To do cd and dvd duplication, one usually first creates a disk image with a full file system designed for the optical disc, and then burns the image to the disc. The disc image is a single file, built and stored on the hard drive, which contains the entire information to be contained on the disc.
Many programs create the disc image and burn in one bundled operation, so that end-users often do not know the distinction. However, a useful motivation for learning this distinction is that creating the disc image is an "expensive" (time-consuming) process. Most disc writing applications will silently delete this image from the "temporary directory" in which it was built unless users instruct the disc burning application to preserve the image, which can then be used for creating further copies of the same image without the need to rebuild the image each time.
There are also packet-writing applications that do not require writing the entire disc at once, but allow writing parts at a time, allowing the disc to be used in the same way as rewritable media such as floppy disk.
There exist many optical disc authoring technologies for optimizing the authoring process and preventing errors. Discs writeable only once whose burn failed are colloquially termed coasters since that is almost all they are good for, as well being primitive frisbees.
Some operating systems are aware of disc images as a filesystem type, and can mount these images so that they appear as actual mounted discs. This feature can be useful for testing a disc image after authoring but before writing to the disc media.
However, cd replication is different and doing it involves different tasks.
To do so, a glass master from a client original master need to be created, a nickel stamper also need to be created from that glass master. Afterwards, the molding of clear optical-grade polycarbonate substrates (clear discs) is injected from that stamper. Finally,
the metallizing and lacquering of those substrates is done in order to produce compact discs and DVDs. |
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