NDSA:Standards and Best Practices Working Group/Optical MeetingNotes

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

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

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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.

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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
    • Cabrinety Collection
    • WNYC - Audio disc project
• 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

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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.