What is Opus Audio?
Complete guide to the OPUS file format
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What is Opus Audio?
Opus is a modern, open-source audio codec designed for internet streaming, VoIP calls, and real-time communication. It is the audio codec used by Discord, WhatsApp, and WebRTC.
Opus is unique in its ability to switch between speech and music compression modes dynamically, making it exceptional for applications that handle both voice and music audio.
How Opus Works
Opus is a hybrid codec that merges two underlying technologies: SILK, a speech codec contributed by Skype, and CELT, a low-latency transform codec from Xiph.Org; it can use either alone or both together and switch seamlessly as the audio shifts between voice and music.[4] It supports bitrates from about 6 kbit/s up to 510 kbit/s, sampling rates from narrowband to fullband 48 kHz, and algorithmic delays as low as a few milliseconds, making it suitable for interactive, real-time use.[2]
Standardization
Opus was standardized by the IETF as RFC 6716 in 2012 and is deliberately royalty-free, which contributed to its adoption as a mandatory-to-implement audio codec for WebRTC.[2] Its reference implementation is maintained by the Xiph.Org Foundation as free software.[3]
Opus vs Other Codecs
At comparable bitrates Opus generally outperforms older codecs such as MP3, AAC, and Vorbis, particularly at low bitrates and for speech.[1] Opus audio is most often stored in an Ogg container with the .opus extension, and is widely supported by modern browsers and communication platforms.[1]
Technical Details
OPUS vs Other Audio Formats
| Feature | OPUS | MP3 | AAC | Vorbis |
|---|---|---|---|---|
| Compression | Lossy[1] | Lossy | Lossy | Lossy |
| Low-bitrate quality | Excellent[2] | Moderate | Good | Good |
| Latency | Very low[2] | High | Moderate | Moderate |
| License | Open, royalty-free[3] | Patented (now free) | Patented | Open, royalty-free |
| Device support | Growing | Universal | Wide | Moderate |
| Best for | Streaming & voice | General music | Streaming | Open-source music |
Opus outperforms older codecs at low bitrates and latency, while MP3 and AAC still have the widest device compatibility.
Pros and Cons
Advantages
Opus has very low latency making it ideal for real-time communication and gaming.
Outperforms MP3, AAC, and Vorbis at most bit rates in quality tests.
Switches between speech and music modes automatically for optimal encoding.
Completely free and open-source with no licensing fees or patent restrictions.
Disadvantages
Dedicated music players and iPods often do not support Opus format.
Opus is designed for streaming/communication, not for distributing music files.
iTunes and Apple Music do not support Opus format.
Less well-known than MP3 or AAC outside of developer communities.
When to Use Opus Audio
Here are the most common situations where Opus Audio is the right choice:
VoIP Calls
Discord, WhatsApp, and Zoom all use Opus for voice and video call audio.
Web Audio
WebRTC applications use Opus as the standard audio codec for web-based communication.
Gaming
Online games use Opus for in-game voice chat due to its low latency.
Podcasts (Web)
HTML5 podcast players can use Opus for high-quality, efficient podcast streaming.
Convert Opus Audio Files
Need to convert your OPUS files? Use our free online converter.
Try Audio Converter FreeFrequently Asked Questions about Opus Audio
Is Opus better than MP3?
For streaming and VoIP, Opus significantly outperforms MP3. For stored music files, MP3 has better player support.
Can I play Opus files on my phone?
Android supports Opus natively. iOS requires a third-party app like VLC to play Opus files.
What is Opus used for?
Opus is primarily used for VoIP calls (Discord, WhatsApp), WebRTC, and web audio streaming.
Is Opus royalty-free?
Yes, Opus is completely royalty-free and open-source.
How do I convert Opus to MP3?
Use our free online converter or VLC media player to convert Opus files to MP3.