Effect of enriched sewage sludge on soil urease activity

Video storage is shown in which stripes of video data, derived from video frames or video fields, are written to respective magnetic storage disks. Each disk is provided with a unique serial number during manufacture and the position of a stripe within an image frame is mapped to these unique serial numbers. In this way, it is possible for the physical locations of the disks within the array to be changed while maintaining correct alignment of the stripes making up each image frame.