by Mike Casey, Director of Technical Operations, Audio/Video, Media Digitization and Preservation Initiative, Indiana University
The primary job of a digitization facility is, of course, to digitize. This is hands-on work that must be completed onsite. With the onset of the COVID-19 pandemic, our audio digitization engineers were facing weeks, if not months, of working from home. The prospect of developing work-at-home projects was beginning to seem a bit daunting when Tony Tadey, multimedia specialist at the Jacobs School of Music, reminded me of the Digital Audio Tape (DAT) transfer project from a couple of years ago that had ‘a few issues.’ These issues prompted the use of words such as unlistenable, glitchy, distorted, and ‘that awful screechy sound’ by staff and students listening to the files.
During the DAT transfer project, we learned that 30% or more of tapes held at IU Libraries Cook Music Library were either unusable or of limited use to researchers due to overwhelming digital errors that resulted in audio that can best be described using the colorful words in the paragraph above. It can be an extremely violent interruption of the intended audio. DAT has long been considered a problem format with degradation, machine alignment, and playback equipment obsolescence issues complicating the transfer to digital files.
We were saved by a decision made back in the 1990s when DAT was in heavy use, and another made five years ago.
Jacobs School staff were concerned about the longevity and stability of the DAT format from the beginning. To mitigate the risk of entrusting archival content to this format, many recitals and concerts were recorded onto two DAT tapes simultaneously. Some may have raised their eyebrows at this, but Jacobs School staff were prescient—and right.
At the beginning of the DAT transfer project in 2015, IU and its vendor, Sony Memnon, decided to use the NOA system which collects error rate, interpolation, and concealment data for each transfer. Nearly 9,000 DATs were transferred using NOA.
With two recordings of the same event, there exists the possibility that passages with errors in one may be fine in the other. With error information for all transfers, there also exists the possibility that we could predict which tapes have errors and their level of severity, rather than attempting the impossible task of listening to all 9,000 end-to-end.
So, QC specialist Glenn Hicks listened to 400 files, assigning each to a category representing the severity of its errors. From this, we were able to develop a metric that enabled us to predict the condition of the audio on each tape. Audio engineer Dan Figurelli then sampled the files and confirmed that, indeed, there were many occasions where good audio on one tape could replace bad audio on another.
To begin a project comparing files from two recordings and constructing a compilation file with the best of both, all we needed were the files, audio editing software, and audio editing chops.
Did I tell you about my four audio engineers who needed work that could be done at home? Bingo! A most worthwhile, not to mention substantial, work-at-home project was born. We can supply the files, the engineers have the editing chops, and they all have appropriate software in their home studios. (In fact, they all use Pro Tools at home.)
Productivity is something that we often prioritize within MDPI, but productivity is a lesser concern in this project. More important is the fact that our audio engineering staff is able to stay safe and healthy while also tackling work that moves our project forward. Many of these files are not usable in part or in toto. Every time we successfully construct a compilation file, we rescue content that becomes usable for research. Before COVID-19, no one had the resources available to work with the DAT content. COVID-19 has dealt all of us a very difficult hand. We are trying to make the best of it, saving audio file-by-file.
That is a victory!
(Above: A segment from a DAT with digital errors)
(Above: The same DAT after compilation)
(Above: Another segment from a DAT with digital errors)
(Above: The same DAT after compilation)
P.S. The title of this post references the fact that most of the content on these tapes is classical music. It also references this classic Saturday Night Live skit: