TOSHIBA-NEC SYSTEM CHOSEN FOR HIGH-DEFINITION DVD
Advanced Optical Disc (AOD) format proposed by Toshiba and NEC has been approved as standard for next-generation HD-DVD by 212-member DVD Forum. In establishing AOD as standard, Forum signaled abandonment of efforts to merge Toshiba-NEC technology with Blu-ray Disc format being developed by Hitachi, LG, Matsushita, Philips, Pioneer, Samsung, Sharp, Sony, Thomson.
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DVD Forum will develop AOD specs and publish them in spring, Nikkei reported. Member companies won’t be required to support AOD format, but those that do can use DVD logo. Blu-ray camp has said its format differs from DVD so it doesn’t need Forum’s blessing or logo. After announcement of standard, NEC said it would release AOD drive for PCs and PC with built-in AOD drive next year. Toshiba plans to market AOD home recorder in 2004, Nikkei said. Those companies and Blu-ray members couldn’t be reached for comment Thurs. owing to time zone differences.
Blu-ray Group didn’t propose its format to Forum, but Forum set up working groups to investigate possibility of combining AOD and Blu-ray. Apparently that was deemed unworkable because of technical differences between 2 blue laser systems that had been considering whether they could combine Blu-ray and AOD. And a Blu-ray disc holds up to 27GB of data on one side, while an AOD holds up to 20GB. Although Blu-ray offers higher capacity (up to 27 GB) than AOD (20 GB), NEC and Toshiba contend AOD discs can be manufactured easily on existing DVD production lines. Blu-ray camp has contended its software is no more difficult or expensive to make.
When first announced in late Aug. by NEC and Toshiba (CED Aug 30 p1), partners described as-yet-unnamed system that would use 405-nanometer blue laser to play 15/30 GB prerecorded HD-DVD discs and to record 20/40 GB blank discs. Capacities cited for Toshiba-NEC system are for single-sided discs, both single- and dual-layer. Partners said system would be backward-compatible to play current DVD-Video discs, but they were silent on other key details. Toshiba spokeswoman told us it would have 2-3 hours’ recording time for HDTV-quality signal on single-sided, single- layer 20 GB disc. Blu-ray provides 2 hours of HD recording time on single-sided, single-layer disc with up to 27 GB storage, and 50 GB single-sided, dual-layer disc is planned.
Like Blu-ray, AOD format can record 13 hours or more of standard definition programming. Toshiba spokeswoman said HD recording could be expanded to 4 hours by using “more advanced compression technology.” Actual compression system for Toshiba- NEC format hadn’t been decided at time, but would be either MPEG- 2 or MPEG-4, spokeswoman told us.
Blu-ray format uses MPEG-2, same compression as for DTV and current DVD-Video. Latter is read with red laser and will be playable in Toshiba-NEC system, which will use single pickup that combines red laser for reading DVD-Video and blue laser for reading and writing HD-DVD. It’s not known yet whether system also will incorporate infrared laser for reading CD formats. Although sources said it technically was possible to use blue laser to read prerecorded DVD-Video disc, it wasn’t feasible for playback of dye-based blank discs used for home DVD recording. Among other reasons, dyes used for DVD blanks are optimized for reflectivity of red laser, they said.
Prerecorded and blank HD-DVD media for Toshiba-NEC proposal are based on current DVD-Video standard, which uses 1.2 mm-thick disc made by back-to-back bonding of 2 discs, each 0.6 mm thick. System’s 405 nanometer blue laser, used for reading and writing HD discs, has lens with numerical aperture of 0.65 -- close to that of 0.60 used for DVD-Video. Data transfer rate for HD video is 36 Mbps. Data transfer rate is same for Blu-ray, but that system uses different disc structure that has 0.1 mm “optical transmittance protection layer” above data layer on 1.1 mm substrate. Blu-ray data is played and recorded by 405 nanometer laser with 0.85 numerical aperture lens. Among other differences, Toshiba-NEC system uses land-and-groove track structure like DVD-RAM, while Blu-ray records only in grooves like DVD-R/RW and DVD+R/RW.
Disc construction similar to today’s DVD is key argument made by Toshiba and NEC for new system. Besides permitting playback compatibility with current prerecorded discs, they contend that retaining dual 0.6 mm bonded layers will enable DVD replicators and blank media makers to continue to protect their investments in current equipment. Partners also say their disc doesn’t need protective caddy or cartridge for insertion into hardware, which makes it possible to manufacture slim drives, including for portables. Original specs released by Blu-ray Founders called for protective cartridge that would be 7 mm thick and 9-11 mm larger than disc’s 120 mm diameter. However, we have been told that goal of Blu-ray developers is to eliminate need for caddy with blank discs; prerecorded Blu-ray discs don’t need caddy.