![]() Ordinary WAV software skips over chunk types it doesn't recognize, so it will play Broadcast WAV files even though it can't take advantage of the extra information.īWF supports new chunk types for metadata. Every Broadcast WAV file has to have a "bext" chunk. It identifies the originator of the file, the date and time of creation, and various technical and administrative data. The main difference is that it defines a new chunk type, Broadcast Audio Extension ("bext"). The Library of Congress recommends it for preservation projects. Its purpose is to exchange audio files among different broadcast environments. The European Broadcast Union has defined a refinement of the format called Broadcast Wave Format, or BWF. Software developers try to be strict when writing files and forgiving when reading them, so this doesn't happen too often. Archivists like that feature.īecause the specification is vague in points, some software may fail to read a file that another application handles without trouble. The files can support any kind of metadata. The sample rate is a 32-bit number, so the format can handle frequencies far beyond the limits of human hearing. Most software will put implementation limits on those values, but there shouldn't be a problem with, for example, eight 32-bit channels. The format lets a file have thousands of channels and an effectively unlimited number of bits per sample. However, WAV is flexible in many respects. Audio samples look too much like random values to be compressed efficiently by general-purpose techniques. The format allows other codecs, but not all software supports them.Įven compressing a file using ZIP or GZIP won't help very much. They're often called ADPCM files rather than WAVE files. It's possible to use other codecs Microsoft's software supports the lossy ADPCM codec, which yields smaller files. The storage is lossless, meaning it's the best possible representation of the original audio. The reason why WAV files are so big is that they normally use the LPCM codec. The software that handles the bits of audio data is the codec (coder-decoder). It holds metadata about the recording, as well as technical information about how the audio is encoded. The container establishes the file structure. Getting down to specifics, what is a WAV file exactly? Like many media formats, WAV is an example of the container-codec paradigm. Some codecs may require proprietary information and licensing, though. The publicly available information is sufficient to create and play normal WAV files, and no license is needed. ![]() Microsoft's definition is mostly in terms of an API. No formal standard has ever been published for WAV. It provides better support for multichannel audio, including information on the positioning of speakers. In Windows 2000, Microsoft introduced Wave Format Extensible. Both use a similar chunk structure, but they aren't compatible with each other. The format is similar to AIFF, an early Apple audio encoding format. A chunk holds a particular kind of information, such as encoded audio, timestamps, and encoding parameters. A RIFF file consists of "chunks," each of which has a four-character type. The format is a special case of RIFF (Resource Interchange File Format), a general-purpose format for packaging data and metadata. While it's primitive compared with other audio file formats, its simplicity has earned it a niche as an archival and editing format. It isn't efficient, but the original intent was to use the format for sound effects of a second or two, not for symphonies. With WAV, each sample is encoded directly as its bit value. Compression could have made files smaller, but it would have put a major computing burden on the processor. IBM and Microsoft wanted to define a format for sound files, and it had to work with the slow processors and limited memory of the time. The WAV file format has been around since 1991.
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