LAS VEGAS — It was supposed to be the grand unveiling of a new generation in home entertainment when Kevin Collins of Microsoft Corp. popped an HD DVD disc into a Toshiba production model and hit "play."

Nothing happened.

The failed product demo at this week's International Consumer Electronics Show was hardly an auspicious start for the HD DVD camp in what's promising to be a nasty, drawn-out technology format war reminiscent of the Betamax/VHS videotape battle.

Backers of the two competing high-definition DVD formats are betting that the millions of people shelling out thousands of dollars for new high-def TVs and home theater sound systems will spend a few hundred more for new DVD players and discs that offer sharp pictures and interactive features.

Analysts say those who rush out and buy whatever new technology is available will jump right in and pay $1,800 for a Blu-ray player from Pioneer or $499 for the Toshiba HD DVD player.

But a prolonged struggle between the two incompatible formats may mean consumers have a long wait for a clear winner to emerge, potentially delaying widespread adoption of high-def DVDs for years.

"There's no question that a format war is not a good idea," said Howard Stringer, chairman and chief executive officer of Sony Corp. Sony is a developer and backer of Blu-ray.

The Blu-ray team is confident of getting content from most of the top Hollywood studios. It also believes that the new PlayStation 3, which will come equipped with a Blu-ray drive when it debuts later this year, will tip the odds in their favor.

Blu-ray discs will have the larger capacity, at 25 gigabytes or more. The HD DVD will have the virtue of being more similar to regular DVDs, which simplifies production, according to its backers.