Free online OPUS to VOX converter

Brief explanation of the source format

OPUS is a modern audio codec and file format based on the Opus compression standard. It is widely used for internet voice and music streaming, VoIP calls, web audio, gaming chat, and other applications where low latency and good quality at small file sizes matter. OPUS files are often found in containers such as .opus, .ogg, or .webm, and they are commonly created by communication apps, browsers, and audio tools.

Brief explanation of the target format

VOX usually refers to a very low-bitrate, telephony-oriented audio format associated with Dialogic ADPCM or similar voice codecs. It is designed for speech storage rather than high-fidelity music, so it produces much smaller files but with noticeably reduced audio quality. VOX is typically used in legacy voice systems, call recording archives, IVR systems, and older telephony software that expects this format.

How to perform the conversion

The most reliable way to convert OPUS to VOX is with FFmpeg, because it can decode OPUS and encode to VOX-compatible audio formats when supported by the build you use. Since VOX is a niche format, the exact codec support may vary by FFmpeg version and by the VOX variant required by your target software.

1. Install FFmpeg on your computer.
2. Open a terminal or command prompt in the folder containing your OPUS file.
3. Run a conversion command such as ffmpeg -i input.opus output.vox.
4. If your target system requires a specific VOX codec variant, you may need to set the audio codec explicitly, for example by using the codec name supported by your FFmpeg build.
5. Test the resulting output.vox file in the application that will use it.

If you prefer a simpler workflow, you can also convert the file on 101convert.com for free without installing any software.

In some desktop audio editors, the process is similar: open the OPUS file, then use File → Export or File → Save as and choose a VOX-compatible output format if available. However, many editors do not support VOX export directly, which is why FFmpeg is usually the best option.

Notes on quality, compatibility, or limitations

Quality loss is expected when converting OPUS to VOX because OPUS is a modern, efficient codec, while VOX is intended for narrowband speech and much lower fidelity. Music, stereo content, and wideband audio will sound significantly degraded after conversion.

Compatibility is the main limitation: not every player or editor can open VOX files, and not every FFmpeg build can write every VOX variant. If the destination software is strict about the VOX subtype, you may need to match its required sample rate, channel count, and codec settings exactly.

For best results, convert only when the receiving system specifically requires VOX. If you need general playback or archiving, keeping the audio in OPUS, WAV, or another widely supported format is usually a better choice.