NF Audio Archiving Standards - noolahamfoundation/standards GitHub Wiki

NF Audio Archiving Standards
Title NF Audio Archiving Standards - நூலக நிறுவனத்தின் ஒலிப்புகளுக்கான காப்பகத் தரநிலைகள்
Document Type Standards
Security Classification Technology, RB
Department NF Technology
Author (s)
Approval
Version Draft 1 - April 17, 2015

Table of Contents

Purpose of the Document

The purpose of this document is to provide standards and guidelines for digitization, preservation and archiving of audio records managed by Noolaham Foundation.

Audience

This document is intended for Management, Staff, Technology Team and RB.

Technical Challenges In Preserving Audio Records

Authenticity, quality, storage, record integrity, metadata, and software and hardware obsolescence are major technical challenges in creating, preserving and using audio records.

Quality Standards

Quality Measure Description Standard Reasoning
Sampling Rate "Sample Rate is the number of samples or “snapshots” taken of the signal and is measured in hertz/second. The higher the sample rate (or the more samples per second) the better the digital representation will be." CD quality is 44.1 kHz 96 kHz (oversampling delta-sigma A/D converter with dither added prior to sampling) http://www.historicalvoices.org/papers/audio_digitization.pdf
Bit Depth "Bit Depth refers to the number of bits used to represent a single sample." 24 bit http://www.historicalvoices.org/papers/audio_digitization.pdf
Channels (non-single channel; stereo - 2 channels; 5.1 - 6 channels; 7.1 channels) 1) Oral history - stereo recording
2) Digitization
2 channels http://ohda.matrix.msu.edu/2012/06/digital-audio-recording/
Bit Rate (bit depth) x (sampling rate) x (number of channels) Example: 24-bit/96KHz/.wav/Stereo/ = 2 gb per hour
Compression No Compression
Storage Format File format to use for storing audio files FLAC/WAV/Mp3?
Storage Media Hard Drive
Delivery Format MP3?

Digital Recording

Video and audio or audio only records can be created from various projects such as oral history preservation and events recordings. Please follow the above quality standards and the following guide lines: http://ohda.matrix.msu.edu/2012/06/achieving-good-audio/

Digitization

“Given the available technologies and the demands of archival preservation, weighed against expense and storage, the following digitization practices were determined acceptable for digitizing spoken word resources; sample rate: 96,000 Hz; bit-depth: 24-bit; and oversampling delta-sigma A/D converter with dither added prior to sampling.” http://www.historicalvoices.org/papers/audio_digitization.pdf

Storage and Data Integrity

The digital audio data files should be stored in hard drives. A checksum should be generated and added to its metadata.

Avoiding Software and Hardware Obsolescence

Software format, the software that plays that format, and the software operating system that supports that audio application all can become obsolescence. Converting the audio data files into upto date formats is a required preservation activity for audio files. Software application and operation system may be emulated into a virtual machine to ensure the availability of those application for the long term.

Appendix 1 - Audio Standards

Audio files can be analog (ex: cassettes) and they will need to be converted into a digital form. PCM (Pulse-code modulation) is used for digital audio. Various vendors have or support various audio file formats. FLAC is usually recommended for archiving purposes.

Analog audio files should be digitalized at rate sampling rate of 44, 100 Hz and saved at 24 bit FLAC files. Although 16 bit may be sufficient, 24 bit is recommended in order to capture details and to minimize nosie and distortion.

Audio Formats
WAV - Microsoft & IBM (Compressed/Uncompressed)
VOX - Similar to WAV, poor quality
AIFF - Apple (Compressed/Uncompressed)
AU - Sun, Unix
MP3 and Related Formats - lossy digital audio
OGG - Free and Open Source standard comparable to MP3
OGGPCM - lossless
FLAC - Free and Open source - lossless digital audio - FLAC is recommended for archiving.
Various other propitiatory formats (WMA, AAC, OMA, OMG, ATP, RA etc)

Additional Notes

  • Post Processing and Restoration
  • Audio Metadata Standards
  • Suggested Equipments
  • Audio Tape to Digital File
  • CD/DVD to Digital File

References

http://eap.bl.uk/downloads/guidelines_sound.pdf

https://www.youtube.com/watch?v=QKHk_UiQboA

http://storycorps.org/about/executive-team/

http://www.pbs.org/pov/storycorps/interview_isay.php

http://www.soundportraits.org/about/

http://www.arsc-audio.org/pdf/ARSCTC_preservation.pdf

http://cool.conservation-us.org/bytopic/audio/

http://www.edb.utexas.edu/minliu/multimedia/PDFfolder/DigitizingSound.pdf

மூல ஆவணம்

https://docs.google.com/document/d/1UJQiSgBpJn_27y1YatmvwdL-6PqehGPdyoYJAwwvrhM/edit?usp=sharing

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