WMA (Windows Media Audio) is a collection of multiple sound codecs and their respective coding formats. It was developed by Microsoft in 1999 as part of its Windows Media framework. WMA features up to four codecs, including WMA, WMA Pro, WMA Lossless, and WMA Voice. Each codec has its own distinct function.
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AU is an audio format standard in early web pages NEXT systems. It is also called u-law or Sparc-audio format. Typically, AU files can store audio data and annotation blocks. Initially, it was a headerless audio format, but newer versions have a header, thanks to the six unsigned 32.bit words.