Is a multimedia container format from Microsoft, which stores video and audio file streams. Distinctive feature is a the lack of information on the coding data. The container defines the structure of the stream so it can, like AVI, contain videos with different codecs, as well as operate during synchronization of streams.
As opposed to the more common RealMedia container, which holds streaming media encoded at a constant bitrate (CBR), RMVB is typically used for multimedia content stored locally. Files using this format have the file extension .rmvb.