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 |
The purpose of this document is to provide standards and guidelines for digitization, preservation and archiving of audio records managed by Noolaham Foundation.
This document is intended for Management, Staff, Technology Team and RB.
Authenticity, quality, storage, record integrity, metadata, and software and hardware obsolescence are major technical challenges in creating, preserving and using audio records.
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? |
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/
“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
The digital audio data files should be stored in hard drives. A checksum should be generated and added to its metadata.
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.
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.
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)
- Post Processing and Restoration
- Audio Metadata Standards
- Suggested Equipments
- Audio Tape to Digital File
- CD/DVD to Digital File
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
https://docs.google.com/document/d/1UJQiSgBpJn_27y1YatmvwdL-6PqehGPdyoYJAwwvrhM/edit?usp=sharing