Digital Preservation

Future tape archaeology: speculations on the emulation of analogue environments

At the recent Keeping Tracks symposium held at the British Library, AV scoping analyst Adam Tovell stated that

‘there is consensus internationally that we as archivists have a 10-20 year window of opportunity in which to migrate the content of our physical sound collections to stable digital files. After the end of this 10-20 year window, general consensus is that the risks faced by physical media mean that migration will either become impossible or partial or just too expensive.’

This point of view certainly corresponds to our experience at Greatbear. As collectors of a range of domestic and professional video and audio tape playback machines, we are aware of the particular problems posed by machine obsolescence. Replacement parts can be hard to come by, and the engineering expertise needed to fix machines is becoming esoteric wisdom. Tape degradation is of course a problem too. These combined factors influence the shortened horizon of magnetic tape-based media.

All may not be lost, however, if we are take heart from a recent article which reported the development of an exciting technology that will enable memory institutions to recover recordings made over 125 years ago on mouldy wax cylinders or acid-leaching lacquer discs.

IRENE (Image, Reconstruct, Erase Noise, Etc.), developed by physicist Carl Haber at the Lawrence Berkeley National Laboratory, is a software programme that ‘photographs the grooves in fragile or decayed recordings, stitches the “sounds” together with software into an unblemished image file, and reconstructs the “untouchable” recording by converting the images into an audio file.’

The programme was developed by Haber after he heard a radio show discuss the Library of Congress’ audio collections that were so fragile they risked destruction if played back. Haber speculated that the insights gained from a project he was working on could be used to recover these audio recordings. ‘“We were measuring silicon, why couldn’t we measure the surface of a record? The grooves at every point and amplitude on a cylinder or disc could be mapped with our digital imaging suite, then converted to sound.”’

For those involved in the development of IRENE, there was a strong emphasis on the benefits of patience and placing trust in the inevitable restorative power of technology. ‘It’s ironic that as we put more time between us and the history we are exploring, technology allows us to learn more than if we had acted earlier.’

Can such a hands-off approach be applied to magnetic tape based media? Is the 10-20 year window of opportunity described by Tovell above unnecessarily short? After all, it is still possible to playback wax cylinder recordings from the early 20th century which seem to survive well over long periods of time, and magnetic tape is far more durable than is commonly perceived.

In a fascinating audio recording made for the Pitt Rivers Museum in Oxford, Nigel Bewley from the British Library describes how he migrated wax cylinder recordings that were made by Evans Pritchard in 1928-1930 and Diamond Jenness in 1911-1912. Although Bewley reveals his frustration in the preparation process, he reveals that once he had established the size of stylus and rotational speed of the cylinder player, the transfer was relatively straightforward.

You will note that in contrast with the recovery work made possible by IRENE, the cylinder transfer was made using an appropriate playback mechanism, examples of which can accessed on this amazing section of the British Library’s website (here you can also browse through images and information about disc cutters, magnetic recorders, radios, record players, CD players and accessories such as needle tins and headphones – a bit of a treasure trove for those inclined toward media archaeology).

Perhaps the development of the IRENE technology will mean that it will no longer be necessary to use such ‘authentic’ playback mechanisms to recover information stored on obsolete media. This brings us neatly to the question of emulation.

Emulation

Insides of a beta-hi-fi machine

If we assume that all the machines that play back magnetic tape become irrevocably obsolete in 10-20 years, what other potential extraction methods may be available? Is it possible that emulation techniques, commonly used in the preservation of born-digital environments, can be applied to recover the recorded information stored on magnetic tape?

In a recent interview Dirk Von Suchodoletz explains that:

‘Emulation is a concept in digital preservation to keep things, especially hardware architectures, as they were. As the hardware itself might not be preservable as a physical entity it could be very well preserved in its software reproduction. […] For memory institutions old digital artifacts become more easy to handle. They can be viewed, rendered and interacted-with in their original environments and do not need to be adapted to our modern ones, saving the risk of modifying some of the artifact’s significant properties in an unwanted way. Instead of trying to mass-migrate every object in the institution’s holdings, objects are to be handled on access request only, significantly shifting the preservation efforts.’

For the sake of speculation, let us imagine we are future archaeologists and consider some of the issues that may arise when seeking to emulate the operating environments of analogue-based tape media.

To begin with, without a working transport mechanism which facilitates the transmission of information, the emulation of analogue environments will need to establish a circuitry that can process the Radio Frequency (RF) signals recorded on magnetic tape. As Jonathan Sterne reflects, ‘if […] we say we have to preserve all aspects of the platform in order to get at the historicity of the media practice, that means archival practice will have to have a whole new engineering dimension to it.’

Yet with the emulation of analogue environments, engineering may have to be a practical consideration rather than an archival one. For example, some kind of transport mechanism would presumably have to be emulated through which the tape could be passed through. It would be tricky to lay the tape out flat and take samples of information from its surface, as IRENE’s software does to grooved media, because of the sheer length of tape when it unwound. Without an emulated transport mechanism, recovery would be time consuming and therefore costly, a point that Tovell intimates at the beginning of the article. Furthermore, added time and costs would necessitate even more complex selection and appraisal decisions on behalf of archivists managing in-operative magnetic tape-based collections. Questions about value will become fraught and most probably politically loaded. With an emulated transport mechanism, issues such as tape vulnerability and head clogs, which of course impact on current migration practices, would come into play.

Audio and video differences

On a technical level emulation may be vastly more achievable for audio where the signal is recorded using a longitudinal method and plays back via a relatively simple process. Audio tape is also far less propriety than video tape. On the SONY APR-5003V machine we use in the Greatbear Studio for example, it is possible to play back tapes of different sizes, speeds, brands, and track formations via adjustments of the playback heads. Such versatility would of course need to be replicated in any emulation environment.

helical scanThe technical circuitry for playing back video tape, however, poses significantly more problems. Alongside the helical scan methods, which records images diagonally across the video tape in order to prevent the appearance of visible joints between the signal segments, there are several heads used to read the components of the video signal: the image (video), audio and control (synch) track.

Unlike audio, video tape circuitry is more propriety and therefore far less inter-operable. You can’t play a VHS tape on a U-Matic machine, for example. Numerous mechanical infrastructures would therefore need to be devised which correspond with the relevant operating environments – one size fits all would (presumably) not be possible.

A generic emulated analogue video tape circuit may be created, but this would only capture part of the recorded signal (which, as we have explored elsewhere on the blog, may be all we can hope for in the transmission process). If such systems are to be developed it is surely imperative that action is taken now while hardware is operative and living knowledge can be drawn upon in order to construct emulated environments in the most accurate form possible.

While hope may rest in technology’s infinite capacity to take care of itself in the end, excavating information stored on magnetic tape presents far more significant challenges when compared with recordings on grooved media. There is far more to tape’s analogue (and digital) circuit than a needle oscillating against a grooved inscription on wax, lacquer or vinyl.

The latter part of this article has of course been purely speculative. It would be fascinating to learn about projects attempting to emulate the analogue environment in software – please let us know if you are involved in anything in the comments below.

Posted by debra in audio tape, audio technology, machines, equipment, video tape, video technology, machines, equipment, 0 comments

Digital preservation – a selection of online resources

d1-mini-dv-tape-comparison

The confusing world of digital preservation…

If you are new to the world of digital preservation, you may be feeling overwhelmed by the multitude of technical terms and professional practices to contend with, and the fact that standards never seem to stay in place for very long.

Fortunately, there are many resources related to digital preservation available on the internet. Unfortunately, the large amount of websites, hyperlinks and sub-sections can exacerbate those confounded feelings.

In order to help the novice, nerd or perplexed archivist wanting to learn more, we thought it would be useful to compile a selection of (by no means exhaustive) resources to guide your hand. Ultimately if content is to be useful it does need to be curated and organised.

Bear in mind that individual websites within the field tend to be incredibly detailed, so it is worth having a really good explore to find the information you need! And, as is the norm with the internet, one click leads to another so before you know it you stumble upon another interesting site. Please feel free to add anything you find to the comment box below so the list can grow!

Digital Preservation

  • AV Preserve are a US-based consultation company who work in partnership with organisations to help them implement digital information preservation and dissemination plans. They have an amazing ‘papers and presentation’ section of their website, which includes research about diverse areas such as assessing cloud storage, digital preservation software, metadata, making an institutional case for digital preservation, managing personal archives, primers on moving image codecs, disaster recovery and many more. It is a treasure trove, and there is a regularly updated blog to boot!
  • The Digital Preservation Coalition‘s website is full of excellent resources including a digital preservation jargon buster, case studies, preservation handbook and a ‘what’s new’ section. The Technology Watch Reports are particularly useful. Of relevance to the work Great Bear do is the ‘Preserving Moving Pictures and Sound’, but there are many others including Intellectual Property and Copyright, Preserving Metadata and Digital Forensics.
  • Preservation Guide Wiki – Set up initially by Richard Wright, BBC as early as 2006, the wiki provides advice on getting started in audiovisual digital preservation, developing a strategy at institutional and project based levels.
  • The PrestoCentre’s website is amazing resource to explore if you want to learn more about digital preservation. The organisation aim to ‘enhance the audiovisual sector’s ability to provide long-term access to cultural heritage’. They have a very well stocked library that is composed of tools, case studies and resources, as well as a regularly updated blog. 

Magnetic Tape

  • The A/V Artifact Atlas is a community-generated resource for people working in digital preservation and aims to identify problems that occur when migrating tape-based media. The Atlas is made in a wiki-format and welcomes contributions from people with expertise in this area – ‘the goal is to collectively build a comprehensive resource that identifies and documents AV artifacts.’ The Atlas was created by people connected to the Bay Area Video Coalition, a media organisation that aims to inspire ‘social change by empowering media makers to develop and share diverse stories through art, education and technology.’
  • Richard Hess is a US-based audio restoration expert. Although his website looks fairly clunky, he is very knowledgeable and well-respected in the field, and you can find all kinds of esoteric tape wisdom on there.
  • The National Film and Sound Archive of Australia have produced an in-depth online Preservation Guide. It includes a film preservation handbook, an audiovisual glossary, advice on caring for your collection and disaster management.
  • The British Library’s Playback and Recording Equipment directory is well worth looking through. Organised chronologically (from 1877 – 1990s), by type and by model, it includes photos, detailed descriptions and you can even view the full metadata for the item. So if you ever wanted to look at a Columbia Gramophone from 1901 or a SONY O-matic tape recorder from 1964, here is your chance!

Digital Heritage

  • In 2005 UNESCO declared 27 October to be World Audiovisual Heritage Day. The web pages are an insight into the way audiovisual heritage is perceived by large, international policy bodies.
  • Be sure to take advantage of the 35 open access digital heritage articles published by Routledge. The articles are from the International Journal of Heritage Studies, Archives and Records, Journal of the Institute of Conservation, Archives and Manuscripts and others.
  • The Digital Curation Centre works to support Higher Education Institutions to interpret and manage research data. Again, this website is incredibly detailed, presenting case studies, ‘how-to’ guides, advice on digital curation standards, policy, curation lifecycle and much more.
  • Europeana is a multi-lingual online collection of millions of digitized items from European museums, libraries, archives and multi-media collections.

Digital Preservation Tools and Software

  • For open source digital preservation software check out The Open Planets Foundation (OPF), who address core digital preservation challenges by engaging with its members and the community to develop practical and sustainable tools and services to ensure long-term access to digital content. The website also includes the very interesting Atlas of Digital Damages
  • Archivematica is a free and open-source digital preservation system that is designed to maintain standards-based, long-term access to collections of digital objects.

 Miscellaneous Technology

  • The BBC’s R & D Archive is an invaluable resource of white papers, research and policy relating to broadcast technology from the 1930s onwards. As the website states, ‘whether it’s noise-cancelling microphones in the 1930s, the first transatlantic television transmission in the 1950s, Ceefax in the 1970s, digital radio in the 1990s and HD TV in the 2000s, or the challenge to “broadcasting” brought about by the internet and interactive media, BBC Research & Development has led the way with innovative technology and collaborative ways of working.’

As mentioned above, please feel free to add your website or project to the comment box below. We will continue to update this list!

Update 2020: We are updating and maintaining this list of useful web links in the Resources section of our website here: Digital and Audiovisual Preservation – Online Resources

Posted by debra in audio tape, video tape, 1 comment

Software Across Borders? The European Archival Records and Knowledge Preservation (E-Ark) Project

The latest big news from the digital preservation world is that the European Archival Records and Knowledge Preservation – (E-Ark), a three year, multinational research project, has received a £6M award from the European Commission ‘to create a revolutionary method of archiving data, addressing the problems caused by the lack of coherence and interoperability between the many different systems in use across Europe,’ the Digital Preservation Coalition, who are partners in the project, report.

What is particularly interesting about the consortium E-Ark has brought together is commercial partners will be part of a conversation that aims to establish long term solutions for digital preservation across Europe. More often than not, commercial interests have driven technological innovations used within digital preservation. This has made digital data difficult to manage for institutions both large and small, as the BBC’s Digital Media Initiative demonstrates, because the tools and protocols are always in flux. A lack of policy-level standards and established best practices has meant that the norm within digital information management has very much been permanent change.

Such a situation poses great risks for both digitised and born digital collections because information may have to be regularly migrated in order to remain accessible and ‘open’. As stated on the E-Ark website, ‘the practices developed within the project will reduce the risk of information loss due to unsuitable approaches to keeping and archiving of records. The project will be public facing, providing a fully operational archival service, and access to information for its users.’

Vectorscope

The E-Ark project will hopefully contribute to the creation of compatible systems that can respond to the different needs of groups working with digital information. Which is, of course, just about everybody right now: as the world economy becomes increasingly defined by information and ‘big data’, efficient and interoperable access to commercial and non-commercial archives will be an essential part of a vibrant and well functioning economic system. The need to establish data systems that can communicate and co-operate across software borders, as well as geographical ones, will become an economic necessity in years to come.

The task facing E-Ark is huge, but one crucial to implement if digital data is to survive and thrive in this brave new datalogical world of ours. As E-Ark explain: ‘Harmonisation of currently fragmented archival approaches is required to provide the economies of scale necessary for general adoption of end-to-end solutions. There is a critical need for an overarching methodology addressing business and operational issues, and technical solutions for ingest, preservation and re-use.’

Maybe 2014 will be the year when digital preservation standards start to become a reality. As we have already discussed on this blog, the US-based National Agenda for Digital Stewardship 2014 outlined the negative impact of continuous technological change and the need to create dialogue among technology makers and standards agencies. It looks like things are changing and much needed conversations are soon to take place, and we will of course reflect on developments on the Great Bear blog.

 

Posted by debra in audio tape, video tape, 0 comments