View source for NDSA:Standards and Best Practices Working Group/Optical MeetingNotes

'''Meeting minutes - NDSA Standards and Practices, September 15, 2014
*Minutes: Lauren Sorensen, [mailto:lsor@loc.gov 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)''' [https://twitter.com/archivetype @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
***[http://howtheygotgame.stanford.edu Cabrinety Collection]
***WNYC - Audio disc project
*'''Morgan Morel (George Blood Audio & Video)''' [https://twitter.com/av_morgan @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)''' [https://twitter.com/WNYCarchives @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.