Sustainability of Digital Formats: Planning for Library of Congress Collections

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Ogg FLAC Audio Format, Version 1.0

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name Ogg FLAC Audio Format, Version 1.0
Description Compressed FLAC data encapsulated in an Ogg transport layer, which helps overcome certain shortcomings of the transport system elements included in the "native FLAC" format. These native elements do not comprise a transport layer in terms of standard codec design; the transport cannot be entirely separated from the payload, and this approach does not support more elaborate transport mechanisms such as multiple logical streams.
Production phase Generally used for final-state, end-user delivery.
Relationship to other formats
    Subtype of Ogg, Ogg File Format
    Contains FLAC_1_1_2, FLAC (Free Lossless Audio Codec), Version 1.1.2

Local use Explanation of format description terms

LC experience or existing holdings None
LC preference WAVE_LCPM preferred for master copies of waveform sound.

Sustainability factors Explanation of format description terms

Disclosure Developed by xiph as an open source and patent-free project.
    Documentation Published online at https://xiph.org/flac/ogg_mapping.html. This text includes the phrase "Version 1.0 of the FLAC-to-Ogg mapping."
Adoption Unknown to the compiler of this document.
    Licensing and patents None.
Transparency Wrapper is transparent; encoding depends upon algorithms and tools to read; requires sophistication to build tools.
Self-documentation See Ogg and FLAC.
External dependencies None.
Technical protection considerations None.

Quality and functionality factors Explanation of format description terms

Sound
Normal rendering Good support.
Fidelity (high audio resolution) Potentially excellent. See FLAC.
Multiple channels See FLAC.
Support for user-defined sounds, samples, and patches See FLAC.
Functionality beyond normal rendering Not investigated at this time.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension Not found.  Comments welcome.  May be the same as Ogg.
Internet Media Type See note.  May be the same as Ogg.
Magic numbers See related format.  See Ogg. See also Notes below.

Notes Explanation of format description terms

General Regarding file type signifiers, https://xiph.org/flac/ogg_mapping.html reports that Version 1.0 of the FLAC-to-Ogg mapping is a simple identifying header followed by pure native FLAC data. The first packet of a stream consists of:
  • The one-byte packet type 0x7F
  • The four-byte ASCII signature "FLAC", i.e. 0x46, 0x4C, 0x41, 0x43
  • A one-byte binary major version number for the mapping, e.g. 0x01 for mapping version 1.0
  • A one-byte binary minor version number for the mapping, e.g. 0x00 for mapping version 1.0
  • A two-byte, big-endian binary number signifying the number of header (non-audio) packets, not including this one. This number may be zero (0x0000) to signify 'unknown' but be aware that some decoders may not be able to handle such streams.
  • The four-byte ASCII native FLAC signature "fLaC" according to the FLAC format specification
History  

Format specifications Explanation of format description terms


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Last Updated: Wednesday, 22-Feb-2017 12:37:43 EST