[header] How to understand security camera systems [title] Be aware that the dvr (digital video recorder) is what records the video cameras. [step] The video is stored on the dvr's hard drive. H.264 compression dvr is the new compression industry standard. 
The h.264 compression dvr stores 3x longer video than the older mpeg and mpeg4 compression dvr's. I is old technology with less video storage.