MKV File Format: Home

Obsolescence: file formats evolve and are created to incorporate new features and accommodate new software and technologies

Proliferation: file formats in an organization require normalization to avoid having many different file formats and versions to manage

Complexity: moving image file formats are complex because they contain audio and video, and possibly subtitle tracks, metadata, and still images, so its important to choose formats that are capable of sustaining all of their content

Container: the container that determines the type of data, codec, compression, and software used to hold and access the video and audio data

• e.g. MOV, AVI, MPEG-4, MKV, FLV, MXF

Video and audio: the actual video and audio data

• includes the frame size, aspect ratio, frame rate, bitrate, sample rate, etc. 

Codec: the software that is used to encode and decode the video/audio data

• e.g. H.264, H.263, H.261, Apple ProRes

Choosing the most appropriate file type is one of the most important aspects in maintaining preservation. File formats are the standard for describing a file's type and characteristics, and how to open the file. Preservation file formats differ from access formats in that they aim to look ahead to what formats will be most accessible in the future rather than what is most popular right now. As formats are created, evolve, and become obsolete, it's important to stay ahead of the curve. Currently, Virginia Tech's preservation file format for moving images (videos) is MOV, a popular proprietary file format developed by Apple, Inc. This is a common preservation format at other universities as well because it is stable and popular. However, the MKV file format developed by Matroska is a rising video preservation file format that is non-proprietary, and when compared to AVI, MPEG-4, and MOV file formats, is the most adaptable and flexible. This guide exists to explore the various options for moving picture preservation file formats and provide evidence for the MKV format being the current best practice.

Open source vs proprietary

Open source formats are generally more accessible to users and have fuller documentation than proprietary formats. Proprietary formats are more at risk for upgrades or obsolescence at the discretion of the owner, though they are usually considered to be more powerful. Proprietary formats have limits on the software that can open them. Open source formats are ideal for preservation because it lessens the likelihood that the format will upgrade or cease to be supported, and are able to be opened by more software. 

Documentation and standards

Accessibility to documentation and the standardization of the format are both important for understanding the format. Self-documentation is another aspect that combines the object with its metadata and therefore makes it more sustainable over time. Transparent documentation that is accessible and also human readable is ideal.

Adoption and community

A file format that is largely adopted and has a stable community foundation offers more information, discussion, and collaboration, as well as troubleshooting assistance.. This also increases the use of the file format and decreases the likelihood of obsolescence. 

Lossless vs lossy

Lossless and lossy are two types of data compression. Lossy formats lose part of their encoding when they compress files in order to decrease the file size, such as a JPEG. Lossless files compress data without losing any information, such as a TIFF, and the ideal compression for encoding. 

Metadata support

File formats need metadata support so that metadata can be paired directly with its object rather than stored separately. 

External dependencies

Some file formats rely on specific hardware and software to function. For example, an MOV is limited by Apple software. Less dependability on other technologies provides a more stable and usable ile format.

• Digital Preservation Coalition: File formats and standards
• Library of Congress Sustainability Factors
• Library of Congress Moving Images
• Abrams, S. (2007). "Installment on 'File Formats.'" DCC Digital Curation Manual. Verson 1. 
• Wikipedia: File format