Source: https://opus-codec.org/license/ (retrieved 2026-10-07)

License – Opus Codec
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License
Opus has a freely available specification, a BSD-licensed, high-quality
reference encoder and decoder, and protective, royalty-free licenses for
the required patents. The copyright and patent licenses for Opus are
automatically granted to everyone and do not require application or
approval. The Opus FAQ has more information on
why Opus is freely
licensed
.
In brief:
(see
below
for details)
You can encode or decode Opus-compatible streams
    for any purpose at no cost.
You can integrate the reference Opus encoder and
    decoder in any application, program or product, even commercially,
    at no cost.
You can create your own compatible implementations
    of the Opus specification and give them away or sell them.
You may
not
do these things if you engage on
    Opus-related patent litigation against
any
user of Opus.
Licensing details
Copyright
Specification
The specification is freely available as part of IETF RFC 6716.
The RFC includes the reference implementation, which is available
under the three-clause BSD license (see below).
Implementation
Both the reference implementation and the revised implementations on
opus-codec.org are available under the three-clause BSD license. This
BSD license is compatible with all common open source and commercial
software licenses.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
- Neither the name of Internet Society, IETF or IETF Trust, nor the
names of specific contributors, may be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Tools
Most of the command-line Ogg-based tools that are shipped as part of the
separate opus-tools package are also released under the three-clause BSD
license. The only exception is the opusinfo tool, which is released
under the GPLv2 license. Proprietary software developers wishing to use
Opus may copy code from opusenc and opusdec, but they may not copy code
from the opusinfo tool to build their applications.
Patents
Opus is covered by several patents. These patents are available under
open-source-compatible, royalty-free licenses. If you are not trying to
attack Opus with your patents, you will not have problems with these
licenses.
Some of these licenses have been updated in the past and may be updated
again in the future. However, updates never invalidate the old licenses
and users are always free to rely on any of the previously available
licenses.  In other words, newer licenses can give more rights, but
never fewer.
Xiph.Org Foundation
The Xiph.Org foundation has several patent applications on techniques
used in Opus. When issued, these patents will be automatically available
under the terms provided in the below license. The license covers the
listed patent applications, along with any other patent or application
covering Opus that is owned by Xiph.Org.
Xiph.Org Patents/Applications covered:
US 61/284,154
US 61/450,041
US 61/450,053
US 61/450,060
and any other applicable
License Grant
Xiph.Org Foundation (“Xiph”) hereby grants to you a perpetual,
worldwide, non-exclusive, no-charge,royalty-free, irrevocable (except
as stated in this license) license under Licensed Patents to make,
have made, use, offer to sell, sell, import, transfer, and otherwise
run, modify (in a way that still complies with the Specification), and
reproduce any Implementation.
Definitions. Specification means, and includes the following, both
individually and collectively, (a) any standard specification of the
Opus codec adopted by the IETF Codec Working Group (“Standard”) and
(b) any reference implementation (each, a “Reference Implementation”)
published by the IETF Codec Working Group in the request for comments
(“RFC”) issued by the IETF for the Specification draft for which this
License is issued, or any RFC that is issued as an update or new
version thereof. An Implementation means any Reference Implementation,
or another implementation that complies with the Specification.
Licensed Patents means all patents currently owned by Xiph or acquired
hereafter that Xiph has the right to license as set forth above and
that are necessarily infringed by the Specification, where
“necessarily infringed” means: in the case of (a) above, there is no
commercially viable means of implementing the Specification without
infringing such patent; in the case of (b) above, use of the reference
implementation to the extent it infringes such patent.
Termination. If you, directly or indirectly via controlled affiliate
or subsidiary, agent, or exclusive licensee, file a Claim for patent
infringement against any entity alleging that an Implementation in
whole or in part constitutes direct or contributory patent
infringement, or inducement of patent infringement (a “Claim”),
provided that a Reference Implementation also infringes the patents
asserted in the Claim, then any patent rights granted to you under
this License shall automatically terminate retroactively as of the
date you first received the grant.  Claims made against an
Implementation in part will only trigger termination if the
Implementation in part was done for the purpose of combining it with
other technology that complies with the Specification so that the
technology’s ultimate use will be consistent with the Standard as a
whole.
This license is also filed on the
IETF site
.
Broadcom
Broadcom has both issued patents and outstanding applications covering
Opus. These are available under the same license as the Xiph.Org
patents. The license covers the listed patents and patent applications,
along with any other patent or application covering Opus that is owned
by Broadcom.
Broadcom Patents/Applications covered:
US 61/406,106
US 61/394,842
US 7,353,168
and any other applicable
License Grant
Broadcom Corporation (“Broadcom”) hereby grants to you a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except
as stated in this license) license under Licensed Patents to make,
have made, use, offer to sell, sell, import, transfer, and otherwise
run, modify (in a way that still complies with the Specification), and
reproduce any Implementation.
Definitions. Specification means, and includes the following, both
individually and collectively, (a) any standard specification of the
Opus codec adopted by the IETF Codec Working Group (“Standard”) and
(b) any reference implementation (each, a “Reference Implementation”)
published by the IETF Codec Working Group in the request for comments
(“RFC”) issued by the IETF for the Specification draft for which this
License is issued, or any RFC that is issued as an update or new
version thereof. An Implementation means any Reference Implementation,
or another implementation that complies with the Specification.
Licensed Patents means all patents currently owned by Broadcom or
acquired hereafter that Broadcom has the right to license as set forth
above and that are necessarily infringed by the Specification, where
“necessarily infringed” means: in the case of (a) above, there is no
commercially viable means of implementing the Specification without
infringing such patent; in the case of (b) above, use of the reference
implementation to the extent it infringes such patent.
Termination. If you, directly or indirectly via controlled affiliate
or subsidiary, agent, or exclusive licensee, file a Claim for patent
infringement against any entity alleging that an Implementation in
whole or in part constitutes direct or contributory patent
infringement, or inducement of patent infringement (a “Claim”),
provided that a Reference Implementation also infringes the patents
asserted in the Claim, then any patent rights granted to you under
this License shall automatically terminate retroactively as of the
date you first received the grant. Claims made against an
Implementation in part will only trigger termination if the
Implementation in part was done for the purpose of combining it with
other technology that complies with the Specification so that the
technology’s ultimate use will be consistent with the Standard as a
whole.
This license is also filed on the
IETF site
.
Microsoft
Microsoft acquired patents and applications related to Opus through
their purchase of Skype. These patents (and any other Microsoft might
have had) are available under a different, but still royalty-free,
license detailed below. The license covers the listed patent
applications, along with any other patent or application covering Opus
that is owned by Microsoft.
Microsoft Patents/Applications covered:
US-2008-0201137-A1
US-2010-0174535-A1
US-2010-0174534-A1
US-2010-0174547-A1
US-2010-0174532-A1
US-2010-0174537-A1
US-2010-0174542-A1
US-2010-0174531-A1
US-2010-0174541-A1
US-2010-0174538-A1
US-2011-0077940-A1
and any other applicable
Microsoft Opus Patent Terms
11-7-2012
1. Patent Terms.
1.1. Specification License. Subject to all the terms and conditions of
this Agreement, I, on behalf of myself and my successors in interest
and assigns, hereby grant you a non-sublicensable, perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable license
to my Necessary Decoder Claims for your Specification Implementation.
1.2. Code License. Subject to all the terms and conditions of this
Agreement, I, on behalf of myself and my successors in interest and
assigns, hereby grant you a non-sublicensable, perpetual, worldwide,
non-exclusive, no-charge, royalty-free, irrevocable patent license to
my Necessary Reference Implementation Claims to make, use, sell, offer
for sale, import or distribute a Code Implementation.
1.3. Conditions.
1.3.1. Availability. If you own or control Necessary Claims, the
licenses set forth in Section 1 are subject to and will become
effective starting on the date that you make a binding public
irrevocable commitment to license, on reasonable and
non-discriminatory royalty-free licensing terms 1) your Necessary
Decoder Claims to all implementers for Specification Implementations,
and 2) your Necessary Reference Implementation Claims to all
implementers for Code Implementations, where the terms of this
Agreement satisfy any reciprocity requirements in your reasonable and
non-discriminatory royalty-free licensing terms. The promises set
forth in Section 1 will remain in effect so long as you continue to
make such claims available for Specification Implementations and Code
Implementations under reasonable and non-discriminatory royalty-free
licensing terms. In addition, as a condition of the licenses set forth
in Section 1, you acknowledge and agree that you have not and will not
knowingly take any action for the purpose of circumventing the
conditions in this Section 1. Notwithstanding the foregoing, you are
not required to make the commitments set forth in this Section 1.3.1
as a result of merely using a Specification Implementation or a Code
Implementation as an end-user.
1.3.2. Additional Conditions. This license is directly from me to you
and you acknowledge as a condition of benefiting from it that no
rights from me are received from suppliers, distributors, or otherwise
in connection with this license. This license is not an assurance (i)
that any of my issued patent claims covers a Specification
Implementation or Code Implementation or are enforceable or (ii) that
a Specification Implementation or Code Implementation would not
infringe intellectual property rights of any third party.
1.4. Termination. All rights, grants, and promises made by me to you
under Section 1 are immediately terminated if you or your agent file,
maintain, or voluntarily participate in a lawsuit against me or any
person or entity asserting that a Specification Implementation
infringes Necessary Decoder Claims or a Code Implementation infringes
Necessary Reference Implementation Claims, unless that suit was in
response to a corresponding suit regarding a Specification
Implementation or Code Implementation first brought against you. In
addition, all rights, grants, and promises made by me to you under
Section 1 are terminated if you, your agent, or successor in interest
seek to license Necessary Decoder Claims for Specification
Implementations or Necessary Reference Implementations Claims for Code
Implementations on a royalty-bearing basis, unless that
royalty-bearing licensing activity is in addition to, and not in lieu
of, reasonable and non-discriminatory royalty-free licensing terms for
Necessary Decoder Claims for Specification Implementations or
Necessary Reference Implementation Claims for Code Implementations.
This Agreement may also be terminated, including back to the date of
non-compliance, because of non-compliance with any other term or
condition of this Agreement.
2. Patent License Commitment. On behalf of me and my successors in
   interest and assigns, I agree to offer alternative reasonable and
   non-discriminatory royalty-bearing licensing terms 1) to my
   Necessary Decoder Claims solely for your Specification
   Implementation and 2) to my Necessary Reference Implementations
   Claims solely for your Code Implementation.
3. Past Skype Declarations. You may, at your option, continue to rely
   on the terms set forth in Skype’s past declarations made to the
   IETF for the Opus Audio Codec, subject to the terms of those
   declarations and in lieu of the terms of this Agreement solely for
   the patents set forth in those declarations.
4. Good Faith Obligations. I agree that I have not and will not
   knowingly take any action for the purpose of circumventing my
   obligations under this Agreement. In addition, I will not 1) seek
   an injunction or exclusion order against a) Code Implementations
   for Necessary Reference Implementation Claims or b) Specification
   Implementations for Necessary Decoder Claims or 2) require that an
   implementer license its patents back to me, except for Necessary
   Reference Implementation Claims for Code Implementations and
   Necessary Decoder Claims for Specification Implementations. I will
   not transfer Necessary Reference Implementation Claims or Necessary
   Decoder Claims unless the transferee is subject to these
   obligations.
5. Disclaimers. I expressly disclaim any warranties (express, implied,
   or otherwise), including implied warranties of merchantability,
   non-infringement, fitness for a particular purpose, or title,
   related to the Specification or Reference Implementation. The
   entire risk as to implementing or otherwise using the
   Specification, Specification Implementation, or Code Implementation
   is assumed by the implementer and user. IN NO EVENT WILL ANY PARTY
   BE LIABLE TO ANY OTHER PARTY FOR LOST PROFITS OR ANY FORM OF
   INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OF ANY
   CHARACTER FROM ANY CAUSES OF ACTION OF ANY KIND WITH RESPECT TO
   THIS AGREEMENT, WHETHER BASED ON BREACH OF CONTRACT, TORT
   (INCLUDING NEGLIGENCE), OR OTHERWISE, AND WHETHER OR NOT THE OTHER
   PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Nothing
   in this Agreement requires me to undertake a patent search.
6. Definitions.
6.1. Agreement. “Agreement” means this document, which sets forth the
rights, grants, limitations, conditions, obligations, and disclaimers
made available for the particular Specification.
6.2. Code Implementation. “Code Implementation” means making, using,
selling, offering for sale, importing or distributing 1) the Reference
Implementation, or 2) an implementation that, in the case of an
encoder, produces a bitstream that can be decoded by a Specification
Implementation solely to the extent it produces such a bitstream, and,
in the case of decoder, is a Specification Implementation, where that
Specification Implementation may also infringe Necessary Reference
Implementation Claims.
6.3. Control. “Control” means direct or indirect control of more than
50% of the voting power to elect directors of that corporation, or for
any other entity, the power to direct management of such entity.
6.4. I, Me, or My. “I,” “me,” or “my” refers to the party making this
declaration, and any entity that I Control.
6.5. Necessary Claims. “Necessary Claims” means Necessary Decoder
Claims and Necessary Reference Implementation Claims.
6.6. Necessary Decoder Claims. “Necessary Decoder Claims” are those
patent claims that a party owns or controls, including those claims
acquired after the date of this declaration, that are necessarily
infringed by an implementation of the required portions (including the
required elements of optional portions) of the decoder Specification
that are described in detail and not merely referenced in the
Specification.
6.7. Necessary Reference Implementation Claims. “Necessary Reference
Implementation Claims” are those patent claims that a party owns or
controls, including those claims acquired after the date of this
declaration, that are necessarily infringed by the Reference
Implementation. Necessary Reference Implementation Claims do not
include claims that would be infringed only as a consequence of
further modification of the Reference Implementation.
6.8. Reference Implementation. “Reference Implementation” means the
implementation of the Opus encoder and/or decoder code extracted from
Appendix A of the Specification.
6.9. Specification. “Specification” means IETF RFC 6716 dated
September 2012.
6.10. Specification Implementation. “Specification Implementation”
means making, using, selling, offering for sale, importing or
distributing any conformant implementation of the decoder set forth in
the Specification 1) only to the extent it implements the
Specification and 2) so long as all required portions of the
Specification are implemented. Specification Implementation also
includes any implementation of a decoder included in subsequent
versions of RFC 6716 1) only to the extent that it implements the
decoder Specification, and 2) so long as all required portions of the
decoder Specification are implemented.
6.11. You or Your. “You,” “you,” or “your” means any person or entity
who exercises patent rights granted under this Agreement, and any
person or entity you Control.
This license is also filed on the
IETF site
.
The
old license
is still available.
Other disclosures
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 Dergosits & Noah 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, Cisco and Google are also supporting Opus in some products.
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.
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