Blu-ray and HD DVD

This year is the year of high definition. We’ve had HDTV for a few years, but that means you can only get the programs offered by the TV stations, not necessarily the ones that you want.

Now two new types of movie disc will give the choice to you.

They are Blu-ray and HD DVD. Both are more similar than different, but unfortunately they are not compatible with one another. Remember, neither is compatible with a standard DVD player.

Both discs look pretty much the same as a DVD or a CD. They are the same size and thickness, and have the same sized hole in the middle. But they manage to pack a lot more movie onto their surface. That’s because they use a blue laser instead of the red laser used by DVD.

Increased capacity

A HD DVD has more than three times the capacity of a regular DVD, while Blu-ray discs (BDs) have more than five times the capacity. Like regular DVDs, both formats can have either one or two layers of data, so both can double their basic capacity.

In each case, the discs are big enough to carry four hour movies in full high definition, with a resolution of 1920 x 1080 pixels. They also support a far greater rate at which the digital information can be pulled off the disc than DVDs, so improved video and audio standards are included.

DVDs use a compression technology called MPEG2, which was developed way back in the early 1990s. Both formats support newer, better, compression technologies providing even better picture quality. And both support new, higher resolution sound, with more channels.



 Storage capacity

 Single layer/dual layer 

 25/50 GB    15/30 GB  4.7/8.5 GB

 Playback time

(Dual layer discs) SD/HD

 Up to 22.2/8.5 hours  Up to 13.3/5.1 hours  Zero/Up to 3.8 hours 
Max. video resolution  1920 x 1080/24p/50/60i  1920 x 1080/24p/50/60i  720 x 576p 50/60i SDTV
Internet connection  Optional  Required  Not applicable


Better sound

While both high definition DVD formats provide the 5.1 and extended (7.1) versions of DTS and Dolby Digital surround common to most DVDs, they may also offer Dolby Digital Plus and DTS HD. The former provides 7.1 channels of better-than-DVD-quality sound in a compressed format, while DTS HD offers the equivalent, but as lossless audio.

The benefit of this is that the audio tracks are offered with no compression, which makes for higher sound quality. The newly minted lossless Dolby TrueHD and DTS Master Audio surround formats offer even higher resolution sound than DTS HD, with TrueHD mandatory on HD DVD discs and optional on Blu-ray discs.



Dolby TrueHD provides 7.1 channels of high definition, surround sound and is found on all HD DVD discs. It is an option only for Blu-ray movies.  DTS Master Audio is similar, but optional on both high definition disc formats.

Improved extras and interactive features

In addition to sound, the interactive features have been improved with both formats, mainly through pop-up menus. Today, with a DVD, if you want to go back to the Scene Selections menu to find another point on the disc, you have to press the ‘Menu’ button, then wait while the menu is displayed, then select the ‘Scene Selections’ button on the screen. Meanwhile, you have lost your place in the movie.

With both Blu-ray and HD DVD, you press the pop-up menu key, and even as the movie continues to play, the main menu is laid out over the top of it. You can choose the ‘Scene Selections’ menu, or the audio or subtitles menus, or even the special extras menu. Change your mind, and you can just cancel out of the menus, without having missed a thing.

Both high definition disc formats offer a video Picture-in-Picture feature where both the full screen and inset picture (say, a director’s commentary) play simultaneously. Blu-ray and HD DVD software will also playback on notebooks and computers with Blu ray and HD DVD drives.