AU to AMR — Format Comparison & Online Converter
Fast, instant AU to AMR conversion. No signup required. Just drop your .au file and get .amr in seconds.
Batch Settings
大切な音声ファイル、AU形式からAMR形式への変換でお困りではありませんか？「AU」は、かつて多くの環境で親しまれた音声フォーマットですが、現代のモバイルデバイスや通信環境では、「AMR」形式の方がより効率的で、特に音声通話など帯域幅が限られた状況での利用に適しています。当社の変換ツールは、お客様のAUファイルを、音質の劣化を最小限に抑えつつ、AMRの利点を最大限に引き出す形でスムーズに変換いたします。煩雑な設定は一切不要。どなたでも直感的にご利用いただけるよう設計しましたので、ご安心ください。大切な音声を、新しい形でこれからも活用していきましょう。
- 携帯電話での音声メモ
- ビジネス会議の議事録共有
- アニメ声優のオーディション提出
日本では、フィーチャーフォン時代にAU形式の音声が利用されることがありましたが、スマートフォンへの移行に伴い、AMRのようなモバイルに特化した形式の需要が高まりました。特に、通信コストを抑えつつ音声を共有したいというニーズに合致しています。
About AU to AMR Conversion
AU and AMR (introduced 1999) are both audio formats, but they differ in important ways. AU is a widely used file format. AMR is a speech-optimised audio codec used in mobile voice recordings.
When you convert AU to AMR, the goal is to convert between formats quickly. Converting AU to AMR maintains high quality with CocoConvert's optimised encoder settings. Understanding these technical differences helps you choose the right format for your workflow.
Your AU file is decoded and re-encoded as AMR. The conversion involves 4 steps: (1) your au file is uploaded and validated, (2) the file is decoded (parsed into its raw data), (3) the data is re-encoded in amr format, (4) the converted file is ready for download.
CocoConvert's converter handles the entire pipeline server-side using FFmpeg, Sharp, and qpdf — battle-tested libraries used by streaming platforms and enterprise tools. Files are encrypted in transit and deleted within 24 hours.
This conversion is ideal when you When you need a AMR file. For the opposite direction, CocoConvert also supports AMR to AU conversion.
How to Convert AU to AMR
- 1
Upload .au file
Select your AU file by dragging it to the upload zone or using the file picker. Batch upload is available for multiple files.
- 2
Choose .amr
Set AMR as the output format. The converter uses optimal settings based on the AU→AMR conversion profile.
- 3
Convert
The server-side engine decodes your AU file and re-encodes it as AMR. Processing time depends on file size and complexity.
- 4
Download result
Grab your converted .amr file. Multiple output files can be downloaded together.
What Happens When You Convert AU to AMR
Your AU file is decoded and re-encoded as AMR.
Your AU file is uploaded and validated
The file is decoded (parsed into its raw data)
The data is re-encoded in AMR format
The converted file is ready for download
Format Comparison
AU
.au file
| Extension | .au |
| MIME Type | audio/basic |
| Category | Audio |
AMR
.amr file
| Extension | .amr |
| MIME Type | audio/amr |
| Category | Audio |
Should You Convert AU to AMR?
When to Convert
- ✓When you need a AMR file
Frequently Asked Questions
What is the difference between AU and AMR?
AU is a widely used file format. AMR is a speech-optimised audio codec used in mobile voice recordings.
Does AU to AMR conversion affect quality?
Converting AU to AMR maintains high quality with CocoConvert's optimised encoder settings.
Which format has better compression, AU or AMR?
AU is a common audio format. AMR uses lossy compression. The better choice depends on whether you prioritize file size or quality.
How long does AU to AMR conversion take?
Most conversions finish in seconds. Larger files or complex audio content may take 10–30 seconds. CocoConvert processes files in parallel for batch jobs.
Is AU or AMR better for long-term storage?
Both formats use lossy compression, so consider keeping your original source file for long-term storage.
Versions are pinned in our worker Dockerfile and re-built via CI on every change.