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Tale Of The Tape: DVD+RW vs. DVD-RW

LAS VEGAS -Supporters of DVD+RW cited several advantages of their format over -R during CES.

Although both are rewritable about 1,000 times, +RW discs would be playable in a greater percentage (more than 90 percent) of the home DVD player installed base, while at least one -RW supporter cited “not quite 80 percent” for -RW compatibility.

For -RW to get to a higher level of compatibility in existing home players, flash-memory upgrades or chip replacement would have to be performed by a technician, the supporter said.

As for disc compatibility with DVD-ROM drives, both camps said that to achieve a high level of backward compatibility, DVD-ROM drives would need a firmware upgrade, downloadable from a website, to enable them to identify -RW or +RW discs.

An -RW supporter claimed 90-95-percent compatibility after such a firmware upgrade is made.

One +RW supporter said he was unable to quantify +RW compatibility but claimed “the compatibility of +RW would be somewhat better” because on -RW discs, “there is some discontinuity between the ‘pre-embossed’ lead-in area and the writable area.” As a result of the discontinuity, “some drives are known to crash in that area.”

Another key DVD+RW advantage is the backward compatibility of DVD+RW discs recorded in long-play modes when played back in the installed base of DVD players and DVD-ROM drives. Users can select one-, two-, three- and four-hour modes per side.

No existing DVD home players can play DVD-RAM discs, nor can current DVD-ROM drives read the 4.7GB DVD-RAM discs, the +RW supporter said. Other +RW advantages, the supporter said, include:

  • No disc finalization required.
  • 1x to 2.4x writing speed for data and for fast access to random data.

Although the Philips-developed DVD+RW format is not officially sanctioned by the DVD Forum, a Forum member said the group can’t do anything to prevent any company from marketing such a recorder as long as it has a valid DVD-technology license. Although the Forum could prevent companies from using the DVD logo on that product, it cannot stop anyone from using the letters “DVD,” he said.