Matroska Media Container — Homepage
Welcome to the Home of Matroska the extensible, open source, open
standard Multimedia container. Matroska is usually found as .mkv files
(Matroska video), .mka files (Matroska audio), .mks files
(subtitles) and .mk3d files (stereoscopic/3D video). It is also the
basis for .webm (WebM) files.