Introduction:
- Format name: WMA / Windows Media Audio
- Format type: Audio
- File extensions: .WMA
- Compression Type: Lossy
The term WMA (WindowsMedia Audio) is normally used to refer to Microsoft's first audio codec that it originally developed to compete with the highly successful MP3 format. WMA is actually a set of audio compression codecs that form part of Microsoft's multimedia framework; the other codecs that have been developed are, WMA Pro, WMA Lossless, and WMA Voice. For simplicity, WMA in this article will refer to the format used by media software players, and various compatible hardware devices such as media/MP3 players. The WMA format is a lossy audio format that has become one of the most popular formats in use today.
Popular Compatible Hardware:
There are now many hardware devices on the market that are compatible with the WMA format. As well as PlayForSure devices (a Microsoft certification for hardware and online services) there is also a significant number of uncertified hardware that supports WMA playback. The majority of these compatible devices are portable MP3/media players, but there are also other consumer electronics such as DVD players, cell phones, in-car/home entertainment systems that can handle WMA files. Incidentally, if you own a PlayStation Portable (V2.60 or higher), you can use it to listen to WMA audio files.
Sampling Frequencies & Bitrates:
The WMA format provides the following sampling frequency range:
- 8 - 48 kHz
The bitrates that can be used with the WMA format are flexible and gives this format an advantage over MP3 when encoding audio. The bitrate range is:
- 5 - 320 kbps.
Compression Algorithm:
The WMA format uses a lossy compression algorithm. It is a transform codec that uses a psychoacoustics model and employs the modified discrete cosine transform (MDCT) to process the WMA bit stream.
Digital Rights Management:
WMA files can be protected with DRM using Microsoft's WMDRM system. The files that are downloaded from online digital music services are encapsulated using ASF (Advanced Systems Format); this is a container format that is used for audio and video files. DRM-protected WMA files are usually downloaded from subscription-based online services. If a subscription ends, then the files that the user has downloaded become unplayable. WMA protected audio files can also be downloaded from a la carte services and come with copy restrictions designed to inhibit distribution.
