When comparing the two leading high-definition optical
storage formats, the immediate difference between the two is that Blu-ray Disc can store
20GB more than HD DVD. Of course, the HD DVD side had its answer to the apparent
deficiency when Toshiba announced at the Consumer Electronics Show 2007 that had
developed a
triple-layer HD DVD-ROM (read only) disc with a capacity of 51 gigabytes.
The 51GB standard announced early this year, has finally
been approved by the DVD Forum – the body responsible for the DVD and HD DVD
standard. The 51GB HD DVD standard, which was submitted by Toshiba in April,
received approval on August 31, 2007, according to Screen
Digest.
HD DVD discs hold 15GB per layer. In order to reach a
dual-layer Blu-ray Disc-besting capacity, an extra 2GB per layer was squeezed
in, for a total of 51GB. Toshiba states that continued improvement in disc
mastering technology has achieved further minimization in the recording pit,
allowing for the boost in capacity to 17GB in single layer and a full 51GB on a
single-sided triple-layer disc.
The new disc shares the same disc structure as standard DVD
and previously announced HD DVD formats: two 0.6-mm thick discs bonded
back-to-back. According to Toshiba, the added cost to produce discs with the
third layer is minimal, thanks to the use of the same physical disc structure
as DVD.
Right now, it is still unclear if the 51GB media requires
any change in hardware specification. Should the 51GB HD DVD be incompatible
with existing hardware, then current owners of HD DVD players may be left in a
situation even less desirable than the Blu-ray Disc Association’s decision to mandate a hardware
change this fall. Neither the DVD Forum nor Toshiba has indicated if the
new media requires an upgraded optical assembly.