The Matroska format is a multimedia container envelope for video, audio and subtitle files. An entire CD or DVD can fit inside a single file. The extension for a Matroska file containing video is MKV; for audio only MKA, and for subtitles only, MKS. The MKV format has many advantages over competing containers like Microsoft®’s Audio Video Interleave (AVI), Apple®’s Quicktime® MOV, Moving Pictures Experts Group (MPEG) and others.
While each of the container formats in use today fulfills some or even many of the features desired in a container format, Matroska aims to be the standard that meets them all, setting it apart from virtually all others. Built on EBML (Extensible Binary Meta Language), it is highly flexible for meeting future needs.
The first advantage of the MKV format is that it is open source, making the code freely available to developers the world over, and to the public. Most other container formats contain mostly proprietary code, developed solely by the originating company and licensed parties. Open source programs have an arguably higher potential for more creative solutions and broader implementation.
The MKV format supports menus like a DVD, chapters, and multiple audio streams for the inclusion of audio tracks in different languages. Just like a DVD, you can choose the language of your choice, providing the creator included multiple choices.
Soft subtitles are also supported in the MKV format. A soft subtitle is a separate subtitle track within the container that can be turned off or on by the user. If you have ever downloaded an AVI file with unneeded subtitles and was unable to turn them off, you will appreciate this feature.
MKV can contain variable bitrate audio and variable framerate video, plus B-frame compression. But unlike most other containers, it also supports virtually any video format, including MPEG-1, MPEG-2, MPEG-4, MPEG-4 Part 2 (H.263), MPEG-4 Part 10/Advanced Video Coding (AVC)/H.264, Windows® Media Video (WMV), RealVideo and more.
The MKV format also supports virtually any audio format, including lossless audio like FLAC, and audio container formats like Ogg. It also supports Speex, a lossy format for compressing audio speech. The design team of Matroska is confident future audio and video formats will also be supported, thanks to the EBML foundation of the MKV format.
Not every audio player supports MKV files. The VLC player, a free and open source, cross-platform audio and video player, supports the MKV format without need of plugins or special codecs. Mastroska’s own CorePlayer Pro and Mobile are other options. Microsoft® players based on DirectShow® can play MKV files with the Combined Community Codec Pack (CCCP) installed. A full list of players, codecs and plugins that support MKV are available from the Matroska website at the “Downloads” link.
Support for MKV is spreading offline as well. Manufacturers like Samsung® and LG® are already making specific models of high-definition televisions and Bluray® players with support for streaming MKV content.