 | Control and preservation of videotapes An introduction to the handling, storage and conservation of analog and digital videotapes. read more » |
Best Practice Video Art Preservation
[beginPage: Media Storage Conditions]
Storage conditions vary between tapes which will occasionally be viewed, and those which are purely being preserved.
For optimal preservation the information stored on a tape should be transferred to another carrier within seven, or at the very most ten, years. To prevent the tapes from blocking and oxidation, they should be wound and rewound once a year. For optimal conservation and control, the ideal temperature for storage of tapes which are occasionally viewed is 18°C ( /- 1°C ) and humidity level 40%RH ( /- 5%). The ideal temperature for solely preserved tapes is approximately 10°C , with 40% relative humidity (RH). In both instances stability of conditions are most important. Tapes will wear when they are used, so where possible copies should be made and used for presentation purposes.
Additional considerations also include:
- Store videotape on metal shelving in cool, dry, stable conditions.
- Store tapes upright, like books (or upright with the case opening seam down – to prevent dust entering the case).
- The storage space should be as free of dust as possible, and situated away from sunlight. Containers should be kept clean and dust-free.
- Make sure there is no acidic plastic or paper inside videotape containers; it could accelerate decomposition.
- File valuable paper materials found inside the case separately from the tape, but note their existence and location in the relevant catalogue record.
- Record temperature and humidity levels regularly to make sure environmental conditions are not fluctuating over time.
- At the same time check your collection on a micro level-take care that the tape containers are free of debris and dust.
- Before putting a cassette on the shelf, disable the record tab to prevent accidental erasure in the future.
Please see the article, Control and Preservation of Videotapes, for an introduction to the handling, storage and conservation of analog and digital videotapes.
| Control and preservation of videotapes An introduction to the handling, storage and conservation of analog and digital videotapes. read more » |
SOURCES
Electronic Arts Intermix
Independent Media Arts Preservation
Variable Media Network
Netherlands Media Art Institute
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[beginPage: Equipment Storage]
Being able to wind and transfer tapes properly is dependent on maintaining functional equipment. It can be as important to preserve equipment in your collection as it is to preserve tape, though it should be noted that the media is more likely to outlive the technology.
Keep the following things in mind when determining equipment needs:
- Buy the best quality equipment available.
- Machinery must be kept clean and properly aligned so it will not damage tape or cause playback errors.
- In particular, keep tape path and heads clean.
- If you plan to keep tapes for many years after the format becomes obsolete, you should keep the service manuals and a stock of spare parts and/or spare decks.
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[beginPage: Video Art Preservation Strategies]
Preservation refers to the overall process by which the content of an item is saved, and its long-term viability ensured. Part of the preservation process is migration which involves duplicating a videotape to a new, archival format in order to keep the content accessible in the long term.
To migrate an artwork involves upgrading equipment and source material. The major disadvantage of migration is that the original appearance of the artwork is likely to change in its new medium.
Archival Formats
There are a variety of analog and digital videotape formats that have been manufactured to serve specific user needs. In preserving videotapes, there has been no official designation of a standard archival tape stock. However, videotapes that are recommended as good archival formats are those that are ubiquitous and widely supported in the broadcast and production industries, on professional tape stocks that are thick and strong. It is not acceptable to use a consumer tape format in generating a preservation master.
In the report from January 1999 Montevideo/TBA they put forward a list of “Criteria for Archiving Formats”:
- Theer should be no visible change of image of image compared to the original.
- There should be as much possible compatibility with industrial standards.
- The system must be able to process Betacam SP, U-matic and VHS tapes, while preserving the best possible quality.
- Montage and editing must be possible.
- The stored material must have a long to very long life span.
- The stored material must be able to be copied into any desired (tape) format without any appreciable loss of quality.
- The system must guarantee the possibility of transferring the preserved material to newly designed carriers, in the 21 st century.
In view of these criteria, and a test with different formats/carriers, Montevideo/TBA came to the conclusion that currently “Digital Betacam is the most suitable option for archive purposes”. As a digital format, this sturdy and reliable stock has a number of benefits: it can provide the best quality video image available; there is no generation loss of content when re-mastering from Digital Betacam because it is an exact digital clone of the original. However, a drawback in using this tape stock is that it is a costly format. Playback equipment is expensive and predominantly available only in professional production environments.
Betacam SP-an uncompressed analog format that is very durable, reliable, and, through migration, able to maintain the maximum level of information compared to most tape stocks. However, because it is an analog stock there can be generation loss on subsequent tapes made from this master.
Digital Files
At this point, there is no general consensus within the archival community regarding a digital file format that is appropriate for the long-term preservation of video images. The advantages are the ability to replicate digital files with no generational loss-theoretically. There are also cost and space advantages related to storage: digital file storage continues to decline in price and will do so for the foreseeable future.
However, there are a number of variables that come into play when digitizing video; among them are issues of compression, codecs, and file compatibility. These issues have yet to be resolved among archivists, though there have been recent exciting developments in this area.
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[beginPage: Assessing the Risks]
To initiate and maintain a preservation program, you will need to identify the tapes that require immediate attention and develop a plan for the resources you can commit to the project. Prioritise which tapes to preserve first based on their physical condition and provenance. These are the two main factors that will determine the costs and time needed to preserve your holdings. In addition:
- Before migrating a tape, determine if another organization has an original or high-quality version of the work that might be a better source-or if the work has already been preserved by another agency, thus avoiding duplication of resources.
- Migrate the first-generation original or the generation closest to the original in order to get the highest quality preservation master possible (unless a subsequent generation is significantly less deteriorated, which is sometimes the case.)
- Note that there can be multiple masters and multiple definitions of the term "master," so it may be necessary to consult with the artist and play back multiple tapes to compare image quality.
- Take care in playing back older, deteriorated tapes as it can cause permanent damage.
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[beginPage: Migration Basics]
Migration requires a balance of short-term and long-term planning. Here's an outline of the basic procedure:
- Create a preservation master by re-mastering or migrating tapes onto an archival format.
- Create more than one master and keep the duplicate copy in an off-site storage space in case of disaster.
- At the head of the tape, the preservation master should have one minute of color bars and tones, which are reference signals that can be used to ensure the aesthetic integrity of the original tape's content.
- Make sure that a timecode is generated on your preservation master. This signal provides a timing reference and aids in the accurate synchronization of the video content.
- Make at least one screening copy of the work on VHS or DVD for viewing purposes.
- Take care that the archival master stored off-site is never played unless it is for inspection or for creating new clones for archival or display purposes.
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