Dual-layer DVD recorders are finally here, but the DL format is still a work in progress.
Media remain scarce and expensive, and the first generation of DL recorders and application software currently produces discs that many DVD set-top boxes and computer drives cant read. We expect most of these issues to be resolved before the end of the year, but if you buy a dual-layer recorder today, steel yourself for an early-adopter experience.
None of these caveats dampen our enthusiasm for this new format. Unlike single-layer discs, which hold 4.7 billion bytes (or 4.37GB) of data, dual-layer recordable media store a whopping 8.5 billion bytes (7.95GB), matching the capacity of the dual-layer DVD-Video discs used to distribute Hollywood movies.
This last issue is especially important, because one of the biggest selling points for DVD rewriters has been their ability to back up movies, a task that usually requires two single-layer discs. Splitting a DVD-Video can disrupt its logic, preventing menus from locating assets, and even making some movies impossible to copy. We copied unprotected discs for our testing purposes; expect problems if you try copying protected ones.
DL recording is equally useful for authoring professionals who want to produce single-disc prototypes of dual-layer projects without being forced to recompress content. The format also nearly doubles the space for home video productions, system backups, and data-archiving applications, and may someday be used instead of DLT (Digital Linear Tape) to create dual-layer DVD masters for replication.