Convert images, documents, video and audio in your browser. Your files stay on your device.
Extract the audio from a MKV video and save it as OPUS: the music from a clip, a recorded lecture, an interview.
Drag one or more MKV files onto the dashed area, or tap it to pick them from your device.
OPUS is already selected: you can adjust bitrate, channels and volume.
Press “Convert to OPUS”. When it’s done, download the files one by one or all together in a ZIP archive.
Good to know. For the best quality choose FLAC or WAV; for compatibility, MP3.
Source format
Matroska Video
An open, flexible container that accepts almost any codec, several audio tracks and subtitles. It’s loved for films and series, but TVs, iPhones and some editors can’t read it.
Target format
Opus Interactive Audio Codec
The most efficient audio codec available today: it’s the one behind WhatsApp voice messages and video calls. At 64 kbps speech is crystal clear and music surprisingly good.
Audio and video use WebCodecs: they work in up-to-date Chrome, Edge, Opera and Samsung Internet, in Firefox 130+ and Safari 17+ (with a few limits on the formats they can create). If your browser can’t create the chosen format, we tell you before you start.
No. The conversion from MKV to OPUS happens entirely in your browser, using your device’s computing power. Files aren’t sent or stored anywhere: when you close the page they’re gone from memory too.
Up to 100 files at a time. There’s no fixed size limit: it depends on your device’s memory. On smartphones it’s best to work in smaller batches with heavy files such as videos.
Yes, with up-to-date Safari, Chrome, Firefox, Edge and Samsung Internet. On phones, converted files end up in the Downloads folder or the Files app.
Only to open the page (and, the first time, to download the components needed for that type of file). After that the conversion keeps working even if the connection drops.