EFFICIENT PRE-ALARM BUFFER MANAGEMENT

摘要

A hard disk (100) in a video data storage apparatus (20) includes a first section in which video data is stored and appointed for permanent recording (216), and a second section in which the video data is stored subject to rewriting after a short period of time. If an alarm event occurs (204), some or all of the data in the second section may be secured for permanent storage (216). The process to be employed in securing the data in the second section for permanent storage (216) is adapted to the proportion of the data in the second section which is desired to be secured.