Free online AUD to M4A converter

What the AUD format is

In the Audio category, AUD usually means the Westwood Studios compressed audio format. It was used by games such as Command & Conquer, Red Alert, and related Westwood titles for music, speech, and sound effects. You may encounter AUD files in extracted game directories, archival collections, or old game-mod projects.

AUD is not a general-purpose audio container like M4A. Its codec and file structure are associated with Westwood's game audio system, so many ordinary media players do not recognize it.

What the M4A format is

M4A is an MPEG-4 audio container commonly containing AAC audio, although it can also contain lossless ALAC audio. AAC M4A files offer broad support on phones, computers, browsers, and media players while usually taking less space than uncompressed WAV files.

Use M4A for normal playback, editing in software that supports AAC, sending audio to modern devices, or storing compressed copies. Choose ALAC only when lossless preservation is required and the receiving software supports it.

How to convert AUD to M4A

You can convert the file on the 101convert.com website for free without installing software. Upload the AUD file, select M4A as the output format, start the conversion, and download the resulting file when processing finishes.

For desktop conversion, use a recent FFmpeg build with Westwood AUD demuxer and decoder support:

1. Install FFmpeg from a trusted package source and place the AUD file in an accessible folder.
2. Open a terminal or Command Prompt in that folder.
3. Run ffmpeg -i "input.aud" -c:a aac -b:a 192k "output.m4a".
4. Play output.m4a and check its duration, channel layout, and audible content.

Use a different AAC bitrate when needed: -b:a 128k creates a smaller file, while -b:a 256k retains more detail but produces a larger file. If the FFmpeg build cannot decode the file, extract or convert the AUD to WAV with a Westwood-aware utility such as XCC Mixer, then run ffmpeg -i "input.wav" -c:a aac -b:a 192k "output.m4a".

Quality and compatibility limitations

Most AUD files already use lossy compression, so converting them to AAC is a second lossy encoding step. Keep the original AUD and, if possible, a decoded WAV archive; do not expect a high AAC bitrate to restore detail discarded by the AUD codec.

Do not rename .aud to .m4a; the internal container and codec data remain unchanged. If FFmpeg reports an invalid or unknown format, verify that the file is a Westwood audio file rather than another application-specific AUD variant. M4A compatibility is broad, but some older players accept AAC M4A and reject ALAC or unusual MPEG-4 metadata.