At the fork in the security video road, at the intersection of digital with network video recorders, you can see as far as convergence. In the beginning, there was the eyewitness account. Then came the camera and monitor, closely followed by the videocassette recorder. VCRs could record one stream to a three-hour tape. Technology advances brought the multiplexer, which allowed numerous streams to be recorded onto the same tape and separated out into discrete, viewable streams on replay. Time-lapse enabled the dropping of frames, permitting recording over much longer periods, at the cost of lost information.

The rapid development of video compression algorithms (JPEG, MJPEG, MPEG-4, etc.), computer processing speeds and reduction in data storage costs gave rise to the digital video recorder.

The DVR provided a convenient, if limited, replacement for the multiplexer and VCR combination, allowing non-linear access to recorded material usually selected by camera ID, time and date.