NLE-FFS: a flash file system with PRAM for non-linear editing

摘要

For efficient non-linear editing (NLE) operations, a flash file system should be designed considering three factors: data indexing, system calls and frame header updates. Based on the hybrid architecture of phase-change RAM (PRAM) and NAND flash, we introduce a non-linear editing flash file system (NLE-FFS) which is designed for mobile multimedia devices that support NLE. In the proposed file system, the following three features are proposed. First, new data indexing scheme is proposed that is not limited by page-alignment constraint. Not only does it deal effectively with large multimedia files, it also facilitates flexible data management. Second, new system calls are proposed that minimize re-write overhead due to NLE operations by updating a small amount of metadata. Finally, an H-data block is proposed to reduce the overhead caused by frame header updates. The H-data block is a PRAM region reserved for frame header data updates. It allows byte-level updates instead of page-level updates; hence, several bytes of frame headers can be effectively updated in this region. The experimental result of this study shows that only one second is enough for a cut operation on a five-minute video irrespective of the cutting position in NLE-FFS, whereas up to 118.7 seconds are required for the same video depending on the cutting position in YAFFS2.1