RealAudio

RealAudio (RM) is an audio format created by RealNetworks, Inc.

It is predominantly used in real-time internet transmissions. This means that a radio station can broadcast its signal live, directly to the end user, without first needing to download the entire audio file. Or, the user can listen, on demand, to a file stored on an external server. In both cases, the audio file is not downloaded to the end user's computer. Playback is done using "packages" that the server sends the user to a Real brand player, called RealPlayer. Each "package" audio is played while another one is received that replaces it in a temporary folder. This process is called Buffering. The advantage of this for the distributor is that the files cannot be copied or shared. The disadvantage for the user is that he can only listen to the online broadcast.

Unlike Shoutcast's mp3 transmission, which maintains the same sampling rate, RealAudio technology allows it to automatically adapt to the end user's reception capacity, depending on their connection speed, processor and memory. This means that if the user can receive high-quality audio packets without interruptions, the server will provide it that way. Otherwise, the server will reduce the sampling rate (and thus the audio quality) until the user does not experience interruptions in their signal.

Currently, Realnetworks allows real-time audio and video playback with a huge amount of additional information. As well as applications for cell phones and portable audio and video player devices.

The first version of RealAudio was released in 1995. As of 2009, the current version is RealAudio 10.

File extensions

RealAudio files were originally identified by the extension.ra (for Real Audio). In 1997 RealNetworks began offering a video format called RealVideo. The combination of audio and video formats was called RealMedia and uses the.rm extension. However, the latest version of RealProducer, the official RealNetworks encoder, reverted to using.ra for audio-only files, started using.rv for video files (with or without audio), and.rmvb for VBR video files..

The.ram (Real Audio Metadata) and.smil (Synchronized Multimedia Integration Language) formats are sometimes found as links to web pages.