REAL-ly grainy video streams
RealVideo is much like its sibling: RealAudio -- the streaming music format from RealNetworks. First released in 1997, RealVideo has seen a lot of nasty Internet images over the course of its decade-long tenure. It is currently in its tenth version (via the release of the 2006 RealVideo 10). Because it was developed to enhance RealAudio, the two codecs are packaged together as part of the RealMedia (.rm) container.
RealVideo is one of the more popular video codecs and, as a result, it is widely supported. Most operating systems, including Windows, Macintosh, and Linux, all back the format.
There are two relatively simple ways to employ RealVideo. First, a user can view the codec's visuals through a RealMedia file. In many cases, users are viewing RealVideo online through streaming. When doing this over a network, a user will be employing the Real Time Streaming Protocol (RTSP), which is a standard protocol for streaming any type of media.
As for the speed and quality, both RealAudio and RealVideo use a constant bitrate encoding method. This means that the exact same amount of material is sent through the network per second. This keeps the trains running on time, per se, but for better quality RealNetworks has introduced a few new measures. Users can now employ the RealMedia Variable Bitrate, or rmvb, which allows for improved visuals at the cost of streaming efficiency. Much like WMV HD, RealVideo's improved bitrate streaming will be a better experience when used on a faster computer.
Fast-paced action can actually cause RMVB to stop
Obviously, the main player necessary for those interested in using RealVideo will be RealPlayer, although alternatives exist with the open source MPlayer and Real Alternative.