RealAudio is a proprietary audio format developed by RealNetworks. It is especially designed to conform to low bandwidths, and it can be used as a streaming audio format, i.e. played at the same time as it's downloaded. Many radio stations use RealAudio to stream their programming over the internet in real time. The first version of RealAudio was released in 1995. As of 2005, the current version is RealAudio 10.

RealAudio files normally have a file extension of .ra, .rm or .ram.

The main player for RealAudio content is RealNetworks' RealPlayer. With RealPlayer, it is not possible to save an audio stream to a file. The free programs MPlayer and StreamBox VCR can be used for this purpose. Another free program to play RealAudio files is RealAlternative.

Codecs

RealAudio files are compressed using several different audio codecs. Below is a list of the codecs and the version each was introduced in:

• 8 kbit/s Linear Predictive Coder (RealAudio 1)
• Code Excited Linear Prediction (RealAudio 2)
• Dolby AC3 (RealAudio 3)
• Sipro Lab Telecom ACELP-NET (RealAudio 4/5)
• G2/Cook Codec (RealAudio 6)
• Sony ATRAC3 (RealAudio 8)
• MPEG-4 AAC (RealAudio 10)
• RealAudio Lossless Format (RealAudio 10)

While the newest version of RealPlayer should be able to play any RealAudio file, other programs may not support all codecs.

See also

• Icecast -- a free streaming server for internet radio stations, supports formats MP3, Ogg Vorbis and NSV
• Shoutcast -- a free, MP3-based program for internet radio stations
• Windows Media Audio -- Microsoft's media formats

External links

• Description of the codec, from RealNetworks
• Unofficial StreamBox VCR download
• How to download Real Audio streams and convert Real Audio to MP3