Free digital container formats

Ogg is a digital multimedia container file format designed to provide for efficient streaming and manipulation of digital multimedia. It is maintained by the Xiph.Org Foundation and is free and open, unrestricted by software patents. Its name is derived from "ogging," jargon from the computer game Netrek, alluding to the high processing cost of early versions of the software.

WebM (from "Web Movie") is an audiovisual media file format. It is primarily intended to offer a royalty-free alternative to use in HTML video and HTML audio elements. It has a sister project for images: WebP. The development of the format is sponsored by Google, and the corresponding software is distributed under a BSD license. WebM was a collaborative effort first released in 2010.

Matroska (styled Matroška) is a project to create a container format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. The Matroska Multimedia Container is similar in concept to other containers like AVI, MP4, or Advanced Systems Format (ASF), but is an open standard.