## What Is Opus?
**Opus** — standardized in 2012 (RFC 6716) — is completely open and royalty-free. Versatile: from 6 kbps (voice) to 510 kbps (high-fidelity audio). Combines SILK (from Skype, voice-optimized) and CELT (from Xiph.org, music and ultra-low latency).
## Opus vs MP3 vs AAC
| Bitrate | MP3 | AAC | **Opus** |
|---------|-----|-----|---------|
| 32 kbps | Poor | Acceptable | **Good** |
| 64 kbps | Acceptable | Good | **Very good** |
| 128 kbps | Good | Very good | **Transparent** |
| 192 kbps | Very good | ~Transparent | **Transparent** |
"Transparent" = indistinguishable from source in double-blind tests.
**Algorithmic latency:** Opus 2.5 ms minimum vs MP3 26 ms vs AAC 21 ms — ideal for real-time communication.
## Opus on the Web: WebRTC
Google Meet, Zoom Web, Discord, Teams — all use Opus as the mandatory audio codec in WebRTC.
## Convert with FFmpeg
```bash
# MP3/FLAC to Opus
ffmpeg -i song.flac -c:a libopus -b:a 128k song.opus
# High quality
ffmpeg -i song.flac -c:a libopus -b:a 192k song.opus
# VoIP (low latency)
ffmpeg -i voice.wav -c:a libopus -b:a 32k -application voip voice.opus
# VBR (recommended for music)
ffmpeg -i song.flac -c:a libopus -vbr on -b:a 128k song.opus
```
## Compatibility
Chrome, Firefox, Edge, VLC, Android 5+, iOS/macOS (since 2023): ✅. Windows Media Player: ❌.
## When to Use Opus
✅ Podcasts, audiobooks, web apps, projects you control the playback chain. ❌ Streaming platforms (Spotify/Apple Music use AAC), hardware legacy players.
## Conclusion
**Opus is technically superior to MP3 and AAC** in virtually all metrics. For web projects and apps where you control the playback chain, Opus is the ideal choice.
Guide