AU vs SPX — Comparison & Free Converter
Fast, instant AU to SPEEX conversion. No signup required. Just drop your .au file and get .spx in seconds.
Batch Settings
大切な音声ファイル、AU形式で保存されたものを、クリアで効率的なSPX形式へとスムーズに変換したいとお考えでしょうか。ビジネスの重要な会議録から、趣味で録音したお気に入りのアニソン、あるいは声優さんのボイスサンプルまで、様々なAUファイルをより扱いやすいSPX形式にすることで、ファイルサイズを抑えつつ、品質を保つことが可能です。特に、携帯デバイスでの再生や、ウェブサイトへの埋め込み、あるいはメールでのやり取りなど、多様なシーンでその利便性を実感していただけるでしょう。複雑な設定は一切不要。どなたでも直感的に操作できるシンプルなインターフェースで、迅速かつ確実に変換を完了させます。あなたの貴重な音声を、最適な形で次世代へと繋ぐお手伝いをさせていただきます。
- ビジネス会議録の共有
- 同人音声作品の配布
- 携帯端末向けコンテンツ最適化
日本のビジネスシーンでは、メール添付ファイルのサイズ制限が厳しいため、SPXのような高圧縮率の形式は非常に重宝されます。また、同人文化が盛んな日本では、音声作品の配布においてもファイルサイズの最適化が重要視される傾向にあります。
About AU to SPEEX Conversion
AU or SPX — which format should you use? The answer depends on your needs. Here's a quick breakdown.
AU is a widely used file format. It has common platform support. SPX is a widely used file format. It has common platform support.
So when should you convert AU to SPX? This conversion is ideal when you When you need a SPX file. This conversion helps you convert between formats quickly.
Converting AU to SPX maintains high quality with CocoConvert's optimised encoder settings.
If you've decided SPX is the right choice, CocoConvert makes the conversion effortless. Upload your .au file, pick SPX, and click Convert — done in seconds. The converter runs on secure servers in Germany, powered by FFmpeg, Sharp, and qpdf. Files are encrypted via TLS and erased within 24 hours.
Free tier: 5 files/hour, 250 MB each. Pro: 100 files/hour, 5 GB each. Works in every modern browser on desktop and mobile.
How to Convert AU to SPEEX
- 1
Choose your AU file
Upload your .au file using drag-and-drop or the file browser. Batch mode lets you add multiple files.
- 2
Set format to SPX
Select .spx from the output options. The converter applies optimal quality settings automatically.
- 3
Run the conversion
Click Convert. Server-side processing means your device stays fast — even for large audio files.
- 4
Get your SPX file
Download your converted file instantly. Batch downloads are available as a zip archive.
What Happens When You Convert AU to SPEEX
Your AU file is decoded and re-encoded as SPX.
Your AU file is uploaded and validated
The file is decoded (parsed into its raw data)
The data is re-encoded in SPX format
The converted file is ready for download
Format Comparison
AU
.au file
| Extension | .au |
| MIME Type | audio/basic |
| Category | Audio |
Speex
.spx file
| Extension | .spx |
| MIME Type | audio/ogg |
| Category | Audio |
Should You Convert AU to SPEEX?
When to Convert
- ✓When you need a SPX file
Frequently Asked Questions
Should I use AU or SPX?
It depends on your goal. AU preserves full quality. SPX preserves full quality. Choose based on whether file size or quality matters more for your use case.
Is SPX higher quality than AU?
Not necessarily. Converting AU to SPX maintains high quality with CocoConvert's optimised encoder settings. Quality depends on the compression type and settings, not just the format name.
Can I convert AU to SPX on Mac and Windows?
Yes. CocoConvert is a web-based tool that works in all modern browsers — Chrome, Safari, Firefox, Edge — on any operating system including macOS, Windows, Linux, iOS, and Android.
Is CocoConvert free for AU to SPX?
Yes. Free users get 5 conversions per hour (250 MB each). Pro subscribers unlock 100 files per hour, 5 GB per file, and priority processing.
What tools does CocoConvert use for AU to SPX?
CocoConvert uses FFmpeg for audio/video, Sharp for images, and qpdf for documents — the same open-source libraries used by Netflix, YouTube, and major enterprise platforms.
Versions are pinned in our worker Dockerfile and re-built via CI on every change.