Thursday, March 11, 2010

Digital Preservation Matters - March 9, 2010

Accelerated Life Cycle Comparison of Millenniata Archival DVD [corrected link].. Ivan Svrcek. Naval Air Warfare Center. March 2010. [75 p. PDF]
The Life Cycle and Environmental Engineering branch at China Lake installation performed an accelerated aging test of Millenniata discs with current archival grade DVDs (Delkin, MAM-A, Mitsubishi, Taiyo Yuden, and Verbatim). The test evaluated the disc stability when exposed to combined light, heat and humidity. Besides using the standard tests for predicting the lifetime of a disc, the test included looking at the initial write quality and exposure to full spectrum of light. The test also looked at the drives used to burn the discs, and which drives worked best with which discs. One conclusion with the drives was that “the device used to record an optical media can have a great impact upon the write quality and should be considered in all data storage situations.” According to the ECMA standards, “All dye-based discs failed.” That is in contrast to the Millenniata discs: “none of the Millenniata media suffered any data degradation at all. Every other brand tested showed large increases in data errors after the stress period. Many of the discs were so damaged that they could not be recognized as DVDs by the disc analyzer.”

“Ensuring that valuable digital assets will be available for future use is not simply a matter of finding sufficient funds. It is about mobilizing resources—human, technical, and financial—across a spectrum of stakeholders.” Major questions are what should we preserve, who is responsible, and who will pay for it. This looks at scholarly publications, research data, commercially owned culture content, and collectively produced web content. Three important components in developing preservation strategies :
  1. When talking about preservation, make the case for use of the materials. A decision to preserve something now does not mean a permanent commitment of resources. The value and use may be clearer later.
  2. Incentives to preserve must be clearly shown as being in the public interest.
  3. There must be agreement on the roles and responsibilities of all concerned: the information creators, owners, preservers, and users.
It is important to reduce the cost of preservation as digital information increases. The areas for priority action include:
Organizational: Develop partnerships; ensure access to skilled personnel; sustain stewardship chain.
Technical : build capacity to support stewardship in all areas; lower the cost of preservation overall.
Policy: Create incentives; clarify rights of web materials; empower organizations.
Educational: promote education and training; raise awareness of the urgency of timely preservation actions.
  • Sustainable preservation strategies are not built all at once, nor are they static. Sustainable preservation is a series of timely actions taken to anticipate the dynamic nature of digital information.
  • Commitments made today are not commitments for all time. But actions must be taken today to ensure flexibility in the future.
  • Sustainable digital preservation requires a compelling value proposition, incentives to act, and well-defined roles and responsibilities.
  • Decisions about longevity are made throughout the digital lifecycle.
  • A sustainable preservation strategy must be flexible enough to span generations of data formats, access platforms, owners, and users.
  • Preservation decisions can often be seen as an incremental cost, and are often the same as decisions made to meet current demand.
Five conditions required for economic sustainability are:
  1. recognition of the benefits of preservation by decision makers;
  2. a process for selecting digital materials with long-term value;
  3. incentives for decision makers to preserve in the public interest;
  4. appropriate organization and governance of digital preservation activities; and
  5. mechanisms to secure an ongoing, efficient allocation of resources to digital preservation activities.
AAC Audio and the MP4 Media Format. JISC Digital Media. 12 February 2010.
From the JISC advice site: This is a guide to creating and using the AAC compressed audio resources. AAC is the successor to the MP3 format; this site explains the advantages of AAC over MP3. AAC offers significant reduction of audio file size while still retaining good sound quality. The AAC audio standard is a subsection of the MPEG-4 standard and the MP4 file type is often used to deliver content. Apple added the .m4a and .m4p extensions to designate audio content. AAC requires a compatible codec for the final user to be able to listen to it. AAC uses a lossy compression; so for standards-compliant sound archiving, Broadcast WAV format should be used according to the guidelines of the International Association of Sound and Audiovisual Archives (IASA). More on BWAV at the BBC site.
If you don’t need standards compliance or absolute fidelity for your archive, or if you don’t have the storage space for the much larger uncompressed BWAV files, “then you may want to consider AAC as the overall best currently available lossy compression method.” This is an excellent site for information and contains much more on the container, encoding, versions, filetypes, bitrate, metadata, the iTunes schema, and a simplified visual representation of an MP4.

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