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Waveform Audio File Format (WAVE)
WAV.png
Filename extension .wav or .wv
Internet media type audio/vnd.wave[1], audio/wav, audio/wave, audio/x-wav[2]
Type code WAVE
Uniform Type Identifier com.microsoft.waveform-audio
Developed by Microsoft & IBM
Initial release 1991 (1991)[3]
Latest release Multiple Channel Audio Data and WAVE Files / 7 March 2007; 3 year(s) ago (2007-03-07) (update)[4][5]
Type of format audio file format, container format
Extended from RIFF
Extended to BWF, RF64

WAVE or WAV, short for Waveform Audio File Format,[6][3][7][8] (rarely also named Audio for Windows[9]) is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs. It is an application of the RIFF bitstream format method for storing data in “chunks”, and thus is also close to the 8SVX and the AIFF format used on Amiga and Macintosh computers, respectively. It is the main format used on Windows systems for raw and typically uncompressed audio. The usual bitstream encoding is the Linear Pulse Code Modulation (LPCM) format.

Contents

Description

Both WAVs and AIFFs are compatible with Windows, Macintosh, and Linux operating systems. The format takes into account some differences of the Intel CPU such as little-endian byte order. The RIFF format acts as a “wrapper” for various audio compression codecs.

Though a WAV file can hold compressed audio, the most common WAV format contains uncompressed audio in the linear pulse code modulation (LPCM) format. The standard audio file format for CDs, for example, is LPCM-encoded, containing two channels of 44,100 samples per second, 16 bits per sample. Since LPCM uses an uncompressed storage method which keeps all the samples of an audio track, professional users or audio experts may use the WAV format for maximum audio quality. WAV audio can also be edited and manipulated with relative ease using software. The WAV format supports compressed audio, using, on Windows, the Audio Compression Manager. Any ACM codec can be used to compress a WAV file. The UI for Audio Compression Manager may be accessed through various programs that use it, including Sound Recorder in some versions of Windows.

Beginning with Windows 2000, a WAVE_FORMAT_EXTENSIBLE header was defined which specifies multiple audio channel data along with speaker positions, eliminates ambiguity regarding sample types and container sizes in the standard WAV format and supports defining custom extensions to the format chunk.[4][5][10]

There have been some WAVE format inconsistencies reported, for example how 8-bit data is unsigned, but 16-bit data is signed; and many of chunks duplicate the same information found in other chunks. WAV file can contain imbedded IFF "List"s, that may contain several "sub-chunks".[11][12][13]

Popularity

Uncompressed WAV files are quite large in size, so, as file sharing over the Internet has become popular,[citation needed] the WAV format has declined in popularity.[citation needed] However, it is still a commonly used file type, suitable for retaining “first generation” archived files of high quality, for use on a system where disk space is not a constraint, or in applications such as audio editing, where the time involved in compressing and uncompressing data is a concern.

More frequently, the smaller file sizes of compressed but lossy formats such as Ogg Vorbis, MP3, ATRAC, AAC, Musepack and WMA are used to store and transfer audio. Their small file sizes allow faster Internet transmission, as well as lower consumption of space on memory media. However, lossy formats trade off smaller file size against loss of audio quality, as all such compression algorithms compromise available signal detail. There are also lossless codecs, such as FLAC, Shorten, Monkey's Audio, ATRAC Advanced Lossless, Apple Lossless, WMA Lossless, TTA, and WavPack, but none of these is yet a ubiquitous standard for either professional or home audio.

The usage of the WAV format has more to do with its familiarity, its simplicity and simple structure, which is heavily based on the RIFF file format. Because of this, it continues to enjoy widespread use with a variety of software applications, often functioning as a 'lowest common denominator' when it comes to exchanging sound files between different programs.

In spite of their large size, uncompressed WAV (though that format can be different from the Microsoft WAV) files are sometimes used by some radio broadcasters, especially those that have adopted the tapeless system. BBC Radio in the UK uses 44.1 kHz 16 bit two channel .wav audio as standard in their VCS system. The ABC “D-Cart” system, which was developed by the Australian broadcaster, uses 48 kHz 16 bit two channel .wav files, which is identical to that of Digital Audio Tape.

Limitations

The WAV format is limited to files that are less than 4 GiB in size, because of its use of a 32-bit unsigned integer to record the file size header (some programs limit the file size to 2–4 GiB).[14] Although this is equivalent to about 6.8 hours of CD-quality audio (44.1 kHz, 16-bit stereo), it is sometimes necessary to exceed this limit, especially when greater sampling rates or bit resolutions are required. The W64 format was therefore created for use in Sound Forge. Its 64-bit header allows for much longer recording times. The RF64 format specified by the European Broadcasting Union has also been created to solve this problem.

Non-audio data

Since the sampling rate of a WAV file can vary from 1 Hz to 4.3 GHz, and the number of channels can be as high as 65536,[15] .wav files have also been used for non-audio data. LTspice, for instance, can store multiple circuit trace waveforms in separate channels, at any appropriate sampling rate, with the full-scale range representing ±1 V or A rather than a sound pressure.[16]

Audio CDs

Audio CDs do not use WAV as their sound format, using instead Red Book audio. The commonality is that both audio CDs and WAV files have the audio data encoded in PCM. WAV is a data file format for a computer to use that can't be understood by CD players directly. To record WAV files to an Audio CD the file headers must be stripped and the remaining PCM data written directly to the disc as individual tracks with zero-padding added to match the CD's sector size.

WAV file compression codecs compared

As mentioned wav files can be encoded with a variety of codecs to reduce the file size (for example the GSM or MP3 codecs).

This is a reference to compare the monophonic (not stereophonic) audio quality and compression bitrates of the different codecs available for .wav files including PCM, ADPCM, GSM, CELP, SBC, Truespeech and MPEG Layer-3.

Format Bitrate 1 Minute = Sample
11,025 Hz 16 bit PCM 176.4 kbit/s[17] 1292 KiB[18] 11k16bitpcm.wav
08,000 Hz 16 bit PCM 128 kbit/s 0938 KiB 8k16bitpcm.wav
11,025 Hz 8 bit PCM 088.2 kbit/s 0646 KiB 11k8bitpcm.wav
11,025 Hz µ-Law 088.2 kbit/s 0646 KiB 11kulaw.wav
08,000 Hz 8 bit PCM 064 kbit/s 0469 KiB 8k8bitpcm.wav
08,000 Hz µ-Law 064 kbit/s 0469 KiB 8kulaw.wav
11,025 Hz 4 bit ADPCM 044.1 kbit/s 0323 KiB 11kadpcm.wav
08,000 Hz 4 bit ADPCM 032 kbit/s 0234 KiB 8kadpcm.wav
11,025 Hz GSM6.10 018 kbit/s 0132 KiB 11kgsm.wav
08,000 Hz MP3 16 kbit/s 016 kbit/s 0117 KiB 8kmp316.wav
08,000 Hz GSM6.10 013 kbit/s 0103 KiB 8kgsm.wav
08,000 Hz Lernout & Hauspie SBC 12 kbit/s 012.0 kbit/s 0088 KiB 8ksbc12.wav
08,000 Hz DSP Group Truespeech 009 kbit/s 0066 KiB 8ktruespeech.wav
08,000 Hz Mp3 8 kbit/s 008 kbit/s 0060 KiB 8kmp38.wav
08,000 Hz Lernout & Hauspie CELP 004.8 kbit/s 0035 KiB 8kcelp.wav

The above are WAV files; even those that use the MP3 codec have the “.wav” extension.

See also

References

  1. ^ Microsoft Corporation (June 1998). "WAVE and AVI Codec Registries - RFC 2361". IETF. http://tools.ietf.org/html/rfc2361. Retrieved 2009-12-06. 
  2. ^ http://filext.com/file-extension/WAV
  3. ^ a b IBM Corporation and Microsoft Corporation (August 1991) (TXT), Multimedia Programming Interface and Data Specifications 1.0, http://www.kk.iij4u.or.jp/~kondo/wave/mpidata.txt, retrieved 2009-12-06 
  4. ^ a b P. Kabal (2006-06-19). "Audio File Format Specifications - WAVE or RIFF WAVE sound file". McGill University. http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html. Retrieved 2010-03-16. 
  5. ^ a b "Multiple Channel Audio Data and WAVE Files". Microsoft Corporation. 2007-03-07. http://www.microsoft.com/whdc/device/audio/multichaud.mspx. Retrieved 2010-03-16. 
  6. ^ IBM Corporation and Microsoft Corporation (August 1991). "Multimedia Programming Interface and Data Specifications 1.0". http://www.tactilemedia.com/info/MCI_Control_Info.html. Retrieved 2009-12-06. 
  7. ^ Library of Congress (2008-09-12). "WAVE Audio File Format". http://www.digitalpreservation.gov/formats/fdd/fdd000001.shtml. Retrieved 2009-12-06. 
  8. ^ Microsoft Corporation (June 20, 1999). "Waveform Audio File Format, MIME Sub-type Registration - INTERNET-DRAFT". IETF. http://tools.ietf.org/html/draft-ema-vpim-wav-00. Retrieved 2009-12-06. 
  9. ^ "Information about the Multimedia file types that Windows Media Player supports". Microsoft Help and Support. Microsoft Corporation. 12 May 2008. http://support.microsoft.com/kb/316992. Retrieved 29 May 2009. "Windows uses the Wave Form Audio (WAV) file format to store sounds as waveforms. One minute of Pulse Code Modulation (PCM)-encoded sound can occupy as little as 644 kilobytes (KB) or as much as 27 megabytes (MB) of storage." 
  10. ^ EBU (2009-07) (PDF), EBU Tech 3306 - MBWF / RF64: An Extended File Format for Audio, http://tech.ebu.ch/docs/tech/tech3306-2009.pdf, retrieved 2010-01-19 
  11. ^ "WAVE File Format". archive.org. 1999-11-15. http://web.archive.org/web/19991115123323/http://www.borg.com/~jglatt/tech/wave.htm. Retrieved 2010-03-16. 
  12. ^ "WAVE PCM soundfile format". archive.org. 2003-01-20. https://ccrma.stanford.edu/courses/422/projects/WaveFormat/. Retrieved 2010-03-16. 
  13. ^ "The WAVE File Format". http://www.lightlink.com/tjweber/StripWav/WAVE.html. Retrieved 2010-03-16. 
  14. ^ 1 GiB = 1024 MiB; 1 MiB = 1024 KiB; 1 KiB = 1024 B
  15. ^ http://www.dragonwins.com/wav/
  16. ^ http://ltspice.linear.com/software/scad3.pdf#page=98
  17. ^ 1 kbit = 1000 bit
  18. ^ 1 KiB = 1024 B

External links


Simple English

Waveform Audio File Format
File extension:.wav
MIME type:audio/vnd.wave
audio/wav
audio/wave
audio/x-wav
Type code:WAVE
Uniform Type Identifier:com.microsoft.waveform-​audio
Developed by:Microsoft & IBM
Type of format:audio file
Extended from:RIFF

WAV (or WAVE), short for Waveform Audio File Format, is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs. It resembles the RIFF bitstream format in the sense that it stores data in “chunks”. It is also close to the IFF and the AIFF format used on Amiga and Macintosh computers, respectively. It is the main format used on Windows systems for raw and typically uncompressed audio. The default bitstream encoding is the Microsoft Pulse Code Modulation (LPCM) format.









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