Multimedia Container Format (MCF) is an unfinished specification for container format, designed to be completely free and open. The project was abandoned in early 2004, but many of its innovative features have since found their way into Matroska, MCF's de facto successor. History MCF was the first project to create an open and flexible media container format that could encapsulate multiple video, audio and subtitle streams in one file. The project was started in 2000 by the developer Lasse Kärkkäinen (Tronic) as an attempt to improve the aging AVI format. The first draft specification was published in 2001. At first the project generated some confusion about its intended goals. This was solved when the lead developer created a simple player for the format which supported embedded subtitles, which sparked interest and the community began to grow. Several new features were added, and the specification refined. The crucial event in the project's history was the invention of EBML in the fall of 2002, a binary meta-format inspired by XML, by the programmer Steve Lhomme, quickly followed by a six-month long coding break by Kärkkäinen due to military service. Since MCF was deemed nearly release-ready at the time, EBML was not accepted, which led Lhomme to fork his own Matroska project based on EBML. Due to the absence of the lead developer, most of the interest quickly shifted to the new project; by the time Kärkkäinen returned from the army, the developer community around MCF had completely disintegrated. Lack of manpower and educational commitments caused Kärkkäinen's attempts at reviving the project to fail. The final specifications were never published, and the last news entry on the project's SourceForge web page is dated September 6th, 2003. Features One of the objectives of the new format was to simplify its handling by players. This was to be done by making it feature-complete, eliminating the need for third-party extensions and actively discouraging them. Because of the simple, fixed structure, the time required to read and parse the header information was minimal. The small size of the header (2.5 kB), which at the same time contained all the important data, facilitated quick scanning of collections of MCF files, even over slow network links. The key feature of MCF was being able to store several chapters of video, menus, subtitles in several languages and multiple audio streams (e.g., for different languages) in the same file. At the