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| FREQUENTLY ASKED QUESTIONS | |||||
| What
is CCTV?
What are the benefits of CCTV? What is a DVR? How does the DVR differ from traditional Analog Video systems? What is the difference between Digital Video verses DVR’s?
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What is CCTV? What are the Benefits of CCTV? What is a DVR (Digital Video Recorder)? How does the DVR differ from traditional Analog Video systems? While it can be argued that VHS cassette tapes reproduce images accurately, they are plagued by several other problems that reduce video quality. Tape suffers from "noise", dropouts (periodic loss in signal level), and image inconsistency (periodic changes in brightness and clarity due to the mechanics of the VCR or the stretching of the tape itself). Expensive, commercial grade VCRs attempt to get around many of these problems with special electronics and high quality mechanisms. Analog tape is not an especially robust medium. Inexpensive consumer-grade VHS cassette tapes start to lose quality after they have been played even a few times. The most expensive VHS cassettes last only a few hundred plays and/or records before noticeable degradation occurs, providing the VCR is in proper working order. Most important, however, is the fact that we are committed to continuously improving our product, based upon the suggestions and comments from our customers. As a result, our customers and end-users are getting the features that they need now. As the DVR product software continues to improve, enhancements are always available for download to our customers from this web site. What is the difference between Digital Video verses DVR’s? Contrary to popular opinion, digital video is not new. Digital Video Recorders (DVR’s), available to the consumer are relatively new. Companies have been using digital video for years in a number of industries, and for a variety of purposes. From medical imaging to process control, the ability to capture, store and analyze images digitally has become more commonplace. Only recently, with the advancement in new technologies, has digital video become an affordable option for more practical applications, such as surveillance. As the potential market has increased, prices have fallen, and in so doing opened up the possibilities of digital video to an entirely new audience. In the early 1990s, a digital video system capable of capturing full-screen video images would have cost thousands of dollars. The biggest cost element was the compression hardware, needed to reduce the huge files that result from the conversion of an analog video signal into digital data, to a manageable size. Less powerful 'video capture' cards were available, capable of compressing quarter-screen images - 320 x 240 pixels - but even these were far too expensive for the average user. The consumer end of the market was limited to basic cards that could capture video, but which had no dedicated hardware compression features of their own. These low-cost cards relied on the host PC to handle the raw digital video files they produced, and the only way to keep file sizes manageable was to drastically reduce the image size. With the arrival of the Pentium processor in 1993, even the most powerful PCs were limited to capturing images no more than 160 x 120 pixels. For graphics cards running at a resolution of 640 x 480, a 160 x 120 image filled just one-sixteenth of the screen. As a result these low-cost video capture cards were generally dismissed as little more than toys, incapable of performing any worthwhile real-world application. The turning point for digital video systems came as processors finally exceeded 200MHz. At this speed, PCs could handle images up to 320 x 240 without the need for expensive compression hardware. The advent of the Pentium II and ever more processing power made video capture cards which offered less than full-screen capability virtually redundant and by the autumn of 1998 there were several specialized video capture devices on the market which provided full-screen video capture for under a thousand dollars. It is a combination of high-tech hardware and innovative, cutting-edge software which enables digital video to be efficiently utilized in areas which were once reserved for VHS tapes and time-lapse VCRs. DVR However, to view digital video on a traditional television set, the process has to be reversed. A digital-to-analogue converter (DAC) is required to decode the binary information back into the analog signal. Technically, a digital image is comprised of a series of bits, represented by 1s and 0s. The arrangement and pattern of the bits reveal the necessary and crucial information needed to "reconstruct" the image so that it may be viewed on a monitor or printed on a printer. The viewable image is comprised of tiny pixels, or dots. If the image is a color image, each pixel appears in a specific color. In the case of a black and white image, each pixel is displayed with a certain "brightness" making some appear pale gray and others appear black. The actual number of pixels depends on the size and resolution of the image. Obviously, the larger the image size selected, the greater number of pixels. In the DVR, digital video recording of images (frames) from a camera, are "captured" and stored to hard disk in binary form (as described above). Because the digital system is not mechanical like a VCR, such factors as frame speed and video quality are software adjustable. Most digital systems on the market today allow users to adjust these settings as they see fit. Most video capture devices employ some sort of compression scheme to compress the captured images so they occupy less space on the storage media. Inversely, this means that the images must be decompressed before they can be viewed. In the digital video world, this dual functionality is encapsulated in a "CODEC"; short for compressor / de-compressor. A codec is any technology for compressing and decompressing data. Codec’s can be implemented in software, hardware, or a combination of both. Because compression and decompression are "processor-intensive" operations, the hardware-based codec is generally considered to be more efficient. |
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