AMR to AU Converter
FileFlip converts AMR to AU entirely inside your browser, using FFmpeg compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an AMR file to AU?#
- Drop your AMR file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to AU and the conversion starts on its own. FileFlip downloads 30.8 MB of WebAssembly the first time and nothing after that, then runs FFmpeg on your own machine.
- Save the AU file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting AMR to AU lose quality?#
It depends on what is inside the file. AMR is a container rather than a codec, so whether the AU conversion copies the streams across untouched or re-encodes them is decided by the codecs that particular file happens to use.
Is it safe to convert AMR files online?#
Yes, because nothing is uploaded. FileFlip converts AMR files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What AMR to AU actually does to the file#
Converting AMR to AU runs on FFmpeg, downloads 30.8 MB of WebAssembly the first time and nothing after that, re-encodes or copies through depending on the codecs in the file, and drops encoded streams.
| Engine | FFmpeg |
|---|---|
| Conversion path | One step: AMR → AU |
| Downloaded to your browser | 30.8 MB, once, then cached by your browser |
| Quality | Decided by the codecs inside the file |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Encoded streams | Dropped | The target format has nowhere to put it. |
What is an AMR file?#
An AMR file holds speech compressed with Adaptive Multi-Rate, the narrowband codec 3GPP standardized in 1999 for GSM phone calls, which is why voice memos and MMS voice messages recorded on older phones end up in this format.
There is rarely a reason to keep audio as AMR once it is off the phone that made it, since the format exists for the transmission link, not for storage.
Convert AMR to MP3 or WAV so an old voice memo or MMS recording opens in ordinary media players and editing software, keeping in mind the recording will still sound like a phone call because that ceiling was set at capture, not by the format.
What is an AU file?#
An AU file holds audio in Sun Microsystems' Unix workstation format, a plain header followed by raw sample data that was the standard system-alert and early web audio format before WAV and MP3 took over.
AU still shows up as the format Java's javax.sound and some Unix system tools default to for short sound effects, where its simplicity is the point.
Convert AU to WAV or MP3 when the audio needs to play in modern media players, browsers, or editing software that no longer ship AU support by default.
AMR to AU questions people ask#
Why are my voice memos and MMS recordings AMR files?
AMR is the speech codec GSM and 3G phones use for voice calls, so many phones' voice recorder apps and MMS voice messages reused the same codec rather than encoding a separate format. That link to phone-call audio is also why AMR recordings sound like a phone call, thin and narrowband, rather than like a full-range voice recording.
What plays AMR files?
VLC plays AMR files on every major platform, and Android's own voice recorder and messaging apps read them natively since AMR originated on that ecosystem. Standard desktop media players such as Windows Media Player or QuickTime generally do not.
What should I convert AMR to?
Convert AMR to MP3 or WAV so the recording opens in any media player or editor. Converting will not improve the sound, since AMR only ever captured the narrow speech frequency range a phone call uses, and no conversion can add back detail the codec discarded at recording time.
What creates an AU file?
AU files come from Unix and Sun workstation software, from Java's built-in sound APIs, and from older system sound effects, since AU was the default audio format on SunOS and NeXT machines. Websites in the 1990s also used it for embedded sound clips before WAV and MP3 became standard.