Free online AUD to AAC converter

Older Westwood Studios games store sound effects, speech, and music in AUD files that current players and editors often cannot open. Converting them to AAC provides a smaller file for playback, sharing, or use in software that supports modern AAC audio.

What the AUD format is

In audio conversion, AUD usually refers to a proprietary compressed format developed by Westwood Studios for games such as Command & Conquer, Red Alert, and Lands of Lore. AUD files commonly contain mono, low-sample-rate, 8-bit game audio, although the exact properties depend on the game and the AUD compression variant.

You may find AUD files in game directories, archive files, or extracted resource packages. Standard media players and many audio editors do not recognize them because AUD is a legacy game-audio format rather than a general-purpose recording format. The file extension alone does not identify every technical variant, so a decoder may support some AUD files but not others.

What the AAC format is

AAC means Advanced Audio Coding. It is a lossy audio codec supported by phones, browsers, media players, video editors, and many streaming systems. At comparable bitrates, AAC generally preserves more audible detail than MP3, making it suitable for compact speech, effects, and music files.

A raw AAC file normally uses the .aac extension and contains AAC frames with an ADTS header. AAC can also be stored in an MP4 container, commonly using the .m4a extension. Use raw .aac when the destination specifically requests an AAC stream; use .m4a when the destination expects a container or needs broader metadata and player compatibility.

Convert with 101convert.com

1. Open the AUD-to-AAC converter on 101convert.com.
2. Select or drop the .aud file.
3. Choose AAC as the output format and start the conversion.
4. Download the resulting file when processing finishes.

This option is free and requires no installed software. It can convert only AUD variants supported by the service; an unknown-format or failed-decoding message usually indicates an unsupported variant or damaged source file.

Convert with FFmpeg

Recent FFmpeg builds can decode some Westwood AUD variants directly. To create a raw AAC file with an ADTS header, run:

ffmpeg -i "input.aud" -c:a aac -b:a 128k -f adts "output.aac"

Choose a bitrate that matches the source. Around 96 kbps is generally adequate for mono game speech; 128–192 kbps is more suitable for music or stereo effects. A higher bitrate cannot restore detail that the AUD source already discarded.

To create AAC inside an MP4 container instead, omit the ADTS output format and use an .m4a filename:

ffmpeg -i "input.aud" -c:a aac -b:a 128k "output.m4a"

If FFmpeg reports an unknown input format or cannot decode the stream, extract the audio to WAV with a compatible Westwood resource tool, such as XCC Mixer, and encode the WAV:

ffmpeg -i "extracted.wav" -c:a aac -b:a 128k -f adts "output.aac"

When using a desktop audio editor, first confirm that it can import the AUD variant. Export to AAC or M4A only after successful decoding; installing an FFmpeg component may add import and export support, but it does not guarantee support for every Westwood AUD variant.

Quality and compatibility limits

AUD audio is often already compressed and may have a low sample rate, limited bit depth, and a single channel. Encoding it as AAC adds another lossy compression step, so it cannot recover missing detail. Keep the original AUD file and, when available, an extracted WAV for archival use.

Retain the source channel layout and sample rate unless the destination requires different settings. Converting low-quality mono speech to stereo or increasing its sample rate increases the file size without adding information.

Test the result in the application that will use it. If that application rejects raw .aac, create an AAC-in-MP4 .m4a file instead. If only certain files fail, the cause is more likely an unsupported AUD variant or damaged game resource than the filename extension.