| Recording and Storage |
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DVR (Digital Video Recorder)What is a DVR? - A DVR is a digital video recorder that receives analog NTSC / PAL video signal and coverts the signal to digital format, which is then saved to a hard disk (storage device). DVR's come in different shapes and sizes, from small and portable to commercial grade. DVR's can extract choice segments of video for playback from the hard disk. Today's DVR replaces the older VCR (tape storage) technology. 
DVR's are part of your complete analog surveillance system. DVR's can record video data on the hard drive for upwards of 3 months or more, and the video data can be retrieved instantly for viewing. DVR's can replace the need for motion sensors and time lapse recorders, for they can be programed to record what you want, when you want it, by means of software filters and triggers. DVR's offer live and/or recorded video viewing either locally or from a remote device located anywhere in the world, if the DVR is equipped with an Ethernet/CAT5 connection to an IP network. NVR (Network Video Recorder)The future is in NVR - The NVR is a networked solution for storing digital data for instant viewing, playback, or filtering. Unlike the DVR, the NVR does not need to convert video signal to digital format. The NVR receives the data from IP (Internet Protocol) cameras which have already converted, compressed and encoded the video signal to digital format (usually in MPEG-4/H.264 standards). As well, IP cameras send the data over Ethernet/CAT5 cable using the same IP communication technology in use by today's internet, which is accessible anywhere in the world. NVR's can be accessed remotely or send images to remote devices. The remote device could be another computer located on the internet, or a device like a cell phone, which supports the receiving of video images. The NVR stores the digital data to a hard disk sub-system similar to DVR's.
NVR vs DVRComparision - When comparing DVR's to NVR's you must consider their history. DVR's were introduced to analog CCTV systems to replace the aging VCR and multiplexer, and introduce the benefits of digital recording. The DVR permitted non-linear access to recorded data using camera ID, time and date. Traditional analog CCTV systems require the camera cables to network back to the DVR's physical location and connect. For some installations this can be a problem or added cost, especially when wishing to move the DVR to a new location, even to the other side of the room. Since modern DVR's do have IP network access, they are not required to be in the same physical location as your security office, as the case in the past with VCR's. The NVR is part of the next wave of technology involving digital format. As IP cameras continue to dominate the market, NVR solutions (both hardware and software), will continue in growth. Unlike the DVR, the NVR is not acting as a central multiplexer, so a mass of cables converging on its physical location is not required. A NVR can be located in any physical location that has IP network access. This means the NVR can be located at a remote site and still communicate to the IP cameras trasmitting the encoded digital data. The NVR can be relocated to a different location in the room, building or campus, without the impacts imposed by a traditional analog solution. Here are some comparison points:
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