DIGITAL PRESERVATION OF YOUR ARCHIVES GUIDELINES

At its most basic, looking after archives is about ensuring they are safe and protected from extreme temperatures and humidity, wherever and whatever they are. Expected levels of care for different types of material are set out in the guidance for Archive Service Accreditation.

Archives are vulnerable to many forces, ranging from unthinking neglect, to natural disasters such as storm or flood, to deliberate criminal acts such as burglary, arson or terrorist attack. In many circumstances it will of course be necessary to seek the professional guidance of an archivist and/or archive conservator. Where the emergency services have to be called in, care should also be taken to inform them of the nature and vulnerability of the material.

Preserving digital collections 

Digital preservation is a vital issue for almost all archives and there is an increasing demand for storage of, and access to, digital information in a discoverable format. There is an expectation that the vastly increased public access achieved in recent years will continue to expand. To get started you will need to: evaluate the digital records you have, or are likely to receive, to identify formats and potential volumes identify records held on removable storage media (such as memory sticks or floppy disks) with a view to transferring them to a more secure storage environment, such as a server ensure there are at least two copies of a digital record. This will allow you to work on a copy and allow you to revert to an earlier version if required. 

Technical obsolescence of standard formats (such as Windows) is not likely to be an immediate threat so it may be possible to retain the original format on a separate secure server develop a system of governance by creating a digital preservation strategy think about funding. 

Public archives are likely to acquire digital records from a variety of sources and will need to be able to sustain access to them. If the archive is unable to support digital preservation they will not be able to present the records to users over time. Archives creating digital surrogates need to remember that these assets will also need to be preserved and should be managed through the digital preservation strategy. 

A 'paper only' service may lead investors to decide that the archive no is longer helping the organisation to meet its business objectives You can use and modify established archival skills (such as description, appraisal, access and service provision) to manage digital preservation. These skills can be integrated into business as usual with minimal impact or requirements for specialists. Alternatively, you could source specialist knowledge: the use of existing expertise within the organisation (for example, the ICT department) sharing knowledge and experiences within your archival network contracting out the service (or parts of it) to a third party either as a shared service or individually, depending on need and scale.     

The 'golden rules' of digital preservation 

In most cases the processes for digital preservation will be dependent on the capabilities and resources of the organisation. There are however, some basic principles which should always be employed: only ever work on a copy of a record, to ensure long-term preservation of the content when it was originally entered into the digital preservation process always document what actions and processes have taken place to allow others to learn how digital preservation has been done, and either repeat the processes or develop them as required ensure that the digital records received into the digital preservation process are unaltered.

National Archives

Digital Preservation of Audio Video Image and Text

We play an active role in the conversion of analogue media into digital formats, ready for preservation and access for the future.

National Archives

Compliant to National Archives Guidance and Standards

We play an active role in the conversion of analogue media into digital formats, ready for preservation and access for the future.

Digital preservation for any type of file includes many components, such as: Choosing a sustainable digital format. Choosing a sustainable storage media. Identifying recordings that you want to preserve. Organising materials, including tagging, embedding metadata into files, and placing files in structured directories. Naming the directories with dates and events make them easier to identify in the future. Refreshing the data at regular intervals and storing multiple copies (three is recommended) on different media types, and in different geographical locations if possible. Keeping a copy in the cloud can be part of that strategy, but do not rely solely on the cloud as the only storage solution. Migrating the data from one file format to another as formats markedly improve and/ or evolve. Managing the data by utilising an asset management system that also allows you to easily export content.

Audio Guidance This section contains practical advice on preserving a variety of audio recordings.

Sampling Rate: The frequency at which information from the original recording is sampled or collected from a continuous signal. The rate is given in hertz (Hz) which equals cycles per second. One common example is the audio CD which has a sampling rate of 44,100 Hz, or 44.1 kHz.

Bit Depth: The number of data bits used for each individual sample. The amount of bits determines the number of discrete levels possible to place a sample within. 8-10 bit is common for video; 16-24 bit is common for audio.

Compression: Use of a method to reduce the size of digital files or streams of data, also referred to as data reduction. Compression is used to either save data storage space or better enable movement over networks or transmission lines. There are many different techniques to compress data, but all fall into one of two overall categories: Lossless: Any data removed can be reconstructed. Lossy: Some or all of the data removed is discarded and gone forever.

Audio preservation copies generally have the following characteristics: High sampling rate, High bitrate, No or very little compression, Open or non-proprietary formats,

Audio access copies generally have the following characteristics: Reduced sampling rate, Low bitrate, Fairly compressed Files, may be delivered on hard drive, flash drive or optical disk.

Video Guidance: Playback and Digitisation of Materials

You should ask the vendor for a preservation copy to be stored for the long-term and for an access copy to make your content readily accessible. The purpose of a preservation copy is to create a high quality duplicate of the original record. This way, if the original record deteriorates beyond use the preservation copy will be able to take its place. A preservation copy should last for years or decades – at least long enough to plan for making subsequent copies once these become outdated.

The purpose of an access copy is to create a copy of your record that you can play back easily. For example, if you have a VHS tape that is difficult to play back, you can have a DVD or mp4 file created to allow you to play back that content on a computer or DVD player. An access copy should be a well-supported format that is easy to play back.

Video preservation copies generally have the following characteristics: High resolution High bitrate No or very little compression Open or non-proprietary formats Video access copies generally have the following characteristics: May be reduced resolutions

Low bitrate Fairly compressed Files may be delivered on hard drive, flash drive or optical disk; whichever method you select you should be prepared to make a second, or backup, copy to help ensure the safety of your records.

Resolution: The measure of how well audio, video, or film can faithfully portray images or sound. Picture cell (pixel) density and bit depth are the units of measure for individual images. Sampling rate and bit depth are the units of measure for moving images and sound.

Bit Rate: The amount of sample data that is collected per unit of time. This is usually expressed as ‘bits per second’ (bps) or ‘Megabits per second’ (Mbps), and is the result of sampling rate multiplied by the number of data bits per sample (or bit depth), plus any additional data such as tracking information.

Compression: Use of a method to reduce the size of digital files or streams of data, also referred to as data reduction. Compression is used to either save data storage space or better enable movement over networks or transmission lines. There are many different techniques to compress data, but all fall into one of two overall categories:

Lossless: Any data removed can be reconstructed. Lossy: Some or all of the data removed is discarded and gone forever.

 

Whichever method you select you should be prepared to make a second, or backup, copy to help ensure the safety of your records.

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