In a “here now, gone tomorrow” world, sometimes you have digital audio content that you want to withstand the test of time. Archiving these files can be time-intensive, and require very specific gear. Today we will go over a recent foray into digital audio archiving, and our approaches to doing so.
Digital Audio Archiving 101
Recently, I was asked to create a proposal for a non-profit organization to archive over 25 years worth of audio recordings. All in various formats, including cassettes, DAT tapes and Minidiscs. Thousands of recordings and all of the formats require real-time transfers. Time is of the essence preserving the content on the DAT tapes, because they are a physically fragile format. They have a lifespan of around 10 years or 15-20 years for ‘archival’ quality tapes.
Professional services will do this kind of digitization, but the costs would have been entirely prohibitive for this organization. Typically around $20/tape or disc. What they did have available was a very willing pool of volunteers. So I based my digital audio archiving proposal on taking advantage of this free labor pool.
Creating a Gameplan
My initial concept was to do all the DAT transfers staying entirely in the digital domain. Utilize the S/PDIF digital outputs from the DAT recorders directly into either computer interfaces or into SD card audio recorders. Many Mac computers have optical digital audio inputs. Although Apple has chosen to eliminate this handy feature on all their newer Macbooks and iMacs. I researched all the digital audio recorders currently on the market and the only 2-track one I could find with this capability was the Tascam DR100-MKII. Unfortunately, Tascam has discontinued this model and replaced it with several others, none of which have digital input capability. I already owned a number of these, so I began running some tests with these and with some older Mac computers.
As is often the case, things were not as simple as they seemed. Consequently, many of the DAT recordings are recorded “long-play” speed. Meaning the sampling rate was 32 Kbps, which the DR100’s would not accept. It also turns out that the core audio in Mac OS-X only handles 44.1 or 48 Kbps up until v.10.10. The older Macs I was planning on using could not handle anything past v.10.8! I also discovered that the DR100’s were extraordinarily finicky when recording from a digital input. If there was any mistracking on the DAT playback, or any kind of a spike, the Tascam would stop recording and freeze. Sometimes, a slight static discharge when I touched one of the machines would cause all 5 machines I was using to freeze up! When near the end of a two-hour transfer, this can be more than frustrating!
In the end, I decided to simply do all the uploads from these LP DATs via analog transfer. First carefully calibrating the DAT machine outputs to the record level inputs on the Tascam recorders. For the non-LP tapes, I transferred directly into an old iMac and an old Macbook using the optical digital inputs and recorded in Twisted Wave. A simple audio editor for Mac. Since these are mostly spoken word recordings, the very slight degradation in audio quality due to the extra D/A and A/D conversion is quite negligible.
Time to go to work!
Since this is appears to be solid, simple, and reliable, it is time to train the volunteers! I found several more used Tascam DR100-MKIIs on eBay. We wound up with a team of 10 people committed to doing at least 2 shifts per month. With a target average 5 sets of uploads a week, or around 25 tapes/week.
Every upload has to transfer to the main storage drive. Then trimmed and checked in an editing program. The titling of each file needed to be consistent as well for search purposes. I do this about once a week to keep up with the flow of uploads.
There is also a Filemaker database to manage with all the information about the content of all these recordings. Eventually, synopses and keywords will be in the database. That way, this process of digital audio archiving becomes more searchable and much more useful.
Of course, when storing so much precious data on a hard drive, there need to be multiple backups. As all of these files are being stored as WAV or AIF files, they are quite huge. We are using a 4 Tb drive as the main archive drive, which is automatically backed up every night using Chronosync. We are also storing an off-site backup in a climate controlled storage locker. That backs up approximately once per month.
Step two will be uploading the thousands of Minidiscs. That should be much smoother sailing. Utilizing the S/PDIF outputs of the minidisc machines, direct digital transfers can occur.
The organization also requests ‘permanent’ long term, disaster-proof storage for a backup of the complete digital audio archiving process. I came to the conclusion that the only current format that met their criteria were ‘Milleniata’ discs, or “M-Discs.” This is a proprietary Blu-Ray disc that is rated for 1000 years of storage without data deterioration. The latest version of these discs can hold up to 100 Gb. They are very slow to burn, so the process of transferring onto these will be very time-consuming. Luckily, ‘M-Disc’ now offers a service where they will burn your content onto discs for you via Dropbox, then mail you the discs. For $89/year they will do up to 1 Tb/month of transfers. So hopefully I will not have torn ALL my hair out by the end of this project!
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