Optical Disc Preservation Master

A preservation master is the highest-quality, least-altered digital representation retained from an optical disc extraction project.

Preservation master versus access copy

For CD audio, uncompressed PCM WAV files can provide a practical preservation representation. For data discs, an appropriate disc image and/or original extracted files may be retained. For authored DVD-Video, preserving the original structure can be important.

Audio masters

The correct master depends on what information must remain recoverable from the source.

Data and disc images

Access copies such as MP3 or MP4 should be derived from verified preservation outputs rather than replacing them.

Video masters

Record technical metadata and checksums for the preservation files.

Integrity verification

Preservation masters should be stored in managed storage with backup and integrity monitoring.

Reference guidance: This article is informed by optical-media preservation guidance from the U.S. National Archives and the Library of Congress Recommended Formats Statement. Where appropriate, the article distinguishes preservation guidance from practical extraction procedures.