Mastering

Mastering is the creation of a single "master" copy of an existing recording for bulk duplication. It includes preparation of the sound recording itself and creation of the ultimate physical master copy (for LPs, the lathe-cut lacquer; for CDs, the glass master) from which all subsequent copies are created.

In some contexts, preparing the sound recording itself is called pre-mastering, with the term mastering referring just to the creation of the physical master.

Preparation of a sound recording may include adjustments such as volume changes, re-equalization, and dynamic compression. These adjustments are usually made to compensate for the sonic characteristics of the original recording, or of the medium that will carry the final copy of the recording. More controversially, these adjustments may be made to meet record label expectations about how the sound should be perceived by the listener (see loudness wars).

Mastering is also used as a noun, to distinguish between versions of a single recording that has been duplicated from more than one distinct master copy. For example, if different master duplication copies were created for a Japanese release than were used for the German release, one would refer to the "Japanese mastering" of the release versus the "German mastering". Many CD releases exist in multiple distinctly different, but unlabeled, masterings -- they can only be distinguished by listening to the CDs themselves, or by knowing which label/packaging designs and matrix codes are associated with each version of the recording.

Remastering

The term remastering simply implies that the recording in question has already been mastered and released to the public previously. There is no technical difference between the process of mastering and the process of "re"-mastering.