Editing Digitization (section)

== Audio digitization and reformatting ==
Audio media offers a rich source of historic ethnographic information, with the earliest forms of recorded sound dating back to 1890.<ref name=":0">{{cite web|url=http://www.clir.org/wp-content/uploads/sites/6/pub164.pdf|title=ARSC Guide to Audio Preservation}}</ref> According to the [[International Association of Sound and Audiovisual Archives]] (IASA), these sources of audio data, as well as the aging technologies used to play them back, are in imminent danger of permanent loss due to degradation and obsolescence.<ref>{{Cite journal|last=Casey|first=Mike|date=January 2015|title=Why Media Preservation Can't Wait: The Gathering Storm|url=https://www.avpreserve.com/wp-content/uploads/2015/04/casey_iasa_journal_44_part3.pdf|journal=IASA Journal|volume=44|pages=14–22}}</ref> These primary sources are called “carriers” and exist in a variety of formats, including wax cylinders, magnetic tape, and flat discs of grooved media, among others. Some formats are susceptible to more severe, or quicker, degradation than others. For instance, lacquer discs suffer from [[delamination]]. Analog tape may deteriorate due to [[Sticky-shed syndrome|sticky shed syndrome]].<ref>{{cite web|url=http://www.clir.org/wp-content/uploads/sites/6/pub164.pdf|title=ARSC Guide to Audio Preservation|access-date=2019-05-04}}</ref>

[[File:Analog tape playback.jpg|thumb|1/4" analog tape being played back on a Studer A810 tape machine for digitization at Smithsonian Folkways Recordings|alt=]]

Archival workflow and file standardization have been developed to minimize loss of information from the original carrier to the resulting digital file as digitization is underway. For most at-risk formats (magnetic tape, grooved cylinders, etc.), a similar workflow can be observed. Examination of the source carrier will help determine what, if any, steps need to be taken to repair material prior to transfer. A similar inspection must be undertaken for the playback machines. If satisfactory conditions are met for both carrier and playback machine, the transfer can take place, moderated by an [[analog-to-digital converter]].<ref>{{cite web|url=https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/technical-bulletins/digitization-audio-tapes.html#a2|title=The Digitization of Audio Tapes – Technical Bulletin 30|last=Institute|first=Canadian Conservation|date=2017-09-14|website=aem|access-date=2019-05-04}}</ref> The digital signal is then represented visually for the transfer engineer by a [[digital audio workstation]], like Audacity, WaveLab, or Pro Tools. Reference access copies can be made at smaller sample rates. For archival purposes, it is standard to transfer at a sample rate of 96&nbsp;kHz and a bit depth of 24 bits per channel.<ref name=":0" />