Earlier this month FFmpeg picked up support for new formats/decoders
and among them were RealVideo 4.0 support. What was missing, however, was support for RealVideo 3.0 with this free software media converting solution. A RealVideo 3.0 decoder though has now been added to FFmpeg. This decoder may still have a few bugs to it, but it's now available via their SVN repository.
For more information checkout the FFmpeg project