Difference between revisions of "Audio"

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[[Main Page]] > [[Documentation]] > [[Media type preservation plans]] > Audio
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[[Main Page]] > [[Documentation]] > [[Format policies]] > Audio
  
  
==[[Significant properties of audio files]]==
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==[[Significant characteristics of audio files]]==
  
 
==Preservation Format==
 
==Preservation Format==
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==Comments==
 
==Comments==
Library of Congress considers WAVE LPCM as the "preferred format for sound recordings." [http://www.digitalpreservation.gov/formats/fdd/fdd000002.shtml Library of Congress Sustainability of Digital Formats: WAVE Audio File Format with LPCM audio]
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*For the preservation master, audio files are normalized to WAVE LPCM with a bit depth of 16 bits per sample. The sampling frequency of the original file is maintained. If the ingested file has a bit depth of greater than 16, normalization will be adjusted to use the higher bit depth.
*Florida Digital Archive normalizes audio streams contained in WAVE files to uncompressed PCM(LPCM) with a sample size of 16 bits/sample. See [http://www.fcla.edu/digitalArchive/formatInfo.htm Preservation action plans: WAVE].
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**Library of Congress considers WAVE LPCM as the "preferred format for sound recordings." [http://www.digitalpreservation.gov/formats/fdd/fdd000002.shtml Library of Congress Sustainability of Digital Formats: WAVE Audio File Format with LPCM audio]
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**Florida Digital Archive normalizes audio streams contained in WAVE files to uncompressed PCM(LPCM) with a bit depth of 16 bits per sample. See [http://www.fcla.edu/digitalArchive/formatInfo.htm Preservation action plans: WAVE].
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**According to [http://www.carli.illinois.edu/mem-prod/contentdm/guidelines_for_audio.pdf Guidelines for the Creation of Digital Collections: Digitization Best Practices for Audio, Consortium of Academic and Research Libraries in Illinois, 2009], WAVE LPCM with with a bit-depth of 16 bits and a sampling freqency of 44100 HZ is the minimum standard for a preservation format (p. 2). Higher bit depth and sampling frequencies may be desirable: "Several specific reasons for richer files include: the accurate capture of noise like clicks, pop, and other inaudible information that resides in frequencies higher than 44.1 kHz; desire to communicate inaudible harmonic information that impact perception of sound; ability to record and provide content that, although not necessarily heard, helps listeners understand and hear better space, depth, and instrument location in stereo and surround sound recordings; and to accommodate future user applications." (p.1)
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*For the access copy, audio files are normalized to MP3 using a bit-rate of 192 kbp/s.
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**According to [http://www.carli.illinois.edu/mem-prod/contentdm/guidelines_for_audio.pdf Guidelines for the Creation of Digital Collections: Digitization Best Practices for Audio, Consortium of Academic and Research Libraries in Illinois, 2009],"Access copies for audio files may be saved in compressed formats that allow for quicker transfer or streaming via the Internet. The MP3 format is widely-supported, is playable on nearly all handheld devices, and is commonly used for web delivery. MP3 is the preferred format. MP3 files saved at 192 Kbps (the bit-rate) are recommended for good quality compressed audio." (p.2)
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Latest revision as of 16:14, 13 February 2013

Main Page > Documentation > Format policies > Audio


Significant characteristics of audio files[edit]

Preservation Format[edit]

LPCM/WAVE

Access Format[edit]

MP3

Normalization tool[edit]

FFmpeg

Comments[edit]