only 2k. MPEG-1, but there are also many deficiencies. First, the compression ratio is not big enough, in the case of multi-channel monitoring, recording the required disk space is too large. Second, the image resolution is not high enough, the maximum resolution is only 352x288, and the third is the bandwidth of the image transfer elm have certain requirements, in the ordinary telephone line can not be narrow-band network, remote multi-channel video transmission. Fourth MPEGI video frames fixed to 25 frames per second, video can not be dropped frames, using less flexibility. Currently on the market the card is mainly used internally MPEG1 MPEG1 hardware compression board. Such cards become obsolete. Completely replace the MPEG-4 products.
4, H.263 has a higher compression ratio, but the image quality than MPEG4.
5, MPEG-4 high compression ratio, image quality variable (VCD to DVD quality), MPEG4 compression ratio is much higher than MPEG1, M-JPEG is can not be compared. MPEG4 video and audio using fully synchronous video hard disk space required is about the same image quality MPEG1 or the space required by M-JPEG 1 / 10, so the user to select a MPEG-4 compression format with hard disk video recorders, using MPEG -4 compressed hard disk video card has two types of software compression and hardware compression board. MPEG-4 hardware compression cards on the market a lot. But MPEG-4 hardware compression software basically secondary development. DVR image quality is also a very important performance indicators, not just image quality and compression of the way, but also with graphics, image processing technology, software technology has relations, technical handled properly, moving picture often there tail, serrated and low-resolution series of drawbacks. Because of these shortcomings is very intuitive, easy user selection and engineering business.
6, in the MPEG-4 hardware compression based on a number of improvements, more conducive to the transmission network, but also it is set way video stream. Is a very cost-effective products.
Real-time is a lot of users are very focused performance, especially in banks, cash registers and other controls, real-time requirements are higher, but the real-time and hard disk consumption, computer configuration, the board is directly proportional to cost, while full-time video monitoring of network traffic caused a lot of pressure. So, in ordinary places as far as possible when monitoring use of non-real-time monitoring video. If images per second, 6.5 to 12.5 to meet the security, hall, factory management, residential quarters, hotels, shopping malls, elevators and other places most of the monitoring, and better network transmission, consumption of small hard disk, hard disk storage for longer. In today's highly developed network, the network DVR remote monitoring has become necessary functions, due to bandwidth limitations, compression ratio, effect of network transmission of MPEG-4 products better most users. Windows Media Player.Mainly by network monitoring client software, Windows Media Player, IE, etc. monitoring. Stability is a hard disk video recorders and other hardware and software products is very important indicator. Stability of a number of factors, the stability of the hard disk video recorders with the following factors: 1: motherboard, video card, video card and hard disk, hard disk, etc. 2: Operating System 3: hard disk video software.
Therefore, the stability of the pursuit of hard disk video should try to choose good reliable motherboard, such as MSI, Asus, Gigabyte etc, hard disk video recorders in the image processing capacity, so do not be cheap too, the use of poor quality, or many years ago technological backwardness of the old graphics card. Operating system is also an important factor affecting stability, install the hard disk video recorders are not recommended as far as possible WINDOWS2000 WINDOWS98, hard disk video software market, many are using MFC, VB, dephi written in other development tools, the use of these tools to prepare the hard disk recording as software and quick, but poor quality software, users may wish to check the hard disk video software executable file (EXE file) in size, if large, larger than 5M or more, is probably using MFC, VB, dephi such as the development from . Hard disk video software executable file (EXE file) the size of the smaller, indicating the software to do even better, good stability.
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