Convert images, documents, video and audio in your browser. Your files stay on your device.
Convert OPUS audio to M4A, choosing bitrate, channels and sample rate. You can also trim the track or adjust its volume.
Drag one or more OPUS files onto the dashed area, or tap it to pick them from your device.
M4A is already selected: you can adjust bitrate, channels and volume, and trim the track.
Press “Convert to M4A”. When it’s done, download the files one by one or all together in a ZIP archive.
Good to know. For music, 192 kbps is an excellent compromise; for speech, 64 kbps mono is enough.
Source 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.
Target format
MPEG-4 Audio
AAC audio in an MP4 container: it’s the format of iTunes, iPhone voice memos and many recordings. At the same size it sounds better than an MP3.
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 OPUS to M4A 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.