optical.md

Optical Media

Sector format

CD-ROM sectors are 3234 bytes in length on the media, but only around 2448 bytes of this is visible to the computer.

struct sector {
    struct frame {
        uint8_t data[33];
    } frames[98];
};

To-Do

• Describe various sector formats.
  • 2048-byte sectors are what you see if you try to "image" a CD-ROM using /dev/sr0 and ddrescue. This is what gets put into an .iso file and is good enough for most stuff. This contains no subcodes or ECC information.
  • 3234-byte sectors are the true format of a CD, but you'll never see this. Only the drive firmware does.
  • 2448-byte sectors are returned by cdrdao read-cd --read-raw --read-subchan rw_raw and put TRACK MODE1_RAW RW_RAW in the .toc file. It includes 96 bytes of subchannel data, 2048 bytes of data, ...

    struct sector {
    
    }

  • 2352-byte sectors ...

Software

• cdrdao: Disk-At-Once Recording of Audio and Data CD-Rs/CD-RWs
• wodim and readom: wodim allows you to create CDs or DVDs on a CD/DVD recorder. It supports writing data, audio, mixed, multi-session, and CD+ disc and DVD data and video disks on DVD capable devices, on just about every type of CD/DVD recorder out there.
• dvd+rw-mediainfo: Retrieves media DVD media type and information.
• cdemu: A software suite designed to emulate an optical drive and disc.
  • libMirage: A CD-ROM image access library.
• Alcohol 120%: Creates backups of CDs and DVDs. Can also determine the type of copy protection used on some discs.
• DiscImageCreator: This is redump.org's tool for dumping optical discs.