5.6.3 Selection of Best Copy

5.6.3.1  Unlike copying analogue sound recordings, which results in inevitable loss of quality due to generational loss, different copying processes for digital recordings can have results ranging from degraded copies due to re-sampling or standards conversion, to identical “clones” which can be considered even better (due to error correction) than the original. In choosing the best source copy, consideration must be given to audio standards such as sampling and quantisation rate and other specifications including any embedded metadata. Also, data quality of stored copies may have degraded over time and may have to be confirmed by objective measurements. If there is only one copy in poor physical condition in a collection, it may be wise to contact other sound archives to determine whether it is possible to find a better preserved copy of the same item.

5.6.3.2  As a general rule, a source copy should be chosen which results in successful replay without errors, or with the least errors possible. Replicated discs are more stable than recordable media and would normally be preferred if a choice is available. Physical condition may provide an indication of quality, however the only certain method for choosing an error free disc is to institute routine error checking and reporting as part of the transfer process.Even with error checking and reporting,the extraction of best possible signal is problematic as the lack of standards with drives means that different players may produce different results on the same disc (see 8.1.5 Optical Discs – Standards). As with all digital to digital transfers,an error status report must be made and incorporated in the administrative metadata of the digital archive file, along with a record of the drive used.