M4A to OPUS Converter

What happens when you convert M4A to OPUS

• The audio is decoded and written as Opus at 192 kbps.
• Going from one lossy format to another adds a small generation loss. Choose a bitrate at least as high as the source to keep it inaudible.

How to convert M4A to OPUS online

1. Press "Choose M4A files" and select one or more files, or drag them onto the box. You can add files of any size your device can hold in memory.
2. Adjust the settings if you need to: the bitrate controls quality and size. The defaults suit most people.
3. Press "Convert to OPUS". The first audio or video conversion downloads the converter engine, about 32 MB, which your browser then keeps for next time.
4. Save each OPUS with its download button. Close the tab and every trace of the files is gone from memory.

Why convert M4A to OPUS?

M4A files usually come from iTunes purchases, iPhone voice memos and Apple Music downloads. People convert them to OPUS because Opus sounds good at very low bitrates, so voice recordings stay tiny.

In short, M4A is good at what it was made for, and OPUS is the more practical choice when the file has to play on another device or app. M4A plays in all current browsers and every Apple device, while OPUS plays in current browsers; many car stereos and older players cannot.

How to convert M4A to OPUS on Windows, Mac, iPhone and Android

On Windows

Open this page in Chrome, Edge or Firefox, drag your M4A files in from File Explorer, and press Convert. Each OPUS is saved to your Downloads folder. If you prefer a desktop program, VLC can also convert M4A to OPUS: choose Media, then Convert / Save.

On a Mac

Safari, Chrome and Firefox all work. Drag the M4A files from Finder onto the drop zone and the OPUS files land in Downloads.

On iPhone and iPad

Open the page in Safari and tap Choose M4A files. You can pick from Photos or from the Files app. The converted OPUS appears in Files, in the Downloads folder.

On Android

Open the page in Chrome, tap Choose M4A files and pick them from Files or your gallery. The OPUS is saved to the Download folder, where any file manager can find it. Keep the screen on while a long video converts, because Android may pause a tab in the background.

Best settings for M4A to OPUS

OPUS is a lossy format, so the bitrate decides both the sound quality and the file size. Size grows in a straight line with bitrate: double the bitrate and the file doubles.

The M4A was already compressed, so pick a bitrate at least as high as the original. Going higher does not add quality back, it only makes the file bigger.

M4A vs OPUS: the differences

About M4A and OPUS files

What is an M4A file?

M4A is an MP4 file that only holds audio, which is why renaming one to .mp4 often works. Voice Memos on iPhone saves recordings as M4A.

What is an OPUS file?

Opus was built for speech and music over the internet, and it holds up at bitrates as low as 16 kbps. Voice messages from WhatsApp and Telegram usually arrive as Opus files.

M4A to OPUS not working? Common problems

• The conversion is slow. Audio and container changes take seconds, but re-encoding video runs on your own processor. Lower the resolution to 720p, close other tabs, and keep the device plugged in.
• The tab stops or reloads on a very large file. Browsers limit how much memory one tab can use, around 2 GB and less on phones. Split long recordings or convert them on a computer.
• Song titles are missing. Tags such as title and artist are copied when OPUS can store them, but cover art is not carried over.

Convert M4A to OPUS with ffmpeg

This converter runs ffmpeg inside your browser. If you would rather use the ffmpeg command line on your own computer, this command produces an equivalent OPUS with the same kind of settings:

ffmpeg -i input.m4a -vn -c:a libopus -b:a 192k output.opus

Replace input.m4a with the name of your file. For a whole folder of M4A files, run the command in a loop, or drop them all on the converter above, which processes them one after another.