NDSA:September 15, 2014 Standards and Practices Working Group Agenda and Notes

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Meeting minutes - NDSA Standards and Practices, September 15, 2014

  • Minutes: Lauren Sorensen, email me with any changes/updates

Announcements & Project Updates

Kate Murray: Ranking stumbling blocks for video preservation, put a call out to NDSA members, meeting on 26th of Sept. Contact Kate at kmur@loc.gov to join for meeting details

Andrea Goethals: next call S&P call will be on October 20th - continue discussion on optical media 1-2pm.

August 25th, a closed meeting happened about preserving and accessioning email records; attendees included Stanford, Harvard, NARA. Interest in opening this up to any NDSA members working with this material, aim to host listservs and list of toolsets. Coming soon: Signal blog post from Chris Prom about this meeting.

Different aspects of optical discs; still interest in our group. Welcome anyone working in this area to contribute to discussions.

Today's discussion topic: Optical Media

Topics and Speakers:

Speakers today: Michelle Youket (LOC), Alex Duryee (AVPS), Morgan Morel (George Blood Audio & Video).

  • Michelle Youket (LOC)
    • Goal is to develop strategies for preservation of optical media
    • Natural and accelerated aging
    • 1996 - pilot study - 125 random optical discs were selected from LOC collections
    • Monitor effects of storage and use
    • Later expanded to 1200 discs and wide range of dates of manufacture
    • Follow 1SO 18921 standard
    • Adhesive labeled disc after 1000 hours aging error rates higher
    • Measured effects of laser engraving
    • CD-R more stable than DVD - larger size of data pitch for CD, more data to be corrupted in a smaller area with DVD.
    • Dye and reflective composition - significant factor in degradation - gold more stable than silver.
    • Cyanine, meant as long strategy dye.
    • Phthalocyanine - at times, hard to differentiate upon inspection.
    • LOC created error checker software as an assessment tool.
    • JVC archival disc system error checker disc drive
    • Disc-to-disc migration
    • Burn tests
    • Report fields: media / brand / dye / jitter
  • Alex Duryee (AudioVisual Preservation Solutions) @archivetype
    • Article, meant to be intro to optical disc preservation: http://www.avpreserve.com/wp-content/uploads/2014/04/OpticalMediaPreservation.pdf
    • Research being done by colleagues - studying preservation of physical media but little information exists about the process of extraction and logical structure of what is on a disc.
    • What is on this disc? How to view and assess? There is no go-to process for examining.
    • Precedent is law enforcement - however, few criminals use CDs and optical discs so often not supported by forensics tools.
    • 92% migration failure rate for data extraction.
    • Researching discs as carriers of data.
    • Two major types of discs - audio and data
    • Audio: one of first uses of consumer optical media - designed to replace 8 track
    • Instead of filesystem paradigm these discs featured a single stream of modulated data running uninterrupted throughout the disc, with byte level metadata, such as track names.
    • Audio CDs more akin to tapes and vinyl because of this uninterrupted stream - only metadata differentiates “pieces” on the CD.
    • The human ear is bad at detecting small errors - CD audio standard is 44.1khz - 16 bit depth.
    • Even the best consumer/ professional hardware has a 98-99% accuracy in a given read - not good for preservation, as don’t know if you’re getting what you need - is it capturing important metadata?
    • CD-ROM/ data CDs - ISO 9660 - Similar to audio discs except broken to sessions and tracks
    • See it in a file browser and directories - convenient for archivists, what you see is what you get.
    • Data cds can contain multiple filesystems - older, early mid-90s HFS file systems were common.
    • Can contain all 3 filesystems and operating system used to extract data will default to one it can read. So: sometimes the OS can’t see the filesystem.
    • UDF filesystem started being used, manufacturers getting together to consistently use this filesystem.
    • ISO Buster - tool for this filesystem breakdown.
    • Other projects
  • Morgan Morel (George Blood Audio & Video) @av_morgan
    • 500 once written DVDs - American Folklife Collection Veterans History Project.
    • Staff at vendor asked to create findings report; outlining troubles and tools used.
    • Formats for medium term storage white paper; ISO disc image recommended.
    • ISO disc image can be mounted filesystem as if it were inserted into drive
    • Extract production master files
    • VideoTS folder and AudioTS folder
      • [Going through folders as they appear:] VideoTS is all video content - IFO is info about playback and navigation
      • VOB - audio and video data _0 menus - limit to 1GB content - need to connect to make more than one to make it playable
      • All folders listed needed to be intact
    • CLI: *ended up using most for project on-site at George Blood.
      • hdiutil*
      • dd
      • ddrescue*
    • GUI:
      • Mediagrabber
      • DVD Decrypter
      • Used hdutil and ddrescure - powerful for automated systems run from server
      • make workable iso images in case of damage etc
    • Tools for extraction: *ended up using most for project on-site at George Blood.
      • GUI: compressor, handbrake, mpegstreamclip, streamz
      • CLI: FFmpeg*
    • Out of 500 DVDs, 49 were problematic
    • 9 had physical issues - ok after polishing
    • Cloning errors for rest - ddresue could still make working ISO images
    • 31 were DVD-ROM instead of DVD-video.
    • http://www.digitizationguidelines.gov/audio-visual/documents/IntrmMastVidFormatRecs_20111001.pdf
  • John Passmore (WNYC) @WNYCarchives
    • 30,000 CD-DA - CD-Rs with encoded audio
    • Created in early 2000s by WNYC staff
    • Considered preservation masters for that era
    • Group of CDs were made using same machines, same brands of discs, so in a sense a control group
    • CDs function as material for the reference library for a long time - Librarians noticed that pulling CDs some were not playing, ripping properly, determined a need to get data off of the CDs ASAP, purchased equipment and made a RIP station.
    • Ripped about 8k CDs, dumping wav files at digital asset management station, cataloging.
    • First wanted to test some to learn about increase in errors and condition of collection.
    • Plextor drives used.
    • Large spectrum of discs regardless of year they were from and different levels of accessibility.
    • 2400 Mitsui silver CD-Rs
    • 20% of silver cds measuring previously detectable errors
    • None passed IASA’s specs for errors - technicians instead looking for what CD is getting kicked out and why.
    • Not gradual increase based on date - totally random variables
    • Conclusion: CD-DAs don’t last long and are unpredictable, accelerating aging only part of issues with optical media - hardware to make data, care and handling etc.
    • More open source solutions would be great to use with hardware that exists
    • Contact John Passmore at WNYC: jpassmore@nypublicradio.org

Kate: Running out of time, John Spencer will present on MDisc at next month's meeting.

  • Discussion
    • Spencer: Plextor: only been a year that current iteration of the company has been making their own drives and have dropped support for some of their software tools.
      • Observation that understand nature of companies - rebranding burners.
    • Passmore: Optidrive (?), other software
    • Duryee: Secondary market now for equipment - price spike in true quality plextor drives - going for a lot used before bought by another company (current iteration of brand).
    • Blood: we’re always talking about a system - drive from trusted manufacturer, CD that isn’t playing, sometimes a cheap player can help resolve playability issue.
    • Youket: differences in disc composition - many different dyes with different patents - that’s why focus was on developing and using error checkers.
    • Blood: Interest in how to optimize burn speeds to get low error rates. Batch variation: Mitsui sold 4 times in 5 years.
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