AIRCC's International Journal of Computer Science and Information Technology

Open Access Open Access  Restricted Access Subscription Access

Compact Preservation of Scrambled CD-ROM Data


Affiliations
1 Computer Science Department, The University of Alabama in Huntsville, Huntsville, Alabama, United States
 

When preserving CD-ROM discs, data sectors are often read in a so-called “scrambled mode” in order to preserve as much data as possible. This scrambled data is later unscrambled and further processed into a standard CD-ROM disc image. The process of converting the scrambled data into a standard CD-ROM disc image is potentially lossy, but standard CD-ROM disc images exhibit much higher software compatibility and have greater usability compared to the scrambled data from which they are derived. Consequently, for preservation purposes, it is often necessary to store both the scrambled data and the corresponding standard disc image, resulting in greatly increased storage demands compared to storing just one or the other. Here, a method that enables compact storage of scrambled data alongside the corresponding (unscrambled) standard CD-ROM disc image is introduced. The method produces a compact representation of the scrambled data that is derived from the unscrambled disc image. The method allows for (1) storage of the standard unscrambled disc image in unmodified form, (2) easy reconstruction of the scrambled data as needed, and (3) a substantial space savings (in the typical case) compared to storing the scrambled data using standard data compression techniques.

Keywords

Compact Disc, Compression, Data Preservation, Scrambled.
User
Notifications
Font Size

  • M. Guttenbrunner, C. Becker, and A. Rauber, ―Keeping the game alive: Evaluating strategies for the preservation of console video games,‖ International Journal of Digital Curation, vol. 5, no. 1, Jun. 2010. [Online]. Available: https://doi.org/10.2218/ijdc.v5i1.144

  • F. Cifaldi, ――It’s just emulation!‖ - The challenge of selling old games,‖ in Game Developers Conference, 2016. [Online]. Available: https://www.gdcvault.com/play/1023470/contactUs

  • J. Newman, ―The music of microswitches: Preserving videogame sound—a proposal,‖ The Computer Games Journal, vol. 7, no. 4, pp. 261–278, 2018. [Online]. Available: https://doi.org/10.1007/s40869-018-0065-8

  • N. Nylund, P. Prax, and O. Sotamaa, ―Rethinking game heritage–towards reflexivity in game preservation,‖ International Journal of Heritage Studies, vol. 27, no. 3, pp. 268–280, 2021. [Online]. Available: https://doi.org/10.1080/13527258.2020.1752772

  • E. P. Conaway, Server Worlds: Preservation, Virtualization, and Infrastructures of Control in Online Gaming. University of California, Irvine, 2021.

  • ―Data interchange on read-only 120 mm optical data disks (CD-ROM),‖ Ecma International, Geneva, Switzerland, Standard, Jun. 1996. [Online]. Available: https://www.ecma-international.org/publications-and-standards/standards/ecma-130/

  • L. B. Vries and K. Odaka, ―CIRC-the error-correcting code for the compact disc digital audio system,‖ in Audio Engineering Society Conference: 1st International Conference: Digital Audio. Audio Engineering Society, 1982.

  • K. Immink, ―Modulation systems for digital audio discs with optical readout,‖ in ICASSP ’81. IEEE International Conference on Acoustics, Speech, and Signal Processing, vol. 6, 1981, pp. 587–589.

  • ―Multimedia command set - 5 (MMC-5),‖ T10, Washington, D.C., USA, Standard, Oct. 2006. [Online]. Available: http://www.t10.org/cgi-bin/ac.pl?t=f&f=mmc5r04.pdf

  • Redump.org Community, ―Combined offset in eac,‖ 2010, accessed Jun. 15, 2022. [Online]. Available: http://forum.redump.org/topic/7649/combined-offset-in-eac/

  • Accuraterip.com, ―Accuraterip,‖ 2010, accessed Jun. 15, 2022. [Online]. Available: http://www.accuraterip.com/

  • Redump.org Community, ―CD dumping guide with audio tracks (old),‖ 2022, accessed Jun. 15, 2022. [Online]. Available: http://wiki.redump.org/index.php?title=CD_Dumping_Guide_with_Audio_Tracks_(Old)&oldid=46420

  • ——, ―DiscImageCreator: Optical disc drive compatibility,‖ 2022, accessed Jun. 15, 2022. [Online]. Available: http://wiki.redump.org/index.php?title=DiscImageCreator: _Optical_Disc_Drive_Compatibility&oldid=48878

  • sarami, ―DiscImageCreator,‖ https://github.com/saramibreak/DiscImageCreator, 2022, accessed Jun. 15, 2022.

  • K. Kaspersky, CD Cracking Uncovered: Protection Against Unsanctioned CD Copying. Wayne, PA, USA: A-List Publishing, 2004.

  • Human Head Studios, ―Rune,‖ 2000, accessed Jun. 15, 2022. [Online]. Available: https://web.archive.org/web/20130622083143/http://www.rune-world.com/

  • Redump.org Community, ―Moderating guidelines for IBM PC and other systems,‖ 2021, accessed Jun. 15, 2022. [Online]. Available: http://wiki.redump.org/index.php?title=Mode rating_guidelines_for_IBM_PC_and_other_systems&oldid=45839

  • ——, ―Issues dumping pc disc with ―code lock‖ copy protection,‖ 2021, accessed Jun. 15, 2022. [Online]. Available: http://forum.redump.org/topic/29842/issues-dumping-pc-disc-with-code-lock-copy-protection/page/2/

  • J. P. MacDonald, ―xdelta: open-source binary diff, differential compression tools, VCDIFF (RFC 3284) delta compression,‖ 2016, accessed Jun. 15, 2022. [Online]. Available: http://xdelta.org/

  • I. Pavlov, ―7-Zip,‖ 2021, accessed Jun. 15, 2022. [Online]. Available: https://www.7-zip.org/


Abstract Views: 108

PDF Views: 90




  • Compact Preservation of Scrambled CD-ROM Data

Abstract Views: 108  |  PDF Views: 90

Authors

Jacob Hauenstein
Computer Science Department, The University of Alabama in Huntsville, Huntsville, Alabama, United States

Abstract


When preserving CD-ROM discs, data sectors are often read in a so-called “scrambled mode” in order to preserve as much data as possible. This scrambled data is later unscrambled and further processed into a standard CD-ROM disc image. The process of converting the scrambled data into a standard CD-ROM disc image is potentially lossy, but standard CD-ROM disc images exhibit much higher software compatibility and have greater usability compared to the scrambled data from which they are derived. Consequently, for preservation purposes, it is often necessary to store both the scrambled data and the corresponding standard disc image, resulting in greatly increased storage demands compared to storing just one or the other. Here, a method that enables compact storage of scrambled data alongside the corresponding (unscrambled) standard CD-ROM disc image is introduced. The method produces a compact representation of the scrambled data that is derived from the unscrambled disc image. The method allows for (1) storage of the standard unscrambled disc image in unmodified form, (2) easy reconstruction of the scrambled data as needed, and (3) a substantial space savings (in the typical case) compared to storing the scrambled data using standard data compression techniques.

Keywords


Compact Disc, Compression, Data Preservation, Scrambled.

References