RedDisc (REDundant DISC) is a system to add parity information to optical medias, to avoid data losses.
The system is made up of two parts: an encoder and a decoder.
The former uses the free space left on the media to add transparent parity data. The latter, in case of unreadable sectors, tries to recover them by using the parity data.
Specifications
RedDisc parity data is stored raw outside the filesystem of the media, so that even the structures of the filesystem are protected. Special markers are placed outside the filesystem as well allowing the recovery data to be found simply by a raw sectors scan. The parity data is obtained by XORing together tuples of surface-distant sectors.
At the present moment, only the encoder is implemented, and will be available soon.
The specifications of the system are being written and will be freely available soon as well.
Future directions
Possible changes include: better surface-distant sector selection, better ECC codes selection, library creation to allow easy inclusion of the system in third-party applications.