HD-DVD/Blu-Ray specs

HD-DVD and Blu-Ray are the successors to DVD. The reason there are TWO successors is long and complicated. Suffice it to say, there are two formats both in High Definitions video and audio. It should be states that unless you have a huge surround sound system or a big HDTV, then neither HD-DVD nor Blu-Ray will make any difference in sound or picture quality. That said, it seems likely that one of these formats will become the standard, like DVD is now. Currently, these two next generation formats are fighting a bitter war for supremacy, and right now they are neck and neck.

For audio comparison purposes, movie audio is uncompressed 24 bit sound, at 48000 samples per second.

HD-DVD size: 30 to 51 gigabytes

HD-DVD video: 1920 by 1080 pixels, VC1 codec

HD-DVD audio: Dolby Digital Plus at 1536 kilobits a second, Dolby True HD (lossless compression), DTS MA (lossless compression), linear PCM (uncompressed)

Blu-Ray size: 25 to 50 gigabytes

Blu-Ray video: 1920 by 1080 pixels, mpeg2 or VC1 codecs

Blu-Ray audio: Dolby Digital Plus at 1536 kilobits a second, Dolby True HD (lossless compression), DTS MA (lossless compression), linear PCM (uncompressed), Dolby Digital, DTS. (Some players only decode Dolby Digital and DTS)

Blu-Ray are mostly 50 gigabytes, while HD-DVD are mostly 30 gigabytes. Blu-Ray uses mostly the superior VC1 codec on recent titles, while HD-DVD exclusively uses VC1. HD-DVD uses mostly 5.1 Dolby Digital Plus, while Blu-Ray mostly uses PCM (since many Blu-Ray players cannot decode Dolby True HD or DTS MA).

A note about audio compression: Dolby Digital Plus uses very good compression, and on most tracks keeps the 24 bit at 48000 samples per second that is originally recorded for movies. Dolby True HD is lossless, meaning it is compressed, but sound exactly the same as the original recording. However, Dolby True HD currently only uses 16 of the original recording's 24 bits. Fortunately, new titles are coming out in Dolby True HD at 24 bit at 48000 samples per second. PCM is uncompressed (in fact, it is the same format as a CD, only in surround sound), which means it is also exactly the same as the original recording, but it too currently only uses 16 bits. DTS-MA is both lossless and uses 24 bit at 48000 samples a second, but it is unfortunately not available on any titles yet. ALL of these formats currently use 5.1 surround sound, not the 6.1 found on some DVDs, though they can all do 7.1, and will very soon. The audio at first glance seems to favor Blu-Ray because it uses more PCM, but HD-DVDs have more 24 bit/48000 samples per second tracks. Plus, many Blu-Ray players cannot decode the advanced audio found on Blu-Ray discs, while all HD-DVD players can play advanced audio. Warner Brothers is also releasing HD-DVDs with True-HD tracks, while the same Blu-Ray titles are only given a 16 bit DD+ track. This is because Warner Brothers wants HD-DVD to win the format war.

A note about video compression: mpeg2 is an old, inefficient compression technique, while VC1 is a recent, excellent compression. At first, Blu-Ray looked horrible because it used mpeg2, but most titles now have VC1. The picture quality now is about equal, though the absolute best picture quality is arguably King Kong, on HD-DVD.

A note about playing the new audio on a surround sound system: Any receiver can play the new audio formats. All HD-DVD players and Blu-Ray players mix sound onboard. However, some Blu-Ray players do not decode the advanced audio (though they can output PCM). A standard DVD player would send digital audio to the receiver to decode. On older receivers, an HD-DVD or Blu-Ray player will downsample the audio signal to 1536-kilobits-a-second DTS. This will sound better than almost any standard DVD. However, to access the true new audio formats, a receiver is needed that either accepts 5.1 analog inputs, or accepts 5.1 PCM over HDMI. The HD-DVD and some Blu-Ray players will decode the next generation audio WITHIN the player, and send the decoded streams as PCM over either the analog outputs or the digital HDMI. Many current receivers can accept these signals, playing them back at the highest quality possible.