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Video Recording Equipment
(Chapter 2   Video Surveillance, Continued)

Digital recorders

The security industry now has access to technology that allows the digital recording of full-motion video. Over the next few years this type of system will likely become even more accessible, with an increase in digital storage technology and a decrease in the overall costs associated with hardware. Digital storing and recording have many advantages over a time-lapse or event recorder. The most important advantage is that digital recorders require no human intervention, which means no maintenance and no cleaning. On the other hand, a major disadvantage is that the security industry has yet to establish standards for compressing digital information for recording (compressed digital information takes up less storage space). Hence, it is common to experience compatibility problems between alarm monitoring systems.

For school applications, a major consideration is the increased cost of digital recorders over conventional video recorders. A minimum system for digitally stored images on a hard drive is estimated to cost at least $3,000. Without video compression hardware/software, the digital storage system is not very practical; it has been estimated that the cost for a single stored image is $0.94 for black-and-white and $2.81 for color. Using the compression methods available today increases the storage capacity with acceptable video quality by approximately 10 times. The additional cost of the compression system is at least $1,500, making the cost of the complete digital recording system about $4,500, which yields a cost-per-image of $0.047 for black-and-white and $0.141 for color video. For comparative purposes, the cost of storing images on a typical video cassette recorder is many times less—each T120 video cassette holds 432,000 black-and-white or color images at a cost of roughly $0.003 per image (including the cost of the VCR).

While the cost of digital storage systems has been decreasing and will continue to decrease as technology improves and the capacity of these devices increases, the cost of tape will probably be much lower than the cost of hard drives for some time to come. Consequently, the security industry will likely parallel the computer industry in storage techniques, using hard drives for short-term storage but keeping archival storage on low-cost tape systems.

 



Research Report:   The Appropriate and Effective Use of Security Technologies in U.S. Schools