DVD & CD Information


DVDs come in recordable and non-recordable formats, originally used for data storage and now used mainly for media, film and video presentation.





Disc replication is done in a number of steps. First a glass master is created, from the original master disc supplied from the client. This glass master is then used to create a nickel stamper. This stamper is then used to injection mould clear optical discs (polycarbonate substrates). This process is quite different from disc 'duplication', which is outlined below.


This process involves burning content onto blank media such as CDR or DVDR discs, and does not involve the creation of a master or stamper. It is therefore suited to smaller quantities of discs.


A CD (which stands for Compact Disc) is an optical storage disc, for digital data (originally digital audio). CDs were later adapted for use as CD-ROM discs which could store significantly larger quantities of data. CD Drives use an optical sensor to read CD disc layers and the data content within. CDs are made from polycarbonate plastic, 1.2mm thick, with a thin layer of super purity aluminium (or rarely, gold) applied to the surface and protected by a film of laquer. Printing methods for CD cover art and label art are silk-screening and offset printing. Data on a CD is stored in a series of tiny indentations (or pits) encoded in a spiral of pits in the top layer of the disc. In between the pits are areas known as 'lands'. The most common size of CD is 120mm in diameter, with typically, a 74 or 80 minute capacity for music, or a 650-700MB data capacity. Singles were released on 80mm discs, which can hold 21 minutes of audio, or 184MB of data.