Motion Picture Film Maximum - Soundtrack Audio Data [MPD-P6]

Record Type Digital Moving Images from Film-based Source Material
Expected Use Preservation Master
Product Name Motion Picture Film Maximum - Soundtrack Audio Data [MPD-P6]
Product Purpose

The purpose of this product is to mitigate risk for loss of information. 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

All ONT, DNT, MPT and MAG soundtrack elements

  • in an advanced stage of deterioration as demonstrated by a determination of “High” or above on the At Risk Assessment Guide and
  • where a preservation film element cannot be created by photochemical means and
  • all possible significant visual picture quality and auditory information is carried forward.
File Properties Data Format
  • Broadcast WAV (.wav) as defined by The European Broadcasting Union in document Tech 3285
  • Uncompressed
  • Version: 1
Capture Information
  • Encoded to Linear Pulse Code Modulation (LPCM)
  • Sampling frequency: 96 kHz
  • Bit depth: 24
  • Sound field: mono or dual mono

Typical file size: Mono: ~ 17.28 MB/minute or 1 GB/hour; Stereo: 134.5 MB/minute or 2 GB/hour

Possible File Derivatives

The audio data in this product is is integrated with DPX image data for reproduction masters and distribution copies.

Quality Control 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.

Embedded metadata compliance: NARA follows the FADGI Embedded Metadata in Broadcast WAVE File Guidelines. NARA does not embed metadata into MP3 files.
Technical metadata: NARA is finalizing a technical metadata schema for audio files based on the same structure as its reVTMD schema for video technical metadata.

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.

Technical Characteristic Warning/Pass/Fail or Logged Data
  • Sampling Frequency (Hz)
  • Audio Channels (Number)
  • Bits per sample (Number)
  • Duration
  • Average audio level
  • Peak levels
Logged data

For digital products created from film-based source material, the specifications are dictated by the source material’s original characteristics including format and condition. A separate WAV file is created for all at risk stand alone sound elements as identified on the At Risk Assessment Guide.

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The U.S. National Archives and Records Administration
1-86-NARA-NARA or 1-866-272-6272