RMVB is a file format with a variable bitrate developed by RealNetworks. Actually it is an improved version of RM format. It gives greater bandwidth to videos that are difficult to compress. The extension keeps a high video definition. RMVB files are very popular in Asia and they are not supported by all popular players, so the easiest way to playback them is to convert them to another most common format.

RM is a proprietary video container created by RealNetworks Inc. – the pioneers in streaming media over the internet market. This format supports DRM and was widely used to stream video and audio data online in the early 2000s with more than 80% of online streaming was in the RealMedia format. RM is supported by iPhone, Android, Windows and Mac. This container is often used by online radio stations. Nowadays it is still necessary to install Real Player plugin to be able to play RM files on such streaming websites.