What Is Dual-Layer DVD Extraction?

Dual-layer DVDs store data across two recording layers and can contain authored video or computer data. Extraction must account for the complete disc rather than treating it as a simple single-layer file store.

Dual-layer structure

Dual-layer media can contain substantially more data than a single-layer DVD and is commonly encountered in authored video and large data collections.

DVD-Video

The extraction process should read the complete disc and verify that content from both layers has been recovered.

Data DVDs

Where the original disc structure matters, retain an image or faithful source representation before creating access derivatives.

Layer transitions

Do not use file size alone as proof of successful recovery; compare the expected structure and verify extracted files.

Verification

Record disc identifiers, recovered structures, errors and checksums.

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.