HOW CAN 50GB BE STORED ON ONE DISC?The structure of a Blu-ray (BD) disc fundamentally differs from the structure of a DVD/CD. Because the data layer on a Blu-ray disc is placed much “closer” to the laser lens than on a DVD/CD, the laser beam provides more precision. (fig. A)
The LaCie d2 Blu-ray Drive uses a blue-violet laser and improved lens specifications (wavelength, NAnumerical aperture) allowing for a laser beam focus that’s approximately one-fifth smaller than the red laser used to burn DVDs.
This combination enables recording much smaller and higher density pits onto BD discs. (fig. B)
Also, because the disc’s first data layer is positioned at the very top of the disc structure, there is more space left underneath it for an additional layer, allowing for storage on 2 layers (50GB).
HOW CAN THE LACIE d2 BLU-RAY DRIVE READ AND WRITE TO BD/DVD/CD?The optical parameters of BD, DVD and CD are different (see previous paragraph). Therefore, the LaCie d2 Blu-ray Drive combines:
WHY ARE BLU-RAY DISCS A SAFE, LONG-TERM ARCHIVING SOLUTION?The recording layer of a Blu-ray disc is located just under the cover layer, which is only 0.1 mm thick. To protect it and thus ensure long-term Blu-ray disc content reliability, several technologies have been developed by media manufacturers:
WHICH HD VIDEO COMPRESSION STANDARDS DOES BLU-RAY COMPLY WITH?HD video is a data-hungry application. MPEG-2 codec allows storing a full-length feature film in HD, plus bonus material on just one 25GB disc. MPEG-4 AVC (H.264) and VC1 are two other video compression standards that can match the best possible MPEG-2 quality at up to half the data rate.
Since the LaCie d2 Blu-ray Drive complies with each of these, the user can choose the most suitable one for a particular application.
Typical HD Video Transfer Rates:MPEG-2 = 21 Mbits/s
MPEG-4 AVC (H.264) = 8 Mbits/s
VC1 = 8Mbits/s