Convert M4A to OPUS

Tested on Windows 11, 24 October 2026

Convert M4A audio to OPUS in your browser or in the Filoshi app for Windows. OPUS is lossy: Filoshi uses a high-quality setting, and you can choose the bitrate. Nothing is uploaded.

Get Filoshi · $29Many files at once, no size limit, on Windows.

How to convert M4A to OPUS in your browser

  1. 1
    Drop your M4A file
    Drag it onto Filoshi above, or press Choose your M4A file to pick it on your computer.
  2. 2
    Filoshi converts it
    OPUS is chosen already. FFmpeg, compiled to WebAssembly, converts it inside this browser tab.
  3. 3
    Save your OPUS file
    Download it when it is ready. Nothing was sent to a server.
Source format

What is M4A?

MPEG-4 Audio (.m4a). M4A is an MP4 file that holds only audio, normally AAC (sometimes Apple Lossless). It is what iTunes, Apple Music downloads without DRM and iPhone voice memos use.

Common use: Apple Music and iTunes, voice memos, podcasts

Output format

What is OPUS?

Opus Audio (.opus). Opus is an open, royalty-free codec standardised by the IETF in 2012. It sounds very good at low bitrates for both speech and music, and it is the codec of WebRTC video calls and many voice-message apps.

Common use: Voice messages, calls, streaming, podcasts

Questions about M4A to OPUS

Is converting M4A to OPUS free?
Yes, one file at a time: the converter on this page runs in your browser, files up to 100 MB, no sign-up. The Filoshi desktop app ($29 once, for Windows) converts many files at once and has no size limit.
Does converting M4A to OPUS lose quality?
Yes, a little. OPUS is a lossy format, so some detail is thrown away when the file is saved. Filoshi uses a high-quality setting by default, and you can choose the bitrate in the file viewer. M4A is lossy too, so this is a second round of compression; convert from the original, not from earlier conversions.
Is my M4A file uploaded anywhere?
No. The converter on this page runs in your browser with FFmpeg compiled to WebAssembly; your M4A file is read and converted on your device and never sent to a server. The desktop app works the same way, offline.
Has M4A to OPUS been tested?
Yes. M4A to OPUS is one of the 1,841 conversions that passed Filoshi's automated test matrix on Windows 11.
Can I convert many M4A files at once?
Yes, in the desktop app. Drop as many M4A files as you like on the window, pick OPUS once for all of them, and each file shows its own progress. The new files appear next to the originals, which are never changed.

Related conversions

Other M4A conversions

M4A to MP3M4A to AACM4A to OGGM4A to FLACM4A to AIFFM4A to AC3M4A to AUM4A to CAF

Convert to OPUS

MP3 to OPUSWAV to OPUSAAC to OPUSOGG to OPUSFLAC to OPUSWMA to OPUSAIFF to OPUSALAC to OPUS

Need M4A to OPUS for many files?

The browser converter handles one file at a time. The Filoshi app for Windows converts as many as you drop, runs offline, and has 1,841 tested conversions.

Get Filoshi · $29