Extract from [http://www.openmash.org/]
Consortium that supports the Mash streaming media toolkit and distributed collaboration applications based on the Internet Mbone tools and protocols.
Mash is an open-source project, toolkit for multimedia communication and collaboration over the Internet using IP multicast. Mash supports live media broadcasting, N-way conferencing, and session capture and replay. Mash is an outgrowth of the Internet MBone tools developed to support streaming audio and video applications. MASH is a "Multimedia Architecture that Scales across Heterogeneous environments".
Mash is coded in both C/C++ (media encoders and decoders) and Tcl/Tk.