What Is a .WMA File?

Windows Media Audio (.wma)

Overview

WMA (Windows Media Audio) is Microsoft's compressed audio format, introduced in 1999 as a competitor to MP3. A .wma file is an ASF container, the same wrapper used by WMV video, holding audio compressed with one of the Windows Media Audio codecs.

WMA was the default ripping format in Windows Media Player for a decade, which is why large personal music collections from the 2000s are in it. Some of those files are DRM-protected copies of purchased tracks; most are plain rips of CDs.

Technical Specifications

• MIME Type: audio/x-ms-wma
• File Extension: .wma
• Category: Audio
• Container: ASF (Advanced Systems Format)
• Codecs: WMA (standard, lossy), WMA Pro (surround, high resolution), WMA Lossless, WMA Voice
• Introduced: 1999
• Magic bytes: 30 26 B2 75 8E 66 CF 11 A6 D9 00 AA 00 62 CE 6C

Identification

The 16-byte ASF Header Object GUID is the same for .wma, .wmv and .asf:

00000000  30 26 b2 75 8e 66 cf 11  a6 d9 00 aa 00 62 ce 6c  |0&.u.f.......b.l|

A file with this signature and no video stream in its header is audio-only, which is what the .wma extension conventionally means.

The four WMA codecs

Codec	Purpose	Notes
WMA (Standard)	General music, 64 to 192 kbps	What Windows Media Player ripped to by default
WMA Pro	Multichannel and 24-bit audio	Rarely used outside Windows
WMA Lossless	Bit-exact archiving	Microsoft's answer to FLAC; little support elsewhere
WMA Voice	Speech at very low bitrates	Dictation and voicemail systems

Only standard WMA is widely decodable outside the Microsoft ecosystem. WMA Lossless and WMA Pro need ffmpeg or a Windows machine.

History and Development

Microsoft released WMA in 1999, claiming CD quality at half the bitrate of MP3. The claim was contested, but the format's real draw was integration: Windows Media Player ripped to it by default and the Zune, Xbox and early Windows phones played it. Microsoft's PlaysForSure DRM scheme made WMA the format for most non-Apple music stores of the mid-2000s.

The arrival of the iPod, which never played WMA, and of DRM-free MP3 sales from 2007 onward ended its growth. Windows Media Player switched its default rip format to MP3 and later AAC, and WMA became a legacy format.

Common Use Cases

• CD rips from the 2000s made with Windows Media Player
• Purchased music from Napster, MSN Music, Zune Marketplace and similar closed stores, often DRM-protected
• Voice recordings from Windows dictation software and some digital recorders
• Corporate audio such as training and conference recordings on Windows systems

How to Open a WMA File

Windows

• Windows Media Player, Media Player (the new app) and Groove all play WMA natively.
• VLC, foobar2000 and MusicBee also handle it, including WMA Lossless.

macOS

• Music.app and QuickTime do not play WMA.
• VLC plays every variant. Elmedia Player and IINA also work.

Linux

• VLC, Audacious, Rhythmbox and mpv, which all use ffmpeg's decoder.

iPhone and Android

• No native support on iOS; VLC plays it. Android's built-in player handles standard WMA on most devices, and VLC covers the rest.

DRM-protected files

A WMA that refuses to play, or plays only on the original computer, carries PlaysForSure or Zune DRM. The licence servers were shut down (Zune in 2015, MSN Music in 2008), so these files cannot be unlocked. The practical options are to re-rip from the CD if you have it, or to re-buy. Burning to CD and re-ripping was the sanctioned workaround while the licences still worked.

How to Convert a WMA File

To MP3 or AAC

# MP3, high-quality variable bitrate
ffmpeg -i song.wma -codec:a libmp3lame -q:a 2 song.mp3

# AAC in an M4A container, for Apple devices
ffmpeg -i song.wma -codec:a aac -b:a 192k song.m4a

# A whole folder
for f in *.wma; do ffmpeg -i "$f" -codec:a libmp3lame -q:a 2 "${f%.wma}.mp3"; done

Standard WMA is lossy, so every conversion is a second lossy pass. Use a generous bitrate on the output, and if the source CD is available, rip it again rather than converting.

WMA Lossless to FLAC

This conversion is lossless and worth doing, since FLAC is supported everywhere WMA Lossless is not:

ffmpeg -i song.wma -codec:a flac song.flac

Graphical tools

• Windows Media Player itself cannot convert, but Windows Media Player Legacy will burn to CD.
• fre:ac, dBpoweramp and MediaHuman Audio Converter batch-convert with tag preservation.
• VLC: Media, Convert / Save, choose an MP3 profile.
• iTunes / Music.app on Windows imports WMA and converts it to AAC on import (it cannot read DRM-protected files).

Advantages

• Good quality at low bitrates for its era, especially WMA Pro.
• Native on every Windows version since 2000.
• Lossless variant exists, unlike MP3.

Limitations

• Poor support outside Windows: no native Apple playback, inconsistent mobile support.
• DRM: a share of existing files are permanently locked.
• Obsolete: no current store or device targets it.
• Lossy source: converting to another lossy format degrades it further.

Related Formats

• WMV: the video sibling in the same ASF container.
• MP3: the format WMA competed with and lost to.
• FLAC: the open lossless format to convert WMA Lossless into.
• WAV: uncompressed Windows audio.