Remastering
Remastering is the process of making a new master for an album, movie, or any other creation. It tends to refer to the process of porting a recording from an analogue medium to a digital one, but this is not always the case.
For example, a vinyl LP originally pressed from a worn-out pressing master many tape generations removed from the "original" master recording could be remastered and re-pressed from a better-condition tape. All CDs created from analogue sources are technically digitally remastered.
The process of creating a digital transfer of an analogue tape remasters the material in the digital domain, even if no equalization, compression, or other processing is done to the material. Ideally, because of their high resolution, a CD or DVD (or other) release should come from the best source possible, with the most care taken during its transfer.
Additionally, the earliest days of the CD era found digital technology in its infancy, which sometimes resulted in poor-sounding digital transfers. The earliest days of the DVD era were not much different, with early DVD copies of movies frequently being produced from worn prints, with low bitrates and muffled audio. When the first CD remasters turned out to be bestsellers, companies soon realized that new editions of back-catalogue items could compete with new releases as a source of revenue. Back-catalogue values skyrocketed, and today it is not unusual to see expanded and remastered editions of fairly modern albums.
Master tapes, or something close to them, can be used to make CD releases. Better processing choices can be used. Better prints can be utilized, with sound elements remixed to 5.1 surround sound and obvious print flaws digitally corrected. The modern era gives publishers almost unlimited ways to touch up, doctor, and "improve" their media, and as each release promises improved sound, video, extras and others, producers hope these upgrades will entice people into making a purchase.
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