DVD-R (DVD-Recordable) is a recordable medium with an organic dye in its recording layer which does not allow data to be rewritten or deleted once it is written on the disc. DVD-RW (DVD-Rewritable), on the other hand, is a rewritable medium with a metallic phase transitioning material in the recording layer, allowing data to be deleted and rewritten.
Both types of media are compatible with the DVD geometry and are used widely in applications that do not adapt well to mass production. When used for data exchange on a personal computer, it seems it is easier to ensure compatibility when the data is recorded using the disc-at-once method rather than the incremental write method. The service life of a recording medium is estimated based on the results of accelerated aging tests. Because a rise in temperature and humidity and ultraviolet light are known to reduce the life of the disc significantly, the disc is best stored in a dry, cool and dark location. Due to a higher recording density compared to CDs, DVD-R and DVD-RW are more susceptible to the effects of soiling such as dust, scratches and fingerprints on the disk surface, and must be handled with care and kept clean.
The specifications for DVD-R and DVD-RW were drawn up by the DVD Forum (a standardization body made up of companies and organizations involved in the research, development and manufacture of DVD products). Sales of its specifications book and licensing are done by the DVD Format/Logo Licensing Corporation. However, since it does not have a system for ensuring the quality of the widely distributed recording media, inferior media is being circulated which cannot even record or has a very short life span. The ECMA General Assembly on July 4, 2007 in Germany rather belatedly approved Standard ECMA-379, Test Method for the Estimation of the Archival Lifetime of Optical Media, which was produced by CDs21 Solutions and the Optical Storage Technology Association (OSTA) and this is expected to be adopted shortly as a standard by the International Organization for Standardization (ISO). In the final stage of the manufacturing process, recordable and rewritable DVDs have a Media Key Block (MKB) code key and a unique media ID for each medium prewritten to the DVD. These are used to generate keys for coding and decoding recorded content when using Content Protection for Recordable Media (CPRM). Because this information cannot be copied, the content is locked in the medium. If an application is used to read the manufacturer’s identification code which is included in the media ID, it is possible to find out the name of the manufacturer even if it is an OEM product or unlabeled content.
- The structure of a DVD-R (single-sided single-layer)
- The structure of a DVD-RW (single-sided single-layer)
- If you look at the reading surface at different angles, you can see the color differences. The inside is the recorded area, and the outside is the unrecorded area.
- DVD logos and symbols
- DVD drives and DVD media