Recently, RealNetworks has introduced a variable bit rate form called RealMedia Variable Bitrate ( RMVB). To facilitate real-time streaming, RealVideo (and RealAudio) normally uses constant bit rate encoding, so that the same amount of data is sent over the network each second. However, the open source MPlayer project has now developed software capable of playing the RDT streams. This tactic has drawn criticism because it made it difficult to use RealVideo with other player and server software. The actual video data is sent with their own proprietary Real Data Transport (RDT) protocol.

However, RealNetworks uses RTSP only to set up and manage the connection. RealVideo can be played from a RealMedia file or streamed over the network using the Real Time Streaming Protocol (RTSP), a standard protocol for streaming media developed by the IETF. These identifiers have been the source of some confusion, as people may assume that RV10 is RealVideo version 10, when it is actually the first version of RealVideo. RV30 and RV40 are RealNetworks' proprietary H.264-based codecs. RV10 and RV20 are the H.263-based codecs. RealVideo codecs are identified by four-character codes. RealVideo continued to use H.263 until RealVideo 8, when the company switched to a proprietary video format. However, support for ClearVideo quietly disappeared in the next version of RealVideo. At the time, RealNetworks issued a press release saying they had licensed Iterated Systems' ClearVideo technology and were including it as the RealVideo Fractal Codec. The first version of RealVideo was announced in 1997 and was based on the H.263 format.

Streaming video can be used to watch live television, since it does not require downloading the entire video in advance. RealMedia is suitable for use as a streaming media format, that is one which is viewed while it is being sent over the network. RealVideo is usually paired with RealAudio and packaged in a RealMedia (.rm) container. RealVideo is supported on many platforms, including Windows, Mac, Linux, Solaris, and several mobile phones.

It was first released in 1997 and as of 2008 was at version 10. RealVideo, or also spelled as Real Video, is a suite of proprietary video compression formats developed by RealNetworks - the specific format changes with the version. Product Website at the Wayback Machine (archived May 31, 2009)

Real time video player