Basics of HD DVD Format

• HD DVD, High Density DVD, or High-Definition DVD is a high-density optical disc format designed for the storage of data and high definition video.
• The HD DVD disc is designed to be the successor to the DVD format and can store roughly 3-4 times the amount of data as its predecessor.
• Although it uses the same blue-violet 405 nm laser as Blu-ray Disc uses, technical differences make the two formats incompatible.
• In comparison to its main competitor, Blu-ray Disc, HD DVD has less information capacity per layer (15 gigabytes instead of Blu-ray Disc's 25).
• HD DVD has a single-layer capacity of 15 GB and a dual-layer capacity of 30 GB. There is also a double-sided hybrid format which contains standard DVD-Video format video on one side, playable in regular DVD players, and HD DVD video on the other side for playback in high definition on HD DVD players.
• Like previous optical disc formats, HD DVD supports several file systems, like ISO 9660 and Universal Disk Format (UDF). Currently, all HD DVD titles use UDF version 2.5 as the file system, the same one used for Blu-ray releases.
• HD DVD can be mastered with up to 7.1 channel surround sound using linear(uncompressed) PCM, Dolby Digital, Dolby Digital EX, DTS and DTS ES formats also used on DVDs. In addition, it also supports Dolby Digital Plus and the lossless formats Dolby TrueHD and DTS HD.
• The HD DVD format supports a wide variety of resolutions, from low-resolution CIF and SDTV, all video resolutions supported by the DVD-Video standard, and up to HDTV formats such as 720p, 1080i and 1080p.

You may want to visit http://en.wikipedia.org/wiki/HD_DVD for more information about HD DVD formt.