In what constitutes a subtle backing down, Sony has announced plans to sell a consumer DVD video recorder that uses the DVD-RW format, rather than its home-grown proprietary format.

Late last week Sony said it will back a rival DVD format in preference to its own. It will sell a consumer DVD video recorder based on the DVD-RW format and not its proprietary DVD+RW format.

These formats are two of three systems battling to become the industry standard rewritable optical disc technology in both the consumer electronics and personal computer markets.

To the casual eye, the formats are differentiated by little more than the '-' and '+' in their names. The two technologies have the same basic capabilities - they can both record about 5GB on discs that can also be played back on read-only DVD video players.

But DVD-RW and DVD+RW are not compatible with each other and were developed by different teams of companies. A third format, DVD-RAM, was developed by yet another set of companies and uses a disc enclosed in a plastic cartridge. The use of this casing is one of several reasons industry-watchers think DVD-RAM is ultimately doomed.

"Sony's concept is to use DVD-RW for consumer electronics and DVD+RW for PC-related use," said Sony spokeswoman Aki Shimazu. The company may introduce a consumer recorder later that also supports DVD+RW, she said, but at present it has no plans to produce a device for consumer video applications based solely on DVD+RW. "If the market demands change, we might consider switching to DVD+RW for consumer electronics," she added.

The announcement redraws the boundaries in the rewritable DVD battle. With Sony's weight behind DVD-RW, the battle for the living room looks almost settled, say analysts. The only major consumer electronics maker now backing DVD+RW for consumer video player use is Philips.

"The major concern for rewritable DVD is compatibility," said Masaki Suzuki, senior analyst for storage at market research company Gartner Japan. "The major application for rewritable DVD may be video recording. At the moment, DVD-RW and DVD+RW have some advantage over DVD-RAM in terms of compatibility with DVD video players."

Masaki Moriyama, a senior analyst at research firm IDC Japan, said the RW formats also get strength from the rapid sales of CD-R/RW drives.

Analysts seem happy to discuss DVD-RAM’s disadvantage in the rewritable market, but won’t speculate on the eventual winner of the DVD-RW vs DVD+RW battle.

IDC is a member of the IDG group of companies, as is PC Advisor.