Blu-ray Discs contain their data relatively close to the surface (less than 0.1 mm) which combined with the smaller spot size presents a problem when the surface is scratched as data would be destroyed. To overcome this, TDK, Sony, and Panasonic each have developed a proprietary scratch resistant surface coating. TDK trademarked theirs as Durabis, which has withstood direct abrasion by steel wool and marring with markers in tests.[7] At this point only TDK recordable 25GB Blu-ray discs and DVD-R discs use the Durabis coating.[8]
HD DVD uses traditional material and has the same scratch and surface characteristics of a regular DVD. The data is at the same depth (0.6 mm) as DVD as to minimize damage from scratching. As with DVD the construction of the HD DVD disc allows for a second side of either HD DVD or DVD.
A study performed by Home Media Magazine (August 5, 2007) concluded that HD DVD discs and Blu-ray discs are essentially equal in production cost. Quotes from several disc manufacturers for 25,000 units of HD DVDs and Blu-rays revealed a price differential of only 5-10 cents. (Lowest price: 90 cents versus 100 cents. Highest price: $1.45 versus $1.50.)[9] Another study performed by Wesley Tech (February 9, 2007) arrived at a similar conclusion. Quotes for 10,000 discs show that a 15 gigabyte HD DVD costs $11,500 total, and 25 gigabyte Blu-ray or a 30 gigabyte HD DVD costs $13,000 total.[10] For larger quantities of 100,000 units, the 25 gigabyte Blu-ray was less expensive than the 30 gigabyte HD DVD ($1.49 versus $1.55).[11]
Sales of high definition media in the United States. Week of December 23, 2007. Source: Nielsen VideoScan[56]According to a market research company Nielsen VideoScan, U.S. sales of Blu-ray discs were ahead of HD DVD with 61% of the market for the week ended 2007-12-23. In 2007 U.S. sales, Blu-ray leads with 64% of the market. Since inception, US market share was 62% for Blu-ray and 38% for HD DVD.[57][56] Nielsen also releases normalized sales data (presented in the table to the right). The 2007 sales numbers are in contrast with much of 2006 (before the release of the PlayStation 3) when HD DVD held an early lead. The sales figures Nielsen tracks, however, do not include all points of sale, such as Wal-mart.
Although Blu-ray has sold more discs, the HD DVD group claims that the attach rate (the number of movies bought per player) is higher for HD DVD than for Blu-ray.[58]