While Xiph.Org, Broadcom, and Microsoft filed IPR disclosures giving royalty-free licenses to their patents used in Opus, four companies that did not directly participate in the development of Opus, Qualcomm, Huawei, France Telecom, and Ericsson filed IPR disclosures with potentially royalty-bearing terms. The IETF allows anyone (and their dog) to file an IPR disclosures if they think that their patents "covers or may ultimately cover" a standard. In fact, for any organization who can be said to have contributed in any (very loosely defined) way, these IPR statements are not just allowed, but required. It is thus safer for organisations to declare as much as they can. As an example, one can find similar non-free Qualcomm IPR statements on both SIP and SDP. To our advantage, however, the IETF IPR disclosure policies require companies to provide the actual patent numbers. This allows anyone to verify these claims for themselves, which is definitely a good thing.
When it comes to patents, it is difficult to say much without making lawyers nervous. However, we can say something quite direct: external counsel has advised us that Opus can be implemented without the need to license the patents disclosed by Qualcomm, Huawei, France Telecom, or Ericsson. We can also say that Mozilla is confident enough in Opus to ship it to hundreds of millions of Firefox users. Similarly, Google now supports Opus in Chrome and Cisco also supports Opus in at least one product. More companies are expected to do the same soon.
Mozilla invested significant legal resources into avoiding known patent thickets when designing Opus. Whenever possible, we used processes and methods that have been long known in the field and which are considered patent-free. In addition, we filed numerous patent applications on the new things we invented to help defend the Opus community. As a result, Opus is available on a royalty-free basis and can be deployed by anyone, including other open-source projects. Everyone knows this is an incredibly challenging legal environment to operate in, but we think we've succeeded.