Whatever happened to DVD+RWs ?
Question : Why
aren't there any rewriteable double-layer DVDs ? I can find dual-layer discs
only in write-once formats that I can't reuse.
Answer : REcordable DVDs can hold 4.7GB of data, and once that
must have seemed like an inexhaustible capacity.
But now that one year's worth of digital photos can max out a disc, the
8.5GB allowed by dual-layer discs looks a lot more attractive.
That's not because DVD technology prohibits such a thing.
A few years ago, the DVD Forum, which sets industry standards, approved a
set of specifications for dual-layer rewriteable DVD-RW media, and the same
work has been done for the competing DVD+RW format.
But other factors hold back these higher-capacity rewriteable discs --
starting with high prices and limited compatibility, said Hugh Bennett, and
industry consultant in London, Ontario.
He said that dual-layer rewriteable discs are expensive and inefficient
to make and that they don't work in existing DVD players and drives.
Andy Marken, a spokesman for the disc vendor Verbatim, also pointed to
the historically poor sales of rewriteable discs, noting that sales of
write-once CDs and DVDs have outpaced those of rewriteable discs by a factor
That gives manufacturers little incentive to make dual-layer DVD-RW or
DVD+RW formats work.