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.
