Free online AU to VOX converter
Convert AU audio to VOX voice format with FFmpeg or 101convert.com
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How to convert au to vox file
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1. Source format: AU
AU is a simple audio file format originally associated with Sun Microsystems and early Unix systems. It is often used for basic uncompressed or lightly compressed audio, especially in older software, legacy archives, and technical environments where compatibility with classic Unix tools matters. AU files may contain different encodings, but they are generally considered a legacy format today.
2. Target format: VOX
VOX usually refers to the Dialogic/OKI ADPCM audio format, a compact voice-oriented format designed for speech storage and telephony applications. Its main advantage is small file size for spoken audio, which makes it useful for voice prompts, IVR systems, and older voice-recording workflows. VOX is not ideal for music because it is optimized for narrow-band voice rather than full-fidelity audio.
3. How to perform the conversion
The most reliable way to convert AU to VOX is with FFmpeg, a widely used desktop command-line tool that supports both formats in many builds.
- Install FFmpeg on your computer if it is not already available.
- Open a terminal or command prompt in the folder containing your AU file.
- Run a conversion command such as
ffmpeg -i input.au -ar 8000 -ac 1 -c:a adpcm_ima_wav output.vox. - If your FFmpeg build does not accept
.voxdirectly, try saving as.wavwith ADPCM encoding first, then rename or remux only if your target application specifically expects VOX. - Test the resulting file in the software or device that will use it, since some programs are strict about the exact VOX variant they accept.
If you prefer a web-based workflow, you can convert the file on 101convert.com for free without installing any software.
4. Quality, compatibility, and limitations
AU to VOX is usually a lossy conversion because VOX is a speech-oriented compressed format. If the AU source contains music, stereo audio, or high sample rates, the result will lose detail and may sound noticeably degraded. For best results, convert mono voice audio sampled at 8 kHz or similar telephony rates.
Compatibility can vary because VOX is not a single universally standardized container in the same way as WAV or MP3. Some applications expect a specific ADPCM flavor, headerless raw data, or a particular file extension. If playback fails, check whether the destination system wants raw VOX, Dialogic VOX, or another voice format variant.
Also note that AU files with uncommon encodings may need an intermediate conversion step before encoding to VOX. In those cases, converting first to a standard PCM WAV and then to VOX can improve reliability.
Note: This au to vox conversion record is incomplete, must be verified, and may contain inaccuracies. Please vote below whether you found this information helpful or not.
AU vs VOX: format comparison
How the AU and VOX formats compare on the properties that matter most for this conversion.
| Property | .AU Sun/NeXT audio file | .VOX Dialogic ADPCM audio |
|---|---|---|
| Compression | Uncompressed | Lossy |
| Audio quality | — | Low |
| Audio channels | — | Mono |
| Metadata support | Basic | None |
| Streaming | Yes | No |
| DRM protection | No DRM | — |
| Opens in a web browser | Partial | No |
| Typical file size | Large | Very small |
| Open standard | Yes | No |
| Best used for | Speech and voice | Speech and voice |
| Introduced | 1988 | — |
| Developer | Sun Microsystems / NeXT | Dialogic (Intel/Dialogic) |
| MIME type | audio/basic | audio/voxware |
Frequently asked questions
Is the AU to VOX converter free?
Yes, converting AU to VOX on 101convert.com is completely free. No registration, email address or installation is required.
How large can my AU file be?
You can upload AU files up to 1000 MB and convert up to 100 files at once in a single batch.
What happens to my uploaded files?
Files are processed automatically and deleted from our servers within a few minutes after conversion. We never view or share your files.
Do I need to install any software to convert AU to VOX?
No. The AU to VOX conversion runs entirely online in your browser and works on Windows, Mac, Linux, Android and iPhone.
Did the conversion fail?
In most cases, the cause is an incorrect file format. Please upload a valid AU file for this AU to VOX conversion. Occasionally, the issue may be on our side. We analyze recurring conversion failures and disable or fix the converter if we detect a defect.