The process of preparing a DVD master source.  Premastering is a term which can describe a broad range of activities, including editing, compression, authoring, multiplexing (particularly, creating VOB files), or file structure creation.  It usually includes the writing process (to DVD-R or DLT).  Most DVD replication facilities include a Premastering department, which receives incoming DVD master sources (DVD recordable discs, DLTs, or Internet Transfer of DDP Images), checks these sources out, and transfers them to the glass mastering department or subcontractor.