Real Audio is an audio file format for Real Media, which is mainly used for audio data streams ( streaming audio) is used.

The compression method of RealAudio are usually lossy. Here, RealAudio uses similar to MP3 and Vorbis for compressing the fact that the human ear does not perceive certain sound information.

The term RealAudio different codecs are used, of which the least -house developments of RealNetworks. For the most part there are implementations of existing standards or licensed from other companies codecs. The various codecs are identified by a FourCC:

For standardized formats IS-54 ( 14_4, lpcJ ), G.728 ( 28_8 ), AC -3 ( dnet ) and AAC ( raac, RACP ) there are free decoder implementations ( for example, in FFmpeg ), which means these formats can also be played outside of the RealPlayer. Also for the proprietary codec cook there since December 2005 FFmpeg a free implementation. The necessary information was obtained through reverse engineering.

Developed and patented side RealAudio RealNetworks also the counterpart for video applications RealVideo.

The file extension of RealAudio is. Era, the MIME type is audio / x - pn - realaudio. . Ending with rm the playlist ( Playlist ) is in the Real Audio files: it contains a plain text file, the ra files that play or " stream " should. . RealAudio is also used in RealMedia, mostly related to RealVideo. Real Audio can also be used in Matroska.