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What You Need to Know About Digital Video Recorders
November 9, 2009
Digital Video Recorders (DVR) record videos that are in digital format to a medium. A disk drive is a sample of this medium. DVRs come in a stand-alone set-top box that is connected to a monitor or television set for viewing. By connecting a digital video recorder to your video surveillance system, you can easily record the images captured by your security camera.
DVR vs. VCR
Unlike the VCR and other older methods, the digital video recorder can impress you with its wide array of functions and benefits. For one thing, you can store more video footages when you use a digital video recorder since the video is compressed onto a hard drive.
Another advantage of using a digital video recorder is having more viewing and recording options. Recording only when there is motion is most popular but scheduled and alarm recording are also available. Being able to mark the footages that you store can make it easier for you to find them later on. There is no more need for you to go through piles of video tapes just to find the footage that you are looking for. With an IP-based digital video recorder, you also have the option of sending video feeds over the Internet allowing you to view them wherever you go. This system is usually used by companies for monitoring their employees all over the world.
With a digital video recorder, you also have the option of storing the footage taken by more than one camera at the same time. You can also view more than one camera on your monitor during live or playback mode. You just need to choose a digital video recorder that has the number of channels that you need. This benefit is not available in conventional recording devices like VCRs.
Another advantage of having a digital video recorder instead of older recording devices is that you can also command it to alert you when it detects certain security threats. Because some digital video recorders have built-in sensors that can detect movements as well as changes in the environment, you can program it to send you a notification through your e-mail in order to warn you of the event. With the help of a digital video recorder, business owners can watch over their employees even though they are far away. Even parents who are away on a business trip can make sure that their kids are safe. And, they don’t have to worry about leaving their kids to a babysitter because they can monitor her every move.
Video Compression Formats
Video compression in DVR is necessary since raw video takes up gigabytes of space on a hard drive. So in order to make use of limited hard drive space the video is compressed when recorded and decompressed when viewed. You’ve probably seen a number of DVR stating different compression formats such as MJPEG, MPEG-2, MPEG-4, Wavlet, H.263, H.264. These are different methods of compression called Codec’s, Codec is a short name for coder-decoder. When purchasing a DVR what you will mainly find is MJPEG will be used in less expensive models intended for the homeowner or individuals that may not be recording continuously. These models do a good job of compressing and decompressing the video adequately and their playback quality is good. In many cases MJPEG is all you need. However if you intend to use networking and view or record the video remotely MPEG-4 or H.264 are better choices. Their per frame size is smaller resulting in more frames per second that you can receive when viewing over the internet and they also take up less space on your hard drive. The MPEG-4 and H.264 digital video recorders will cost more but may be worth the investment in the long run.