Introduction
Windows Media Audio is Microsoft’s family of audio codecs, introduced in 1999 as a rival to MP3 and played by Windows Media Player. The family includes the standard lossy codec, WMA Pro for multichannel and high-resolution audio, WMA Lossless and WMA Voice. WMA files were common in online music stores of the 2000s, some protected with DRM.
Structure
A .wma file uses Microsoft’s Advanced Systems Format (ASF), the same
container as .wmv video. ASF is made of objects, each a 16-byte GUID and
a 64-bit little-endian size. The file starts with the Header Object, whose GUID begins
with the bytes 30 26 B2 75. It holds further objects: file properties
(duration, packet size), stream properties (the codec and its settings) and content
description (title, author). The Data Object follows with the audio in fixed-size
packets, and an optional Index Object helps seeking.
0Header Object file and stream properties, tagsvaries…Data Object audio in fixed-size packetsvaries…Index Object optional, for seekingvaries
Links
Software
- Windows Media Player – Microsoft’s media player, built into Windows (Windows)
- VLC media player – free player for almost any audio or video file (Windows, macOS, Linux, mobile)
- foobar2000 – free music player and converter (Windows, macOS, mobile)
- FFmpeg – command-line tool that converts WMA to other formats (Windows, macOS, Linux)
Developers
- libavcodec – FFmpeg’s codec library, which decodes WMA (C)