01 November 2007
Behind the Scenes: Digitisation
There are two main reasons for digitising analogue sound formats: ensuring long-term preservation of content held on unstable or obsolescent media and providing ease of access.
We are currently digitising the ICA (Institute of Contemporary Arts) Talks collection, comprising nearly 1000 hour-long cassettes. The process takes considerable time and effort. A single engineer can process four cassettes in parallel, but this still adds up to 250 man-hours - the equivalent of seven working weeks.
To get the best quality digital transfer, we continuously analyse the signal extracted from the original carrier, set appropriate recording levels and convert the signal into an uncompressed WAV file - the digital archival standard. This file is sent to a computer server, where the engineer can correct for peaks or troughs in signal level, and apply noise-reduction where needed to produce an 'improved' playback WAV. The server automatically generates mp3 and Windows Media files for access on the Archival Sound Recordings website. All audio files are stored permanently in the British Library's new Digital Object Management System.
Digitisation is a key step in the process of making the recordings accessible. Documentation for ICA Talks is running in parallel with the digitisation process and this involves listening to the recordings, referring to documentary sources such as ICA event leaflets and online sources of information about those that contributed to the talks. We have identified approximately 5,000 contributors and we will be seeking to contact as many of them as we can to gain their permission to mount the recordings on the ASR service. This illustrates the complexity of the processes to make recordings accessible and most importantly discoverable.
For more information on transferring audio from analogue to digital formats, take a look at IASA's TC04 Guidelines on the Production and Preservation of Digital Objects.
Peter Findlay ASR Project Manager