"Swiss chemical company Clariant International and Japan's Toshiba have jointly developed a dye that is necessary for dual-layer recordable HD-DVD discs capable of storing 30GB of data, they said Friday.

HD-DVD is one of two next-generation optical disc formats that are competing to replace today's DVDs. The other format is Blu-ray Disc.

In addition to developing the dye, which is used on each recording layer, the two companies also produced prototype dual-layer discs and verified that they work, said Junko Furuta, a spokeswoman for Toshiba in Tokyo.

At present, the highest capacity HD-DVD-R discs that have been standardised are single-layer 15GB discs. The two companies have already proposed the dual-layer disc to the DVD Forum standards body with the hope that approval will come by the end of this year, said Furuta.

There are two other formats that make up the HD-DVD family. The read-only HD-DVD-ROM format will be used for prerecorded content like movies and has already been standardized at 15GB single-layer and 30GB dual-layer. A triple-layer version capable of storing 45GB is going through the standardisation process. There is also a rewritable format called HD-DVD-RW that has been standardised at 20GB. A future version of the rewritable disc that can hold around 32GB is under development."