libtheora

libtheora is a C library that provides encoding and decoding of Theora video streams, the free, open video codec used in the Ogg Theora container format. It forms part of Xiph.org's family of multimedia libraries and is designed to be used in conjunction with libogg to read and write Theora streams inside Ogg files. The library exposes a C API that supports creating encoder and decoder state, configuring parameters, and processing raw video frames into Theora-encoded data or reconstructing frames from Theora-encoded data for playback.

libtheora is released under a permissive BSD-style license, allowing broad use in free and proprietary software. It is commonly used by players and converters that support Ogg Theora, and can be integrated into applications by linking with libogg and theora components.

As part of the Xiph.org project, libtheora provides a reference implementation of the Theora codec and serves as a stable, documented API for developers needing to handle Theora video within Ogg streams. It interoperates with other Xiph components such as libogg and the Ogg container format, facilitating open, royalty-free video workflows in multimedia applications.