Comparison of high definition optical disc formats Blu-ray disc players since the end of the format war. Blu-ray Disc has a higher maximum disc capacity than HD DVD (50 GB vs. 30 GB for a double layered disc). In September 2007 the DVD Forum approved a preliminary specification for the triple-layer 51GB HD DVD (ROM only) disc though Toshiba never stated whether it was compatible with existing HD DVD players. In September 2006 TDK announced a prototype Blu-ray Disc with a capacity of 200GB. TDK was also the first to develop a Blu-ray prototype with a capacity of 100GB in May 2005. In October 2007 Hitachi developed
Ultra Density Optical Ultra Density Optical Ultra Density Optical (UDO) is an optical disc format designed for high-density storage of high-definition video and data. An Ultra Density Optical disc or UDO is a 133.35 mm (5.25") ISO cartridge optical disc which can store up to 30 GB of data. The second generation UDO2 media was introduced in April 2007 and has a capacity of up to 80 GB. Utilising a design based on a Magneto-optical disc, but using Phase Change technology combined with a blue violet laser, a UDO/UDO2 disc can store substantially more data than a magneto-optical disc or MO, because of