Audio Limited Capture [AUD-P2]
|Record Type||Audio Recordings|
|Expected Use||Preservation Master|
|Product Name||Audio Limited Capture [AUD-P2]|
The purpose of this product is to capture less complex analog audio recordings at appropriate levels according to their content and original quality levels.
|Nature of Source Material||
Analog recordings with a limited dynamic range and/or smaller frequency bandwidth such as spoken word recordings, and possibly material of high quantity and low cultural/historical significance where there is a need to ensure that all appropriate auditory information is carried forward. Examples include spoken word performances where only the spoken content is essential.
|File Properties||Data Format|
Typical file size
Mono: ~ 5.8 MB/minute or .345 GB/hour
|Possible File Derivatives||
This master file can be used to create any reproduction or distribution file of equal or lesser capture quality.
This file will not be altered in any capacity except for level adjustment to be employed at the initial capture stage.
Quality Control for Digital Audio Files
Using automated batch-processing software tools, test plans are developed for each format and/or each appropriate project. The test plan allows for some characteristics to be evaluated on an actionable basis (warning, fail or pass depending on the defined parameters). Others are logged for internal use but are not actionable as a warning, pass or fail. Aim points for these benchmarks are evaluated against NARA's product specifications as well as NARA defined aim points which may change depending on specific project goals. The following represents the quality test plan technical characteristics for WAV and MP3 products.
Item Level Evaluation: Automated Quality Analysis
Fixity: NARA is evaluating workflows to create and validate checksums for each digital file.
Terms used in the QC protocols are defined in the Glossary of Terms.
The digital preservation masters products produced by the Audio Preservation Lab are in line with published guidelines and best practices including the IASA TC-04: Guidelines for the Production and Preservation of Digital Audio Objects and ARSC Preservation of Archival Sound Recordings.
Reproduction masters are also BWF files but at the minimum CD Quality specification.
Distribution copies include a CD output option as well as an online delivery option.