RealMedia is a proprietary
multimedia container format created by
RealNetworks. Its extension is ".rm". It is typically used in conjunction with
RealVideo and
RealAudio and is used for
streaming content over the Internet. Typically these streams are in CBR (
constant bitrate), but a container for VBR (
variable bitrate) streams, named
RMVB (RealMedia variable bitrate), has been developed. Support of RealMedia is available in a few multimedia players for different architectures/platforms, including
RealPlayer and the
Real Alternative codec pack. The open source
DAP firmware
Rockbox has added support for reading RM containers as of 6 July 2009, although only certain formats used in RM files are playable.