by Anton Shilov
01/04/2010 | 04:28 PM
Sony Corp. and Panasonic Corp. reportedly want to ratify extensions to Blu-ray disc standard with the Blu-ray disc Association that would enable further capacity increase for the type of media. If the key developers of Blu-ray technology succeed in standardizing their recent achievements, then it will be possible to make dual-layer BD mediums with up to 66.8GB capacity.
Read and write at 33.4GB per layer would be implemented by utilizing partial response maximum likelihood (PRML) signal processing, reports Tech-On web-site. PRML assumes inter-symbol interference, which makes it difficult to base optical disc quality evaluation on jitter, as is widely done now for Blu-ray and other optical discs. The new method can continue to use the existing Blu-ray optics: a blue-violet laser diode with a 405nm wavelength, and an object lens with a numeric aperture (NA) of 0.85.
“At high-density recording, such as 33.4GB [per layer], the relationship between the error rate and jitter collapses, and it becomes extremely difficult to evaluate jitter. i-MLSE (Maximum Likelihood Sequence Estimation) exhibits the same relationship to signal quality as conventional jitter,” a source from Sony is reported to have said.
Unfortunately, i-MLSE calculation is very complex and Sony hopes that only recent or forthcoming hardware can calculate it in real time, hence, existing Blu-ray players and drives may be incompatible with the forthcoming BD media.
Sony plans to propose widespread adoption of i-MLSE via the BDA.
Last year the BDA said officially that existing Blu-ray disc players would not be compatible with 100GB or 200GB BD media. Nevertheless, BDA indicated that 50GB should be enough for movies for many years to come.
“I think there will be applications for larger capacity recordable discs, but it would be difficult for [discs larger than 50GB] to achieve compatibility with the installed base of players. This is because player manufacturers design players to meet published specifications that define maximum media capacity, which in the case of Blu-ray Disc, is 50GB on two-layer media,” said Andy Parsons, the chairman BDA’s promotion committee in the U.S., in an interview.