Free online BONK to OPUS converter

What the BONK format is

BONK is the audio format used by BonkEnc, an older open-source CD-ripping and audio-encoding program; its successor, fre:ac, may also encounter or support BONK depending on the version and build. BONK files contain compressed audio and are most commonly found in older personal music archives or projects created with BonkEnc. They are not the same format as Ogg, MP3, or Opus, so applications that support only standard modern audio codecs may reject a .bonk file.

What the OPUS format is

Opus is a lossy audio codec normally stored in an Ogg container with the .opus extension. It is designed for both speech and music, supports low latency, and provides good quality at relatively small bitrates. Opus is suitable for web playback, voice recordings, messaging, streaming, and storage where file size matters, but it is not an ideal archival target because encoding discards audio information.

How to convert BONK to OPUS

Using BonkEnc or fre:ac and FFmpeg

1. Open the .bonk file in BonkEnc or a fre:ac version that supports BONK input.
2. Choose WAV as the output format through File → Convert or the program's equivalent output-format settings. Use the original sample rate and channel layout when those options are available.
3. Install FFmpeg and convert the resulting WAV file with:

   ffmpeg -i input.wav -c:a libopus -b:a 128k output.opus

4. Use a lower bitrate for speech, such as 64k, or a higher bitrate for music, such as 160k to 192k. The output filename must end in .opus.

Some FFmpeg builds include a BONK decoder and can perform the conversion directly:

ffmpeg -i input.bonk -c:a libopus -b:a 128k output.opus

If FFmpeg reports that the input format or codec is unsupported, decode the file to WAV with BonkEnc or fre:ac first.

Using the online converter

You can also convert the file for free on 101convert.com without installing software: select BONK as the input format, upload the .bonk file, choose OPUS, start the conversion, and download the generated .opus file. Do not upload recordings containing confidential or sensitive material unless the service's handling policy is acceptable for that data.

Quality and compatibility limitations

The conversion is normally a decode-and-re-encode process. If the BONK source is already lossy, encoding it again as Opus can add artifacts; converting to WAV first avoids an additional loss before the Opus encoder but cannot restore information discarded by the original BONK encoding.

Opus support is common in current browsers, media players, and communication software, but some older hardware players and editing applications recognize only WAV, MP3, or AAC. Check the target application's supported container and codec, not just whether it accepts an .opus filename. For archival preservation, retain the original BONK file and use Opus as a playback or distribution copy.