How to Convert FLAC to Opus

Opus was developed by the Xiph.Org Foundation and standardized by the IETF in 2012. It combines the SILK codec (from Skype, optimized for voice) and the CELT codec (optimized for music) into a single adaptive format. At 128 kbps, Opus is perceptually transparent for most music — equivalent to MP3 at 192–256 kbps. At 96 kbps, Opus outperforms MP3 at 128 kbps on most content. Discord uses Opus natively for voice channels. WebRTC (used by browser video calls, online games, and many streaming applications) requires Opus. Firefox and Chrome natively play Opus audio in the browser. For any streaming application where bandwidth matters, Opus is the modern choice.

Converting FLAC to Opus is a lossy step — you are discarding the lossless audio data and encoding a perceptually optimized version. The FLAC source is ideal because it gives the Opus encoder the full original audio to work with. If you were converting from MP3 to Opus, the encoder would only have the already-compressed MP3 data. Starting from FLAC means the Opus encoder can make optimal decisions about which frequencies to prioritize. In AudioUtils, upload your FLAC file, select Opus as the output format, choose your bitrate (128 kbps for music, 64 kbps for voice, 96 kbps as a balanced compromise), and download the resulting .opus file.

Discord bots built with discord.js or discord.py use Opus encoding internally. If you are building a music bot, pre-encoding your audio library to Opus means the bot does not need to transcode in real time — it streams the Opus file directly. This reduces CPU usage on your bot server and improves responsiveness. For web developers embedding audio on a webpage, the HTML5 audio element plays Opus in Chrome and Firefox. Safari added Opus support in version 15.4. For broad browser compatibility, include an MP3 or AAC fallback using the source element within your audio tag. Opus files use the .opus extension and the audio/ogg MIME type (since Opus is packaged in an Ogg container).

Opus bitrate recommendations differ significantly from MP3 guidelines because of the codec's efficiency. For pure voice content (podcasts, narration, voice memos): 32–48 kbps Opus is excellent — clear and intelligible with small file sizes. For music: 96 kbps Opus matches or exceeds 192 kbps MP3 in quality. For high-quality music archiving in Opus: 128 kbps is the recommended target. For transparent quality that most listeners cannot distinguish from lossless: 160–192 kbps Opus. Opus is designed to work well at all bitrates from 6 kbps up to 510 kbps, but for FLAC conversion purposes, 96–128 kbps covers the vast majority of use cases. Going above 192 kbps Opus provides diminishing returns on any realistic listening system.

Opus is natively supported in Chrome, Firefox, Edge, and Opera. Safari supports Opus from version 15.4 (released September 2021), which means essentially all modern Safari users can play it. Android supports Opus natively from version 5.0. iOS supports Opus from iOS 11. Windows 10 and later play Opus files in the native media player. macOS supports Opus through most media players; the native QuickLook preview does not play Opus, but VLC, IINA, and other common macOS players do. Linux playback via GStreamer and FFmpeg is excellent. The main limitation is older systems: Windows 7/8, iOS 10 and earlier, and Safari before version 15.4 do not support Opus natively.