Time Lapse Recorders

Written by Kevin Tavolaro
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Time lapse recorders are video devices, usually associated with surveillance and security equipment, used to steadily record extended lengths of time to a single source. The source used to record the data is usually videotape, although digital video mediums can be employed as well. Whether digital or video, however, both mediums have limitations regarding the amount of data that they can store. Although this limit is usually quite high, it is often not sufficient to store all of the data captured by a video camera over an extended period, such as one or more days. Time lapse recorders make it possible to store such lengthy footage by decreasing the overall size of the data without affecting the information. This is accomplished through time lapse technology.

Traditional video devices record visual information at a speed of 30 frames-per-second (fps). This means that every second of video footage actually consists of 30 separate, sequential pictures, which are played back in rapid succession, recreating movement. Time lapse recorders minimize the amount of space needed to store video data by reducing the amount of frames per second used. While this can alter the consistency of the data, with proper planning you can use time-lapse devices to reliably record several days of video footage at a time.

How Time Lapse Devices Work

Most of us have spent a period or two in grade school attempting to make a simple animation by illustrating the sequential actions of a stick figure along the bottom corners of several textbook pages, then flipping the pages to create the illusion of movement, as the stick figure runs from one point to another. Let's say the stick figure's journey takes him 30 pages to complete. If you were to remove every other page, the basic details of the animation would remain intact. The stick man would still run from one point to another, only now it would take half the time. Time lapse recorders operate on this same basic principle. By recording information only at specially programmed intervals, they can still provide a digital record without requiring nearly as much storage.

The images created by time lapse recorders are dependent on the recording intervals they employ, as well as the overall length of time recorded to a single videotape or digital device. For example, a surveillance camera might record 24 hours of material at a time. In this situation, a time lapse recorder might record every fourth frame. This would result in a slightly jerky, rapid movement, but the basic information would remain the same. However, if several days of footage need to be recorded to one tape, the time lapse device might be set for a much larger interval, recording several frames at a time, than waiting many frames before recording again. This approach can make it look as though people are jumping around the screen, appearing, disappearing, and changing into other people. Due to this lack of continuity, this practice is best suited to non-security related applications.


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