aic 2015 issues in cd-da preservation and archiving
TRANSCRIPT
This is who I am.
Our worries have been confirmed by studies
NIST/Library of Congress (LC) Optical Disc Longevity
study. 2007.
30 - 45 years
Pulse-code modulation
Figure 3. The pulse-code modulation stream to digital signal to analog signal chain. An Introduction to Optical Media Preservation, http://journal.code4lib.org/articles/9581
The CD-DA
YES – 44.1/16 WAV
YES – 44.1/16 WAV
MediaInfo XML > PBCORE XMLPBCore XM
L > BEXT CHUN
K / DAVID DBX
YES – 44.1/16 WAV
MediaInfo XML > PBCORE XML
YES – 44.1/16 WAV
NO
PBCore XML > BEXT CH
UNK / DA
VID DBX
YES – 44.1/16 WAV
MediaInfo XML > PBCORE XML
YES – 44.1/16 WAV
NO
NO
PBCore XML > BEXT CH
UNK / DA
VID DBX
BLER - It represents correctable random error and is
generally not used as an indicator of failure or lost
information.
E22 - The second tier of error correction. Correctable errors
but require more robust methods of correction.
E32 - Uncorrectable errors that are present after C2 error
correction. cannot be played at all because they contain
data that cannot be recovered.
PlextoolsThe results of the tests may differ from system to system, and should always be viewed in context, like test environment, used hardware, software, media, etc.
IASA TC-04
Fig 1. Section 8.1: Accumulated errors in a CD-R over time
8.1.11.6.1 There are a number of downloadable testers available online which use a computer’s inbuilt CD/DVD drive to measure error in written CD and DVDs. However, due to the limitations of the software and inaccuracy of the drives, most, if not all, are unsuitable for archival purposes.
IASA TC-04 8.1.9 Errors, Life Expectancy and Testing and Analysis
BLER average < 10
BLER peak < 220
E 22 (correctable errors) 0
E 32 (uncorrectable errors 0
● 2398 silver Mitsui Silver CD-Rs ripped (CDs were created from 2001 - 2003)
● Tested 20% of the silver CDs randomly using Plextools, measuring for BLER, E22, E32 errors
No discs passed the IASAs specifications for errors, even though the test results varied widely.
The Good
The Good The Bad
The Good The Bad The Ugly
TAKEAWAYS1. CD-DA don’t last long, maybe less long that we thought.
2. It is really hard to know why CD-DAs go bad.
3. Accelerating aging tests only tell a part of the story, but there does seem to general trend of decay over time.
4. New solutions for comprehensive testing and ripping of CD-DAs into archives.
QC Tools for CD-DA$30,000 - $50,000● Audio Development● DaTARIUS● Expert Magnetic Corporation
$3,000 - $8,000● Clover Systems
$0 - $25.00● Plextools PlexUtilities● QPxTools/Qscan● OptiDrive Control● Nero● PXScan/PXView
