OAC, the successor to Opus: what it is and why it matters

OAC (Open Audio Codec) is the new open-source audio codec developed by the Alliance for Open Media (AOMedia) —the same alliance that created the AV1 video codec— designed to be the long-term successor to Opus and, by extension, to the veteran MP3. The project was published in early 2026 on GitHub and, while still experimental, it points toward what the next generation of free digital audio will look like. And it looks promising.

What is OAC and why does it matter?

If you’ve been around digital audio, VoIP, or anything related to transmitting sound over a network, the name Opus will be very familiar. It’s been the reference codec for over a decade in practically everything: WebRTC, Discord, Spotify, YouTube, browsers, conference systems… it’s everywhere.

But as with everything in technology, today’s standard has a successor tomorrow. And that successor now has a name: OAC.

OAC stands for Open Audio Codec. Its reference implementation is called liboac and is publicly available in the official repository: https://github.com/AOMediaCodec/oac. The technical foundation doesn’t start from scratch: liboac is built directly on top of libopus. That makes all the sense in the world: if Opus is already very good, the smart thing is to take that solid base and improve from there, rather than reinventing the wheel.

Behind AOMedia are names you’ll likely recognize: Google, Mozilla, Microsoft, Apple, Netflix, Amazon, or Meta, among others. The fact that an alliance of that caliber decides to tackle audio is a pretty clear signal that the free audio ecosystem is still very much alive.

Is OAC the successor to MP3?

Here comes the question many are asking. If Opus already surpassed MP3 in practically every way —better quality at the same bitrate, lower latency, versatility for both voice and music— does it make sense to also call OAC the successor to MP3?

The answer is yes, but with nuance. MP3 remains the most recognized audio format on the planet due to sheer historical inertia. Its patents expired in 2017, it’s completely free, and millions of devices, cars, players, and applications support it. It’s not going to disappear overnight, that’s clear.

But technically it was already surpassed by Opus, and OAC comes to consolidate that trend toward modern, free, higher-quality formats. If OAC fulfills its promises, both MP3 and the current Opus will be regarded as the previous generation’s formats.

Technical features of OAC

Although the project is at a very early stage —and the developers themselves warn that it’s not ready for production— the current specifications inherited from Opus are quite solid, with eyes set on surpassing them:

• Sample rates from 8 kHz to 48 kHz (from narrowband phone quality to high-fidelity audio).
• Bitrates from 6 kb/s to 510 kb/s, allowing both extreme bandwidth savings and studio quality.
• Support for constant (CBR) and variable (VBR) bitrates.
• Multichannel: from mono up to 255 audio channels.
• Frame sizes from 2.5 ms to 60 ms, allowing latency adjustment as needed.
• Packet loss concealment (PLC): critical in VoIP and any real-time transmission.
• Floating-point and fixed-point implementation, making it suitable for embedded devices with limited hardware.
• BSD 3-Clause license: free for commercial and non-commercial use.

OAC vs Opus vs MP3: a direct comparison

Where does OAC stand right now?

Let’s be realistic, and there’s nothing wrong with that: OAC, as of April 2026, is basically Opus under another name and under the AOMedia umbrella. The code was forked from libopus, internal symbols have been renamed with the oaci_ prefix, and all the real work still lies ahead: the final specification, technical improvements over Opus, the standardization processes, and integration into browsers, operating systems, and applications.

The project itself makes it clear: there’s no finalized specification, no standardization timeline, and no backward compatibility guarantee. So what you generate with OAC today might not be compatible with what you generate with OAC a year from now. We’re in the “laying the foundations” phase, and that’s fine. You’ve got to start somewhere.

When will OAC be ready and should I worry now?

No, don’t worry. Opus will remain the de facto standard for years. For those of us working in VoIP, streaming, or any audio-related environment, the sensible thing right now is to keep a close eye on the project without rushing to migrate.

The interesting thing is that AOMedia has a proven track record: with AV1 they achieved something spectacular in the world of free video. There are reasons to be optimistic about what they may ultimately do with audio.

In the meantime, if you’re curious or just want to take a look, the official repository is public and active: https://github.com/AOMediaCodec/oac.

Frequently asked questions about OAC

What does OAC stand for?
OAC stands for Open Audio Codec. It’s the name of the Alliance for Open Media project to develop the successor to Opus.

Who develops OAC?
It’s developed by the Alliance for Open Media (AOMedia), the same consortium that created AV1 and AVIF, made up of companies like Google, Mozilla, Microsoft, Apple, Netflix, Amazon, and Meta, among others.

Is OAC better than Opus?
Not yet. As of today, OAC is a fork of Opus with renamed symbols and little real functional difference. Its goal is to surpass it in the future, but there are no documented advantages over Opus in production yet.

When can OAC be used?
There is no official date. The project has no finalized specification or standardization schedule. It is recommended to continue using Opus for any production project.

Does OAC also replace MP3?
In the long term, OAC is designed to cover all digital audio use cases, including those of MP3 (music storage and playback). That said, MP3 will remain compatible in billions of devices for many more years. There’s no rush.