Sustainability of Digital Formats: Planning for Library of Congress Collections

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WAVE Audio File Format

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name WAVE. Waveform Audio File Format
Description File format for audio. Wrapper file format that can incorporate an audio bitstream with other data chunks. One common bitstream encoding is LPCM (Linear Pulse Code Modulation). Preservation reformatting projects generally use the one of the Broadcast WAVE variants, WAVE_BWF_1 or WAVE_BWF_2, both standards of the European Broadcast Union.
Production phase Used for content in initial, middle, and final states.
Relationship to other formats
    Subtype of RIFF, Resource Interchange File Format (RIFF)
    Has subtype WAVE_LPCM, WAVE Audio File Format with LPCM Audio
    Has modified version WAVE_BWF_1, Broadcast WAVE Audio File Format, Version 1
    Has modified version WAVE_BWF_2, Broadcast WAVE Audio File Format, Version 2
    May contain LPCM, Linear Pulse Code Modulation audio encoding
    May contain µ-Law, µ-Law (Mu-Law) Compressed Sound Format
    May contain A-Law, A-Law Compressed Sound Format
    May contain DPCM, Differential PCM Sound Format
    May contain ADPCM, Adaptive Differential PCM Sound Format
    May contain ADM, Audio Definition Model

Local use Explanation of format description terms

LC experience or existing holdings As of March 2021, The Library of Congress has over 150 TBs of files with the .wav extension in digital storage although the version of WAVE is not specified. For the Library's archival master format for reformatted mono and stereo analog sound recordings, see WAVE_BWF_1.
LC preference

The Library of Congress Recommended Formats Statement (RFS) lists WAVE as a Preferred format for Audio - Media-independent (digital). The RFS does not specify a version of WAVE. See also WAVE_BWF_1.

Sustainability factors Explanation of format description terms

Disclosure Fully documented. Proprietary format developed by Microsoft and IBM as part of the Resource Interchange File Format (RIFF) for Windows 3.1, with documentation freely available.
    Documentation Multimedia Programming Interface and Data Specifications 1.0. IBM Corporation and Microsoft Corporation, August 1991. Available online, e.g., at

Multimedia Data Standards Update April 15, 1994 at

Widely adopted. With LPCM encoding, a preferred or recommended format for sound in many long-term archives. Examples include Stanford Library (under preservation and streaming file formats), Libraries and Archives Canada (link via Internet Archive).

    Licensing and patents No licensing required.
Transparency Depends on audio codec employed for bitstream encoding (which may incorporate compression); see LPCM, µ-Law, A-Law, DPCM, and ADPCM.
Self-documentation Metadata can be placed in the INFO chunk (aka "LIST" chunk with a list type of "INFO") associated with all RIFF files. Additional metadata is a feature of the bext (Broadcast Audio Extension) associated with WAVE_LPCM_BWF (Broadcast WAVE Audio File Format). Additional metadata chunks have been defined: aXML, iXML, and the CART/Audio Delivery Extension to BWF, from the Audio Engineering Society in AES46-2002.
External dependencies None
Technical protection considerations None

Quality and functionality factors Explanation of format description terms

Normal rendering Excellent.
Fidelity (high audio resolution) Varies according to encoding; see LPCM, µ-Law, A-Law, DPCM, and ADPCM.
Multiple channels Requires use of WAVE Format Extensible (WAVE_FORMAT_EXTENSIBLE). See
Support for user-defined sounds, samples, and patches Not supported.
Functionality beyond normal rendering WAVE_FORMAT_EXTENSIBLE also supports the creation of files greater than 4 GB, using a structure also defined by EBU for BWF files under the rubric RF64 (a reference to the 64-bit offsets required to extend the quantity of date). See Notes.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension wav
Internet Media Type audio/wav
Selected from The File Extension Source. See Notes below for more information on IANA Media Types.
Internet Media Type audio/x-wav
From Pronom. See
Internet Media Type audio/vnd.wave
From (historic - last updated 2008). No examples found in IANA MIME Media Types.
Magic numbers Hex: 52 49 46 46 xx xx xx xx 57 41 56 45 66 6D 74 20
From Gary Kessler's File Signatures Table.
Microsoft uniform type identifier (UTI) for Microsoft Waveform Audio File Format. See
Microsoft WAVE format registry See note.  Varies according to the audio codec selected; see archived version of Microsoft registry, current Microsoft page for identifying audio types, Audio Subtype GUIDS, or the Audio Tags page.
Pronom PUID fmt/6
Wikidata Title ID Q217570

Notes Explanation of format description terms


From the Wikipedia article RF64 (consulted April 25, 2022): "RF64 is a BWF-compatible multichannel file format enabling file sizes to exceed 4 GB. It has been accepted as the ITU recommendation ITU-R BS.2088. The file format is designed to meet the requirements for multichannel sound in broadcasting and audio archiving. It is based on the Microsoft RIFF/WAVE format and Wave Format Extensible for multichannel parameters. Additions are made to the basic specification to allow for more than 4 GB file sizes when needed (the new maximum filesize is now approximately 16 exabytes). . . . In its basic form, the 32-bit chunk size field at offset 4 in the file is set to -1 (0xFFFFFFFF), and immediately following that a new 'DS64' chunk is inserted (before the FMT chunk). This new DS64 chunk will contain the 64-bit sizes of the DATA chunk(s), using a simple sequential table mechanism to point to additional DATA chunks. The first 4 bytes of the file are then changed from 'RIFF' to 'RF64'. . . . An RF64 file with a bext chunk becomes an MBWF-file. The terms ‘RF64’ and ‘MBWF’ can then be considered synonymous.

According to an exchange on the ARSCLIST on March 8 2021 (Subject: Re: MIME Type for wav files), Dave Rice explains why there's no audio/wav media type registered for WAVE files: "In the IETF, the registration of “audio/wav" was taken up by the vpim (Voice Profile for Internet Mail) working group which has concluded their work. As part of the working group, the registration status was discussed in their mailing list as well as Charles Eliot’s wav/audio registration draft." The document had ongoing registration issues that were left unresolved so workarounds were used, especially with enabling browser support, to avoid continuing with a cumbersome registration process.


Format created by Microsoft and introduced with Windows 3.1. Adopted as basis for European Broadcasting Union (EBU) Broadcast Wave standard.

With Windows 2000, Microsoft introduced a WAVE_FORMAT_EXTENSIBLE header which specifies multiple audio channel data (surround sound) along with speaker positions. This enhancement provided for custom extensions to the format chunk. Ambiguity relating to sample types and container sizes in the standard WAV format was also addressed.

Format specifications Explanation of format description terms

Useful references


Last Updated: 03/26/2024