The Matroska Multimedia Container is a free, open standard container format, a file format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. It is a universal format for storing common multimedia content, like movies or TV shows. Matroska is similar in concept to other containers like AVI, MP4, or Advanced Systems Format (ASF), but is entirely open in specification, with implementations consisting mostly of open-source software. Matroska file extensions are .MKV for video (which may or may not include subtitles and audio), .MK3D for stereoscopic video, .MKA for audio-only files, and .MKS for subtitles only.
"Matroska" is derived from matryoshka (Russian: матрёшка ), which refers to the hollow wooden Russian matryoshka doll which opens to expose another doll that in turn opens to expose another doll, and so on. That may be confusing for Russian speakers, as the Russian word "Matroska" (Russian: матроска) actually refers to other things, e.g. it could refer to a sailor suit, or a sailor's wife, or a female sailor. The logo uses "Matroška", with the caron over the "s", as the letter š represents the "sh" sound (/ʂ/) in various languages.
The project was announced on 6 December 2002 as a fork of the Multimedia Container Format (MCF), after disagreements between MCF lead developer Lasse Kärkkäinen and soon-to-be Matroska founder Steve Lhomme about the use of the Extensible Binary Meta Language (EBML) instead of a binary format. This coincided with a 6-month coding break by the MCF's lead developer for his military service, during which most of the community quickly migrated to the new project.
In 2010, it was announced that the WebM audio/video format would be based on a profile of the Matroska container format together with VP8 video and Vorbis audio.
On 31 October 2014, Microsoft confirmed that Windows 10 would support HEVC and Matroska out of the box, according to a statement from Gabriel Aul, the leader of Microsoft Operating Systems Group's Data and Fundamentals Team. Windows 10 Technical Preview Build 9860 added platform-level support for HEVC and Matroska.
The use of EBML allows extension for future format changes. The Matroska team has expressed some of their long-term goals on Doom9.org and Hydrogen Audio forums. Thus, the following are "goals", not necessarily existing features, of Matroska:
In parentheses are the statuses of these design goals.
Matroska is supported by a non-profit organization in France (association loi 1901), and the specifications are open to everyone. The Matroska project is a royalty-free open standard that is free to use, and its technical specifications are available for private and commercial use. The Matroska development team licenses its libraries under the LGPL, with parsing and playback libraries available under BSD licenses.