chromium/third_party/opus/src/LICENSE_PLEASE_READ.txt

Contributions to the collaboration shall not be considered confidential.

Each contributor represents and warrants that it has the right and
authority to license copyright in its contributions to the collaboration.

Each contributor agrees to license the copyright in the contributions
under the Modified (2-clause or 3-clause) BSD License or the Clear BSD License.

Please see the IPR statements submitted to the IETF for the complete
patent licensing details:

Xiph.Org Foundation:
https://datatracker.ietf.org/ipr/1524/

Microsoft Corporation:
https://datatracker.ietf.org/ipr/1914/

Skype Limited:
https://datatracker.ietf.org/ipr/1602/

Broadcom Corporation:
https://datatracker.ietf.org/ipr/1526/