How to Convert AU to MP4 — Quick & Free
Fast, instant AU to MP4 conversion. No signup required. Just drop your .au file and get .mp4 in seconds.
Batch Settings
お持ちのAUファイルをMP4形式へ変換し、より多くのデバイスやプラットフォームで活用しませんか？ 音声に特化したAUファイルは、その高音質ゆえに特定の用途で重宝されますが、汎用性の高いMP4へ変換することで、動画コンテンツとの統合はもちろん、スマートフォンやタブレットでの再生、Web上での共有が格段に容易になります。この変換は、大切な音声資産を新たな表現へと昇華させる第一歩です。複雑な設定は一切不要。どなたでも直感的に、そして迅速に作業を完了できるよう設計されています。あなたのクリエイティブな発想を、ファイル形式の壁なく実現してください。
- アニメ・ドラマのセリフ分析
- ビジネス会議の議事録共有
- 朗読コンテンツの動画化
AUファイルは古くから特定の業務用音響機器で使われてきましたが、日本の一般的なPC環境や動画共有サービスでは、MP4への変換がスムーズな再生と共有の鍵となります。
About AU to MP4 Conversion
Short answer: yes, you can convert AU to MP4 online for free, and quality is well preserved with the right settings. Just upload your .au file to CocoConvert, pick MP4 as the output, and click Convert. The whole process takes seconds.
Now for the details. AU is a widely used file format. MP4 (MPEG-4 Part 14) is the universal video container supporting H.264/H.265 codecs — plays on virtually every device. Converting between these two formats lets you convert between formats quickly.
Your AU file is decoded and re-encoded as MP4. Converting AU to MP4 maintains high quality with CocoConvert's optimised encoder settings.
CocoConvert runs entirely online — no software to install, no account to create. Your files are encrypted during upload (TLS), processed on isolated servers in Germany, and permanently deleted after 24 hours. It works in Chrome, Safari, Firefox, Edge, and all mobile browsers.
Need to convert more than one file? Free users can do 5 per hour. Pro gets 100 per hour with files up to 5 GB each.
How to Convert AU to MP4
- 1
1. Upload AU
Drop your .au file onto the page (or tap "Browse" on mobile). Add multiple files for batch conversion.
- 2
2. Select MP4
Choose .mp4 from the output dropdown. Settings are pre-configured for best results.
- 3
3. Convert
One click. The server handles all the heavy lifting using FFmpeg and Sharp.
- 4
4. Download
Your .mp4 file is ready. Download it directly or get all files as a zip archive.
What Happens When You Convert AU to MP4
Your AU file is decoded and re-encoded as MP4.
Your AU file is uploaded and validated
The file is decoded (parsed into its raw data)
The data is re-encoded in MP4 format
The converted file is ready for download
Format Comparison
AU
.au file
| Extension | .au |
| MIME Type | audio/basic |
| Category | Audio |
MP4
.mp4 file
| Extension | .mp4 |
| MIME Type | video/mp4 |
| Category | Audio |
Should You Convert AU to MP4?
When to Convert
- ✓When you need a MP4 file
Frequently Asked Questions
Is AU to MP4 conversion free?
Yes. CocoConvert offers free AU to MP4 conversion with generous daily limits — 25 minutes of processing time and up to 5 files per hour (250 MB each). Pro plans remove these limits.
How fast is AU to MP4 conversion?
Most files convert in 2–10 seconds depending on size. Large audio files may take 30 seconds. Batch jobs process in parallel for maximum speed.
What happens to my files after conversion?
Your uploaded AU file and the converted MP4 file are both automatically deleted from our servers within 24 hours. They are never shared, sold, or analysed.
Does converting AU to MP4 lose quality?
Converting AU to MP4 maintains high quality with CocoConvert's optimised encoder settings.
Can I convert MP4 back to AU?
Yes, CocoConvert supports MP4 to AU conversion as well. However, if the original conversion involved lossy compression, converting back won't recover the lost data.
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