Optical disc an additional tolerance to allow the use of less-than-perfect analog audio pre-filters to remove any higher frequencies. The first version of the standard allowed up to 75 minutes of music which required 650MB of storage. The DVD disc appeared after the CD-ROM had become widespread in society. The third generation optical disc was developed in 2000–2006 and was introduced as Blu-ray Disc. First movies on Blu-ray Discs were released in June 2006. Blu-ray eventually prevailed in a high definition optical disc format war over a competing format, the HD DVD. A standard Blu-ray disc can hold about 25 GB of
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