9. Preservation of carriers and replay systems after transfer

In the future, technological developments may allow improved information retrieval from physical audiovisual carriers. Similarly, new research findings or methodologies may allow users to identify additional secondary information in the original carriers.

Because of this potential for improvements in information retrieval, transfers of primary and secondary information from carrier-based formats cannot necessarily be considered definitive. Original physical carriers and suitable reproduction equipment must therefore be preserved after digitisation of their contents whenever possible.

It is quite possible however, that carrier degradation, technological obsolescence and the sheer cost of the digitisation process will prevent any further attempt. All transfers must therefore be carried out to the highest standards possible at that time.

Comment:

Original analogue sound carriers may contain secondary information which falls outside the frequency range of the primary information, and which may assist in correcting inaccuracies in the original recording. Most current transfer technologies result in an irretrievable loss of this information. For analogue magnetic audio tape for example, information about speed fluctuations (wow and flutter) may be found in the variations of the reproduced bias frequency, AC traces or background noise. Processes that can use this information to correct the primary information are now available and may become part of future transfer routines.

Another recent improvement in audio transfer technology is the non-contact, optical scanning of primary content from mechanical sound carriers. Best practices have yet to be developed, however see section 10 comments.