...but we're back! Mike, Dallas and I have been busy preparing for an workshop next week at Personal Digital Archiving (PDA) 2016 on free and/or open source tools for digital preservation. My part's on the theory and practice of migrating files to preservation formats, including tutorials for different file types (with single and batch conversion examples using both GUIs and the command line). I thought I'd share it here.
For your convenience, here's a little navigation bar that will be updated as new posts come out.
- Still Images
- Text(ual) Content
- Audio and Video
The Performance Model and the Fundamental Nature of Digital Records
The Concept of Essence, or Significant Characteristics
That all sounds fine and dandy until you start to think that changing files sounds (and, in fact, is) pretty risky! How do we ensure the the moving image from the videotape on a VCR and TV is the same moving image as the earlier one from the nitrate film on a projector and screen? I'll quote the article at length here:
The performance model demonstrates that digital records are not stable art[i]facts; instead they are a series of performances across time. Each performance is a combination of characteristics, some of which are incidental and some of which are essential to the meaning of the performance. The essential characteristics are what we call the ‘essence’ of a record.These essential characteristics (also known as significant characteristics or, sometimes, significant properties, although this usage seems to be falling out of favor) are what's really important about a record; they provide "a formal mechanism for determining the characteristics that must be preserved for the record to maintain its meaning over time" (p. 13).
Consider our Word 2.0 file. It's a type of word processing document. The essential characteristics may include:
- it's message:
- the textual content; and
- the message's qualifiers:
- formatting such as bolded text;
- font type and size;
- color; and
- embedded graphics.
The Elephant in the Room: Emulation
Since I'm talking to a bunch of archivists, I'll add that migration isn't the only strategy for overcoming the challenges of digital preservation. It's often contrasted with emulation, an approach that, using the Performance Model, "keeps the source digital object in its original data format but recreates some or all of the processes (for instance, the hardware configuration or software applications such as operating systems), enabling the performance to be recreated on current computers” (p. 12). There are convincing arguments to be made in favor of both approaches, and it seems like they all come down to what one considers to be the true essence of a digital record!