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Opus Audio Codec

Logo of the Opus audio codec.

Opus is a multipurpose audio codec that combines the balance of high-quality audio signal compression with low delay rates. It was developed in 2012 by the IETF working group. Its flexibility lies in adapting to changes in channel’s bandwidth capacity and support of any kind of audio encoding. Nowadays, Opus audio codec is considered to be the best in all respects among its rivals, because its quality is even superior to the widely used MP3.

All existing codecs can be relatively divided into two groups: general-purpose codecs with long delays, but high quality (Vorbis, AAC and MP3) and codecs for speech encoding with small delays, but low quality (Speex, G.719, G.722.1, G.722.2, G.729, iLBC, AMR-NB). None of these codecs is capable of maintenance of the highest audio encoding quality and keeping delay at a minimal level at the same time.

However, Opus audio codec can be considered a successful exception, as it is suitable for reproducing a signal at 6 kbit/s, as well as at 510 kbit/s. Signal compression is performed with minimal losses, almost imperceptible to the human ear. Opus audio codec can dynamically switch to compression with different bitrate depending on changes in bandwidth capacity.

Comparison of audio codecs showing Opus offering highest quality across bitrates, outperforming MP3, AAC, and others.

Features and Benefits:

  • Supports any sample rate from 8 to 48 kHz.
  • Bit-rates from 6 to 510 Kbps.
  • Support for mono and stereo.
  • Support for both constant bit-rate (CBR) and variable bit-rate (VBR).
  • Using a fixed-point arithmetic.
  • 5 ms delay.
  • Easily scalable audio stream with the ability to change settings dynamically.

Opus Audio Codec in TrueConf Video Conferencing Products

As a result of numerous studies and tests, Opus audio codec was recognized as the most suitable codec for speech compression. That is why our company has implemented it in all our solutions. Good audio quality in video conferencing is just as important as the quality of the video.

Resulting from comparison with other popular speech codecs, used in video conferencing: Speex and G.729, Opus scored the highest productivity and the ability to quickly switch between various encryption mechanisms. This made it ideal for use in video conferencing during data transfer. Video conference participants can continue to communicate with each other in the most comfortable audio environment even at a low-speed Internet connection.

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FAQ

How does the Opus codec handle unstable or slow internet connections during a video call?

Opus is designed with a highly adaptive variable bit-rate (VBR) that dynamically adjusts to your current network bandwidth in real time. When your connection drops, it seamlessly lowers the bitrate to maintain the call without disconnecting or introducing severe artifacts. TrueConf leverages this exact capability to ensure that your audio remains clear and uninterrupted, even if you are joining a meeting from a low-speed or fluctuating network.

Why is Opus considered superior to older speech codecs like G.729 or general codecs like MP3 for video conferencing?

Older codecs force a compromise between high audio quality and low latency, whereas Opus successfully delivers both by operating efficiently across a massive range of bitrates. It provides the rich sound quality of MP3 but with the ultra-low 5ms delay required for real-time conversation. TrueConf chose Opus as its default audio codec specifically because it eliminates this compromise, giving users crystal-clear speech without the robotic artifacts of legacy systems.

Does using a high-quality audio codec like Opus introduce noticeable delay or lag in conversations?

No, one of the primary advantages of the Opus codec is its incredibly low algorithmic delay of just 5 milliseconds. This ensures that the audio is processed and transmitted almost instantaneously, keeping the conversation perfectly synchronized. By utilizing Opus, TrueConf guarantees that participants experience natural, real-time dialogue without the frustrating echo or lag often associated with high-definition audio processing.

Do I need to purchase expensive, specialized microphones to benefit from the Opus codec’s high audio quality?

While a good microphone always helps, the Opus codec’s advanced compression algorithms work at the software level to optimize whatever audio signal it receives. It efficiently cleans up and compresses the sound without requiring specialized hardware to function properly. When you use TrueConf, the platform automatically applies Opus encoding to your standard laptop or USB microphone, instantly elevating the audio quality for all participants.

Can the Opus codec handle high-fidelity audio like music, or is it strictly limited to human speech?

Opus is a highly versatile, multipurpose codec that supports a wide range of sample rates from 8 kHz up to 48 kHz, making it excellent for both narrowband speech and full-bandwidth stereo audio. It dynamically switches between speech-optimized and music-optimized modes depending on the input signal it detects. TrueConf takes advantage of this full-bandwidth capability to ensure that not only is human speech perfectly clear, but any shared media or high-fidelity audio played during the meeting is transmitted without quality loss.

How does TrueConf manage the Opus codec during a meeting if network conditions change rapidly?

TrueConf’s media engine continuously monitors the network path and instructs the Opus codec to adjust its bitrate and bandwidth usage on the fly. If bandwidth suddenly drops, the codec instantly scales down the audio stream to prevent packet loss, and scales it back up when the connection stabilizes. This seamless, automated switching ensures that TrueConf users always experience the best possible audio quality without any manual intervention or dropped calls.