CVU to AU Converter
Processing entirely on your device — large files may take a moment.
CVSD Unfiltered and Sun Microsystems Audio exist for different jobs: CVU is unfiltered Continuously Variable Slope Delta modulation — the raw codec behind early voicemail and Motorola telephony boards. Converting AU to WAV preserves the samples in a format every modern tool reads.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How CVU compares to AU
| CVU | AU | |
|---|---|---|
| Compatibility | ffmpeg, archive tools | Legacy Unix tools |
| Best for | Rescuing legacy audio | Old system sounds and recordings |
How to convert CVU to AU
- 1
Select your files
Drag & drop your CVU files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to AU". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted AU file individually, or grab everything at once as a ZIP archive.
About the CVU format
CVU is unfiltered Continuously Variable Slope Delta modulation — the raw codec behind early voicemail and Motorola telephony boards.
ffmpeg decodes it natively inside your browser — the audio track is re-encoded to your chosen format with nothing ever uploaded.
+ Strengths
- ✓Decoded natively by ffmpeg
- ✓Runs entirely in your browser
- ✓Free, private, no watermarks
! Limitations
- −Legacy niche format
- −Modern tools rarely open it
- −Keep the original for archival round-trips
About the AU format
AU is Sun Microsystems' audio format from the Unix workstation age: a small header followed by µ-law (or PCM) samples. Java's applet era shipped it everywhere, and old Unix sound tooling still emits it.
Modern players increasingly skip it. Converting AU to WAV preserves the samples bit-for-bit while moving the file into universal territory — the standard rescue path for system sounds and old recordings.
+ Strengths
- ✓Simple, lossless sample storage
- ✓Native to old Unix/Java tooling
! Limitations
- −µ-law flavor sounds dated and mono
- −Dropped by modern players
Why convert CVU to AU?
Think of it as moving your file to the container that fits the job. Legacy niche format AU works differently: Simple, lossless sample storage If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this CVU to AU converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for CVU to AU?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.
Will converting CVU to AU reduce audio quality?
If AU is lossless, the output contains everything the CVU file contains — no further loss is added. If AU is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.