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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M4R is a filename extension for AAC format, which is developed by Apple Inc. It is typically used to save custom iPhone ringtones from Apple iTunes. M4R can only be created from iTunes purchased songs and is usually DRM protected. It can open on iTunes, VLC Media Player, Apple QuickTime Player, and more.