Please see the "Other disclosures" section on https://www.opus-codec.org/license/ https://www.opus-codec.org/license/ You may also be interested in https://hac

Please see the "Other disclosures" section on https://www.opus-codec.org/license/ https://www.opus-codec.org/license/ You may also be interested in https://hacks.mozilla.org/2013/02/defending-opus/ https://hacks.mozilla.org/2013/02/defending-opus/ (warning: contains discussion of specific, unexpired patents).