M4A to Opus converter
Your M4A goes in and an Opus comes out. Opus is the usual choice for voice and video calls, WebRTC and game chat. Your file never leaves your computer.
Need the other direction? Convert Opus to M4A
How to convert M4A to Opus
- 1 Drop your M4A .m4a file onto the page, or click to browse for it.
- 2 Set the quality, or leave the default, which keeps the file small without anything showing.
- 3 Convert. The work happens on your own machine, so how long it takes depends on your computer and the file.
- 4 Download the Opus, or add more files and do the whole set in one go.
Why convert M4A to Opus
- The best sound for the size of any widely supported format.
- Latency as low as 5 ms, suitable for real time.
- Streaming audio on constrained connections.
- M4A: the Apple lossless option is less widely supported than FLAC.
M4A compared with Opus
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | M4A | Opus |
|---|---|---|
| File extension | .m4a | .opus |
| Compression | Lossy or lossless | Lossy |
| Typical file size | Depends on mode | Smaller |
| Browser support | Every browser | All current browsers |
| Introduced | 2001 | 2012 |
| Developed by | Apple / ISO | Xiph.Org and IETF |
Quality and what changes
Opus stores the same content under a different set of rules, so what matters here is compatibility rather than picture quality. Convert once from the best source you have rather than through a chain of intermediate files.
- One Opus limitation to keep in mind: car stereos and standalone players mostly will not open it.
Questions about M4A to Opus
Is my M4A file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your M4A is read straight from your own disk, converted on your machine and handed back as an Opus. Nothing is sent anywhere, nothing is stored and there is no account.
Is there a file size limit?
There is no server-side limit because no server sees the file. The real ceiling is your device memory, since the input and the output both have to fit in the tab. A few hundred megabytes is usually fine on a desktop machine and considerably less on a phone.
Can I convert several M4A files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate Opus downloads or as a single ZIP. Speed depends on your own processor rather than on a queue.
Does the converter work offline?
Yes, after the page has loaded once. The engine is cached by the browser, so you can disconnect, reload and keep converting. That falls out of doing the work locally rather than being a separate mode you switch on.