WAV
From AudioLexic
WAV (or WAVE), short for Waveform audio format, is a Microsoft and IBM audio file format standard for storing audio on PCs. It is a variant of the RIFF bitstream format method for storing data in "chunks", and thus also close to the IFF and the AIFF format used on Amiga and Macintosh computers, respectively. Both WAVs and AIFFs are compatible with Windows and Macintosh operating systems. It 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. It is the main format used on Windows systems for raw audio.
Though a WAV file can hold compressed audio, the most common WAV format contains uncompressed audio in the pulse-code modulation (PCM) format. PCM audio is the standard audio file format for CDs at 44,100 samples per second, 16 bits per sample. Since PCM uses an uncompressed, lossless 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.
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[edit] Popularity
Uncompressed WAV files are quite large in size, so, as file sharing over the Internet has become popular, the WAV format has declined in popularity. However, it is still a commonly used, relatively "pure", i.e. lossless, file type, suitable for retaining "first generation" archived files of high quality, or use on a system where high fidelity sound is required and disk space is not restricted.
More frequently, the smaller file sizes of compressed but lossy formats such as MP3, ATRAC, AAC, Ogg Vorbis 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 compression algorithms compromise available signal detail. There are also more efficient lossless codecs available, 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 both professional and 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 IFF 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. Some PlayStation Portable game software uses the AT3 file format which is a WAV file compressed in an ATRAC codec that can be decoded by the unit's libatrac3plus decoder.
In spite of their large occupancy in size, uncompressed WAV (though that format can be different from the Microsoft WAV) files are sometimes used by a few radio broadcasters, especially those that adopted the tapeless system, so-called "D-Cart", which was developed by the Australian broadcaster ABC. This is because the producers believe that uncompressed WAV files can offer better quality than lossy compressed MPEG-1 Audio Layer 2 (usually at the bit rates of 256 or 384 kbps) files do, and the price of harddisks has relatively decreased these days. In the system of "D-Cart", the sampling rate of WAV files is usually at a 48 kHz 16 bit stereo, which is identical to that of the Digital Audio Tape.
[edit] Limitations
The WAV format is limited to files that are less than 4 GiB in size, due to its use of a 32 bit unsigned integer to record the file size header (some programs limit the file size to 2 GiB). Although this is equivalent to about 6.6 hours of CD-quality audio (44.1 kHz, 16-bit stereo), it is sometimes necessary to go over this limit, especially when higher 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. This format can be converted using the libsndfile library. The RF64 format specified by the European Broadcasting Union has also been created to solve this problem.
[edit] 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 computer 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.
[edit] See also
- BWF, Broadcast Wave Format
- RF64, an extended file format for audio (multichannel file format enabling file sizes to exceed 4 gigabytes)
[edit] External links
- A summary of the WAVE file format
- Another summary of WAVE file format
- WAV file format
- Basic WAV file format
- A detailed explanation of digital audio formats and best practices (pdf)
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