What Open-Source License Governs the Libaom Library?

The libaom library, which serves as the reference software implementation for the AV1 video codec developed by the Alliance for Open Media (AOMedia), is primarily governed by the Alliance for Open Media Patent License 1.0 alongside the BSD 2-Clause License. This article breaks down the dual-licensing structure of libaom, details the specific terms of its open-source and patent grants, and explains the implications for developers and companies looking to integrate this royalty-free video technology into their software or hardware projects.

The Dual-License Structure of Libaom

To understand how libaom can be used, it is essential to look at the two distinct components that make up its licensing framework: code distribution and patent protection.

• Software Code License (BSD 2-Clause): The actual source code of the libaom repository is distributed under the highly permissive BSD 2-Clause License (also known as the Simplified BSD License). This allows developers to freely copy, modify, and distribute the code in both source and binary forms, provided that the original copyright notice, the list of conditions, and the disclaimer are retained.
• Patent License (AOMedia Patent License 1.0): Because video compression technologies heavily rely on complex mathematical methods that are often patented, code permission alone is not enough. To address this, libaom includes a specific patent grant from the Alliance for Open Media. This grant ensures that anyone using the software receives a perpetual, worldwide, non-exclusive, no-charge, royalty-free patent license to utilize the necessary patent claims embodied in the reference implementation.

Key Clauses and the Patent Defense Provision

The combination of these licenses is designed to promote the widespread adoption of the AV1 codec without the fear of sudden royalty demands. However, the AOMedia Patent License contains a crucial reciprocity and termination clause meant to protect the ecosystem:

Patent Litigation Termination: If any entity initiates patent litigation against any other party alleging that the AV1 reference implementation or any implementation of the AV1 specification infringes their patents, the royalty-free patent licenses granted to that litigating entity under this agreement are immediately terminated.

This defensive mechanism ensures that companies cannot benefit from the royalty-free AV1 patents while simultaneously suing others over the same technology.

Practical Implications for Developers

For developers, businesses, and open-source projects, the licensing of libaom offers significant advantages over older, proprietary video standards like HEVC (H.265). It allows commercial entities to integrate AV1 encoding and decoding into web browsers, operating systems, applications, and hardware devices without paying licensing fees or per-unit royalties to a patent pool. Because the BSD 2-Clause license is compatible with most other open-source frameworks, libaom can be easily incorporated into large ecosystem projects such as FFmpeg, VLC, and WebRTC.