Free online CAF to AU converter

CAF and AU are both audio file formats, but they come from different ecosystems. CAF (Core Audio Format) is an Apple-developed container designed for flexible, high-quality audio storage, while AU (Sun/NeXT Audio) is an older audio format commonly associated with Unix-based systems and simple PCM or compressed audio data.

What is CAF

CAF is a modern audio container that supports large files, multiple channels, and a wide range of sample rates and codecs. It is often used in Apple software and professional audio workflows because it can store long recordings without the limitations of older formats.

What is AU

AU is a straightforward audio format originally used on Sun and NeXT systems. It is widely recognized by many audio tools and is often used for basic sound clips, especially in legacy or cross-platform environments.

Why convert CAF to AU

Converting CAF to AU is useful when you need broader compatibility with older software, Unix-based tools, or systems that prefer the AU format. Since AU is simpler and more widely supported in some technical environments, it can be a practical target for distribution or testing.

Best software for conversion

The best choice for CAF to AU conversion is FFmpeg, because it is free, reliable, and supports a very wide range of audio formats. It works on Windows, macOS, and Linux, and is ideal for batch conversion and automation.

Example command: ffmpeg -i input.caf output.au

Other good options include Audacity for manual conversion and VLC media player for simple format export in some cases.

How to convert

To convert CAF to AU with FFmpeg, open a terminal or command prompt and run the conversion command. If the source audio uses an unsupported codec, you may need to re-encode it to a compatible AU-supported format such as PCM.

In Audacity, you can open the CAF file and then use File → Export → Export Audio to save it as AU if the AU export option is available in your version.

Things to check before conversion

Audio codec compatibility is important because not every codec inside CAF can be written directly into AU. If needed, convert to uncompressed PCM for best compatibility.

Sample rate, bit depth, and channel count should also be checked, since some AU readers may have limitations compared with CAF.

Summary

CAF to AU conversion is mainly about improving compatibility with older or simpler audio systems. For the most dependable results, use FFmpeg; for a graphical workflow, use Audacity.