RM

RM is an extension for ReadMedia files. They can be either video or audio. Also .RA (Read Audio) and RMVB RealMedia Variable Bitrate.

Overview

These are proprietary container formats created by Real Networks. They are intended and used for Internet streaming. An RM file has a constant bitrate while RMVB has a variable bitrate. RA was the original audio file format but the extension is seldom used anymore.

See Wiki Multimedia for information on the internal format of these files.