IASA 2022 Annual Conference

Audio preservation (digitization) requires creating a preservation master file that represents the original recording exactly “as-is” with regard to (1) playback speed, (2) track configuration, (3) direction and (4) duration. i.e. the preservation master file is intended to be a digital surrogate of the original recording. This means that the playback machines should be set-up, aligned and calibrated to each item; the audio should be digitized at a high resolution; and there can be no signal processing applied to the digitized preservation master file. However, some historic recordings do not maintain the same playback settings throughout the duration of the recording, which complicates the transfer process and the resulting audio file(s). Some current practices for dealing with setting changes include creating multiple master files for each item/side or creating a continuous transfer that contains the in-between “diagnosis time”. Neither of these approaches meet the requirements for a true digital surrogate and can lead to complications in the future.
This presentation will discuss a new method for creating a “Compiled Preservation Master File” when the original recording changes settings. In short, this involves capturing the item’s analog signal throughout one continuous digitization, then uses markers and zero-crossings to remove segments of the “rewind and diagnosis” time. The resulting file, which is accompanied with an automatically-generated AES-31-3 formatted Audio Decision List; the Digital Audio Workstation session file; and the Initial Transfer file, proves to meet all four criteria for preservation master files, while precisely documenting the necessary edit points.