Matroska

The Matroska Multimedia Container is an open source, open standard multimedia container, that can wrap an unlimited number of audio, video, metadata and/or subtitle-files. Matroska Audio supports a large number of codecs. It has a very large userbase and is the basis for WebM media in HTML5/browsers. Most platforms offer native support for this format. Adoption of the file format is expected to further increase thanks to several outcomes of the PREFORMA project, including the Media Conch toolset, an implementation checker for Matroska. Matroska file extensions are .mkv for video (with subtitles and audio), .mka for audio-only files, and .mks for subtitles only.

Matroska is a DANS preferred container format for audio and video.
Read more about Audio.
Read more about Video.