Windows Media Audio

From Hydrogenaudio Knowledgebase

Windows Media Audio (WMA) are Microsoft's compressed audio formats; "WMA" is a generic name for several codecs. .wma files (and .wmv files) are ASF container files with a suffix indicating content, much like would later be done by renaming audio-only mp4 files into ".m4a".

Use of these codecs largely depend on Windows components, and support has waned over the years to the point where they might be considered abandonware: by 2011, Microsoft's own music store abandoned WMA lossy completely in favour of MP3[1], and certain Windows versions have been shipped with broken WMA Lossless decoding.[2][3]. As of 2024, there is only one major music store offering WMA downloads[4] (Qobuz, offering both lossy and lossless WMA[5]).

Hardware WMA-enabled players are still around – including in-car units; anectodally, several hardware "WMA" players fail to support WMA Lossless, and support for the "Pro" variant is unknown. FFmpeg offers decoding of all the format variants described on this page, and so ffmpeg-based players should be able to handle them.

Windows Media Audio (Standard)

The original WMA codec, later referred to as WMA Standard or WMA Std, was created by Microsoft to compete against MP3, the market leading format for lossy compression. It was released in 1999, and an upgrade later the same year; those are sometimes referred to as WMA 1 and WMA 2.

Upon release, WMA was aggressively pushed by Microsoft with promises of MP3 quality at half the bitrate, a claim debunked by independent listening tests[6]. WMA did become widespread; at one point in time it was the second-most widespread lossy format for end-users.

Windows Media Audio Professional

Windows Media Audio Professional (WMA Pro) was an early 2000s further development to address limitations in WMA Standard. It supports multichannel encoding and high resolutions (24bit, high sampling rates). Improving over WMA standard, WMA Pro scored as statistically tied with top encoders in independent listening tests at the time (without lending credibility to Microsoft's claim of MP3 quality at half bitrate). Supporting multichannel, it was at some time seen as a potential competition to DTS.

Like WMA Standard, WMA Pro also came in revised versions: WMA Pro 10 offers an additional layer atop the original WMA Pro 9, information that will be lost on a "WMA 9" player.

Windows Media Audio Lossless

This is the mathematically lossless codec in the Windows Media family, first released in 2003 (and like WMA Standard and WMA Pro, the format has later been extended). Compression efficiency-wise, it doesn't come close to the default settings of FLAC, WavPack, Monkey's Audio and ALAC, see Lossless comparison for more details. Several releases of Windows 10 had faulty decoders built-in and, lacking a specification, few independent implementations exist and decoding is not always lossless.

Windows Media Audio Voice

This codec, introduced with Windows Media 9, was used in the Microsoft telephones. It was considered to deliver very acceptable voice quality at bitrates around 4 and 20 kbps. It would allow switching over to the WMA Standard algorithm for signals with both voice and music, and Microsoft's encoder could detect music and switch over automatically.

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