DVD+RW is an optical storage rewritable disc format created by the DVD+RW Alliance as a market competitor to the DVD-RW (with a dash) format. It holds a high capacity of audio and video that can be read, written, erased, and re-written dependably up to 1,000 times per disc. The format can accommodate one or two-layer discs. DVD+RW was publicly introduced in 2001 at a 4.7GB storage capacity.
Against usual convention, the DVD+RW debuted before the DVD+R. The DVD+RW Alliance includes but is not limited to (and is subject to change): Phillips, Sony, Hewlett-Packard, Mitsubishi, Yamaha, and Ricoh.
A winner of the DVD format war between the “dash” and “plus” media remains to be determined as the development of more hybrid players and drives puts both these formats on equal footing regarding user compatibility.
The layers of the disc are similar to those of a DVD-RW. The recording layer is a metal alloy that changes states from crystalline to amorphous to alter the reflectivity. The deviations in reflectivity are interpreted as data that is either read, written, erased, or rewritten by the drive’s optical devices.
The DVD+RW has insulated layers to draw excess heat away from the recording layer, a metallic reflective layer and two polycarbonate substrates. Microscopic indentations (called pits and lands) contain binary data that imprints the recording layer via the laser.
What sets the DVD+RW apart from its “dash” format competitor is its lossless linking system. The process of recording data at variable bit rate traditionally utilizes a significant amount of space, causing considerable stopping and starting of the disc, which in turn creates link loss.
Link loss is responsible for incompatibility with players and drives; however, DVD+RW’s system can encode variable bit rate without the loss link. This enables the user to work with more of a disc’s data and have more efficient random access to tracks.
DVD+RW discs can be read by a majority of DVD recorders, DVD-ROM drives, and consumer electronics, but with the lower reflectivity that is characteristic in this media format may cause some occasional incompatibility issues.