Audio Specifications and Standards

From UA Libraries Digital Services Planning and Documentation

Revision as of 19:08, 28 June 2010

Introduction:

The following provides a brief overview of our standard audio specifications.

Technical Information:

Default File/Output Settings

• masters: .wav/WAVE at 24-bit/44.1khz
  • note: IASA TC-04 calls for a minimum sampling rate of 48kHz (preferably 96kHz) [1]. We will discontinue use of 44.1kHz sampling rates pending confirmation of appropriate storage space as 24/48 vs 24/44.1 should yield only an 8% increase in space requirements.- arora, 051309
  • typically, 2s of silence is left or created at the beginning of each .wav, with 1s at the end.
  • RMS levels are typically set fairly low, to -25db
• deliverables: .rm/RealAudio v. 8 at 16-bit/44.1kHz, 105 kbps (stereo)
  • in the near future, our workflow will allow for some enhancement of the Real Audio files (dynamic range compression, higher RMS levels) in order for delivery of pragmatic derivatives; with the preservation .wav file unaffected by such enhancements.

Update 082809: Real Audio will not be the preferred delivery format as we began use of alternate delivery methods. MP3s will be created with the Lame Encoder using the following setting:

  % lame sample.wav sample.mp3 -V4 --noreplaygain --nohist -S

These setting were decided upon after consulting the Hydrogen Audio site.

Associated Hardware

• see Digital Audio Workstation (DAW)

Resources and Links:

• Digitization and Preservation Standards
  • TAPE (Training for Audiovisual Preservation in Europe). European Commission on Preservation and Access.
  • Capturing Analog Sound for Digital Preservation: Report of a Roundtable Discussion of Best Practices for Tranferring Analog Discs and Tapes. (2006) Council on Library and Information Resources and Library of Congress.
  • Sound Directions - project website, maintained by Indiana University Digital Library Program.
    • Sound Directions: Best Practices for Audio Preservation. (2007) Casey, Mike & Bruce Gordon.
  • Grammy foundation® Basic Methodology for Preservation, Conversion and Archiving Recorded Media. (revised 2008) Grammy Foundation, Santa Monica, CA.

• File Formats - from LOC Digital Preservation/Digital Formats site
  • Wave

    see also Waveform Audio Reference - from Microsoft website

  • Broadcast Wave
  • FLAC (Free Losless Audio Codec)
  • MP3 Audio Encoding

• Audio Decision List (ADL)/AES31-3
  • The AES31 Standard (2001) De Lancie, Philip.
  • AES31--Eliminating the File Exchange Conundrum (2001) Lambert, Mel.
  • see also: Open Media Framework Interchange format (OMFI)
  • see also: Advanced Authoring Format (AAF)