Preservation

Audio Born-Digital Original [AUD-P2]

Expected Use: Preservation Master

Product Name: Audio Born-Digital Original [AUD-P2]

Product Purpose: The purpose of this product is to capture born-digital original audio recordings at appropriate levels without altering the native technical characteristics. This file is at an appropriate information capture level to substitute for the original record if the original record copy is no longer viable.

Nature of Source Material: Original technical characteristics are retained rather than upsampling. A digital magnetic tape format such as Digital Audio Tape (DAT) would be an example of the type of source material used to make this product.

Possible File Derivatives: This master file can be used to create any reproduction or distribution file of equal or lesser capture quality.

File Properties

Container Format
Broadcast WAV (.wav) as defined by The European Broadcasting Union in document Tech 3285 Uncompressed Version: 1
File Specifications
Encoded to Linear Pulse Code Modulation (LPCM) Sampling frequency: to match original Bit depth: to match original Sound field: to match original Byte order: Little endian

Quality Control

Quality Control for Born–Digital Audio Products

The National Archives and Records Administration (NARA) uses a commercially available, automated batch processing software tool to evaluate specific quality metrics. Below is an outline of our current processes for WAV products.

Metadata

The filename contains metadata that associates the file with external sources of descriptive and technical metadata. Each filename is a unique identifier composed of the item’s record group, series, and item number.
Embedded metadata compliance: NARA follows the Federal Agencies Digital Guidelines Initiative (FADGI) Embedded Metadata in Broadcast WAVE File Guidelines.
Technical metadata: NARA uses BWF MetaEdit to embed basic technical metadata, including Coding History.

Item Level Evaluation: Automated File Characteristics Analysis

Fixity: NARA creates a checksum on the local workstation where the file is created. This checksum is verified once the file reaches long-term tape storage to ensure that no changes have occurred during quality assurance (QA)/quality control (QC) procedures and file transfers on networked storage.

Item Level Evaluation: Automated Quality Analysis

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 products.

Terms used in the QC protocols are defined in the Glossary of Terms.

Check (Warning/Pass/Fail)
Sampling Frequency (Hz) Audio Channels (Number) Bits per sample (Number)
Logged Data
Duration Average audio level Peak levels

Rationale

The digital preservation masters products produced by the Audio-Video Preservation Lab are in line with published guidelines and best practices including the International Association of Sound and Audiovisual Archives (IASA) TC-04: Guidelines for the Production and Preservation of Digital Audio Objects and Association for Recorded Sound Collections (ARSC) Preservation of Archival Sound Recordings.

Reproduction masters are also Broadcast WAVE Format (BWF) files but at the minimum CD quality specification.

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