Free online AUD to OPUS converter

A Command & Conquer or Red Alert game asset may be stored as an AUD file, while modern browsers, media players, and messaging software more commonly accept Opus. Converting it produces a compact, broadly supported audio file for playback or sharing without the original game tools.

What the AUD format is

In the Audio category, AUD usually refers to the compressed audio format used by Westwood Studios games, including Command & Conquer, Red Alert, and related titles. Game archives store speech, music, and sound effects as individual .aud resources.

Westwood AUD is a game-oriented format rather than a general-purpose delivery format. Files commonly contain low-rate mono audio and use Westwood compression or an IMA ADPCM-derived method. The .aud extension is not a universal audio standard, so a file from another application may require a different decoder.

What the OPUS format is

Opus is a lossy audio codec normally stored in an Ogg container and distributed with the .opus extension. It supports speech and music efficiently, handles low and high bitrates, and is supported by current web browsers, VLC, Firefox, Chrome, Android, and many communication applications.

Opus is useful when the converted file must be small or streamable. Bitrates around 64k are suitable for speech, while 96k to 128k generally preserves more detail in music and complex game audio.

How to actually convert AUD to OPUS

FFmpeg is the most direct desktop method when the installed build includes the Westwood AUD demuxer:

1. Install a current FFmpeg build and place the AUD file in an accessible folder.
2. Run ffmpeg -i input.aud -c:a libopus -b:a 96k output.opus.
3. Replace input.aud with the source filename and adjust 96k to 64k for speech or 128k for music.
4. Check the result with ffprobe output.opus or open it in a player that supports Ogg Opus.

If FFmpeg reports an unknown input format, use XCC Mixer, a Windows utility for Westwood game archives and resources. Open the AUD resource in XCC Mixer, export or convert it to WAV, then encode the WAV with ffmpeg -i extracted.wav -c:a libopus -b:a 96k output.opus. This two-stage method separates AUD decoding from Opus encoding and is useful for older or variant game files.

You can also convert the file for free on 101convert.com without installing software, provided the converter recognizes that particular AUD variant.

Quality and compatibility limitations

Opus encoding cannot restore detail already removed by AUD compression. Converting directly to Opus avoids an unnecessary intermediate lossy format; exporting to WAV first does not improve the source, but it provides a compatible intermediate when direct decoding fails.

Keep the original AUD file if archival recovery matters. Some AUD files are extremely short game effects, use unusual sample rates, or depend on metadata from the game archive; a generic converter may decode the audio but not preserve those original asset relationships.