Kieran O’Leary is Data and Digital Systems Manager at the Irish Film Institute in Dublin
In a moving image archive, there are many objects that can be classified as ‘at-risk’, so it’s hard to pick just one. The one that’s on my mind the most at the moment is optical media, mostly because of an upcoming project involving lots of optical media, specifically DVD-Video. This project is similar to the Loopline Project that resulted in us winning The National Archives Award for Safeguarding the Digital Legacy from the Digital Preservation Coalition. I would like to talk about how optical media became a major focus of this project, a little bit about format-bias, and outlining some of the research that we will have to do.
This project is supported by the wonderful Broadcasting Authority of Ireland Archiving Scheme, and one of the great things about it is that it allows us to focus on understanding formats and developing migration workflows.
Over the last 15 years, I have had a lot of experience with migrating optical media to disc images for my own personal use, and in the Irish Film Institute, we have occasionally created disc images of DVDs in order to fulfil some ad-hoc access requirements, but we have yet to really dig into optical media imaging in order to generate Archival Packages. So the stakes have definitely been raised.
Initially, we didn’t think that we would need to research optical media imaging for this project at all. We knew that there were several hundred DVDs that were to be donated to us, but the understanding was that these were just access/reference copies made from VHS tapes by the donor. So we thought that maybe these DVDs could serve as a cataloguing or quality control aid. The discs would most likely have not been migrated to files as archival packages as the higher quality analogue sources would have been available for migration. We quickly found out that the VHS tapes had been destroyed by the donor at some point after they were recorded to DVD, so the DVD is now the sole copy, and by default, the focus of much of our preservation activities for this project! The project also involves a lot of MiniDV and VHS – more Critically Endangered formats on the Bitlist, so there’s a lot for us to deal with!
When dealing with vendors and others over the years, I have found that various levels of format bias exist. These are thoughts like: ‘JPEG/DVD/MP4/VHS are just low quality and don’t deserve as much care as higher quality formats like TIFF/Digital Betacam /Lossless Video’. I’ve particularly heard such statements regarding consumer physical formats like VHS/DVD from vendors, owners of material and even some people working in our field of preservation. When it comes to born-digital objects, the actual format is rarely any kind of indicator of quality, because something is automatically ‘the best possible quality’ if it is the only copy in the world! These DVDs in our upcoming project are not really ‘born-digital’ as they originated from analogue tape, but they are now sole copies.
Optical Media was classed as ‘Critically Endagered’ in the DPC Bitlist, so even immaculately stored optical media is definitely something that needs to be on the agenda of a memory institution. In our upcoming project, a lot of these discs are very cheap media that were clearly purchased in a supermarket and not stored in optimal conditions, so there will surely be quite a few errors encountered in the process of migrating to file. So these objects need even greater care when it comes to migrating to file than some of the professional broadcast formats like Digital Betacam that we are more used to dealing with. We can’t get hung up on the fact that these are lossy, MPEG-2, 4:2:0 reproductions of an analogue carrier, and we instead need to make sure that our migration to file is the best it can possibly be.
There are many technical factors as to why this kind of media might not survive for very long in poor conditions, but one of the aggravating factors is format bias. As these were used as reference copies, they were not always stored correctly, they were frequently used and damaged, and these was not a lot of care involved in the actual VHS to DVD migration process.
So we now have to deal with optical media in a preservation context, where the primary goal will be the migration to file. This is actually quite exciting as one of my favourite parts of working in an archive involves researching and testing out different methods of migrating physical media and figuring out how to situate that work within the structures of standards like SPECTRUM Collections management, OAIS and documentation standards like PREMIS and PBCore.
It’s also usually an opportunity to connect with folks who are much more knowledgeablein the field. I already got some information Johan Van Der Knijff, whose work on optical disc imaging is incredibly advanced and openly shared.
Some of the challenges that lie ahead for us are things like:
- Which disc imaging format should we use?
- What hardware/software/operating system could we use?
- Storing the original carrier.
- How best to verify that our migration was successful and that it correctly represents the data stored on the disc?
- How can we log as much information as possible and store it in a format that can be represented in our text logs as well as a potential representation in PREMIS XML?
- How will our metadata extraction scripts work with dealing with a disc image, when our PBCore-based database records are looking for AV metadata
- How to deal with problematic discs that will not complete an imaging process
- Dealing with multi-session discs (these discs appear to have been created with a DVD-recorder which allowed for multi recording sessions on rewriteable discs)
We will try to minimise the work and research needed by trying to dive into the published research of our peers, but there will still be a lot that we will have to figure out for ourselves. We hope to share anything new that comes out of this process, so that it will save time for others in the future. Perhaps that will be another blog post in the future!
Thanks to Leanne Ledwidge, Library and Special Collections Manager in the Irish Film Institute for her help with this blogpost.
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