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takyon [soylentnews.org] writes:

Sony Releases Quad-Layer 128 GB BD-R XL Media [anandtech.com]

Sony is about to start selling the industry's first 128 GB write-once BD-R XL optical media. The discs will also be the first quad-layer BDXL media formally aimed at consumers, but bringing benefits to professionals that use BDXL today.

Although the general BDXL specifications were announced back in 2010 [blu-raydisc.com] for multi-layered write-once discs with 25 GB and 33.4 GB layers, only triple-layer BDXL discs with a 100 GB capacity (generally aimed at broadcasting, medical, and document imaging industries) have been made available so far. By contrast, quad-layer 128 GB media has never seen the light of day until now.

As it turns out, increasing the per-layer capacity of Blu-ray discs (BDs) to 33.4 GB via a technology called MLSE (Maximum Likelihood Sequence Estimation) was not a big problem, and most of today's BD players and optical drives support the BDXL standard. However, increasing the layer count to four while ensuring a broad compatibility, signal quality across four layers, yields, and some other factors slow downed release of 128 GB BDXL essentially by eight years.

Related: Ultra HD Blu-Ray Specification Completed [soylentnews.org]

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