Most of today’s DVRs provide functionality that previously required a multiplexer, as well as a VCR. Like a multiplexer, today’s DVR can accept multiple analog cameras and prepare input from all of them for recording onto a single medium. Although DVRs that will accept a single input from a stand-alone multiplexer are available, Gary Perlin, Speco Technologies vice president of video, says multi-channel DVRs are much more popular because they provide more flexibility in recording options.
Unlike multiplexers – which in normal operation record all cameras continuously and at the same frame rate – DVRs may be able to record images from certain cameras only during certain hours or may increase the recorded frame rate during certain hours. Some DVRs have built-in motion detection and can begin recording or increase the recorded frame rate when they sense a change in the image viewed.