Matroska / MKV Video file format

The Matroska Multimedia Container is an open standard free Container format, a file format that can hold an unlimited number of video, audio, picture or subtitle tracks inside a single file. It is intended to serve as a universal format for storing common multimedia content, like movies or TV shows. Matroska is similar in conception to other containers like AVI, MP4 or ASF, but is completely open source. Matroska file types are .MKV for video (and audio) and .MKA for audio-only files.

Matroska is an English word derived from the Russian word "matryoshka" (Russian: матрёшка, IPA: [mɐˈtrʲoʂkə]), which means "nesting doll" (the common Russian egg-shaped doll within a doll). This is a play on the container (media within a form of media/doll within a doll) aspect of the matryoshka as it is a container for visual and audio data. The project was announced on December 7, 2002 as a fork of an earlier container format project, after disagreements with that project's creator about the use of the Extensible Binary Meta Language (EBML) instead of another binary format. The founders of the Matroska project believe that the use of EBML brings them a number of advantages, including making it easier to extend the format for decades into the future as new developments occur and/or as the project goals change.

With Matroska's roots in EBML it has been designed from the ground up for longevity and extendability (unlike formats such as AVI). The Matroska team has spoken openly on Doom9.org and hydrogenaudio.org about some of their long term goals to create a modern, flexible, extensible, cross-platform multimedia container format that can:

• develop robust streaming support;
• develop a "DVD-like" menu system based on EBML;
• develop a set of tools for the creation and editing of Matroska files;
• develop libraries that can be used to allow developers to add Matroska support to their applications;
• work with hardware manufacturers to include Matroska support in embedded multimedia devices;
• provide native Matroska support in various operating systems.

Software support

These players have native Matroska support:

• Azureus Vuze Media Player
• BS.Player
• The Core Media Player
• CorePlayer Mobile
• The Core Pocket Media Player
• GOM Player
• Gstreamer-based Players (Totem, etc.)
• HandBrake
• jetAudio
• The KMPlayer
• Media Player Classic
• MediaPortal 
• Mezzmo Media Player
• MPlayer
• Totem Movie Player
• VLC media player
• VSO Software
• Xbox Media Center
• xine
• Zoom Player

Hardware support

The Sigma Designs 8634 and 8635 ICs, when accompanied by appropriate firmware, can properly decode Matroska files containing H.264 or MPEG-4 ASP video (including HD resolutions), and MP3, AAC, DTS, & AC3 audio. One of the first products based on this chip is the Syabas PopCorn Hour NMT-A100 network streaming client.
The new Cowon A3 is supposed to play back .mkv files (according to its product page in Korea and the US). This Linux based multimedia solution has also MKV support in their technical specs.

Content in Matroska

Initially the uptake of the format was low, it mainly competed with OGM on anime scene, due to both formats' seamless support for multiple audio tracks and embedded subtitle tracks. In recent years however Matroska sees wider use due to the "release scene" adopting it as a format of choice for HDTV rips of TV and next generation video discs (HD-DVD and BluRay). It usually carries H.264 video, AC3/AAC/DTS (also multiple) audio tracks and sometimes subtitle tracks. Before H.264, most MKV files from the above mentioned scene were holding RealVideo (RV9, RV10) encoded video tracks, which at that time was slightly superior to MPEG-4 Part 2 (used e.g. by the DivX and Xvid codecs), especially for anime material, in combination with MP3 or Vorbis encoded audio streams and soft-subtitles.

License

Matroska is an open standards project. This means for personal use it is free to use and that the technical specifications describing the bit stream are open to everybody, even to companies that would like to support it in their products. The source code of the libraries developed by the Matroska Development Team is licensed under GNU LGPL. In addition to that, there are also free parsing and playback libraries available under the BSD license, for proprietary software adaption.