The process and considerations involved in creating digital audio files are fully discussed in a number of JISC Digital Media documents, specifically:

• ‘Choosing a Digital Audio File Format’
• ‘Basic Audio Editing’
• ‘Choosing a Digital Audio File Format’

As discussed in Section 1, the quality of the file is the key consideration when creating digital audio files. In order to ensure that the file being created is of a suitable quality and fit for purpose, data creators should be aware of :

• the relationship between audio container or ‘wrapper’ formats and the codecs that they contain as well as their respective capabilities.
• the fact that, as a component of the codec, audio formats can feature both lossless and lossy compression or come in uncompressed formats. Data creators should be aware of how these affect both data quality and file size at at what stages in the work flow these options will (if at all) be used.
• that many files allow metadata to be embedded within the container format and that data creators may want to utilise this functionality to record important aspects of the data creation process. Steps should be taken to identify or flag up this metadata where it exists so that it can be maintained regardless of format.
• which rights exist (e.g. copyright or moral right). This is particularly relevant to interview situations and data creators should be aware of any ethical implications of their work. In all cases clearance/permission should be sought from those involved in the recording. These issues are discussed in the JISC Digital Media document ‘Copyright and Other Rights for Creating Time-based Media Resources’.

As a general guide – and one that is repeated throughout these Guides – it is advised that data creators create (and archive) audio data at as high a quality level as is available and in an uncompressed format. From this master dataset, lower file size/quality datasets can be derived via format migration or downsampling.