Editing Closed-circuit television (section)

=== Compression ===
There is a cost in the retention of the images produced by CCTV systems. The amount and quality of data stored on storage media is subject to compression ratios, images stored per second, and image size, and is affected by the retention period of the videos or images.<ref name="JVSG Video Compression Guide 2010">{{cite web|title= MotionJPEG, JPEG2000, H.264 and MPEG-4 compression methods in CCTV|access-date=2011-05-01|url=http://www.jvsg.com/cctv-compression-guide/}}</ref> DVRs store images in a variety of [[proprietary file format]]s. CCTV security cameras can either store the images on a local hard disk drive, an SD card, or in the cloud. Recordings may be retained for a preset amount of time and then automatically archived, overwritten, or deleted, the period being determined by the organisation that generated them.