Free online AC3 to VOX converter

Source format: AC3

AC3 (Dolby Digital Audio Codec 3) is a compressed audio format commonly used for movie soundtracks, DVD/Blu-ray audio, broadcast media, and home theater systems. It supports multichannel audio, including 5.1 surround sound, and is valued for delivering good quality at relatively small file sizes. AC3 files are often found in video containers such as .mp4, .mkv, or .ts, but they can also exist as standalone audio files.

Target format: VOX

VOX is a raw audio format most commonly associated with Dialogic ADPCM audio. It is typically used in telephony, voice recording, voicemail systems, and other speech-focused applications where small file size matters more than high fidelity. VOX is usually mono and optimized for voice rather than music or surround sound. Its main advantages are compact size and compatibility with certain legacy voice-processing tools.

How to perform the conversion

The most practical way to convert AC3 to VOX is with FFmpeg, because it can decode AC3 and encode VOX-compatible audio in one step. Since VOX is generally intended for speech, you should usually convert the audio to mono and a lower sample rate before saving it.

1. Install FFmpeg on your computer if it is not already available.
2. Open a terminal or command prompt in the folder containing your AC3 file.
3. Run a command such as ffmpeg -i input.ac3 -ac 1 -ar 8000 output.vox.
4. If your AC3 audio is inside a video file, use the video filename instead, for example ffmpeg -i input.mkv -vn -ac 1 -ar 8000 output.vox.
5. Check the resulting VOX file in the software that will use it, because some VOX workflows expect specific sample rates or ADPCM variants.

If you prefer a graphical workflow, you can also use desktop audio tools that support FFmpeg-based export or conversion. In many cases, the simplest option is to convert the file on 101convert.com for free, without installing any software.

Quality, compatibility, and limitations

This conversion is usually lossy and may reduce audio quality significantly, especially if the source AC3 file contains music or surround sound. Because VOX is mainly a voice format, multichannel AC3 audio will be collapsed to mono, and much of the original detail will be lost. For best results, use this conversion only when the destination system specifically requires VOX.

Compatibility can also vary because VOX is a somewhat specialized format. Some applications expect a particular ADPCM encoding, sample rate, or headerless raw data layout. If the output does not play correctly, try adjusting the sample rate or confirming the exact VOX variant required by the target device or software.