Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
|
|
|
|
| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| 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 |
| LC experience or existing holdings | See WAVE_BWF_1. |
|---|---|
| LC preference | See WAVE_BWF_1. |
| 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 http://www.tactilemedia.com/info/MCI_Control_Info.html Multimedia Data Standards Update April 15, 1994 at http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Docs/RIFFNEW.pdf |
| Adoption |
Widely adopted. With LPCM encoding, a preferred or recommended format for sound in many long-term archives. Examples include Florida Digital Archive, DSpace at MIT, Libraries and Archives Canada. |
| 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 |
| Sound | |
|---|---|
| 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 http://msdn.microsoft.com/en-us/windows/hardware/gg463006.aspx. |
| 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. |
| Tag | Value | Note |
|---|---|---|
| Filename extension | wav |
|
| Internet Media Type | audio/wav audio/wave audio/x-pn-wav |
Selected from The File Extension Source. |
| Internet Media Type | audio/x-wav |
From LC web server configuration (Apache) of 2004-04-28. |
| Internet Media Type | audio/vnd.wave |
From http://www.iana.org/assignments/wave-avi-codec-registry. 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 ASCII: RIFF....WAVEfmt |
From Gary Kessler's File Signatures Table. |
| 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. |
| General | From the Wikipedia article RF64 (consulted October 26, 2012): "RF64 is a BWF-compatible multichannel file format enabling file sizes to exceed 4 GB. It has been specified by the European Broadcasting Union. 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. |
|---|---|
| History |
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. |
|
|