Extract Opus Audio from MKV
Free online audio converter. Pull the audio out of MKV video as Opus right in the browser. Files are never uploaded anywhere.
About MKV and Opus
MKV is the Matroska container — a flexible box that can hold nearly any codec. OBS and most screen recorders write it by default.
Opus is the newest codec here and the most efficient — it outperforms MP3, Vorbis and AAC at low bitrates, which is why WhatsApp, Discord and WebRTC all use it. Support is universal in browsers, patchier in older hardware.
Extracting audio from MKV re-encodes only the audio track — the video is discarded, so even long files finish quickly.
How the conversion works
This tool runs FFmpeg — the same engine behind most media software — compiled to WebAssembly, entirely in the browser. The file is read locally, converted locally and saved straight from memory; nothing is ever uploaded, which also means no queues and no server-side file size limits.
The converter itself is a one-time ~31 MB download on the first conversion, cached by the browser afterwards. Once it is loaded, everything works offline.
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Free and open source from Earthling Digital, an independent creative agency. Built with Earthling UI.