DCA developed a new high-definition 3x DVD-ROM disc. It's a standard red-laser DVD disc that can only be played in HD DVD players:
The transition to 3X will not come without sacrifices, however. In order to burn HD content to a 3X DVD-ROM disc, manufacturers will have to encode using VC-1 or AVC and lower their HD resolution from 1080p to 720p—something that may rub videophiles the wrong way. However, HD movies and TV shows from Xbox Live Video already come encoded in VC-1 at 720p, and appear to be helping the service succeed relatively well. Whether or not 720p movies will take off in HD DVD form will depend highly on the pickiness of HD DVD's early adopters, but we don't think that anyone will be cheering on 3X DVD anytime soon.