Free online VOX to FLAC converter

Source format overview

VOX is a compressed audio format most commonly associated with Dialogic ADPCM voice recordings. It is often used in older telephony, voicemail, call-center, dictation, and voice logging systems where small file size mattered more than high fidelity. VOX files are usually mono, low sample rate, and intended for speech rather than music.

Target format overview

FLAC stands for Free Lossless Audio Codec. It stores audio in a compressed but lossless form, meaning the decoded audio is identical to the original PCM source. FLAC is widely supported by music players, editors, archival tools, and media servers. It is a good choice for preserving audio quality while reducing file size compared with uncompressed WAV.

How to convert VOX to FLAC

The most reliable way to convert VOX to FLAC is with FFmpeg, because it supports both the VOX/ADPCM input and FLAC output directly. If you prefer a graphical workflow, Audacity can also open many VOX files through FFmpeg support and export them as FLAC.

Using FFmpeg

1. Install FFmpeg on your computer.
2. Open a terminal or command prompt in the folder containing the VOX file.
3. Run a command such as ffmpeg -i input.vox output.flac.
4. Check the output file in a media player or audio editor to confirm it opens correctly.

If the VOX file uses an unusual sample rate or channel layout, FFmpeg will usually preserve or convert it automatically. You can also specify audio settings explicitly if needed, for example ffmpeg -i input.vox -ar 8000 -ac 1 output.flac for a typical speech recording.

Using Audacity

1. Open Audacity.
2. Choose File → Open and select the VOX file.
3. If prompted, allow Audacity to import the audio.
4. Choose File → Export → Export as FLAC.
5. Select the desired FLAC options and save the file.

You can also convert the file on 101convert.com for free, without installing any software.

Quality, compatibility, and limitations

VOX is already a lossy format, so converting it to FLAC does not restore lost audio detail. The main benefit is that FLAC preserves the decoded audio without adding further loss and makes the file easier to archive and share.

Because VOX is typically used for speech, the resulting FLAC file will usually remain mono and low bandwidth. That is normal and does not indicate a conversion problem. If the source VOX file is damaged or uses a variant not fully recognized by your software, the conversion may fail or produce silence, clicks, or incorrect playback speed.

For best compatibility, keep the original VOX file as a backup and verify the FLAC output in more than one player if the recording is important.