Optical Media: Reading Damaged CDs, DVDs and Blu-rays
Optical recovery is about read strategy: lower speed, multiple passes, and merging partial reads into one image.
Where the structure lives
ISO 9660 volume descriptors sit at fixed offsets; UDF uses anchors at 256 and near the end of the volume. With either, the directory tree can be reconstructed from a partial image.
Read strategy
Read at the slowest speed, log errors per sector, and repeat with different drives. Merge the best sectors across passes. Scratches on the label side are often worse than on the data side.
FAQ
Will polishing help?
Sometimes for surface scratches; never for delamination or rot.
Can I copy a disc with bad sectors?
Yes — image with error skipping, then rebuild files from the image.