https://wiki.diglib.org/index.php?action=history&feed=atom&title=NDSA%3AStandards_and_Best_Practices_Working_Group%2FOptical_MeetingNotes%2FDuryee 2026-04-16T08:54:36Z Revision history for this page on the wiki MediaWiki 1.44.0 https://wiki.diglib.org/index.php?title=NDSA:Standards_and_Best_Practices_Working_Group/Optical_MeetingNotes/Duryee&diff=6997&oldid=prev 2016-02-11T19:20:48Z

<p>5 revisions imported: Migrate NDSA content from Library of Congress</p> <p><b>New page</b></p><div>*&#039;&#039;&#039;Alex Duryee (AudioVisual Preservation Solutions)&#039;&#039;&#039; [https://twitter.com/archivetype @archivetype]<br /> **Article, meant to be intro to optical disc preservation: http://www.avpreserve.com/wp-content/uploads/2014/04/OpticalMediaPreservation.pdf<br /> **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. <br /> **What is on this disc? How to view and assess? There is no go-to process for examining. <br /> **Precedent is law enforcement - however, few criminals use CDs and optical discs so often not supported by forensics tools. <br /> **92% migration failure rate for data extraction. <br /> **Researching discs as carriers of data. <br /> **Two major types of discs - audio and data<br /> **Audio: one of first uses of consumer optical media - designed to replace 8 track<br /> **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.<br /> **Audio CDs more akin to tapes and vinyl because of this uninterrupted stream - only metadata differentiates “pieces” on the CD.<br /> **The human ear is bad at detecting small errors - CD audio standard is 44.1khz - 16 bit depth.<br /> **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? <br /> **CD-ROM/ data CDs - ISO 9660 - Similar to audio discs except broken to sessions and tracks <br /> **See it in a file browser and directories - convenient for archivists, what you see is what you get.<br /> **Data cds can contain multiple filesystems - older, early mid-90s HFS file systems were common.<br /> **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. <br /> **UDF filesystem started being used, manufacturers getting together to consistently use this filesystem. <br /> **ISO Buster - tool for this filesystem breakdown. <br /> **Other projects<br /> ***Cabrinety Collection<br /> ***WNYC - Audio disc project</div>

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