As you have seen in Session 4: Caring for Paper Collections and Session 6: Media Collections of this course, some visual media and sound recordings have significantly shorter life expectancies than paper collections. This is partly because, unlike paper-based collections, many audiovisual materials must be played in machines to retrieve their information.
Even minimal playback leads to wear and tear, and playback machinery can become obsolete in a relatively short time. Magnetic and optical media may also be subject to catastrophic failure without any warning. In addition, new motion pictures and sound recordings are now often produced in digitally, and these are then subject to the difficulties of preserving born-digital information.
Duplication or analog reformatting onto "archival" quality media is an important preservation activity for audiovisual collections, but -- with the exception of motion picture film -- most reformatting of media collections that takes place today involves digitization of those materials.
Analog and digital reproductions each have advantages and disadvantages. Analog systems are much simpler than digital systems and reproduce the content more accurately—digital copies by definition sample the original information rather than reproducing it exactly—but digital formats can be easily transmitted over the Internet, copied to other media such as DVD, and recopied many times without data loss.
While digitization of photographs and negatives is an option that addresses many preservation and access needs, analog reformatting is still practiced for these formats. If photographic prints do not have negatives, production of a negative (in conjunction with digitization) will assure that, even if the original is lost or damaged, the image will be preserved. Conversely, prints are often made from negatives when an original print does not exist. Duplicate prints of deteriorating historical photographs may be needed if the original is in very poor condition and/or if it is subjected to frequent use. Deteriorating negatives (such as broken glass plate negatives or nitrate- or acetate-based negatives) may also be priority formats for duplication.
There are several options for producing use copies of photographs. Duplicate prints can be produced, a microfilm index of photographs can be created, or a database of digital images can be prepared. A very inexpensive (albeit lower-quality) option is to produce photocopies in-house that can be used to identify which photographs are needed by the researcher.
You may be able to find a local photographer or camera lab that provides copying services for historical photographs. It is a good idea to use a service provider that has experience dealing with older materials. If the duplicate photograph is intended to be used as a preservation copy, it should be printed on traditional photographic paper, not on a digital printer, since prints from a digital printer or a color photocopier will not last as long as traditional processed prints.
Duplication inherently involves a loss of image quality and detail, so it is crucial that duplicate negatives are printed on stable materials and that the reproduced image is the highest quality possible. As with all reformatting, choose a vendor who is experienced with historical collections. Methods for duplicating negatives include:
- producing a print and photographing the print using a large-format camera to produce a copy negative;
- making a direct duplicate negative using duplicating film;
- contact-printing the original negative onto film to produce a positive image, called an interpositive. The interpositive is then contact-printed onto film to produce a duplicate negative. This has the advantage of producing a master (the interpositive) and use copies.
See the NEDCC Preservation Leaflet 6.2 Duplication of Historical Negatives for more information on negative duplication methods and preparation for duplication.
Early sound recordings, a media category that includes cylinders and various disc formats, can be easily damaged during playback. The rigors of the stylus coming in contact with the cylinder or disc to read the information contained in the lateral or vertical grooves can damage the item, especially if it is composed of soft or even brittle material. Dust or other debris can significantly impact the ability of a stylus to read the recorded audio.
The 2006 Council on Libraries and Information Resources publication Capturing Analog Sound for Digital Preservation: Report of a Roundtable Discussion of Best Practices for Transferring Analog Discs and Tapes details the expert the procedures to reformat sound on analog carriers to digital media or files. Professional audiovisual conservators or audio engineers, armed with the appropriate playback tools and equipment, can expertly retrieve sound from cylinder and disc formats.
Over the past decade, imaging techniques developed by particle physicists at the Lawrence Berkeley National Laboratory allow digital imaging to safely retrieve sound from historical recordings made on formats such as discs and wax cylinders without endangering the original carriers. The IRENE/3D system ('IRENE' is the acronym for Image, Reconstruct, Erase Noise, Etc.) creates a high-resolution digital map of a disc or cylinder without touching the object's surface, and processes the images into digital sound files. The "touchless" technology allows damaged recordings, such as broken cylinders and records, to be digitally reassembled. The system has been successfully tested on hundreds of rare recordings at the Library of Congress, as well as on some of the oldest recordings ever made – a group of experimental discs produced by Alexander Graham Bell, now at the Smithsonian Institution. The contents of the Bell recordings had not been heard since they were made 130 years ago.
In 2013, NEDCC received a National Leadership Grant from the Institute of Museum and Library Services (IMLS) to develop, test, and demonstrate a new digital reformatting service for early audio recordings on mechanical sound carriers. A primary goal of the grant project was to move this new technology from a lab environment and use it to create a sustainable and affordable new digital reformatting service for libraries, museums, and archives. The new NEDCC service is now available.
Learn more about the IRENE project and listen to historic recordings digitized: watch the KQED video How Edison Got His Groove Back (10:30) or listen to the NPR story You Can Play the Record, but Don't Touch (6:41).
The optimum scenario for motion picture film preservation is to undertake film-to-film duplication, producing a preservation master film, a high resolution digital copy, and additional access versions in web-ready digital formats. Film-to-film duplication is very expensive, however, and will be justified only for the most valuable and significant historical films.
Creating a new preservation master copy of the original is the best way to ensure preservation of motion picture films. The master can be used to make additional copies in the future, with the original retained in cold storage. This type of copying is a complex and very expensive process and therefore not practical for most institutions—and not justified unless the film is of significant importance. Nonetheless, granting agencies such as the National Film Preservation Foundation require grant recipients to create a film print as part of any reformatting effort.
The high quality of film's resolution and sound is impossible to duplicate digitally, but for many institutions digital reformatting of film creates copies that facilitate access and preservation. HIgh resolution digital masters can be preserved and managed in a digital repository alongside other digital surrogates, and from these preservation masters access copies for online viewing can be created. In this scenario,the original film would be placed into managed cold storage, and while the digital preservation master would not be a complete reproduction, but it would facilitate access to a moving image recording that would be unavailable otherwise.
BetaCam SP (a half-inch analog tape) has often been used for producing preservation masters, though in recent years other institutions have begun to use DigiBeta (a half-inch digital tape) because of its increasing presence in the broadcasting industry.
For more information on film duplication and analog reformatting of film, refer to Chapter 5: Duplication of the Film Preservation Guide; keep in mind that the Guide was published in 2004 and contains outdated advice such as using VHS as a format for service or access copies or original films.
For audiotape and videotape that is deteriorating rapidly and/or becoming obsolete, create a preservation master, which will then be used to produce use copies for viewing and listening. The preservation master, whether an analog reformatting or digital surrogate, should be stored in a stable and moderate environment and that is well-managed but restricted from use.
Over the past decade, the standards for reformatting audio or video magnetic tape recordings have evolved from analog to digital technology. While some institutions still reformat analog audiotape recordings to standard-play preservation masters on quarter-inch polyester tape, many opt for digital preservation masters as well as digital service or access copies.
Likewise, videotape may be reformatted to higher-quality BetaCam SP (a half-inch analog tape) or DigiBeta (a half-inch digital tape) but many institutions choose digital preservation masters in addition to digital and web-based access.
Standards for digital audiovisual formats change as digitization methods improve, and the technology and infrastructure to deliver those digital recordings to users evolve. For background on digital audiovisual formats and other reformatting issues, see the Information Standards Quarterly article Format Considerations in Audio Visual Preservation Reformatting. For more up-to-date advice on standards in audiovisual reformatting, check in with groups like the Audio-Visual Working Group of the Federal Agencies Digitization Guidelines Initiative (FADGI) and the Minimum Digitization Capture Guidelines of the Preservation and Reformatting Section of ALA, and publications from the International Association of Sound and Audiovisual Archives. For videotape reformatting strategies, visit the Video Migration Tools and Techniques guide from the Video Preservation Website.