|Disclosure||Fully documented. Developed as an open source project; see history section of the below which also reports on the CELLAR IETF standardization project launched in 2015.|
Modest adoption in heritage repositories. The City of Vancouver Archives uses FFV1 encoded video wrapped in the Matroska container, as discussed briefly on the archives' blog. This implementation is connected to the open source Archivematica project, whose Wiki lists Matroska-wrapped FFV1 video and LPCM audio as one of its preservation formats. Matroska also plays a critical role in the WebM open media project.
According to the Wikipedia article Matroska, consulted on May 11, 2012, a number of software applications support Matroska, including Zoom Player, MPlayer, VLC, KMPlayer, ALLPlayer, Elmedia Player, foobar2000, HandBrake, Pinnacle Studio, and PowerDVD, as well as media centers such as Plex, Boxee, PS3 Media Server and XBMC, and the Web browser Google Chrome. Hardware support is provided on some Blu-ray players and media centers like Asus, OPPO Digital, Panasonic, LG, Samsung, Sharp, LaCie and Western Digital.
Adoption is expected to increase thanks to several outcomes of the European Union-based PREFORMA project, including IETF-sponsored format specification standardization through the CELLAR project and the open source MediaConch toolset, an implementation checker, policy checker, reporter, and fixer for FFV1, Matroska and LPCM.
|Licensing and patents||The Matroska website says this: "Matroska is an open standards project. This means for personal use it is absolutely free to use and that the technical specifications describing the bitstream 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 L-GPL. In addition to that, there are also free parsing and playback libraries available under the BSD license, for commercial software and Hardware adoption." According to Wikipedia, consulted May 10, 2012, "CoreCodec owns the copyrights and trademarks for the Matroska specification."|
|Transparency||Depends upon included encodings, some of which will depend upon algorithms and tools to read and require sophistication to build tools.|
The Matroska website provides a diagram of the sections of the wrapper. Technical and descriptive metadata can be found in a few different places in the wrapper. Technical metadata appears in the Track section, as described on the Matroska developer website: "The Track section has basic information about each of the tracks. For instance, is it a video, audio or subtitle track? What resolution is the video? What sample rate is the audio? The Track section also says what codec to use to view the track, and has the codec's private data for the track." Matroska has established identifiers for the codecs it supports, similar to the FOURCC and other identifiers that provide a higher level of specificity (often to the coding profile level) than Internet Media Types (aka MIME types). Timecode metadata is provided in the headers for blocks, blockgroups, and clusters.