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{{Short description|Audio file format family based on Microsoft WAV}}
'''BWF''' is an abbreviation of [[Broadcast Wave file Format]] .
{{Infobox file format
It's suggested by [[Europian Broadcasting Union]] in 1996.
| name = Broadcast Wave Format
| logo =
| icon =
| iconcaption =
| screenshot =
| caption =
| extension = {{plainlist|
* .bwf
* .wav
}}
| mime =
| type code =
| uniform type =
| conforms to =
| magic =
| owner = European Broadcast Union (EBU)
| released = {{Start date|1997}}
| latest release version = Version 2
| latest release date = {{Start date and age|2011|05|df=yes}}
| genre = [[audio file format]], [[container format]]
| container for =
| contained by =
| extended from = [[WAV]]
| extended to = [[RF64]]
| standard =
* [https://tech.ebu.ch/docs/tech/tech3285.pdf EBU - TECH 3285 Specification of the Broadcast Wave Format (BWF)]
* [https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1352-3-200712-I!!PDF-E.pdf ITU-R BS.1352-3 File format for the exchange of audio programme materials with metadata on information technology media]
| free =
| url = [https://web.archive.org/web/20241006181236/https://www.ebu.ch/fr/technical/publications/userguides/bwf_user_guide.php Broadcast Wave Format (BWF) user guide]
}}


'''Broadcast Wave Format''' ('''BWF''') is an extension of the popular Microsoft [[WAV]] audio format and is the recording format of most file-based [[Non-linear editing|non-linear]] [[Digital recording|digital recorders]] used for [[Film production|motion picture]], radio and [[television production]]. It was first specified by the [[European Broadcasting Union]] in 1997, and updated in 2001 and 2003. It has been accepted as the [[ITU]] recommendation '''ITU-R BS.1352-3''', Annex 1.
Purpose of this file format is to achieve easiness in exchanging

sound data between different computer platforms. For example,
The purpose of this file format is the addition of [[metadata]] to facilitate the seamless exchange of sound data between different computer platforms and applications. It specifies the format of metadata, allowing audio processing elements to identify themselves, document their activities, and supports [[timecode]] to enable synchronization with other recordings. This metadata is stored as extension chunks in a standard digital audio WAV file.
you can include a lot of machine and application dependent information

inside sound file. (Ex. What machine is used, what configuration is used
BWF is the recommended format for digitizing sound files by the International Association of Sound and Audiovisual Archives.<ref>{{Cite book |last=IASA Technical Committee |first=Guidelines on the Production and Preservation of Digital Audio Objects |url=https://www.iasa-web.org/tc04/data-or-audio-specific-storage |title=Guidelines on the Production and Preservation of Digital Audio Objects |publisher=International Association of Sound and Audio Visual Archives |year=2009 |isbn=9789197619226 |editor-last=Bradley |editor-first=Kevin |edition=2nd |location=Auckland Park, South Africa |language=en}}</ref>
to create and compose this file )

Files conforming to the Broadcast Wave specification have names ending with the [[filename extension]] .WAV.

== Details ==
In addition to the common WAVE chunks, the following extension chunks can appear in a Broadcast Wave file:<ref>{{Cite web|url=https://tech.ebu.ch/docs/tech/tech3285.pdf|title=EBU BWF User Guide}}</ref>
* Original Bext chunk (Broadcast Extension - '<code>bext</code>')
* [[iXML]] chunk ('<code>iXML</code>')
* Quality chunk ('<code>qlty</code>')
* MPEG audio extension chunk ('<code>mext</code>')
* Peak Envelope chunk ('<code>levl</code>')
* link chunk ('<code>link</code>')
* axml chunk ('<code>axml</code>')

Since the only difference between a BWF and a "normal" WAV is the extended information in the file header (Bext-Chunk, Coding-History, etc...), a BWF does not require a special player for playback.

Unfortunately, this compatibility also preserves the [[WAV#Limitations|filesize limitation]] that WAV files have (4 GB of audio data per data chunk).
In order to be able to store audio which would exceed this limit, 2 different chunks exist allowing the audio material to be spread across several files: ''cont'' & ''link'' (see list above)

Since there is no official naming convention for these subsequent files, and it is still desirable to see at a glance which ones belong to a continuous piece of audio, a lot of programs apply a numbering scheme to the file suffix: ''.wav, .w01, .w02, ..., .wNN''.

Each of those segments is a regular Wave/BWF file, but players that are aware of the continue/link chunk will treat all segments as one single, long piece of audio when opening the first segment ".wav".

As an extension, [[RF64]] is a BWF-compatible multichannel file format enabling file sizes to exceed 4 GB that has been specified in 2006.

The axml (additional XML) chunk allows users to incorporate data compliant with the XML format with the audio; the chunk may contain data fragments from one or more schema.

In August 2012, the European Broadcasting Union published a specification for embedding [[International Standard Recording Code]] (ISRC) in the axml chunk of the Broadcast Wave Format.

BWF is specified for use in [[Material Exchange Format|MXF]] by [[SMPTE]] standard 382. BWF is specified for use in [[AES31]].

== See also ==
* [[RF64]], A BWF-compatible multichannel file format enabling file sizes to exceed 4 GB
* [[WAV]]
* [[Material Exchange Format|MXF]], Material eXchange Format
* [[Advanced Authoring Format]]

== References ==
{{Reflist}}

== External links ==
* [https://tech.ebu.ch/docs/tech/tech3285s1.pdf EBU Tech 3285-s1 - Specification of the Broadcast Wave Format (BWF) - Supplement 1, MPEG Audio - first edition (1997)]
* [https://tech.ebu.ch/docs/tech/tech3285.pdf EBU Tech 3285 - Specification of the Broadcast Wave Format (BWF) - Version 1 - second edition (2001)]
* [https://tech.ebu.ch/docs/tech/tech3285s2.pdf EBU Tech 3285-s2 - Specification of the Broadcast Wave Format (BWF) - Supplement 2, Capturing Report - first edition (2001)]
* [https://tech.ebu.ch/docs/tech/tech3285s3.pdf EBU Tech 3285-s3 - Specification of the Broadcast Wave Format (BWF) - Supplement 3, Peak Envelope Chunk - first edition (2001)]
* [https://tech.ebu.ch/docs/tech/tech3285s4.pdf EBU Tech 3285-s4 - Specification of the Broadcast Wave Format (BWF) - Supplement 4, Link Chunk - first edition (2003)]
* [https://tech.ebu.ch/docs/tech/tech3285s5.pdf EBU Tech 3285-s5 - Specification of the Broadcast Wave Format (BWF) - Supplement 5, <axml> Chunk - first edition (2003)]
* [https://tech.ebu.ch/docs/tech/tech3352.pdf EBU Tech 3352 - The Carriage of Identifiers in the Broadcast Wave Format (BWF) (2012 Recommendation)]
* [https://tech.ebu.ch/docs/tech/tech3285s6.pdf EBU Tech 3285-s6 - Specification of the Broadcast Wave Format (BWF) - Supplement 6, Dolby Metadata - <dbmd> Chunk - first edition (2009)]

[[Category:Computer-related introductions in 1997]]
[[Category:Audiovisual introductions in 1997]]
[[Category:Audio file formats]]
[[Category:Film and video technology]]

Latest revision as of 19:27, 4 January 2025

Broadcast Wave Format
Filename extension
  • .bwf
  • .wav
Internet media typeaudio/x-wav
Developed byEuropean Broadcast Union (EBU)
Initial release1997 (1997)
Latest release
Version 2
May 2011; 13 years ago (2011-05)
Type of formataudio file format, container format
Extended fromWAV
Extended toRF64
Standard
WebsiteBroadcast Wave Format (BWF) user guide

Broadcast Wave Format (BWF) is an extension of the popular Microsoft WAV audio format and is the recording format of most file-based non-linear digital recorders used for motion picture, radio and television production. It was first specified by the European Broadcasting Union in 1997, and updated in 2001 and 2003. It has been accepted as the ITU recommendation ITU-R BS.1352-3, Annex 1.

The purpose of this file format is the addition of metadata to facilitate the seamless exchange of sound data between different computer platforms and applications. It specifies the format of metadata, allowing audio processing elements to identify themselves, document their activities, and supports timecode to enable synchronization with other recordings. This metadata is stored as extension chunks in a standard digital audio WAV file.

BWF is the recommended format for digitizing sound files by the International Association of Sound and Audiovisual Archives.[1]

Files conforming to the Broadcast Wave specification have names ending with the filename extension .WAV.

Details

[edit]

In addition to the common WAVE chunks, the following extension chunks can appear in a Broadcast Wave file:[2]

  • Original Bext chunk (Broadcast Extension - 'bext')
  • iXML chunk ('iXML')
  • Quality chunk ('qlty')
  • MPEG audio extension chunk ('mext')
  • Peak Envelope chunk ('levl')
  • link chunk ('link')
  • axml chunk ('axml')

Since the only difference between a BWF and a "normal" WAV is the extended information in the file header (Bext-Chunk, Coding-History, etc...), a BWF does not require a special player for playback.

Unfortunately, this compatibility also preserves the filesize limitation that WAV files have (4 GB of audio data per data chunk). In order to be able to store audio which would exceed this limit, 2 different chunks exist allowing the audio material to be spread across several files: cont & link (see list above)

Since there is no official naming convention for these subsequent files, and it is still desirable to see at a glance which ones belong to a continuous piece of audio, a lot of programs apply a numbering scheme to the file suffix: .wav, .w01, .w02, ..., .wNN.

Each of those segments is a regular Wave/BWF file, but players that are aware of the continue/link chunk will treat all segments as one single, long piece of audio when opening the first segment ".wav".

As an extension, RF64 is a BWF-compatible multichannel file format enabling file sizes to exceed 4 GB that has been specified in 2006.

The axml (additional XML) chunk allows users to incorporate data compliant with the XML format with the audio; the chunk may contain data fragments from one or more schema.

In August 2012, the European Broadcasting Union published a specification for embedding International Standard Recording Code (ISRC) in the axml chunk of the Broadcast Wave Format.

BWF is specified for use in MXF by SMPTE standard 382. BWF is specified for use in AES31.

See also

[edit]

References

[edit]
  1. ^ IASA Technical Committee, Guidelines on the Production and Preservation of Digital Audio Objects (2009). Bradley, Kevin (ed.). Guidelines on the Production and Preservation of Digital Audio Objects (2nd ed.). Auckland Park, South Africa: International Association of Sound and Audio Visual Archives. ISBN 9789197619226.
  2. ^ "EBU BWF User Guide" (PDF).
[edit]
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