Compare HD-DVD and Blu-Ray

by on July 26, 2006

Q: What is HD-DVD and Blu-Ray and how are they different or the same?

A: In the lineage of high definition data storage, both the Blu-Ray and the HD-DVD are direct descendants of the DVD. What makes these formats superior to their predecessor is the use of blue laser technology to read and write data. DVD formats use a red laser. Because a blue laser has a smaller band width, more data can be packed onto the same amount of space. Therefore, both the Blu-Ray and the HD-DVD offer greater storage capacity and superior quality in high definition output. However, this edge that these disc formats have on the DVD format is probably their greatest similarity.

Where storage capacity is concerned, the Blu-Ray format can hold 25 GB while the HD-DVD holds only 15 GB. Structurally, the Blu-Ray and the HD-DVD are put together differently and this too makes a difference in the quality of each one’s respective sound and video output. Both discs are 1.2 mm thick, the HD-DVD is put together very much like its predecessor, the DVD. There are two 0.6 mm substrates which sandwich a record layer. On the other hand, the Blu-Ray is made up of a 1.1 mm record layer covered by a 0.1 mm substrate. Because the Blu-Ray laser has less to penetrate when reading and writing data, the Blu-Ray disc offers greater accuracy in recording and playing back data.

Much hype has surrounded the issue of which disc will triumph to become the standard for the high density storage of high definition data. As mentioned in an article on Blu-Ray technology on, this debate is quite reminiscent of the video tape format war of the 1980s between VHS and Batamax. Today, Blu-Ray is backed by 170 companies that make up the Blu-Ray Disc Association including Apple, Sony Dell and 20th Century Fox. In opposition, HD-DVD is firmly supported by players such as Microsoft, Universal Pictures, and New Line Cinema who make up the group of 230 companies who anticipate releasing content on to HD-DVD.