Filename extension |
|
---|---|
Internet media type | audio/x-wav |
Developed by | European Broadcast Union (EBU) |
Initial release | 1997 |
Latest release | Version 2 May 2011 |
Type of format | audio file format, container format |
Extended from | WAV |
Extended to | RF64 |
Standard | |
Website | 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 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.
In addition to the common WAVE chunks, the following extension chunks can appear in a Broadcast Wave file: [2]
bext
')iXML
')qlty
')mext
')levl
')link
')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.
An audio file format is a file format for storing digital audio data on a computer system. The bit layout of the audio data is called the audio coding format and can be uncompressed, or compressed to reduce the file size, often using lossy compression. The data can be a raw bitstream in an audio coding format, but it is usually embedded in a container format or an audio data format with defined storage layer.
MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, which permit storage and transmission of movies using currently available storage media and transmission bandwidth. While MPEG-2 is not as efficient as newer standards such as H.264/AVC and H.265/HEVC, backwards compatibility with existing hardware and software means it is still widely used, for example in over-the-air digital television broadcasting and in the DVD-Video standard.
Waveform Audio File Format is an audio file format standard, developed by IBM and Microsoft, for storing an audio bitstream on personal computers. It is the main format used on Microsoft Windows systems for uncompressed audio. The usual bitstream encoding is the linear pulse-code modulation (LPCM) format.
Audio Video Interleave is a proprietary multimedia container format and Windows standard introduced by Microsoft in November 1992 as part of its Video for Windows software. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback. Like the DVD video format, AVI files support multiple streaming audio and video, although these features are seldom used.
Audio Interchange File Format (AIFF) is an audio file format standard used for storing sound data for personal computers and other electronic audio devices. The format was developed by Apple Inc. in 1988 based on Electronic Arts' Interchange File Format and is most commonly used on Apple Macintosh computer systems.
Resource Interchange File Format (RIFF) is a generic file container format for storing data in tagged chunks. It is primarily used for audio and video, though it can be used for arbitrary data.
Material Exchange Format (MXF) is a container format for professional digital video and audio media defined by a set of SMPTE standards. A typical example of its use is for delivering advertisements to TV stations and tapeless archiving of broadcast TV programs. It is also used as part of the Digital Cinema Package for delivering movies to commercial theaters.
AES3 is a standard for the exchange of digital audio signals between professional audio devices. An AES3 signal can carry two channels of pulse-code-modulated digital audio over several transmission media including balanced lines, unbalanced lines, and optical fiber.
The Advanced Authoring Format (AAF) is a file format for professional cross-platform data interchange, designed for the video post-production and authoring environment. It was created by the Advanced Media Workflow Association (AMWA), and is now being standardized through the Society of Motion Picture and Television Engineers (SMPTE).
A container format or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Notable examples of container formats include archive files and formats used for multimedia playback. Among the earliest cross-platform container formats were Distinguished Encoding Rules and the 1985 Interchange File Format.
These tables compare features of multimedia container formats, most often used for storing or streaming digital video or digital audio content. To see which multimedia players support which container format, look at comparison of media players.
Digital Item is the basic unit of transaction in the MPEG-21 framework. It is a structured digital object, including a standard representation, identification and metadata.
RF64 is a BWF-compatible multichannel audio file format enabling file sizes to exceed 4 GB. It has been specified by the European Broadcasting Union. It has been accepted as the ITU recommendation ITU-R BS.2088.
MPEG-4 Part 14 or MP4 is a digital multimedia container format most commonly used to store video and audio, but it can also be used to store other data such as subtitles and still images. Like most modern container formats, it allows streaming over the Internet. The only filename extension for MPEG-4 Part 14 files as defined by the specification is .mp4. MPEG-4 Part 14 is a standard specified as a part of MPEG-4.
iXML is an open standard for the inclusion of location sound metadata in Broadcast Wave audio files, video files and also IP video and audio streams. This includes things like Scene, Take and Notes information.
The Open Packaging Conventions (OPC) is a container-file technology initially created by Microsoft to store a combination of XML and non-XML files that together form a single entity such as an Open XML Paper Specification (OpenXPS) document. OPC-based file formats combine the advantages of leaving the independent file entities embedded in the document intact and resulting in much smaller files compared to normal use of XML.
The Core Audio Format is a container for storing audio, developed by Apple Inc. It is compatible with Mac OS X 10.4 and higher; Mac OS X 10.3 needs QuickTime 7 to be installed.
A Digital Cinema Package (DCP) is a collection of digital files used to store and convey digital cinema (DC) audio, image, and data streams.
The Digital Production Partnership (DPP) is an initiative formed jointly by the UK's public service broadcasters to help producers and broadcasters maximise the potential benefits of digital television production.
Timed Text Markup Language (TTML), previously referred to as Distribution Format Exchange Profile (DFXP), is an XML-based W3C standard for timed text in online media and was designed to be used for the purpose of authoring, transcoding or exchanging timed text information presently in use primarily for subtitling and captioning functions. TTML2, the second major revision of the language, was finalized on November 8, 2018. It has been adopted widely in the television industry, including by Society of Motion Picture and Television Engineers (SMPTE), European Broadcasting Union (EBU), ATSC, DVB, HbbTV and MPEG CMAF and several profiles and extensions for the language exist nowadays.